Horse state part B - surgery & orthopaedics

Equine surgery and orthopaedics

1. Principles and indications of local anaesthesia.

Local anaesthesia = numbing an area of the body using medications called local anaesthetics.

• Gives temporary loss of sensation and pain.

• Used for surgical procedures and diagnostic conclusion.

• Reduces the required amount of anaesthetic agent and allows complicated procedures to be performed on a standing horse.

• Injected around the nerve at a site where the nerve is not covered by bone.

• Risks following this type of procedure, including epidural anaesthesia:

  • Ataxia of the hind limbs

  • Hind-limb motor blockage

  • Recumbence

  • Respiratory depression

Indications ✅

• Surgical procedures: removal of teeth, laparoscopy and wound management.

• Lameness diagnostics: pain blocking using peripheral nerve blocks, intraarticular and intrabursal injections, and ring blocks.

Contraindications ❌

• Fracture confirmation

• Septic inflammation, including:

  • Periarticular cellulitis

  • Hoof abscesses

Regional anaesthesia

Regional anaesthesia can be used to localize the area of pain:

➡ Apply local anaesthesia and register any improvement in lameness after 15 minutes.

Start with a palmar digital nerve block and go upwards on the leg if there is no improvement.

Regional anaesthesia is divided into two main regions:

1. Head

2. Limbs

Forelimb nerve blocks 🐴

• Palmar digital nerve (PDN) block – “heel block”

• Semi-ring block at the pastern

• Abaxial sesamoid nerve block – basisesamoid nerve block

• Low 4-point block – low palmar nerve block

• High 4-point block – high palmar nerve block

• Lateral palmar nerve block

Hindlimb nerve blocks 🐴

• Plantar digital nerve block – as in the forelimb

• Abaxial sesamoid nerve block – as in the forelimb

• Low 6-point nerve block – low plantar nerve block

• High 6-point nerve block – high plantar nerve block

• Tibial nerve block

Head nerve blocks 🐴

• Maxillary nerve block

• Infraorbital nerve block

• Mandibular nerve block – inferior alveolar nerve block

• Mental nerve block

• Auricopalpebral nerve block

• Diamond block – supraorbital, lacrimal, zygomatic and infratrochlear nerve blocks

• Retrobulbar nerve block – muscles of the eye

Epidural anaesthesia

⚠ Epidural anaesthesia is injected into the epidural space, not the subarachnoid space. Injection into the subarachnoid space is called intrathecal or spinal anaesthesia.

• Used in a standing horse.

• Analgesics should be warmed to body temperature before injection into the spine.

Indications

Analgesia or anaesthesia of the perineal area, including:

• Perineum

• Rectovestibular laceration repair

• Surgeries involving the rectum

• Anus

• Tail

• Urethra, Bladder, Vulva, Vestibule, Vagina

• Relaxation of abdominal contractions in dystocia

Location

• Between the 1st and 2nd coccygeal vertebrae

• Or the lumbosacral space

⚠ It is forbidden to use proximal epidural anaesthesia in horses because it may cause severe hindlimb motor blockade, ataxia and recumbence.

Drugs

Adjust the dose to prevent ataxia and recumbence because the horse is in a standing position!

• Local anaesthetics: lidocaine, mepivacaine

• Alpha-2 agonists: xylazine, detomidine

• Opioids: morphine, methadone, hydromorphone

• Tramadol: analgesia

• Ketamine: analgesia and systemic effects

Types of local anaesthesia 💉

• Superficial, Infiltration, Perineural, Local perfusion

• Intrasynovial:

  • Intraarticular

  • Intrabursal

• Intrathecal

Local anaesthetic drugs and duration ⏱

Drug	Onset of effect	Duration
Procaine	5–10 min	—
Lidocaine	5 min	30–60 min
Mepivacaine	10 min	60–120 min
Bupivacaine	30 min	120–140 min
Etidocaine	3–5 min	5–10 hours
Proparacaine	<1 min	5–25 min

Equine sedation and incomplete general anesthesia

Sedation = the depression of a patient's awareness to the environment and reduction of its responsiveness to external stimulation.

Sedatives and tranquilizers are commonly used in combinations as pre-anesthetics before general anesthesia to relax and sedate the animal. Some sedatives also provide analgesia.

💊 Drugs

Alpha2-adrenergic agonists

• Xylazine, detomidine, medetomidine, romifidine → sedation + analgesia

• Can be used alone or in combination with opioids.

• Induce bradycardia, decreased CO, hyperglycemia.

• Xylazine: lasts about 15–20 min. Dose: 1.1 mg/kg.

• Detomidine: lasts about 30–60 min.

Phenothiazines

• Acepromazine → sedative, mild tranquilizing, often in combo with alpha2 agonist or opioid, anti-arrhythmic, vasodilation.

Opioids

• Butorphanol, morphine, buprenorphine, meperidine

• Analgesic → always in combo with sedative.

Benzodiazepines

• Diazepam, midazolam → sedative, muscle-relaxing.

• Induce ataxia → not used in standing procedures.

• Foals

⭐ Common sedation in horse: Detomidine + butorphanol (domosedan og tourbugesic IV, 0,1ml av hver per 100kg - pappa)
→ Just know that you combine an alpha2 agonist + opioid.

🐴 Standing sedation

Necessary for a variety of surgical and non-surgical procedures in the standing horse.

Common drug combination for 500–600 kg horse:
💉 Detomidine (0.5 ml) + butorphanol (1 ml)

Benefits:

• Smoother recovery than GA.

• Sometimes cheaper than GA.

• Simpler to do standing sedation in some procedures, like laryngoplasty, dental procedures.

• In head surgeries (a lot of bleeding) → less bleeding in standing position than recumbence.

• Decreased risk for horse compared to general anesthesia, but more risk for staff.

Indications:
- Dental procedures, stomatology
- Diagnostic imaging

- Sinus surgeries
- Urogenital
- Orthopedic
- Wound assessment
- Castration

🐴 Sedation of adult horse

Short-term sedation is achieved by administering a bolus of an alpha2 agonist, with or without an opioid.

When used in combo with an opioid:

1⃣ Alpha2 agonist FIRST → 2⃣ Opioid

The horse must first be sedated with the alpha2 agonist prior to opioid to avoid opioid-induced excitement.

A combo of opioid + alpha2 agonist is only done when:

• Heavy sedation is required.

• Additional analgesia is required.

🐴 Sedation and anaesthesia in foals

Sedation and anesthesia may be required in foal to allow diagnostic and therapeutic procedures.

Differences in foals compared to adult horses:

• ❤ Circulatory system (transition from in-utero to newborn)

• 💊 Metabolism of drugs

• 🌡 Susceptibility to hypothermia and hypoglycemia

❌ Avoid:

• Drugs that lower heart rate → xylazine, detomidine

• Drugs that decrease preload → acepromazine
  → May produce diminished cardiac output and tissue perfusion.

• Premedication if using gases.

• Halothane.

Sedation of foals:

Neonatal foals become recumbent when sedated, and the foal should be supported until it assumes recumbence.

Alpha2 agonist

• Given to healthy foals, minimum dose.

• Older foals are sedated as adult, but with higher dose.

Benzodiazepines – diazepam and midazolam

• Slow administration.

• Ataxia may prolong.

• Don’t repeat dose or give high dose.

• Not analgesic.

💉 Benzodiazepines + ketamine

• Combined for painful procedures.

• Light anesthesia.

• Diazepam/midazolam + ketamine

• Diazepam commonly used for sedation in foals because it provides tranquilization and muscle relaxation with relatively little cardiovascular depression, and is commonly combined with ketamine for induction of GA

Equine general anesthesia

General anaesthesia = controlled and reversible CNS-depression.

It gives:

• 💊 Analgesia

• 🧠 Amnesia

• 🛑 Immobility

• 😴 Unconsciousness

• 💪 Muscle relaxation

📋 Patient preparation

• Obtain medical history.

• Pre-anesthetic clinical exam, with focus on cardiovascular and respiratory system.

• Conditions affecting recovery or induction should be considered and implementing plans for assisting → like musculoskeletal injuries or neurological diseases.

• 🌾 No hay 12 hours before anesthesia.

• Mouth should be flushed to remove debris.

• 💉 A jugular catheter should be placed if GA is intended or prolonged sedation.

• 💧 Preoperatory stabilization of cardiovascular system with IV fluids is necessary for horses undergoing emergency surgery.

• ⚠ Horses must be sedated before induction of any anesthesia → cause excitement in horse without sedative premedication.

Why sedation before induction?

Sedation:

• Improves ease of handling

• Makes induction safer

• Decreases dose of induction

• Decreases dose of maintenance drugs

• Provides analgesia

• Improves quality of recovery by prolonging the time until the first attempt to stand

➡ Sedate with alpha2 agonist / Xylazine → wait 3–5 minutes after apparent effect of sedation before induction of anaesthesia.

💉 Total Intravenous Anesthesia – TIVA

TIVA = the use of intravenous agents for induction and maintenance of anesthesia, by the injection of a liquid anesthetic in a vein and by catheterization of vein (infusion anaesthesia).

✂ Procedures

• Castration

• Cryptorchidectomy

• Crib biting

• Ovariectomy

• Wound management

• Orthopedic → lag screw, implant removal

💊 Induction regimes

⚠ Always first sedate with alpha2 agonist → then induction agent

Induction agents:

• Ketamine

• Ketamine + diazepam

• Ketamine + guaifenesin → muscle relaxant, analgesic

• Thiopental

• Propofol

⏱ Prolongation of anesthesia with injectable drugs:

Short periods:
➡ Bolus of xylazine + ketamine

Prolonged period:
➡ Thiopental + alpha2 agonist

⭐ Importance of TIVA

TIVA is frequently used in horses.

It’s cheaper than standing anesthesia and many procedures can be performed.

TIVA provides:

• Smooth, excitement-free induction phase

• Slow lowering of the body into sternal or lateral recumbence

• Minimal cardio-pulmonary depression

• Calm recovery period

• Minimal ataxia

😷 Inhalation anaesthesia

Most common method of maintaining anesthesia in the hospital setting.

