LAM Final Exam

Pemphigus foliaceus

• Et: Immune mediated

  • destroys intercellular attachments

• Cs: Small Vesicles, blisters, erosions, scaling, crusting, alopecia, pyrexia, urticaria, limb edema, coronitis 

  • starts locally (head/limbs) → generalized

• Dt: Biopsy!!

  • Acantholysis, intraepidermal clefts, neutrophilic exudate, IF IgG staining!!

• Tx: Steroids! (Dex) → remission

  • Immunosuppressive therapy → aggressive treatment!! until complete remission!

• Px: good if young, life long if old

Alopecia areata

• Et: Immune Mediated

  • antibodies to hair follicles

• Cs: Discrete hair loss w/ normal skin

  • hair loss on face, mane, tail

• Dt: Biopsy

• Tx: Steroids help

• Px: most resolve in 1-3 yrs benign neglect

Urticaria (hives)

• Et: Type I hypersensitivity - IgE

  • insects, inhaled allergens, molds, drugs, topicals

• Cs: hives/wheals/plaques, Localized dermal edema

  • face, neck, withers, thorax, generalized

  • Insect bites, drugs, atopic dermatitis, topicals, allergies

• Dt: Allergy skin testing

  • GOAL: determine specific cause

• Tx: Antihistamines, steroids, hyposensitization(long term)

• Px: recede once trigger removed!

Contact dermatitis

• Et: Irritant exposure

  • new/used tack, new bedding, sprays, soaps

• Cs: edema, erythema, vesicles, erosions, crusts

  • localized and caused by contact with irritant

• Dt: History & distribution

• Tx: Eliminate exposure

Queensland itch

• Sweet itch → very common

• Et: Hypersensitivity to Culicoides saliva

  • gnats breed near standing water

  • Piercing mouthparts for blood feeding

• Cs: Pruritic, hives, self trauma crusting, alopecia, leads to lichenification(chronic)

• Dt: Dorsal-ventral distribution, seasonality

• Tx: Stable at dusk, fans/screens, pyrethrin sprays, steroids(significant itch)

  • Aka→ vector control

Ventral dermatitis

• Et: Culicoides, Onchocerca, horn flies, Habronema

  • Aka→ Bugs

• Cs: papules, crusts, alopecia, ulcers, excoriation, leukoderma, can become chronic

  • Ventral abdomen, midline distribution (KEY)

• Tx: Insect control, steroids

Mites (mange)

• Et: Psoroptes, Sarcoptes, Demodex (rare); Trombiculidiasis (chiggers); Chorioptes in drafts(foot manage)

• Sig: drafts

• Cs: Pruritus, scaling, crusts, alopecia 

  • pastern/fetlock of drafts(Choriopte)

• Dt: Skin scraping - visualize 

• Tx: Ivermectin, lime sulfur, organophosphates

Pediculosis (lice)

• Et: Damalinia (chewing), Haematopinus (sucking)

  • Cold weather/crowding

• Cs: VERY Pruritus, scaly coat, alopecia 

  • mane, tailhead, topline

• Dt: Identify lice/nits(eggs)

• Tx: Pyrethrins 

  • KEY: Repeat 2–3× q 2w

    • kill the nits

Dermatophytosis (ringworm)

• Et: Trichophyton & Microsporum

  • spread via direct contact or equipment!

  • Infects hair shafts

• Cs: Crusting, alopecia, pruritic

  • Face, neck, shoulders

• Dt: DTM, cytology, Woods lamp, histopath

• Tx: Self-limiting (healthy adults), iodine, antifungals, lime sulfur, oral antifungals(rare), disinfect equipment

  • not in pregnancy animals

Dermatophilosis (rain scald)

• Et: Dermatophilus congolensis infection after moisture exposure

• Cs: Superficial infection, Crusts, matted hair, neutrophilic dermatitis

• Dt: Cytology 

  • railroad track” cocci

  • Dorsally distributed 

  • DZ sheds in crusts

• Tx: Remove crusts!!, iodine shampoo(best), keep dry, antibiotics

Saddle sores

• Et: Focal Trauma from tack; secondary infection 

  • Staph, Strep, Dermatophilus, Corynebacterium

• Cs: Lesions at points of contact, poor grooming 

• Dt: History, clinical signs, culture, biopsy

• Tx: hygiene, clean, antibiotics

Pastern dermatitis (scratches/grease heel)

• Et: Chronic painful dermatitis of pastern/heel bulbs from mud/wetness, Staph, Dermatophilus, fungi, mites

• Cs: dry/Crusting, alopecia, ulceration, swelling, pain

• Dt: Clinical eval, skin scraping, biopsy

• Tx: remove from mud/wetness, Soak, clip, topically with antifungals, steroids, antibiotics, ivermectins, time

Papillomatosis

• Et: Equine papilloma virus

• Sig: Young horses, yearlings

• Cs: Small, firm, gray/white/tan masses 

  • lips, eyelids, genitals/inguinal region

• Tx: Self-resolving <12m, vax

Aural plaques

• Et: related to Papilloma virus,

• Cs: Depigmented hyperkeratotic plaques on inner ear

  • black fly irritation

  • Have to differentiate from sarcoid

• Tx: Fly repellents, stable during fly season

Nodular necrobiosis (collagen granuloma)

• Et: Collagen degeneration with eosinophilic inflammation

• Cs: Firm dermal nodules on back/girth; non-pruritic, non-painful

• Dt: Histology shows collagen degeneration + eosinophilic inflammation

• Tx: Surgical, inject with steroids

HERDA (Hyperelastosis cutis)

• Et: Hereditary collagen defect

• Sig: QH, autosomal recessive

• Cs: Loose, fragile skin, lesions after minor trauma

  • shows up over back under saddle! 

• Tx: No cure, debilitating

Onchocerca cervicalis

• Et: Nematode infection

  • Adult female in ligamentum nuchae, microfilariae in SQ q 4m 

  • Transmitted by Culicoides gnats

• Sig: Adult horses

• Cs: Dermatitis, conjunctivitis, keratitis, uveitis, blepharitis, chorioretinitis, alopecia, scaling/crusting, depigmented limbus, “bulls eye”, non-pruritic, ocular pain

  • Seasonal ventral midline + periocular + ocular lesions  

• Dt: Positive saline prep or biopsy, response to tx

• Tx: Ivermectin

  • Not effective against adult females

  • Mild side effects fever and swelling → Pre-treat with NSAIDs

Habronemiasis (Summer sores)

• Et: adult stomach worm(wall), passed in feces → fly intermediate

  • Larvae deposited on moist tissues → penis + medial cantus

• Cs: nodules with granulation tissue & yellow “sulfur granules” necrotic center; commonly penis/urethral process, medial canthus

• Dt: Histopath (eosinophils, mast cells, granulation tissue)

• Tx: Ivermectin, steroids

  • Aka → Kill larvae/adults, control flies, reduce inflammation

Thelazia lacrymalis

• Et: Eyeworm of horses of all ages

  • transmitted by Muscid & fruit flies

  • lives in conjunctiva + nasolacrimal system 

• Sig: all ages

• Cs: Mucoid discharge, conjunctivitis, blepharitis, keratitis, dacryocystitis, nasolacrimal duct obx!

  • Often asymptomatic or mild eye irritation

• Dt: Adults visible on cornea/fornix or in nasolacrimal wash cytology

• Tx: Manual removal, irrigate, retrograde flush, multi day fenbendazole, topical organophosphates!!!!

Sarcoids

• Et: bovine papillomavirus + wound + genetics

  • #1 skin tumor!!!! 

  • Locally invasive fibroblastic tumor

• Cs: nodules → face, periocular, ears, neck, genital, distal limbs

  • Can compromise fxn → welfare issue 

• Dt: clinical presentation, excisional biopsy

  • Wide excision →Take everything or nothing 

• Tx: complete wide Sx removal/debulking, injection cisplatin or cryosurgery(adjunctive w/ sx), BCG injection (facial/ocular), benign neglect, no biopsy! 

  • No curative therapy and high recurrence 

Squamous Cell Carcinoma (SCC)

• Ocular and genitals areas most common

• Et: #1 malignant tumor

  • Locally invasive, slow metastasis!!

• Sig: Appaloosa, Paint, Clydesdale, Belgian

  • Colour dilution

• Cs: Nodules of non-pigmented + mucocutaneous areas

  • eyelids, third eyelid, limbus, genitals, lips, muzzle

• Tx: UV masks, wide excision (curative), enucleation, posthectomy, ± local chemo

Equine Melanoma

• Et: Genetic, slow growing, 2/3 mets later in life

  • Melanocytic nevi: small flat, superficial, benign, “birthmark”

  • Dermal melanomas: solitary, pigmented nodules in dermis

  • Dermal melanomatosis: multiple confluent nodules, gray horses

  • Anaplastic malignant melanoma: aggressive, non-gray horses, RARE

• Sig: gray/white horses >15y

• Cs: nodules on ventral tail, perianal region, parotid gland, periocular, genital

• Tx: Benign neglect #1, sx excision/debulking w/cisplatin(problematic ones)

• Px: Recurrence common

Cutaneous Lymphosarcoma

• Genital masses

• Et: B, T, or mixed cell types

• Cs: subcutaneous nodules, rarely metastasize, benign

  • Slowly progressive; sometimes progestin responsive

• Tx: sx excision ± w/ local chemo

Hyperkalemic Periodic Paralysis (HYPP)

• Et: Na⁺ channel mutation → muscle excitability

  • autosomal Dominant trait

• Sig: QH, Paint, Appaloosa breeds, “Impressive” bred horses

• Cs: intermittent episodes muscle twitching, muscle dimpling, 3rd eyelid prolapse, weakness, recumbency, resp distress, hyperkalemia 

  • spontaneous Episodic  → triggered by stress or excitement.

• Dt: Genetic test, ↑ K

• Tx: (Acute)dextrose, ↑Ca, ↑ bicarb, acetazolamide, thiazide

  • avoid K-rich feeds and alfalfa

Sodium Deficiency

• Muscle cramping 

• Dietary 

  • Et: Inadequate intake, sweating loss

  • Sig: Performance horses

  • Cs: Stiffness, cramping, rhabdomyolysis

  • Tx: Feed loose salt, supp electrolytes

• Exhausted Horse Syndrome 

  • Et: Prolonged exercise, dehydration, electrolyte loss

  • Sig: Endurance/working horses → lost though sweat

  • Cs: Hyperthermia, ileus, metabolic alkalosis, cramping, rhabdomyolysis

    • Thumps → synchronous HR + diaphragmatic contractions

  • Dt: ↓ Ca, ↓ K, ↓Cl

  • Tx: fluids, electrolytes, proper conditioning, salt supp, common sense

    • Mild = self limiting

      • severe = emergency

Hypocalcemic Tetany

• Muscle cramping

• Clinical hypocalcemia (<8mg/dl)