• Requires strict monitoring and a professional anesthesiologist

• Expensive and time consuming

• Used for surgeries >1 h

🏥 Equipment

• Endotracheal intubation

• Anesthetic machine

• Recovery box → soft covering, dark and quiet room

➡ Induction starts with injectable → then maintenance with gas.

💨 Gases

• Isoflurane

• Sevoflurane

• Desflurane

High oxygen flow rate should be used during the first 10–15 min of anesthesia to carry the inhalation anesthetic into the circuit and thereby into the horse.

Flow rates:

• First 15 min → 20 ml/kg/min

• Remainder → 10 ml/kg/min

• Foals → 40–60 ml/kg/min

✅ Pros

• Minimal drug accumulation

• Good monitoring

❌ Cons

• Cardiovascular decrease

• No analgesia

• Too rapid recovery

⚠ Recovery from iso and sevo is fast and sometimes uncontrolled.

➡ Sedation decreases speed of recovery.

📊 Monitoring

❤ Heart rate: 28–44 bpm

• Bradycardia → atropine to increase HR

🌡 Body temperature: 37.5–38°C

🫁 Respiratory rate: >4 breaths/min

🩸 Blood pressure: 120/70 mmHg

• Hypotension → dopamine increases BP

🩸 Direct arterial blood gas

• O₂

• CO₂

💨 Capnography

• CO₂ in expired air

❤ ECG

• Heart’s electrical activity

🫁 Pulse oximetry

• Measures oxygen level of blood

• Attached on tongue

🚽 Urinary catheter

• If procedure is >1 hour

• Prevents over-distention of the bladder

⚠ Risks associated with equine anaesthesia

Horse can be dangerous to itself and the veterinarians during excitation stage.

1⃣ Complications at induction

• Intracarotid injection

• Administration of incorrect drug

• Haematoma formation

• Perivascular injections

2⃣ Intraoperative complications

🫁 Hypoxaemia

• Common in all recumbent adult, full-sized horses

🩸 Hypotension

• Higher risk in injectable anaesthetics

• Mean arterial pressure should be >70 mmHg

💨 Hypercapnia

• PaCO₂ >45

• Due to depressant effects of anaesthetic drugs on respiratory function

3⃣ Post-operative complications

1.💪 Myopathy

Dorsal recumbency: gluteal and longissimus dorsi muscles are most likely to be affected due to inadequate circulation.

Prevention:

• Careful positioning

• Adequate padding

• Short operating time

• Maintain BP

2.🦴 Long bone fractures

• Higher after colic surgeries

3.Neuropathy

• Most commonly seen on peripheral nerves, e.g. radial nerve

• Ischemic in origin

🏥 Complications during hospitalization period

• 🩸 Shock

• ☠ Endotoxaemia → fluid + electrolytes are important

• 🐴 Postoperative Ileus (POI)

• 🤕 Colic → some horses suffer from one or more episodes of colic after colic surgery

• 🩹 Wound complications

• Adhesions

• 🩸 Thrombophlebitis

• 🦶 Laminitis → after acute abdomen

• 💩 Postoperative diarrhoea

• 🦠 Septic peritonitis → contamination of ingesta in peritoneal cavity
  → Atb, NSAIDs and hydration!

Equine wounds

Wound = a sudden and violent disturbance of soft tissue connections with simultaneous skin and mucosal damage due to mechanical, physical or chemical factors.

Types of wounds

Open wounds:

• Incisions, Lacerations, Puncture

Closed wounds:

• Abrasion, Contusion, Burn

🔍 Wound Assessment

🐴 General assessment

• General state

• History

• 💉 Important to know tetanus vaccination status!

🔎 Initial assessment

• Influence of healing

• Severity involving structures:

  • Nerves, Blood vessels

  • Ligaments, Bones, Joints

• Degree of contamination

⚠ Factors inhibiting healing:

• Infection, Contamination, Necrosis

• Movement

• Loss of blood supply, Hypoxia

• Loss of tissue, Tumors

• Habronemiasis

• Phytosis

🩹 Methods of Wound Management

1⃣ Primary closure/healing (First intention healing)

• Union of tissue

• Minimal granulation tissue

• Clean and non-infected

• Sutured during golden period = 6–8 h

2⃣ Secondary intention healing

• Left unsutured

• Heals via contraction + epithelialization

• Done with wounds that:

  • Have lost tissue

  • Are infected

3⃣ Delayed primary closure

• Apposition after golden period

• Before granulation tissue → 4–5 d

• Sutured when ready for primary closure

4⃣ Delayed secondary closure

• Closure after granulation tissue formation

5⃣ Grafting

• Used in wounds that are too large to heal or cannot be sutured

🚑 Initial Wound Treatment

🎯 Goal: Decontaminate the wound as much as possible and prevent further contamination.

• 💧 Flush/lavage with saline

• ✂ Sharp debridement of gross contaminants

• 💊 Local antiseptics or ATBs packed into wound to prevent further contamination

• 🦴 Limb immobilization according to injury

• 🩸 Pressure bandage applied directly over bleeding area to control hemorrhages

🔄 Stages of Wound Healing

1⃣ Inflammatory phase

⏱ 2–3 days after wounding

• Increased permeability

• Fibrin clot formation

• Neutrophiles

⬇

2⃣ Debridement phase (lag phase)

⏱ Within 6–8 hours of injury

• Macrophages move into wound

• Remove debris

• Induce fibroblasts and cytokines

• Stimulate fibroplasia + angiogenesis

⬇

3⃣ Repair phase (fibroblastic/proliferative phase)

• Formation of granulation tissue

⬇

4⃣ Remodelling/maturation phase

⏱ Begins 2 weeks after wounding → 6–12 months later

• Formation of scar

🧠 Remember:
Inflammation → Debridement → Repair → Remodelling

🧼 Wound Preparation

1⃣ First treatment – Active immunization

💉 TAT = immunoserum tetanus

• Dosage: 4000–6000 IU (13–20 ml)

2⃣ Anaesthesia / sedation

3⃣ Preparation of wound environment

• Shave the area

• Clean wound with antiseptic soap

4⃣ Surgical debridement

🩸 Living tissue bleeds → dead tissue does not bleed

Can be done:

• Mechanically

• Dakin's solution → less discomfort

Mechanically:

• Cut new edges for wound

• Excise grossly non-viable or damaged skin with scalpel

⚠ If wound contains devitalized tissue or debris → wound should be left open:

• Secondary intention healing OR

• Delayed primary closure

5⃣ Lavage (flushing) of wound

💧 Sterile saline or electrolyte solution

Application under pressure:

• Betadine

• Chlorhexidine
  → antimicrobial activity

6⃣ Wound revision

• Palpation and control of wound for foreign objects

• Sterile gloves and probes

• X-ray examination?

• Bandaging

• Corticosteroid ointment?

• Honey?

🩹 Wound Dressings

Wounds on dorsal and palmar surface of fetlock, tendons and ligaments
➡ Fixation bandage (cast)

Functions of wound protection/bandaging

• 🛡 Protective

• 💧 Absorption

• 🩸 Compression

• 🦴 Stabilizing

🧻 Wound Covering

Types

• Biological → skin grafts

• Synthetic → semi-permeable, impermeable or permeable

1⃣ Underlying materials

• Bandage cotton wool / padding

2⃣ Bandage

• Elastic flexible cohesive bandage

• Plaster padding

• Cast

3⃣ Cast – fixation bandage

• Cast bandage embedded in polyurethane resin

• Hard and solid after 20–30 minutes

• ⭐ Radiolucent! Important for X-ray controls

🧩 Skin Transplant

Used for wounds that are healing unsatisfactory or not at all.

Preparation

• Clip

• Shave

• Disinfection

• ATB ointments + bandage for 3 days

💉 Sedation / anaesthesia

• Butorphanol

• Detomidine

• TIVA

Types

• Pinch grafting

• Punch grafting

• Meshing grafts

• Full-thickness sheet grafting

📍 Donor sites

• Ventrolateral part of abdomen

• Lateral shoulder area

• Cranial area of chest

• Side parts of neck

💧 Wound Drainage

Deep wounds → dead space → accumulation of secretion → bacterial growth → disturbed healing process

Types of drains

Passive:

• Penrose

• Tubular

Active:

• Closed suction systems

• Open suction systems

5. Second Intention Healing Wounds in Horses

Second intention healing = wounds left un-sutured to heal by second intention.

Indications:

Wounds that

• Have lost tissue

• Are infected

• Are susceptible to infection

🔄 Two mechanisms of healing

1. Contraction

2. Epithelization

➡ Both dependent on formation of granulation tissue.

🧼 Treatment

• 💧 Decontaminate/flush wound by lavage saline solution

• ✂ Debridement:

  • Mechanically → cut new edges or scrape off dead tissue

  • Dakin's solution → less discomfort

• 🧩 Skin grafting if needed

• 🍯 Apply topical ointment → Manuka honey (also aid in debride)

• 💊 Topical ATB → silver sulfadiazine

• 💧 Wet dressing with antiseptic → moisture + low pH

• 🩹 Bandage or cast

• 💊 NSAIDs

🔄 Stages of Second Intention Healing

1⃣ Wound Expansion

• Right after a wound is made, the wound enlarges from retraction of the surrounding skin.

• Wounds on the distal limb of horses may expand for 11–13 days before contraction begins.

⬇

2⃣ Granulation Tissue Formation

⏱ Appears 3–6 days after injury.

Granulation tissue provides:

• 🧱 Surface for migration of epithelial cells

• 🦠 Barrier for infection

• 🔄 Myofibroblasts for contraction

• 🧬 Fibroblasts for collagen formation

⚠ There is more granulation tissue in leg wounds VS other places on the body, because of the blood supply and lack of muscles on legs.

Factors promoting formation:

• Larger body size

• 📍 Location → distal portion of limbs, mobile areas

• 🌡 Environment → moisture, warmth, low pH, low O₂ tension

• 🍯 Topical medication → honey, scarlet oil

⬇

3⃣ Epithelization

Epithelialization = the first signs of reparation.