• Et: Lactation, transport, blister beetle toxicosis, exhaustion
  Cs: Severe hindquarter cramping

• Dt: ↓ Ca

• sync diaphragm flutter: “Thumps” → diaphragm contracts in sync w/ atrial depolarization

• Tx: IV Ca gluconate infusion

  • slowly and monitor heart rhythm

Otobius megnini

• Ear tick → Muscle cramping

• Et: Spinous ear tick

  • Larval stages infest external ear canal

• Cs: Head shaking, intermittent cramping & elevated CK(rhabdo), fasciculations, recumbency

  • Intermittent 

• Tx: Local TX: Pyrethrins, piperonyl butoxide, acepromazine(acute)

Rhabdomyolysis

• Muscle cramping

• Et: Skeletal muscle breakdown → myoglobinuria(red urine)

  • Sporadic Exertional “tying up”: Poor conditioning, electrolyte imbalance, CHO excess → excessive exercise

  • Recurrent Chronic Exertional: Abnormal Ca regulation, high strung racehorses 

• Cs: Firm painful muscles, crampling, pain, anxiety, sweating, pigmenturia, stiffness, myoglobinuria

  • “Tying-up” 

• Dt: ↑ CK, ↑ myoglobin, muscle biopsy(chronic)

  • Watch for AKI → #1 risk

• Tx: Stop exercise!!, sedate,IV fluids, NSAIDs, diet

  • ↑ fat + ↓ low starch feed

  • gradual return to work→ hand walk 2-3w

• ** E. Influenza and EHV1 can cause muscle stiffness and rhabdo **

Polysaccharide Storage Myopathy (PSSM)

• Glycogen storage disease

• Type 1 → Young QH & Draft horses

  • Et: GYS1 mutation

  • Cs: recurring rhabdomyolysis, draft horse →weakness

  • Dt: ↑ CK, genetic test, amylase-resistant glycogen m. biopsy 

  • Tx:  ↑ fat + ↓ low starch diet, consistent exercise

• Type 2 → Adult/mature warmbloods

  • Et: unknown

  • Cs: chronic stiffness, exercise intolerance, gait abnormalities, gradual muscle loss 

  • Dt: breed & history, ↑ CK

    • Type 1: genetic test

    • Type 2: muscle biopsy→ amylase-sensitive glycogen

  • Tx:  ↑ fat + ↓ low starch diet, consistent exercise

Equine Myofibrillar Myopathy (MFM)

• Et: Myofibril disorganization and desmin + glycogen accumulation

• Sig: Arabians, WB

• Cs: Rhabdomyolysis(arabians) or muscle atrophy(WB)

  • previous dx RER(arabians) or PSSM2(WB) may be MFM, desmin staining

• Dt: Biopsy

• Tx: Supportive, consistent exercise, diet

Malignant Hyperthermia

• Et: RYR1 mutation, autosomal dominant

• Sig: QH

• Cs: anesthesia: ↑ Temp, rigidity, acidosis, exertional rhabdomyolysis = fatal

  • After anesthesia and exertion → fatal rhabdomyolysis

• Dt: Genetic test of blood/hair roots

• Tx: cooling, avoid triggers

Post-Anesthetic Myopathy

• Complication of general anesthesia 

  • Non-exertional rhabdomyolysis 

• Et: Ischemia from prolonged recumbency or hypotension during surgery with inadequate padding/protection 

  • generalized form: PSSM, Malignant hyperthermia 

• Cs: Muscle pain, swelling in triceps/quadriceps/gluteals

  • Localized into muscles contacting table 

• Tx: fluids, DMSO, NSAIDs, weight bearing support 

  • Emergency treatment

Clostridial Myonecrosis (Gas Gangrene)

• Iatrogenic most often (IM injections, NSAIDS, vaccines)

• Et: C.perfringens type A, anaerobic infection causing necrosis and gas production(gas gangrene)

  • post-injection → NSAIDs or Vax

• Cs: Painful swelling, gas, toxemia

  • Rapid progression 

• Dt: Smear/culture

• Tx: Fluids, fenestrate tissues, ventalate, penicillin, metronidazole

  • Aggressive emergency treatment

• Px: Guarded

Infarctive Purpura Hemorrhagica

• Et: Ab-mediated vasculitic myopathy

  • Post-strangles horses

• Cs:severe Pain, swelling, rhabdomyolysis, recumbency, myositis 

  • Located in large muscle

• Dt: history and CS, dramatic ↑CK, ↑ M protein antibody

• Tx: Steroids, fluids, antibiotics

• Px: guarded to poor

Myosin Heavy Chain Myositis

• Et: mutation in MYH1

  • Triggered by strangles or anaplasmosis or vax

• Sig: QH

• Cs: Rapid(days) gluteal/epaxial atrophy,

  • fatal non-exertional rhabdomyolysis → w/ active strangles, anaplasmosis infections

• Dt: ↑CK without vasculitis, biopsy, genetic testing

• Tx: Corticosteroids: responds well

• Px: Guarded

Toxic Myopathies

• Et: Ionophores,

  • Box elder seeds “seasonal pasture myopathy”