• Formed from the edges of the wound

• Migrating epithelium moves beneath the clot that covers the wound

• Can be seen at about 2 weeks after wounding

• More prominent in distal part because of big skin tension

Factors increasing rate

• 🔥 Heat

• 🫁 Increased tissue oxygenation

• Hyperbaric oxygen therapy

• 💧 Moisture

• 💊 Topical medication

➡ Therefore use:

• 🩹 Bandaging or casting

• 💧 Wet dressing

• 💊 Silver sulfadiazine

Factors decreasing rate:

• 🦠 Infection

• Necrotic tissue

• Exuberant granulation tissue

• Glucocorticoids

• Changing bandage too often

⬇

4⃣ Contraction Phase

Contraction = wound closure by active shrinking/reduction of the wound, by pulling the surrounding tissue centripetally.

• Contraction begins after the lag phase

• ⚠ Wounds distal to the carpus and hock are not capable of significant contraction

Factors inhibiting contraction:

• Hypovolemic anemia

• Hypoalbumin

🧠 Remember the order:

1⃣ Expansion → 2⃣ Granulation → 3⃣ Epithelization → 4⃣ Contraction

EXPAND → FILL → COVER → SHRINK

Equine hernias

Hernia = a protrusion of an organ, or part of it, through a defect in the wall of the anatomical cavity in which it normally resides.

Most are reducible, but in some cases the contents of the hernia cannot be returned to their normal location due to:

• Incarceration

• Strangulation

• Adhesions

📚 Classification

🔹 Origin

• Congenital or Acquired

🔹 Direct vs. indirect

• Direct hernia → occurs through a tear

• Indirect hernia → occurs through a natural passage (inguinal canal, umbilicus)

🔹 External vs. internal

External hernia → occurs through the body wall producing a visible and palpable swelling covered by skin.

Examples:

• Umbilical, Inguinal/scrotal

• Traumatic abdominal wall hernias, Ventral

• Incisional hernias

Internal hernia → within the abdominal cavity.

Examples:

• Epiploic foramen, Mesenteric, Diaphragmatic, Omentum, Mesocolon

• Gastrosplenic ligament, Hepatogastric ligament, Hepatoduodenal ligament

• Ductus deferens

⚠ Incarcerated vs. Strangulated

🟡 Incarcerated hernia

• Passage of ingesta through the protruding loop of intestine is arrested.

• Blood flow in its wall is maintained.

🔴 Strangulated hernia

• Both irreducible + incarcerated, AND blood circulation is also arrested ➡ Results in gangrene unless speedy relief is given.

🧠 Remember:
Incarcerated = contents blocked
Strangulated = contents + blood blocked

Umbilical Hernia

More common in fillies (young female horses) and may be hereditary.

Causes:

• Congenital: Present at birth, Failure of abdominal wall to close

• Acquired: Develop at 3–4 weeks of age, Excessive straining to defecate/urinate, Umbilical infection

Hernial sac comprises:

• Inner peritoneal layer

• Outer layer of skin

• Linked by connective tissue

May contain:

• Small intestine, Cecum, Omentum

⚠ Incarceration and strangulation of herniated intestine is rare!

🔍 Clinical signs

• Typical oval swelling in umbilical region

• Intestine or omentum inside

• Size varies

• Tense, painful swelling → irreducible

🔎 Diagnosis

Palpation of hernia:

• Can it be reduced/put back into abdomen?

• Check hernial ring → size, shape, rigidity

💊 Treatment

Conservative:

• Bandages, Metal clamps, Rubber rings

• Cheap but dangerous

⏳ Smart to wait with surgery until foal is 6–12 months old, because it can disappear by itself.

Surgical:

• GA and Dorsal recumbency

• Elliptical skin incision around hernia

• If no damage to hernial sac/intestine → can be returned to abdominal cavity, but chance of re-herniation

• Resection of hernial sac is the better option

• Suture ring with continuous suture pattern overlapping mattress

Inguinal Hernia

1⃣ Intravaginal (untrue scrotal) hernia in foals

Frequent problem in foals.

➡ Internal inguinal ring is very wide for passage of testes in scrotum up to 6 weeks of age.

➡ Small intestines can pass this ring and canal → enters vaginal process.

🔍 Clinical signs

• Asymmetric scrotum

• Possible to palpate testicles and distal intestine

🔎 Diagnosis

• USG → intravaginal dislocation of intestine

• Possible to reposition

💊 Treatment

• Reposition intestine until inguinal ring gets smaller

• Check every day

• Reposition if it falls back

• Check by palpation for signs of strangulation

➡ Often resolves spontaneously by 3–6 months old.

➡ Application of a truss/bandaging may hasten resolution.

2⃣ Intravaginal (untrue) hernia in adult stallions

Rare, but more dangerous due to narrow inguinal canal → may cause strangulation.

💊 Treatment

Conservative:

• Manual compression of vaginal process

Surgical:

• Laparotomy

• Closure of inguinal canal

• Resection

• Unilateral castration

3⃣ Extra-vaginal (true scrotal) hernia

➡ Rupture of vaginal process

➡ Intestine is in the cavum scroti + traumatisation of serosal surface.

🔍 Clinical signs

• Enlargement of scrotum

• Continuous enlargement

🔎 Diagnosis

• Subcutaneous localisation of intestine in scrotum

• Growing enlargement of scrotum

• Colic

🚨 Treatment

SURGERY IMMEDIATELY!!

• Bilateral castration

• Ligature of processus vaginalis

• Close external inguinal ring with suture

Ventral Hernia

Hernia coming through any part of the abdominal wall other than umbilicus or inguinal canal.

Causes

Mainly seen in mares after:

• Perforation of abdominal cavity from kicks

• Rupture of prepubic ligament

Traumatic:

• Kicks

• Collisions with blunt objects

• Halfway-jump over straddling gates

Incisional/postoperative:

• Improper closure of incision

• Tearing of sutures or sutured tissue

• Postoperative wound infection

🔎 Diagnosis

Signs of:

• Depression

• Abdominal discomfort

• Cessation of defecation → indicates intestinal obstruction

⚠ Important to differentiate from an abscess:

• Palpate swelling

• Rectal palpation

• Ultrasound

• Exploratory surgery

💊 Treatment

Surgery
➡ Reposition intestine → reconstruct and close abdominal wall.

🫁 Diaphragmatic Hernia

Can be:

• Congenital

• Acquired → fractured ribs, dystocia, trauma

🔍 Clinical signs

• 🚨 Violent intermittent colic

• 🫁 Respiratory distress

🔎 Diagnosis

• X-ray

• USG

• Absence of lung sounds

• Intestinal sounds in chest

• Sanguineous fluid in thoracocentesis

💊 Treatment

Surgical repair

• Primary technique OR Mesh technique

🧠 Quick Overview

🐴 Equine hernias

Umbilical → young foals → often resolves spontaneously

Inguinal – foal → intravaginal → intestine enters vaginal process → often resolves by 3–6 months

Inguinal – adult → intravaginal → strangulation risk → unilateral castration

Extra-vaginal → rupture of vaginal process → 🚨 immediate surgery + bilateral castration

Ventral → trauma/incision → reconstruct abdominal wall

Diaphragmatic → colic + respiratory distress → surgical repair

Stallion castration

Castration = surgical removal of the testis.

• Performed at any age

• Most commonly at 12–18 months old

📌 Indications

• Remove masculine behaviour and management problems

• Trauma, Testicular neoplasia, Inguinal herniation, Torsion of the spermatic cord

🔪 Procedure – Two Ways

1. Closed

➡ Amputate whole vaginal process

2. Open

➡ Incision through vaginal process (both layers)

🐴 Standing Castration

⭐ Preferred by Zert

For stallions up to 1 year old.

✅ Advantages

• Popular method, Easy, Quick

• Less assistance, Less space

• Avoid risk of recumbency and recovery

💉 Sedation

• Alpha2 agonist + opioid: Xylazine / detomidine + Butomidor

💉 Local anaesthesia

• 2% procaine

• S.C. incision

• 20 ml 2% procaine intratesticular

• 10 ml in spermatic cord

⚠ No need for suture material → cannot be done aseptically.

➡ Only use emasculator. Possible to ligate.

🔪 Surgical technique:

Scrotal incision
⬇
Opening processus vaginalis
⬇
Transection of lig. caudae epididymitis
⬇
Separation of mesochium
⬇
Sandy emasculator
⬇
❌ No suture!!
⬇
Secondary intention healing

⚠ Complications

• Aseptic

• Bleeding

• Evisceration of intestine

• Evisceration of omentum → inguinal hernia

Recumbent Castration

💉 Anaesthesia

• Xylazine, Ketamine, Diazepam

💉 Local anaesthesia

• Procaine: S.C., Intratesticular, Spermatic cord

CLOSED METHOD

With ligation of vessels + closing of abdominal cavity + wound closure

• Can be used in horses older than 1 year

• Safer method for bleeding

• Insurance cover

• Primary healing

• ❌ More expensive

• ❌ Retention of wound secretion

• Done in dorsal recumbency

3 Types of Closed Castration:

1. Uncovered

➡ One ligature on spermatic cord
+
➡ One ligature on vaginal process

2. Covered ⭐ Zert prefers this

➡ One ligature around spermatic cord + vaginal process

⚠ More dangerous as spermatic cord might slip into abdominal cavity and bleed

3. Castration from Regio inguinalis

➡ Resection of vaginal process

• Opening vaginal process

• Ligation of spermatic cord

• Suture of wall of vaginal process

• Suture of skin

OPEN METHOD

Without ligature

• Recumbent castration

• Without closure and ligation

• Done with emasculator or twisting

• ➡ Stops the bleeding

Spermatic cord can be:

• Uncovered

• Covered

🔧 Emasculators

• Sandy

• Henderson

🔄 Twisting method

Henderson method + Equitwister

➡ Castration by machine and torsion of testicle
➡ Torsion of whole proc. vaginalis
➡ Closure of abdominal cavity