• Cs: acute rhabdomyolysis, myocarditis, death

  • Box elder → seasonal pasture myopathy

• Px: Guarded

White Muscle Disease

• Et: Selenium deficiency

• Sig: Foals, Se-poor soil

• Cs: Skeletal stiffness, weakness, myoglobinuria, acute death

  • 2 forms: Skeletal muscle + cardiac form

• Dt: ↓ Se, ↑ CK, biopsy

• Tx: Skeletal: supportive + Selenium injection

  • Cardiac: poor/grave prognosis

Vitamin E–Responsive Myopathy

• Et: Vitamin E deficiency

• Cs: Weakness, gradual muscle loss, trembling, poor performance

• Dt: Biopsy sacrocaudalis dorsalis medialis muscle

• Tx: Supp Vitamin E

Glycogen Branching Enzyme Deficiency

• Et: GBE1 mutation

  • autosomal recessive

• Sig: QH neonatal foals

• Cs: Weakness, seizures, recumbence, fatal

• Dt: Biopsy, genetic test → post mortem

• Tx: Euth or death

General Principles of Emergency Management of Fractures

• Gain control & calm horse

• Initial exam determines

  • Nature of injury, Feasibility of treatment

• Immobilize limb, address pain & infection

  • Splint, antibiotics (open wound), tetanus toxoid, Pain meds

• Transportation

  • Hind limb fractures face forward

  • Forelimb fractures face backward

Splinting Techniques

• Use: ↓ soft tissue damage, allows weight bearing, ↓ swelling/pain

• Methods: Modified Robert Jones bandage + external support(split)

  • RJB = many layers of cotton + brown gauze + elastic tape

  • Modified RJB uses less padding; bulky bandage can impede movement and cause displacement

Distal Limb Splints

• Et: Injuries between distal phalanx & distal cannon

  • Division 1 fractures: P1, P2, distal MC/MT

  • Luxations of fetlock & pastern

  • Complete Flexor tendon lacerations

  • Suspensory apparatus breakdown

• How: fix phalanges in frontal plane with cannon bone

  • Mod. RJ bandage with rigid support, kimsey limb saver

Forelimb Fractures Splints

• Division 2 fractures: Distal cannon & distal radius

  • Modified RJB + 2 splints → elbow to ground

• Division 3 fractures: Mid-Radius to Elbow

  • RJB + two splints

    • Caudal splint ground to elbow

    • Lateral splint extends to mid scapula

• Olecranon 

  • Support carpus in extension

• Humerus & scapula

  • Protected by muscle; no splint practical

  • Carpal extension bandage possible

Splinting Hind Limb Fractures

• Mid-cannon to hock: division 2

  • Extend padding above hock and lateral splints proximally

    • avoid excessive padding 

  • Wooden wedge on foot helps align phalanges

• Tarsus & tibia: division 3

  • Difficult to stabilize

  • Lateral splint extends to tuber coxae

• Femur: division 4

  • No splint needed

Methods of Fracture Repair

• External coaptation

  • Fiberglass casts: limited to below mid-radius/tibia

    • risk of cast sores

  • External fixation: foals/ponies, mandibular, metacarpal, metatarsal, radius, and tibia fractures

• Internal fixation

  • Lag screws & plates: accurate reduction critical

  • Cancellous bone grafting

  • Nunamaker device: for comminuted phalangeal fractures

• Post-operative Care

  • Extended convalescence

  • Pain management & nutrition

  • Physical therapy: 

    • Controlled exercise, manipulation, hydrotherapy, electrical stimulation

  • Complications: GI problems(colic), support limb laminitis, repair breakdown, delayed/non-union, cast sores

Osteomyelitis

• Inflammation of the bone due to infection

  • Open fractures, sequestrum, hematogenous

• Focal traumatic - sequestrum

  • Et: Detached cortical fragments → infected → sequestrum

    • Cannon, splint, P1, P2, radius tibia 

  • Cs: Draining tract 

  • Tx: removal & curettage

• Septic - open fracture

  • Cs: may lead to failure

• Hematogenous- FPT / sepsis foals 

  • Cs: Osteomyelitis, physitis, septic arthritis

  • Tx: curettage, limb perfusion, lavage

  • Px: Guarded

Tendons & Ligaments Anatomy

• Both attached to periosteum of bone, near joint capsule

  • painful injury!!→ digital flexor and navicular bursae

• Tendons: connect muscle to bone

  • Type I collagen bundles → high tensile strength

  • Longitudinal orientation 

  • ECM of proteoglycans → tenocytes

  • Allow stretch during flexion and extension

• Ligaments: connect bone to bone

  • Dense bands of collagen 

  • Collateral, interosseous, intra-articular types

• Suspensory apparatus: supports distal limb

Tendon Injuries

• Et: Overstretching or Infection

  • Attached closely to periosteum near joints

  • Heal slowly! prone to reinjury

• Cs: Acute lameness, heat, swelling, pain on palpation

• Dt: US

• Tx: Cold therapy, NSAIDs, support wraps, rest and gradual exercise/return, PRP, stem cells

  • Contaminated tendon sheaths + navicular bursa = medical emergency

Traumatic Arthritis

• Path: Final common pathway of articular injury  → Progressive cartilage loss, irreversible

• Et:

  • Type 1: chronic strain, “Wear and tear”

    • chronic low grade synovitis

  • Type 2: acute injury

    • acute synovitis

• Cs: Pain, lameness, synovial effusion

• Dt: lameness exam, nerve block localization, Imaging, fluid analysis 10-30,000 WBC/μl 

  • Type 1: mild effusion, no bony lesions

  • Type 2: fragments, fracture lines, marked effusion

• Tx: Rest, NSAIDs, cold therapy (acute), intra-articular steroids + HA, casts, Arthroscopy, Arthrodesis