🩹 Scrotal Healing

1⃣ Secondary intention healing – MOST COMMON

• Common to stretch the incision to help post-operative drainage

• Ensure excess fascia is trimmed

2⃣ Primary intention healing

• With absorbable sutures

• If performed under sterile conditions

• Requires adequate hemostasis

• ⬇ Decreases risk of post-operative complications

⚠ Complications

1.🩸 Haemorrhage

➡ Grasp and re-crush with emasculator for >30 mins

Usually due to:

• Improper tying before removal of emasculator

• Cord was too large

• Too hard exercise of horse before castration

2. Evisceration

➡ Prolapse of intestinal or omental contents

3.💧 Oedema

➡ Due to insufficient exercise

4.🦠 Septic funiculitis

➡ Infection of cord due to:

• Contaminated emasculator

• Ligature

5.🦠 Clostridial infection

➡ Tetanus

6.🦠 Septic peritonitis

7.⚠ Penile damage

➡ Uncommon

8.💧 Hydrocoele

➡ Idiopathic, painless, fluid-filled enlargement

9.🐴 Persistent masculine behaviour

➡ Caused by improper castration resulting in retention of epididymal tissue

🧠 Quick Overview

STANDING 🐴
→ Up to 1 year
→ Alpha2 agonist + opioid + local procaine
→ Emasculator
→ ❌ No suture
→ Secondary healing

RECUMBENT – CLOSED 🛏
→ Older than 1 year
→ Ligation + closure
→ Primary healing
→ Uncovered / Covered / Regio inguinalis

RECUMBENT – OPEN 🔴
→ No ligature
→ Emasculator or twisting
→ Uncovered or covered

8. Diagnosis and Castration of Cryptorchids

Cryptorchidism = failure of both or one of the testes to descend into the scrotum.

• Can be unilateral → usually still fertile

• Can be bilateral → usually sterile

• Left testicle most commonly affected

• If testicle has not descended by 3–4 weeks of age → unlikely to descend

• Doesn’t count as cryptorchid until 2 years old

🧬 Etiology

Hereditable:

• Genetics

• Improper gubernaculum function

• Too large testis to pass through inguinal canal

Hormonal:

• Inadequate stimulation of androgen or testosterone

⚠ These stallions should not be used for breeding.

📍 Types of Cryptorchidism

1⃣ Complete abdominal cryptorchidism

➡ Both epididymis + testis are within the abdomen

2⃣ Incomplete abdominal cryptorchidism

➡ Epididymis has descended into the inguinal canal, but testis remains in abdomen

3⃣ Inguinal cryptorchidism

➡ Epididymis + testis have descended into the inguinal canal, but NOT into scrotum

Also called “high-flankers.”

🔍 Diagnosis

1. History

• Is the horse castrated earlier?

2. Rectal palpation of inguinal rings

No structures in inguinal region
➡ Cryptorchidism is completely abdominal

Vessels in inguinal region
➡ Cryptorchidism is inguinal or incompletely abdominal

3. External palpation

• Give sedatives to relax m. cremaster

• Can always palpate it in case of inguinal cryptorchidism

4. USG

➡ Typical homogenic echogenic appearance

5. Hormonal assays

• Testosterone concentration

• Blood: ⬆ Anti-Müllerian hormone → from Sertoli cells in cryptorchid testes, ⬇ Testosterone

• Urine: Estrogen

✂ Treatment

➡ Surgical removal of BOTH testes under general anaesthesia

⚠ Always locate and remove cryptorchid testicle FIRST.

If you cannot find the testicle:
➡ Send horse to professional clinic → you will only ruin the situation for other vet.

Surgical method depends on location of testicle.

Other options:

• Laparoscopic surgery

• Immunological castration

💉 Immunological castration

Immunization against luteinizing hormone-releasing hormone (LHRH)

➡ Decreases serum concentration of testosterone
⚠ Variable result

🔪 Methods of Surgery

⭐ Zert's approach:

Open abdominal cavity close to the prepuce and remove both testicles from one operation wound.

1⃣ Inguinal Approach

📍 Used for:

• Inguinal

• Incomplete inguinal testicle locations

Procedure

• Dorsal recumbency

• Incise under inguinal canal

• Cut rectus abdominis

• Locate vaginal process from gubernaculum

• Incise vaginal process to locate testicle and epididymis

• Find proper ligament of testis

• Pull testis through vaginal ring

• Suture superficial inguinal ring with absorbable suture

➡ Prevents evisceration

2⃣ Para-inguinal Approach

📍 Used if inguinal method didn't work.

• Incision several cm medial to inguinal ring

• Incision between raphe scroti and left leg

• Cut rectus abdominis

3⃣ Paramedian Approach

📍 Used in abdominal cryptorchidism

Procedure

Skin
⬇
Subcutis
⬇
External fascia flava abdominis
⬇
Aponeurosis of oblique abdominal muscle → cut
⬇
Rectus abdominis → separate fibers with finger
⬇
Transverse fascia + peritoneum → perforate
⬇
✋ Introduce hand into abdomen
⬇
🥚 Locate + remove testicle
⬇
Ligature
⬇
Reposition stump of spermatic cord
⬇
Suture fascia transversalis

⭐ Fascia transversalis = main structure holding abdominal wall

4⃣ Flank Approach

• 10–15 cm incision

• Through skin + subcutis

• Paralumbar fossa of affected side

• Horse can be standing or recumbent

Layers

Skin + subcutis
⬇
Cut external abdominal oblique
⬇
Split internal abdominal oblique
⬇
Split transversus abdominis
⬇
Cut peritoneum
⬇
🥚 Locate + remove testis

5⃣ Laparoscopic Approach

• Minimally invasive

• Requires expensive equipment

• Done standing or recumbent

Procedure

1. Distend abdomen with gas

2. Insert camera through umbilical region

3. Locate testicle(s) around vaginal ring

4. Remove testicle(s)

🩹 Post-operative Care

• Stall rest

• Lead walking only

• Exercise gradually resumed over 10–14 days

• External sutures removed 7 days post-op

After laparoscopy

➡ Less invasive
➡ Resume activity after first 72 hours

⚠ Complications

Rare, but include:

• Anaesthetic complications

• 🩸 Excessive haemorrhage

• Evisceration

• Bowel damage

• 🦠 Infection

• Post-op swelling

• Incision breakdown

• Continued stallion behaviour

🧠 MOST IMPORTANT TO REMEMBER

📍 Where is the testicle?

Complete abdominal
➡ 🥚 Testis + epididymis = ABDOMEN

Incomplete abdominal
➡ 🥚 Testis = ABDOMEN
➡ Epididymis = INGUINAL CANAL

Inguinal
➡ 🥚 Testis + epididymis = INGUINAL CANAL

🔪 Match location → surgery

Inguinal/incomplete → 🔪 Inguinal approach

Can't access by inguinal → 🔪 Para-inguinal

Abdominal → 🔪 Paramedian / flank

Abdominal, minimally invasive → Laparoscopy

Equine laparotomy

Laparotomy = incision into the abdominal cavity, usually in the case of life-threatening gastrointestinal abnormalities.

Exploratory laparotomies can also be performed to address:

• Reproductive issues

• Lesions in other organs in the abdominal cavity

📌 Indications

• 🐴 Colic → diagnose exact cause of colic when obstructing lesion requires surgery

• No exact diagnosis, but enough evidence that surgery is required to save the horse's life

• No response to treatment of colic

• Recurrent colic over a period of days or weeks

• Obstruction

• Neoplasia

🔪 Different Ways to Open the Abdominal Cavity

1⃣ Inguinal

• Rectus abdominis muscle is cut

• Does not alone allow a thorough exploration and decompression of the non-herniated bowel

• Used in conjunction with ventral midline incision

📌 Used for:

• Stallions with inguinal or scrotal hernia

• Cryptorchid castration

2⃣ Parainguinal

• Incision located cranially to the external inguinal canal

• Rectus abdominis muscle is cut

3⃣ Flank

🐴 Standing approach

📌 Most common for:

• Small colon

• Nondistended large colon

• Uterine torsion

🔪 Incision

Made in a vertical line midway between:

Last rib ↔ Tuber coxae

➡ Starting dorsal → continuing ventral

Layers

Skin
⬇
🔪 External abdominal oblique → sharply divided
⬇
Internal abdominal oblique → bluntly divided parallel to fibers
⬇
Transverse abdominal muscle → bluntly divided parallel to fibers
⬇
🔪 Peritoneum punctured
⬇
Abdominal cavity

🧠 Muscles involved

• External abdominal oblique

• Internal abdominal oblique

• Transverse abdominal muscle

🪡 Closure

Closure is done for 3 layers:

• First two layers of muscles → appositioned and sutured with absorbable material

• Skin → sutured or stapled

4⃣ Paramedian

📍 10 cm lateral to the midline

• Incision on either right or left midline

• Through rectus abdominis muscle

⚠ Careful to avoid:

• Deep epigastric vessels

• Superficial epigastric vessels

🪡 Closure

➡ Suture external fascia of rectus abdominis sheath

5⃣ Ventral Midline ⭐

⭐ Mostly done in linea alba in case of colic

➡ Allows complete revision of abdominal cavity

📏 Incision

• Small intestine → 15 cm

• Large intestine → 60 cm

🔪 Approach

Initial incision made accurately in midline

⬇

Through linea alba

⬇

Extending cranially from umbilicus

⬇

Open peritoneum

⬇

Enter abdominal cavity

🔍 When opening the peritoneum, assess:

• Color and character of any effusion

• Distribution/pattern of distended bowel

• Discoloration of visceral surfaces

• Discoloration of peritoneal surfaces

🪡 Closure

⚠ Do NOT include peritoneum → causes more irritation.