  • avoid steroids with fractures

• Px: Irreversible 

  • collateral ligament injury = guarded

Septic Arthritis

• Et: 

  • Hematogenous infection → FPT foals

  • Penetrating or Iatrogenic wounds

• Cs: Pain, non weight baring lameness, marked synovial effusion

• Dt: lameness exam, nerve block localization, Imaging, fluid analysis 30-50,000 WBC/μl 

  • Severe joint distention and destruction

• Tx: Irrigation, curettage, antibiotics

  • Joint contamination = emergency

  • avoid steroids with sepsis 

• Px:

  • Poor: multiple septic joints or physes

  • Ok: <2 appendicular joints

Developmental Arthritis

• Et: Osteochondrosis and angular limb deformities

  • Articular and physeal cartilage defects

• Cs: Pain, lameness, ↓ ROM

  • Progressive

• Dt: lameness exam, nerve block localization, Imaging, fluid analysis

  • Sclerosis, lysis, narrow joints spaces, minimal effusion changes

• Tx: Rest, NSAIDs, intra-articular steroids + HA, Arthroscopy, Arthrodesis

  • Irreversible

Specific Arthritis Medications

• NSAIDS

  • Use: Mainstay treatment 

  • Types:

    • Phenolbutazone → Firocoxib 

    • Topicals → Diclofenac + DMSO

• Intra-articular steroids

  • Use: suppress inflam

    • NOT fractures or sepsis 

  • Types: Triamcinalone + HA (unsulfated GAG)

Congenital flexure deformity

• “Contracted tendons”

• Genetic, rapid growth leads to crowding/malposition in utero

• Distal interphalangeal joint (DDF)

  • forelimbs and bilateral

• CS: Clinically obvious

• TX:

  • Mild: spontaneous

  • Mod: splints 7-10d

  • Severe: sx

Club foot

• Et: Deformities in coffin joint (DDF) and fetlock(SDF)

  • tendons don’t stretch

• Acquired flexural limb deformities (DDF contracture) 6w-6m

  • Rapid growth of MC3 + radius → steep dorsal hoof wall → Heal grows boxy

• Cs: ↓ weight bearing, boxy foot, Steep hoof wall, high heel, worn toe

• Tx: early intervention, ↓ feed, correct Ca:P ratio, sx check lig desmotomy

Fetlock Contracture

• SDF contracture

• Et: Acquired flexural limb deformities → rapid growth, pain, inactivity

  • Continued growth of radius

• Sig: Yearlings

• Cs: Upright pastern, ↓ weight bearing, Physeal Dysplasia, Osteocondrosis

• Tx: early intervention, ↓ feed, corrective trimming, sx superior check lig desmotomy

Common Digital Extensor and Extensor Carpi Radialis Rupture

• Et: Congenital flexural deformity

  • Extensor tension 

  • Common Digital Extensor = bilateral

• Cs: Knuckling

• Tx: splint 2-4 wks

Angular Limb Deformities

• Et:

  • Congenital: lig laxity, overfeeding late preg, malposition, incomplete ossification

  • Acquired: physeal dysplasia, trauma, overfeeding, contralateral lameness 

• Cs: deviation, joint laxity

  • Lateral (valgus) or medial (varus)

• Tx: Correct before physeal closure 

  • Mild: Self limiting, rest, ↓ feed, trimming, splints

  • Severe: physis changes, >15^o deviation → surgical correction

Osteochondrosis

• Et: Defect in articular cartilage and subchondral bone

  • genetics, rapid growth, Ca:P imbalances

  • Thick cartilage + delayed ossification → soft cartilage, focal necrosis

• Cs: Effusion, lameness, arthritis, physeal dysplasia, OCD, subchondral cysts, angular limb deformities, cervical stenotic myelopathy

  • Stifle > hock > fetlock > shoulder 

• Dt: Rads

• Tx: Rest, ↓ feed, 2:1 Ca:P ratio, NSAIDs, arthroscopic debridement

Subchondral Cystic Lesions and Osteochondrosis Dissecans (OCD)

• Et: Osteochondrosis lesion

  • genetics, rapid growth, Ca:P imbalances

• Sig: Young, TB, QH, male

  • Common 

• Cs: Effusion, lameness

  • Stifle > hock > fetlock > shoulder 

• Dt: Rads

• Tx: Arthroscopic debridement, ↓ feed, 2:1 Ca:P ratio

Physeal Dysplasia (Physitis)

• Et: Enlarged growth plate of long bones

  • Osteochondrosis lesion

    • genetics, rapid growth, Ca:P imbalances

• Sig: Foals 2-18m

• Cs: Physeal swelling, pain, mild lameness, metaphyseal flaring, angular limb deformities, fetlock contracture

  • Distal metacarpal, metatarsal 3, proximal pharynx 1, distal radius, distal tibia, vertebral bodies

• Dt: rads

  • Often bilateral, check both limbs

• Tx: Time, Correct diet, rest, manage pain

  • Transient in mild cases

General lameness

• forelimb lameness (75%)

  • below the carpus in 95%

• Hindlimb lameness

  • hock and below

• Foot is most common

Lameness Signalment

• Neonatal foals: hematogenous septic arthritis, dev orthopedic disease

• Weanlings, yearlings: dev orthopedic disease, osteochondrosis

• 2-yr-olds in training: bucked shins, splints, bowed tendons, suspensory problems  

  • “too much too soon”