1⃣ Linea alba

• Suture 1 cm from wound edge

• Simple continuous suture

⬇

2⃣ Subcutaneous tissue

⬇

3⃣ Skin

• Ford interlocking suture

• Prolene

🧠 Quick Overview

Approach	📍 Location	⭐ Main use
Inguinal	Inguinal region	Inguinal/scrotal hernia, cryptorchid
Parainguinal	Cranial to external inguinal canal	Alternative inguinal access
Flank	Between last rib + tuber coxae	Standing; small colon, large colon, uterine torsion
Paramedian	10 cm lateral to midline	Through rectus abdominis
Ventral midline ⭐	Linea alba	Colic + complete abdominal exploration

🧠 Most important:

COLIC → VENTRAL MIDLINE → LINEA ALBA → COMPLETE EXPLORATION

Equine enterotomy

Enterotomy = the surgical incision into the intestinal lumen.

Commonly performed in:

• Jejunum, Cecum, Small colon

📌 Indications for Enterotomy

• Remove foreign bodies → commonly in right dorsal colon:

  • Enteroliths, Fecoliths, Bezoars

• Removal of fluid and ingesta

• Parasitic infestations → Ascarid larvae in small intestine

• Ileum and cecum → obstruction and impaction

• ⭐ Pelvic flexure enterotomy → most commonly performed in large colon for evacuation of large colon

• Right ventral colon enterotomy → access cecum in cases of cecocolic intussusceptions

• Colonic volvulus → pelvic flexure enterotomy

• Small colon strangulation → pelvic flexure enterotomy to release ingesta

💉 Surgical Preparation

💊 Pre-medication

• Broad-spectrum peri-operative ATB

• Anti-inflammatory medication → Flunixin

🍽 Dietary

• Fasted if possible

• ⚠ Majority of cases are emergent

🔪 Procedure

1⃣ General anaesthesia ➡ Horse is put under GA

2⃣ Midline laparotomy ➡ Abdomen opened using midline laparotomy

3⃣ Secure bowel ➡ Fix with Forceps OR Stay suture

4⃣ Incise intestinal wall

➡ Longitudinally
➡ Antimesenteric side

5⃣ Limit spillage of intraluminal fluid

• Aspirate intraluminal fluid OR

• Restrict flow using extraluminal digital pressure

6⃣ Remove the problem

➡ Remove luminal obstruction / fix whatever problem / do the job

7⃣ Lavage

💧 Lavage bowel with sterile saline

8⃣ Close

🪡 One- or two-layer suture technique:

• Synthetic absorbable

• Cushing or Lambert

• Minimal inversion of serosa

OR

➡ Staple closure with thoracoabdominal (TA) stapler

COLON Enterotomy

📍 Common locations

• ⭐ Pelvic flexure

• Left dorsal → cecocolic intussusception

• Right dorsal colon → enteroliths

Procedure

• Incision on antimesenteric side when possible

• Large colon is exteriorized

• Placed on a colon tray:

  • On left side OR

  • Caudally between horse's hind legs

💧 One hose → inserted into colon
💧 Another hose → continuously lavages serosal surface

🪡 Closure

Two layers:

1⃣ Simple continuous
⬇
2⃣ Cushing or Lambert

➡ Colon rinsed thoroughly with sterile saline
➡ Replaced into abdomen

SMALL INTESTINE Enterotomy

⚠ Enterotomy in SI should be avoided because closure can produce:

• Adhesion formation

• Narrowing of lumen

➡ More common to do enterectomy in SI than enterotomy.

📌 Indications

A longitudinal enterotomy on the antimesenteric surface of SI may be indicated for:

• Removal of obstructions

• Impaction with food components

• Foreign material

• Ascarids → anoplocephala, cyathostomin

• Empty a segment of distended bowel to facilitate reduction of a strangulation in the epiploic foramen

💧 Prevent adherence of intestinal contents to serosa

Use:

• Constant lavage with warm saline OR

• Precoat site of affection with sodium carboxymethylcellulose

🪡 Closure

Single layer:

• Cushing pattern OR Lambert

🩺 Aftercare

• Monitoring

• 💧 Fluid therapy

• Feeding

➡ Slow return to feeding over 24–72 hours

• 💊 Analgesia

➡ Peri- and post-operative NSAIDs

• 💊 Antimicrobial

➡ Peri- and post-operative broad-spectrum ATB

• other med: laxatives/lubricants

• follow up and evaluation after 30 days

⭐ Most Common Sites of Enterotomy

📍 Cecal apex
📍 Pelvic flexure ⭐
📍 Right dorsal colon
📍 Descending colon

🧠 QUICK MEMORY

ENTEROTOMY = ENTER the intestine

GA
⬇
Midline laparotomy
⬇
Exteriorize + secure bowel
⬇
Longitudinal ANTImesenteric incision
⬇
Remove obstruction / ingesta
⬇
Lavage 💧
⬇
Cushing/Lambert closure 🪡
⬇
Rinse + replace

⭐ Large colon → enterotomy common, especially pelvic flexure
⚠ Small intestine → enterotomy avoided if possible → enterectomy more common

Enterectomy

Enterectomy = surgical removal of a portion of the intestine.

📍 Commonly:

• Jejunum

• Ileum

📌 Indications

• Any intestine with:

  • Abnormal color

  • Decreased motility

  • Thickened appearance

⚠ Dead jejunum wall:

• Black serosa

• ❌ No pulsation of vessels

• Strangulation → most commonly

• After correction of obstruction which caused secondary vascular damage without return of:

  • Normal color, Motility, Pulsation

Resection of the Small Intestine

📏 Physiological limit of small intestine resection = maximum 8 metres

➡ SI is 18–21 m long

⭐ End-to-end anastomosis is the simplest and most physiologically compatible method.

🔪 Procedure

1⃣ Isolate bowel

• Fluid-filled ischaemic bowel should be isolated with intestinal clamps before manipulation begins.

⬇

2⃣ Select resection sites

• Suitable site proximal and distal to the strangulated bowel

⬇

3⃣ Ligate vessels

• Mesenteric vessels to compromised bowel are double ligated

⬇

4⃣ Transect intestine

• Distal end of gut is transected

• Mesentery incised between ligatures

⬇

5⃣ Cut vessels

• Each vessel is cut

⬇

6⃣ Anastomosis

• Remaining healthy intestine is joined together

• Long end of proximal gap of mesentery is closed when anastomosis is completed

🪡 Closure Alternatives

Use synthetic absorbable monofilament suture material.

A) ⭐ Zert!

Two-layer closure:
➡ Simple interrupted suture pattern in two layers

• Mucosa

• Serosa

B)

1st layer: Simple continuous
2nd layer: Cushing seromuscular suture

C)

Single layer:
➡ Interrupted Lembert sutures

Resection of the Large Intestine

⚠ Large intestinal resection is performed very rarely in horses.

Why?

1⃣ Most obstructions don't require resection

Many obstructions are caused by:

• Displacement with no/minimal interference of blood supply

• Simple obstruction of lumen → e.g. enteroliths

➡ Can usually be relieved by a simple enterotomy.

2⃣ Strangulation may involve too much bowel

If strangulation obstruction is present:

➡ Length of bowel involved may be so great that resection + anastomosis is not considered

➡ Euthanasia

🔗 Anastomosis

Anastomosis = surgical joining of tubular structures (arteries, veins, intestine) together so they can become continuous.

1⃣ End-to-End Anastomosis ⭐

➡ Connects two open ends of intestine together

Intestine:
━━━━✂　✂━━━━
　　　 ↓
━━━━━━🔗━━━━━━

🪡 Suture

• Simple continuous → serosa

• Cushing → seromuscular layer

⭐ Simplest and most physiologically compatible method.

2⃣ End-to-Side Anastomosis

➡ Connects end of intestine to a larger piece

━━━━━━┓
　　　　┃
　　　　┃

3⃣ Side-to-Side Anastomosis

➡ Connects the sides of intestine together

Used for:
➡ Jejunal anastomosis

━━━━━━━
　　↕
━━━━━━━

⚠ Post-operative Complications

• 💧 Leakage of content

• 🕸 Adhesions

• 🚫 Obstruction / stricture

• 🩸 Bleeding

• 🦠 Infection

💊 Post-op Care

• NSAIDs

• ATB

• Stool softener

🧠 QUICK MEMORY

Enterotomy vs. Enterectomy

ENTEROTOMY
➡ ✂ Cut INTO intestine
➡ Remove obstruction/content
➡ Intestine stays

ENTERECTOMY
➡ ✂ Remove a SECTION of intestine
➡ Usually because bowel is dead/damaged
➡ Join healthy ends = ANASTOMOSIS

⭐ Most important sequence:

Strangulation
⬇
🖤 Dead/damaged intestine
⬇
✂ Resection / enterectomy
⬇
🔗 Anastomosis
⬇
⭐ Usually end-to-end

Disorders of teeth exchange and exodontics

Equine dental developmental abnormalities can involve:

• 🔢 Tooth number

• 🦷 Morphology

• 📍 Position in the dental arcades

🦷 Tooth Anatomy

Horses have hypsodont teeth = continue to grow their whole life → 2–3 mm each year.

Tooth divided into:

• Crown → visible

• Reserve crown → hidden in alveolar bone

• Apex/root of tooth

Tooth consists of:

Outer → inner:

• Cementum, Enamel, Dentin, Pulp

Types

• Incisors, Canines, Premolars, Molars

🔢 Numbering System

Two systems:

1⃣ Based on type of teeth

• PM1, M2, etc.

2⃣ Triadan system

🧮 Dental Formula

Deciduous teeth

I 3/3, P 3/3 × 2 = 24

• 12 incisors

• 12 molars

🐴 Permanent teeth

I 3/3, C 1/1, P 3 or 4/3, M 3/3 × 2 = 36–44

➡ Depends on presence of:

• Canines

• P1 = wolf teeth

⏰ Eruption Schedule

• Foals are born with 4 premolars

• ⚠ Critical age = 2.5 years

• Replacement of 12 teeth
  ➡ Can impact food processing, decline performance and cause health problems

Deciduous Teeth

Foals get deciduous teeth at around 6 weeks old.