• Adults: navicular, laminitis, arthritis 

• TB racehorses: arthritis, fractures, suspensory lig & sesamoid injuries, carpal chips, hyperextension injuries

• STB: rear limb fractures, bowed tendons, suspensory/sesamoids, myositis, sore backs 

• Western: ringbone, bone spavin, navicular, phalangeal fractures

• Hunter-jumpers: ringbone, suspensory injuries, back & SI problems

Lameness Exam

1. Observe at rest

   • Weight shifting in front is abnormal

2. Palpate limbs for swelling, heat, or pain → start at foot and work proximal

   • Foot most common site

3. Observe at walk and trot → straight line and circles

   • Turning accentuates lameness on the inside limb

   • Forelimb lameness: #1 

     1. Head bob → down on sound

     2. Choppy gait → bilateral lameness

   • Hindlimb lameness: hip hike

4. Perform flexion tests, hoof testers, and limb manipulation

   • Apply even pressure across hoof wall, sole, frog, heels → observe reaction

   • Flex joint 60sec → trot horse off → increase in lameness = positive

5. Intrasynovial or Perineural blocks

   1. Block nerves from distal to proximal to isolate pain source → evaluate gait 10min pre + post-block

Normal horse Posture and Gait

• Standing: stand square, only hind end shifting

  • Front end shifting is abnormal

• Stride: breaks over toe, smooth, heel before toe, foot lands square

Grading Lameness

• 0 = Not lame

• 1 = Not lame on straightaway, inconsistent on turn

• 2 = Inconsistent on straightaway, consistent on turn

• 3 = Lameness consistent on straightaway & turn

• 4 = Obvious lameness at walk

  • Sole bruise, abscess, sepsis, laminitis, acute trama

• 5 = Non-weight baring

  • Sole bruise, abscess, sepsis, laminitis, acute trama

Limb Blocks

• Start distally then move up the leg

• Palmar Digital Block: Desensitize heel region, navicular area, frog, digital cushion (foot)

  • Inject lateral and medial palmar digital nerves at collateral cartilage level

• Abaxial Sesamoid Block: Desensitize foot + pastern

  • Inject at base of sesamoid bones, medial and lateral

• Low Palmar (Low 4-Point) Block: Desensitize fetlock and distal limb

  • Inject lateral/medial palmar nerves and palmar metacarpal nerves distal to buttons of splint bones

• Intrasynovial: desensitize joint

  • intra-articular, tendon sheath, navicular bursa

  • Risk of infection

Specialized Orthopedic Imaging

• Radiographs: Primary means of imaging bones & joints

• MRI: Soft tissue imaging

• Scintigraphy: Identify lesions not visible on x-rays → stress fractures

  • Nuclear medicine → technetium-99, gamma camera 

• US: Soft tissue → tenons + lig

• Thermography: Detect abnormal surface temp

  • Hotspots → inflam

Heel Abnormality's

• Under-Run Heels 

  • Et: Long Toe–Low Heel → improper trimming, inactivity

  • Cs: “Broken back” hoof < pastern axis, white line separation, heel bruising, arthritis, suspensory + coffin joint strain

  • Tx: corrective trimming 

• Short Toe-High Heel

  • Cs: hoof > pastern axis, chronic sole bruising, arthritis, suspensory + coffin joint strain

  • Tx: corrective trimming 

Heel issues

• Contracted Heels

  • Et: Immobility → pain, no exercise

  • Cs: Narrow heels, recessed frog, concave sole, ↓ weight baring

  • Tx: Exercise, corrective shoeing

• Sheared Heels - uneven heels

  • Et: 1 longer heel bulb displaced upward → improper trimming,

  • Cs: pain, bruising, cracks

  • Tx: Balance trim, full bar shoe

Underdeveloped hooves

• Flat Feet

  • Et: Lack of concavity 

  • Sig: Draft breeds

  • Cs: Bruising

• Thin Sole and Wall

  • Et: Inactivity and genetic 

  • Cs: Bruising, pedal osteitis

  • Dt: Hoof tester

  • Tx: Protective shoes/pads, diet

Hoof Wall Incongruity

• Keratoma

  • Et: Hyperplastic keratin mass in hoof wall

    • Grows down inner hoof wall

  • Cs: Hoof deformity, white line distortion

  • Dt: Rads 

  • Tx: Sx removal

• Hoof Cracks

  • Et: Dry hooves, poor trimming

Hoof Wall Trauma

• Avulsion

  • Et: disrupts germinal epithelium

  • Tx: remove separated segment, bandage, protective boot

• Coronary Band Laceration

  • Cs: hoof defects

  • Dt: evaluate DIP

  • Tx: Must suture, slipper cast

• Heel Laceration 

  • Tx: suture, bandage, slipper cast 

• Puncture

  • Et: Sharp metal object → nails

  • Cs: Lameness, pain, inflammation, infection, digital pulse 

  • Dt: Hoof testers, rads

  • Tx: Poultice, tetanus toxoid, clean, Sx lavage + antibiotics

    • frog puncture = emergency = Surgical, check for synovial involvement!! to avoid (septic DIP)!!!!!