🦷 Incisors – RULE OF 8 ⭐

• Central → 8 days

• Intermediate → 8 weeks

• Corners → 8 months

🧠 8 days → 8 weeks → 8 months

Premolars

P2, P3, P4
➡ Erupt immediately after birth or within 2 weeks

🐴 Permanent Teeth

Horse has complete set of permanent teeth at 5 years.

🦷 Incisors

All erupted at 4.5 years:

• Central → 2.5 years

• Middle → 3.5 years

• Corner → 4.5 years

🧠 2.5 → 3.5 → 4.5

🐺 Wolf teeth – P1

• 1st premolar

• In maxillary arcades

• Only in some horses

🦷 Premolars

All erupted by 4 years:

• PM2 → 2.5 years

• PM3 → 3 years

• PM4 → 4 years

🦷 Molars

All erupted by 3 years:

• M1 → 1 year

• M2 → 2 years

• M3 → 3 years

➡ Have 2 infundibulum in maxillary arcade

🧠 M1 = 1, M2 = 2, M3 = 3

🦷 Canines

• 4 in stallions

• May not be developed

• Rudimentary

• Erupt around 3.5–5 years

📅 Age Determination of Horse

1⃣ Eruption of teeth

• Presence of deciduous teeth

2⃣ Occlusal surface of lower incisors

• Infundibulum wears away over time

• Gone in central by 8 years

3⃣ Shape of incisors

• Flattened → until 10 years

• Oval → 12–13 years

• Round → 15–20 years

• Triangular → >20 years

4⃣ Angle of incisors

• Young → more vertical/flat

• Older → greater/sharper angle

5⃣ Galvayne's groove

➡ Mark on upper corner incisors that appears and disappears in ageing horse

⚠ Congenital & Developmental Defects

1⃣ Oligodontia

Congenital absence of a tooth germ OR retention and inclusion of a tooth within jaw.

Consequences

Missing tooth →

• Mesial drift

• Tipping of neighboring teeth

• Lack of wear of antagonist

• Dental elongations

• Abnormal mastication

🔎 Diagnosis ➡ X-ray

2⃣ Polyodontia / Supernumerary Teeth

➡ Too many teeth

Can be:

• Retained deciduous teeth

• Supplementary teeth

Often:

• Mandibular premolar

• Maxillary molar

Remnants called “caps.”

Consequences

• Difficulty eating

• Unusual facial development

• Maxillary sinusitis

• Nasal discharge

• Facial swelling

🦷 Developmental Defects

1.Delayed tooth eruption

➡ Due to overcrowding
➡ Usually small breeds with limited jaw space

2.Retained deciduous dentition

➡ Caps retained because of entrapment between adjacent teeth

3.Maleruption / misalignment

➡ Cheek teeth → cause overgrowth of tooth erupting first

4.Dental dysplasia

• Abnormal bending

• Abnormal size

• Double teeth

5.Diastema

➡ Abnormal spaces between teeth
➡ Most common form of periodontitis
➡ Food impaction

6.Abscess

• Apical

• Root

• Periapical

7.Dental caries

➡ Bacterial destruction of dentin
➡ Extraction if caries result in fractures

🕳 Infundibular Caries

Very common in maxillary cheek teeth because they have 2 infundibulums:

• 1 rostral

• 1 caudal

Incisors have 1 infundibulum.

What is an infundibulum?

➡ Funnel-like structure/layer consisting of cementum

⚠ M1 is the oldest permanent tooth in the cavity and is often predisposed to caries.

Hole fills with food
⬇
🦠 Tooth can rot/become infected
⬇
🦷 Tooth becomes weakened
⬇
💥 Fracture

💊 Treatment

• Grade 1 → clean + fill hole with composite

• Grade 2–4 → extract tooth

🔢 Grades of Infundibular Caries

0 = Normal

1 = Hypoplasia of cementum

2 = Cementum + dentinum hypoplasia

3 = Cementum + dentinum + enamel hypoplasia

4 = Fracture of tooth 💥

🧠 0 Normal → 1 C → 2 C+D → 3 C+D+E → 4 Fracture

🦷 Exodontics

Exodontics = teeth extraction

💉 Nerve Blocks

1. Maxillary nerve block

📍 Ventral to zygomatic arch, dorsal to facial vessel

➡ Blocks:

• Maxillary teeth, Maxillary sinuses

2. Infraorbital nerve block

➡ Blocks:

• Upper incisors, Canines, Wolf teeth, Upper Premolar 2

3. Mandibular nerve block

📍 Foramen mandibulae, medial side

➡ Blocks mandibular teeth

4. Mental nerve block

📍 Mental foramen

➡ Blocks:

• Lower incisors, Canines, Wolf teeth

📌 Indications for Extraction

🐺 Wolf teeth

Extract if:

• Rostrally displaced, Unerupted, Fractured, Mandibular wolf teeth

🦷 Incisors, canines & cheek teeth

Extract for:

• Apical infection, Fracture, Severe periodontal disease, Tooth mobility due to trauma

🔧 Extraction Procedures

1⃣ Intraoral Extraction

• Forceps extraction

• Fragmentation

• Segmentation

• Fragment elevation/luxation

🐴 Done in standing sedation

💉 Alpha2 agonist + opioid

2⃣ Surgical Extraction

😴 Done in general anaesthesia

Methods:

• Surgical buccotomy

• Transbuccal extraction → minimally invasive

• Trephination extraction → minimally invasive

⚠ Transbuccal Extraction

Avoid:

• Facial nerve

  • Dorsal buccal branch

  • Ventral buccal branch

• Parotid salivary duct

• Facial artery

• Facial vein

💉 Local Anaesthetics

Drug	⏱ Effect after	⌛ Duration
Procaine	5–10 min	—
Lidocaine	5 min	30–60 min
Mepivacaine	10 min	60–120 min
Bupivacaine	30 min	120–140 min
Articaine	3 min	75 min

🧠 QUICK MEMORY

⭐ Deciduous incisors = Rule of 8

8 days → 8 weeks → 8 months

⭐ Permanent incisors

2.5 → 3.5 → 4.5 years

⭐ Molars

M1 = 1 → M2 = 2 → M3 = 3 years

⭐ Exodontics

Standing + alpha2/opioid
➡ Intraoral extraction

GA
➡ Surgical extraction

⭐ Nerve blocks

Maxillary nerve → maxillary teeth + sinus
Infraorbital → upper front teeth
Mandibular → mandibular teeth
Mental → lower front teeth

Sharp teeth

Sharp teeth = the most common dental/stomatological pathology in horses.

➡ Include minor sharp points → large unopposed overgrowths.

Etiology

Overgrowth of enamel due to:

➡ Lack of wear + continuous eruption

Causes

• Missing teeth

• Malerupted teeth

• Fractured teeth

• Overall disparity in apposition of arcades:

  • Parrot mouth

  • Diastema

• Lack of normal lateral movements of mandible during mastication → due to diet

⭐ Diastema – most common cause

Diastema = abnormal space between two teeth

➡ Leads to malocclusion of opposite tooth

⚙ Pathogenesis

Insufficient/excessive attrition of teeth
⬇
Sharp points/spurs of enamel
⬇
Lack of attrition of occlusal surface
+
Continuous eruption
⬇
🦷 Overgrowth

⭐ Why do sharp points form?

The maxillary arcades are set wider apart than the mandibular arcades.

This leads to areas of lack of wear during mastication.

MAXILLA

➡ Sharp points/spurs form on BUCCAL side

MANDIBLE

➡ Sharp points/spurs form on LINGUAL side

🤕 Consequences

Sharp points can cause:

➡ Abrasion and ulceration of:

• Cheeks and Tongue

🩺 Clinical Signs

⚠ Many horses are asymptomatic.

Most common:

• Dysphagia

• Soft-tissue trauma

• Quidding

• Riding problems

🔎 Diagnosis

Clinical examination

• 💉 Sedation

• Head gag

• Rinse mouth prior to examination

• ✋ Palpation

• 👀 Visual inspection

• 🔦 Light for visualization

• Occlusion probe → inspect for damage

🔧 Treatment – Rasping

➡ Rasping of teeth using:

• Hand rasp or Motorized instruments

Where do you rasp?

MAXILLA → BUCCAL side
➡ Because maxillary cheek teeth form spurs on the buccal side

MANDIBLE → LINGUAL side
➡ Because mandibular cheek teeth form spurs on the lingual side

This occurs because maxillary cheek teeth are wider than mandibular cheek teeth.

⚠ Important During Rasping

❌ Do NOT rasp away too much

➡ Secondary dentine protects the pulp.

When reducing an overgrowth:
➡ Maintain the normal lateromedial angulation of the occlusal arcades.

📈 Prognosis

✅ Good prognosis for most cases.

⚠ Excessive removal of occlusal surface OR heating of tooth structure using uncooled instruments can cause:

➡ Post-procedure quidding

⏱ Can take months to years to resolve.

🧠 QUICK MEMORY

Why sharp teeth?

Continuous eruption + ↓ wear = sharp teeth

Where are the sharp points?

🐴 Upper/MAXILLA
➡ BUCCAL 🫦
➡ Cuts CHEEK

🐴 Lower/MANDIBLE
➡ LINGUAL 👅
➡ Cuts TONGUE

Treatment

🔧 RASP/FLOAT

⚠ Don't rasp too much → protect secondary dentine + pulp

Surgical diseases of nasal cavity and paranasal sinuses

👃 DISORDERS OF THE NARES

1⃣ Wry Nose “campylorrhinus lateralis”

• Congenital damage

• Shortening of premaxilla on one side
  ➡ Upper jaw + nose deviate to one side

• Typically accompanied by deviation of nasal septum
  ➡ Problems breathing

• Different degrees, but often euthanasia is best

2⃣ Hypertrophy of Alar Folds

➡ Vibrant sound during inspiration = high blowing

• Causes exercise intolerance in performing horses

🔎 Diagnosis + Treatment

Confirm noise originates from alar folds during exhalation/inhalation:

➡ Place sutures from skin at dorsal aspect of nose across openings of false nostrils

➡ Compare noise before vs. after suture placement

Positive result
➡ Correct diagnosis
➡ Indication for resection of alar folds

3⃣ Atheroma of False Nostrils

➡ Development of epidermal inclusion cysts (sebaceous cysts) in lining of false nostril.

• Painless

• Usually no respiratory obstruction

• Mainly cosmetic significance

4⃣ Facial Paralysis

➡ Dysfunction of nasolabialis muscle

Causes:

• Facial surgery, Dental extraction

⚠ Can cause an aerodynamic disaster for sport horses

5⃣ Trauma

Usually when nose is caught in a hook.

➡ Requires anatomical restoration

👃 DISORDERS OF THE NASAL CAVITY

🩸 Progressive Ethmoidal Hematoma – PEH

Repeated epistaxis at rest → unilateral or bilateral.

Can progress to:

• Respiratory stridor

• Facial deformity

• ⬇ Airflow through affected nostril

➡ Unknown etiology.

⚙ Pathogenesis

Expanding sub-mucosal hemorrhages develop on surface of ethmoidal turbinate labyrinth

⬇

Mucosal capsule splits

⬇

🩸 Bloody discharge

More common in horses >4 years.

🩺 Clinical Signs

• ⭐ Repeated hemorrhages from one nostril at rest

• Dyspnoea → nasal obstruction, reduced drainage

• Dirty nasal discharge → not fresh blood

• Facial swelling

🔎 Diagnosis

• History, Physical exam, Endoscopy, X-ray, CT

💊 Treatment

First:
➡ Chemical ablation with formalin 10% (inject/apply it on lesion to remove it)

➡ Repeat at 2–3 week intervals until resolved

If not successful:
➡ Surgical removal through frontal flap

Other Nasal Cavity Disorders

• Trauma

• Intra-nasal foreign bodies

• Neoplasia

• Polyps

• Mucoid degeneration of nasal conchae

• Nasal septum deviation

• Hyperplasia of nasal septal mucosae

• Subcutaneous emphysema

• Concha necrosis and metaplasia

🦴 PARANASAL SINUSES

⭐ Five Paired Paranasal Sinuses

1. Frontal

   • Frontal sinus

   • Conchofrontal sinus

2. Caudal maxillary

3. Rostral maxillary

4. Ethmoidal

5. Sphenopalatine

⚠ Paranasal sinuses are not completely separated.

➡ All sinuses communicate with or drain into the middle meatus.

🦠 Primary Sinusitis

Pathogenesis:

Stagnation of mucus
⬇
Inhibited muco-ciliary clearance by URT viral agents
⬇
Opportunistic bacteria follow
⬇
Purulent exudate
⬇
Chronic sinusitis
⬇
Hyperplasia of lining
⬇
Narrowing of ostia + inspissation of pus

🦷 Secondary (Dental) Sinusitis

➡ Caused by dental periapical suppuration

Roots of 4th–6th maxillary teeth lie within maxillary sinuses.

Fracture or necrosis
⬇
Dental infection
⬇
🦠 Secondary sinusitis

🩺 Clinical Signs

Early:
➡ Mucoid unilateral nasal discharge

Later:
➡ Purulent + malodorous discharge

Also:

• Facial swelling, Nasal obstruction

🔎 Diagnosis

• Clinical signs, Percussion, Oral inspection, X-ray

• ⭐ CT = BEST / GOLD STANDARD – Zert

💊 Treatment

Conservative:

• Systemic ATB

• Volatile or steam inhalation

• Light exercise

Surgical:

• Catheter placement

• Radical surgery

🦷 Secondary Empyema

➡ Caused by problems with first molar (M1)

⭐ Most frequent problem of rostral maxillary sinus

Treatment

• Trephination (making a hole through the bone to access the sinus)

• Push tooth out

• Flush bulla

• Make drainage into oral cavity without extraction of tooth

💧 Sinus Cysts

• Unknown etiology

• Common features with PEH

• Often in region of drainage ostium (large sinus cyst → blocks drainage ostium → mucus can't drain → sinus expands → facial swelling/nasal obstruction)

• Cysts contain yellow fluid

🩺 Clinical Signs

• Nasal obstruction, Facial swelling

• Rarely ocular proptosis → exophthalmos

• Mucoid discharge

🔎 Diagnosis

• Clinical signs, Physical exam, Endoscopy, X-ray

🔪 Treatment

➡ Fronto-nasal flap surgery

🍄 Mycotic Rhinitis & Sinusitis

• Unknown etiology

• May be opportunistic fungal infection secondary to other supportive conditions

🩺 Clinical Signs

• Low-grade unilateral purulent discharge

• Maybe epistaxis

🔎 Diagnosis

➡ Endoscopy

💊 Treatment

• Topical benzimidazole

• Foley balloon catheter

🧬 Neoplasia & Polyps

Neoplasia ➡ True tumors are uncommon

Polyps

➡ Pedunculated inflammatory proliferations enclosed in mucous membrane

➡ Can develop from complication of dental periapical disease

🩺 Clinical Signs

• Putrid nasal discharge mixed with blood

• Ocular proptosis

🔎 Diagnosis

• Physical exam, Endoscopy, X-ray, CT

🔪 Treatment ➡ Fronto-nasal flap surgery

🧠 QUICK MEMORY

👃 NARES

Wry nose → congenital deviation
Alar fold hypertrophy → high blowing
Atheroma → painless cyst
Facial paralysis → nasolabialis dysfunction
Trauma → anatomical restoration

🩸 PEH

Older horse + repeated unilateral epistaxis AT REST
➡ Think progressive ethmoidal hematoma

Treatment:
Formalin 10% → if unsuccessful → frontal flap

🦷 SECONDARY SINUSITIS

Dental disease → unilateral → purulent + malodorous discharge

⭐ CT = GOLD STANDARD

💧 SINUS CYST

Facial swelling + obstruction + yellow fluid
➡ Fronto-nasal flap

🍄 MYCOTIC

Unilateral purulent discharge ± epistaxis
➡ Endoscopy → topical benzimidazole

Surgical Diseases of the Pharynx, Larynx & Guttural Pouch

PHARYNX

Pharynx = soft tissue passage for food and air.

Connected with:

• Nares, Middle ears, Oral cavity, Larynx, Esophagus

Supported by striated muscle for:

• Swallowing and Phonation

1⃣ Dorsal Displacement of the Soft Palate – DDSP

🏇 Only a problem in racing horses while exercising.

Likely due to abnormal contraction of muscles of soft palate → causing them to be flaccid.

⚙ What happens?

Soft palate displaces dorsally
⬇
“Sits” on the epiglottis
⬇
🚫 Obstructs opening to trachea
⬇
Difficulty getting air during exercise

🩺 Clinical Signs

• Loud expiration noises

• Unable to maintain speed while running

🔎 Diagnosis

• Clinical signs, History, Endoscopy at rest

• ⭐ Endoscopy during exercise = GOLD STANDARD

🔪 Treatment

• Laryngeal advancement – tie forward

  • Move larynx rostrally + dorsally

• Laser palatoplasty

⚠ Epiglottic Entrapment – Don't Mix with DDSP

➡ Enlargement/entrapment of epiglottis in younger horses

Treatment

➡ Gentle resection of epiglottic folds by laser

Other Pharynx Diseases:

• Choanal atresia/stenosis

• Palatal defects

• Instability of soft palate

• Dynamic collapse of pharyngeal walls

• Intra-palatal cysts

• Pharyngeal cysts

• Neoplasia

• Extra-mural distortion by:

  • Strangles, Abscess, Neoplasia

LARYNX

Larynx = symmetrical, tube-shaped musculo-cartilaginous organ connecting:

Pharynx → Larynx → Trachea

2⃣ Laryngeal Hemiplegia= Recurrent Laryngeal Neuropathy

Progressive functional loss of laryngeal nerves

⬇

Larynx collapses on affected side during inspiration

⬇

Permanent dysfunction of muscles

⬇

🚫 Partial obstruction of airways

⭐ Typical

• Higher prevalence in males

• Long-neck, large breeds . long vagus recurrent nerve, trauma or wear on the nerve

• Usually LEFT side

🩺 Clinical Signs

• Inspiratory noise during exercise (high pitched whistling/roaring sound)

• Exercise intolerance

• Usually asymptomatic at rest

🔎 Diagnosis

Palpation
➡ Atrophy of intrinsic laryngeal musculature

Other:

• Arytenoid depression test

• “Grunt-to-the-stick” test

• Endoscopy

🔪 Treatment

⭐ Prosthetic laryngoplasty

➡ Suture between cricoid + arytenoid

➡ Mimics action of CAD muscle

Other:

• Nerve/muscle grafting

• Permanent tracheostomy

• Cordectomy → Zert does not like

3⃣ Fourth Branchial Arch Defect – 4-BAD= Laryngeal Dysplasia

Syndrome of irreparable congenital defects due to failure of development of some/all derivatives of the 4th branchial arch.

Can be:

• Unilateral or Bilateral

❌ Defective Structures

4 structures:

1⃣ Wings of thyroid cartilage
2⃣ Crico-thyroid articulation
3⃣ Cricothyroideus muscles
4⃣ Crico-pharyngeal sphincter muscles

🩺 Clinical Signs

• Abnormal respiratory sounds during exercise, Eructation, Nasal discharge, Coughing, Recurrent colic

• 4-BAD→ missing/abnormal laryngeal structures → abnormal respiratory sounds + swallowing problems.

🔎 Diagnosis

• Palpation, Dynamic endoscopy, Ultrasonography

Palpation:
➡ Unusually wide gap between:

• Caudal margin of thyroid and Rostral edge of cricoid

Normally, these structures overlap.