  • Px:

    • Good: Subsolar

    • Poor: Frog, DIP, navicular bursa, flexor sheath, sepsis

Inflammation of the external hoof structures

• Coronitis

  • Et: Inflam of coronary band 

    • pemphigus, idiopathic, systemic dz, laminitis

  • Cs: Wall separation + sloughing

• Sole Bruising

  • Et: Hard ground, thin soles, stones, over-trimming

  • Cs: Hematoma, sole abscess, pedal osteitis, ↑digital pulse

  • Dt: Hoof testers

  • Tx: Pare out sole, remove shoes, cold therapy, NSAIDS, rest, pads

Infection of the Hoof

• Thrush

  • Et: Horn + sulci infection → Wet ground, recessed frog

  • Cs: Black, foul-smelling exudate

  • Tx: Debride, dry enviro, clean

• Canker

  • Et: Chronic hypertrophic infection of Frog’s germinal epithelium

  • Sig: Draft horses, humid enviro

  • Cs: Odorous, caseous discharge, of the hind feet

  • Tx: Sx debridement, antibiotics, bandage, dry enviro

• Quittor

  • Et: Infection/necrosis of collateral cartilage

    • heel laceration, overreaching, abscess extension

  • Tx: Surgical debridement

Hoof abscesses

• Subsolar Abscess

  • Et: Sole bruise, FB, misplaced nail, laminitis

  • Cs: grade 4-5 lameness, digital pulse

  • Dt: Hoof testers, rads

  • Tx: Debride, ventral drainage, soaks, antiseptic, tetanus toxoid, NSAIDs

• Subdural Abscess “gravel”

  • Et: Infection ascending through white line to coronet

    • Puncture, chronic lamanitis

• Dt: rads

• Tx: Ventral drainage, antibiotics

Laminitis

• Et: Inflam of laminae → P3 rotation

  • Systemic illness → Endotoxemia, colitis, endometritis, shock, EMS, PPID, trauma, toxins, grain overload

• Acute CS: pain in all four feet, shifting weight, bounding pulses, laminitis stance, heel-loading choppy gait, bulging of sole

• Chronic CS: Abnormal hoof growth, bilateral forelimb lameness  

• Dt: toe sensitive to hoof testers, rads with P3 rotation

• Tx: Cold therapy (dev phase), NSAIDs, sedation, Corrective trimming (lower heel + shorten toe + pads), dietary management

  • Acute = medical emergency

• Px: potentially life + career ending

  • Mild → no chronic changes

  • Severe → chronic bilateral forelimb lameness

Pedal Osteitis - traumatic + septic

• Et: Repeated bruising, thin-soled, laminitic horses

• Cs: Chronic bilateral forefoot lameness, choppy gait, digital pulse, soreness, heat

• Dt: Rads with demineralized P3 solar margin

• Septic: extension of sole abscess or direct injury

• Tx: Rest, Bute, pads, curettage + antibiotics + sx debridement (septic)

Navicular Syndrome (Podotrochleosis)

• Chronic bilateral forelimb lameness “athletes dz”

• Et: navicular bone and soft-tissue degeneration, erosion, and lysis 

  • Chronic concussion, poor conformation, unbalanced trimming, repetitive strain 

• Sig: Middle-aged QH, TB, athletes 

• Cs: contracted heels, shifting Bilateral forelimb lameness, choppy gait, shortened stride

• Dt: Hoof tester pain over ⅓ frog, improvement with heel block, MRI

• Tx: Corrective shoeing, trimming (shorten toe, raise heel)

  • Permanent → no cure
    

Distal phalanx fracture

• uncommon

• Most articular

• CS: acute bilateral lameness, severe/non-weight bearing lameness, bounding pulse

• Dx: radiographs, re-x-ray if negative on the 1st one.

• No periosteum, heals w/ fibrous union!

  • Conservative tx: non-articular

• Tx: lag screws, sx removal

• OA common sequela from fractures

Low Ringbone

• Et: Periarticular bony proliferation of DIP joint

  • Type 1: Chronic synovitis (bilateral)

  • Type 2: trauma (unilateral)

    • collateral ligament tear

• Cs: Short, choppy bilateral gait, pain on flexion, weight shifting, bone proliferation, joint narrowing

• Dt: Rads, perineural + intraarticular anesthesia response

• Tx: Rest, NSAIDs, steroids + HA, arthrodesis, neurectomy

  • Standard arthritis treatments

Synovitis + Capsulitis of the Pastern Joint (PIP) 

• Type 1: often bilateral

  • Et: Chronic repetitive impact + lig strain

  • Sig: QH, polo → quick turns + starts + slides

  • Cs: Low-grade synovitis, bilateral, Pain on flexion

  • Dt: Rads to assess OA, improvement with local anesthetic 

  • Tx: rest, cold therapy, NSAIDs

  • Px: good w/ early tx

• Type 2: collateral lig tear

  • Et: Acute tear of collateral lig, P2 fractures

  • Sig: QH, polo → quick turns + starts + slides

  • Cs: synovitis, sprain, joint instability

  • Tx: rest, cold therapy, NSAIDs, wraps

  • Px: guarded

Middle phalanx fractures

• P2 fractures

• Rear limbs of western horses

• catastrophic articular fractures

  • comminuted/caudal, uniaxial, biaxial

• CS: hear “pop”, intermediate lameness, crepitus

  • AVOID nerve blocks

• biarticular/comminuted: poor prognosis

High Ringbone

• High ringbone OA= distal P1 & proximal P2 bony proliferation

• Et: Pastern arthritis

  • Chronic synovitis or lig injury

  • bony proliferation, joint space narrowing, sclerosis/lysis, osteophytes

• Cs: Chronic bilateral lameness w/ choppy gait, pain on flexion

• Dt: rads

• Tx: Correct foot balance, rest, IA steroids + HA, Arthrodesis (restore fxn)