❌ Treatment ➡ No way to reconstruct the absent structures

GUTTURAL POUCHES = Auditory Tube Diverticulum (ATD)

2 air-filled, balloon-like structures

📍 Located between:

• Base of cranium → dorsally

• Pharynx + esophagus → ventrally

Each pouch:

• Is in contact with the other

• Separated by thin areolar tissue → septum

• Connected to the nasopharynx

4⃣ Guttural Pouch Tympany

⚙ Pathogenesis

Guttural pouch ostium acts as non-return valve

➡ Air can enter
➡ ❌ Air cannot leave
⬇
🎈 Guttural pouch expands

Etiology

• Foals a few days after birth

• Congenital malfunction of pharyngeal opening of pouch

🩺 Clinical Signs

• 🎈 Tympanic swelling of parotid region

• Mucopurulent discharge

  • Bacterial infection → strangles

• Dysphagia, Dyspnea

🔪 Treatment

Improve airflow from guttural pouch:

➡ Opening into larynx OR
➡ Perforation of septum between the pouches

5⃣ Diverticulitis of Guttural Pouch

➡ Inflammation of ATD mucous membranes

Etiology

• Strangles

• Chronic diverticulitis → chronic catarrhal inflammation

• Empyema

• Chondroids

6⃣ Chronic Empyema & Chondroids

⚙ Pathogenesis

Failure of drainage
⬇
Mucus/pus accumulates in pouch
⬇
Pus becomes stagnant
⬇
Formation of solid concretions = CHONDROIDS

⚠ Risk of Streptococcus equi

🩺 Clinical Signs

• Bilateral purulent nasal discharge, Swelling of parotid region

🔎 Diagnosis

• Clinical signs, Lateral X-ray

💊 Treatment

➡ Liquify chondroids by repeated lavage

➡ Drainage via Foley balloon catheter

7⃣ Guttural Pouch Mycosis 🍄

➡ Invasive fungal plaque on mucosal wall of ATD.

🚨 Clinical Signs

⭐ Spontaneous epistaxis AT REST (plaqe erodes internal carotid artery lining the guttural wall)

• Minor hemorrhages

• Dysphagia

• Pharyngeal paralysis

  • ➡ Ingesta in nasal discharge

• Cranial nerve defects:

  • Laryngeal hemiplegia

  • Facial palsy

  • Horner's syndrome

  • Abnormal head posture

🔎 Diagnosis

• Clinical signs

• Endoscopy ⚠ can be dangerous

💊 Treatment

Conservative:
➡ Antimycotic drugs

Surgical:
➡ Occlusion of carotid artery branches

• Ligature OR Transarterial coil embolization (must also do surgery, will be a lot of bleeding. the potensial risk of severe hemorrhage is the risk, not the fungi itself)

Other Larynx Diseases

• Epiglottal hypoplasia

• Laryngeal granuloma

• Neoplasia

• Sub-epiglottal cysts

• Epiglottal entrapment → younger horses → laser

• Arytenoid chondropathy

• Axial deviation of ary-epiglottal folds

🧠 QUICK DIFFERENTIATION

🏇 DDSP

Soft palate → over epiglottis
➡ EXPIRATORY noise
➡ Exercise
➡ Dynamic endoscopy
➡ Tie-forward

🗣 Laryngeal hemiplegia

Usually LEFT arytenoid doesn't function
➡ INSPIRATORY noise
➡ Exercise
➡ Endoscopy
➡ Prosthetic laryngoplasty

🎈 Guttural pouch tympany

Foal + air trapped
➡ Parotid swelling
➡ Create drainage/airflow

Empyema/chondroids

Pus → stagnant → solid chondroids
➡ Purulent discharge
➡ Lavage + Foley catheter

🍄 Guttural pouch mycosis

Fungal plaque
➡ 🚨 Spontaneous epistaxis at rest
➡ Cranial nerve problems
➡ Occlude carotid artery branches

Diseases of the eyelid and conjunctiva

👁 Importance of the Eyelids

• Protect the eye

• Produce and distribute tears

• Aid tear drainage

• Help control the amount of light entering the eye

👁 DISEASES OF THE EYELID

Congenital Disorders

1⃣ Entropion

Entropion = inward rolling of the eyelid margin.

⭐ Common in foals.

Etiology

Foals:

• Dehydration and Congenital disorders

Adults:

• Trauma

⚙ Pathogenesis

• Eyelid edge turns inward → Eyelashes rub against eye surface → Irritation of conjunctiva + cornea

Long term:

• Scarring, Abnormal coloring, Slow-healing sores

🩺 Clinical Signs

• 💧 Epiphora = excessive tearing

• 😣 Blepharospasm = blinking

• Conjunctivitis, Keratitis

💊 Treatment

Temporary repair:

• Vertical mattress suture, Subconjunctival injections

Surgery: rarely required.

⚠ Not recommended until adult age → avoid over-correction / iatrogenic ectropion.

➡ Blepharoplasty = removal of skin below eye

2⃣ Ankyloblepharon

➡ Failure of eyelids to open after birth

3⃣ Dermoid

➡ Focal congenital masses of displaced skin/tissue

May include hair.

🔪 May require surgical removal if causing irritation.

4⃣ Agenesis & Coloboma

Coloboma (dysgenesis)

➡ Full-thickness absence of portions of normal eyelid

Agenesis

➡ Complete absence of eyelid

If ocular disease is present:
➡ Reconstructive blepharoplasty

🐴 ACQUIRED EYELID DISORDERS

5⃣ Trauma / Laceration

⭐ Common because of the horse's prominent lateral eye position.

⚠ All eyelid injuries should be treated ASAP to avoid further damage to eye.

🩺 Clinical Signs & Diagnosis

• Usually obvious: Edema, Bleeding

💊 Conservative Treatment

• Topical compress

• Topical ATB

• Systemic NSAIDs

🔪 Surgical Treatment

• Temporary tarsorrhaphy

• Re-apposition of eyelid margin

🚨 NEVER RESECT / CUT OFF AN EYELID LACERATION!

Preserve as much eyelid tissue as possible.

6⃣ Ectropion

Ectropion = eversion of eyelid margin.

Usually due to complication of eyelid trauma.

⚙ Pathogenesis

Eyelid turns outward → Conjunctiva exposed → Irritants + secondary bacterial infections → Long-term/recurrent conjunctivitis + scarring

🔪 Treatment

➡ Surgical V and Y blepharoplasty:

7⃣ Blepharitis

Blepharitis = inflammation of the eyelids.

🦠 Infectious Causes

Bacteria:

• Moraxella equi

Parasites:

• Oncocerciasis, Habronemiasis

❌ Non-infectious Causes

• Dermatological condition. Photosensitization, Abscess, Neoplasia

🩺 Clinical Signs

• Blepharospasm. Hyperemia, Swelling, Exudation, Alopecia, Pruritus, Epiphora

🔎 Diagnosis

• History, Clinical signs

💊 Treatment

➡ Depends on etiology and condition

8⃣ Neoplasia

Most common

• Squamous cell carcinoma (SCC)

• Sarcoid

• Melanoma

Etiology / Risk Factors

Depends on:

• Age, Breed

• Lack of ocular pigmentation

• Genetics

• ☀ UV radiation

• Infectious agents

• Chronic irritants

🔎 Diagnosis

• Histopathological examination, Biopsy

💊 Treatment

• BCG (Bacillus Calmette-Guérin) → injection used to dissolve sarcoid

• ⭐ Gamma-radiation = best

⚠ Resection could destroy the eyelid margin.

9⃣ Distichiasis

➡ Double set of eyelashes

Extra hair/cilia grow from Meibomian glands.

Treatment

➡ Surgical electrolysis

🔟 Trichiasis

➡ Inward direction of eyelashes

Eyelashes contact cornea
⬇
Irritation

1⃣1⃣ Prominence of Nictitating Membrane= Third Eyelid

Etiology

• Altered globe position or size, Inflammation

• Neoplasia → SCC

• Tetanus

• Horner's syndrome

• Prolapse of orbital fat pad

• Conjunctival amyloidosis

🔎 Diagnosis

• Clinical signs, Biopsy, Cytology

💊 Treatment

Depends on underlying cause:

• Surgical, Antitoxins

CONJUNCTIVITIS

The conjunctiva covers:

• Inner eyelids

• Third eyelid

• Sclera

Conjunctivitis = inflammation of the conjunctiva.

⭐ Common in foals due to:

• Reduced tear production

• Low corneal sensitivity compared to adults

🦠 Etiology

• Primary Irritants: Environmental, Allergic, Chemical

• Foreign bodies

• Infectious: Moraxella equi

• Parasites: Thelazia, Habronema musca, Onchocerca cervicalis

Secondary ⭐ More Common

Secondary to:

• Keratitis

• Disorders of tear production/draining

• Eyelid disease

• Uveitis

• Endophthalmitis

• Trauma

• Ulceration

• Neoplasia → SCC

• Systemic disease

Respiratory viral infections

• Equine influenza, Equine herpesvirus, Rhinovirus

Other infections

• Strangles, Equine viral arteritis, Actinobacillus spp., Corynebacterium spp.

🩺 Clinical Signs of Conjunctivitis

• Swelling, Edema,💧 Epiphora

• Discharge:

  • 💧 Serous → viral

  • 🟡 Purulent → bacterial

• 🔴 Hyperemia

🔎 Diagnosis

• Physical examination

• Scraping + culture

• 💧 Schirmer tear test

• Occasionally biopsy

💊 Treatment

➡ Depends on etiological agent.

• 💧 Flushing of conjunctival sac

• Ophthalmic preparation of ATBs

• Granulomatous lesions:

  • Antihelmintic therapy

  • Anti-inflammatory therapy

• 🪱 Mechanical removal of parasites

🧠 QUICK MEMORY

Eyelid position

Entropion = IN ↩ → eyelashes damage cornea
Ectropion = OUT ↪ → conjunctiva exposed

Eyelashes

Distichiasis = extra/double eyelashes
Trichiasis = eyelashes directed inward

Trauma

🚨 NEVER cut off eyelid laceration → re-apposition

Conjunctivitis

🔴 Inflamed conjunctiva
💧 Serous = viral
🟡 Purulent = bacterial

Useful terminology

Epiphora = excessive tears 💧
Blepharospasm = excessive blinking/squeezing eye 😣
Blepharitis = inflammation of eyelid
Conjunctivitis = inflammation of conjunctiva