  • Standard arthritis tx

• Px: Guarded for performance

Synovitis of the Fetlock 

• Idiopathic

  • Cs: Not painful, “windpuffs”

  • Tx: none

• Traumatic

  • Type 1: “occult osselets” Common Hyperextension, Twisting motions

  • Type 2: Acute bone + cartilage + lig damage

  • Cs: Lameness, Effusion, All get arthritis 

  • Tx: early intervention(key), rest, cold therapy, NSAIDs, IA steroids + HA

  • Px: ok if early, guarded if arthritic

Chronic Proliferative Synovitis (Villonodular Synovitis)

• Et: Synovial pinching of synovium → chronic hypertrophy

• Cs: Low-grade bilateral lameness, dorsal fetlock enlargement, effusion

• Dt: US

• Tx: Sx resection of synovium

Suspensory Branch Desmitis *

• Et: Injury to the branch

  • Medial > lateral

• Cs: Swelling, lameness, pain

• Dt: US of lig, sesamoid rads

• Tx: Ice, wrap, NSAIDs, 1y rest

• Px: guarded, ↑ recurrence

Osteochondrosis of fetlock (OCD)

• Unilateral or bilateral

• Medial condyle cannon bone

• beneath proximal joint of P1

• Tx: removal and debridement till bleeding bone

  • low 4-point block (improves): IA block specific

P1 dorsal chip and comminuted fractures

• Chip:

  • proximodorsal (OCD) chip fracture

  • synovitis/effusion

  • arthroscopic removal

• Comminuted: life threatening

  • Emergency splint or immobilization

  • Internal fixation required

Distal Sesamoidean Ligament Desmitis

• Et: Hyperextension → tearing

  • Near sesamoid origin

• Cs: Pain, Swelling, lameness

• Dt: US

• Tx: Ice, support wrap, NSAIDs, 1y rest

• Px: Guarded, ↑ re-injury risk

• desmitis suspensory lig injury: Medial branch

Sesamoiditis

• Et: Excessive suspensory pull on immature bone

  • “Too much too soon” → tear suspensory ligament

• Sig: Young athletic horses

• Cs: lameness, swelling, enthesiopathy, osteitis

• Dt: Rads → periosteal new bone + osteolytic lesions

• Tx: Prolonged rest

• Px: Guarded

Suspensory Apparatus Failure

• Et: Failure of suspensory branches, sesamoids, or DSLs

  • concurrent phalangeal &/or MC/MT fractures

• Sig: racehorses

• Cs: Acute non-weight-bearing

• Tx: humane euth race horses, arthrodesis (salvage)

  • Emergency stabilization

Sesamoid fractures

• excessive tensile force

  • Pulls bone apart

• CS: acute painful lameness

  • most are articular

• Apical(88%) > basilar > midbody

• Sx removal

  • good: apical/abaxial

Digital Flexor Sheath Tenosynovitis 

• Idiopathic

  • Cs: Painless, windpuffs, no lameness

  • Tx: None required

• Traumatic: tears DDF or manica florexia

  • Et: fetlock + pastern injuries 

  • Dt + Tx: Arthroscopy

  • Px:

    • Good = manica flexoria tears

    • Poor = DDF

• Septic

  • Et: Contamination of tendon sheath

  • Cs: Marked lameness, Suppurative effusion

  • Tx: debridement & lavage, antibiotics, regional limb perfusion, annular lig desmotomy

    • Prompt surgical tx required

  • Px: Guarded

Deep Digital Flexor Tendonitis (Low Bow)

• Et: Traumatic strain/tearing

  • Crimp of type 1 collagen → scar w/ type 3 collagen

• Cs: Acute pain, swelling, hemorrhage, edema

  • Often concurrent tenosynovitis or PAL constriction

• Dt: US

• Tx: Aggressive cold therapy 72h, wraps, heel elevation, NSAIDs, annular lig desmotomy, rest for months

• Px: Guarded, ↑ recurrence

Palmar/Plantar Annular Ligament Syndrome

• Et: Constriction of flexor tendons + digital sheath

• Complication of acute DDF tendinosis, tendosynovitis

• Tx: relief w/ Annular lig desmotomy

Bucked Shins

• Shin splits

• Et: Dorsal metacarpal thickening and soreness 

• Sig: Young, TB (2y)

• Cs: Bilateral lameness, Visible dorsal MC enlargement, Heat

• Tx: Rest, anti-inflammatories

• Px: Good

• Cortical fissure fracture: saucer shaped fracture dorsal lateral MC, does NOT enter medullary cavity

• CS: lameness, firm swelling, fracture line(xray)

• Tx: stall rest 6m, sx if needed(lag screw)

Splints

• Et: Exostosis of MC/MT II & IV

  • Tearing of IO lig → periosteal reaction → new bone formation

• Cs:

  • Acute: variable lameness

  • Chronic: painless bony enlargement

    • suspensory desmitis = blind splint

• Tx:

  • Acute: cold therapy, topicals, steroid injection, bandaging, rest

  • Blind splint: surgical removal of periosteal/bony growth

Cannon Bone Sequestrum + Osteomyelitis

• Et: Focal impact injury → cortical fragment death → sequestrum formation

• Cs: Draining non-healing wound

• Dt: Rads

• Tx: surgical debridement and drainage

Suspensory Desmitis

• Tramatic

  • Et: Acute tear at branches or body

    • Body: secondary to blind splints

    • Proximal: tear at origin 

  • Cs: Lameness, pain on palpation

  • Dt: US

• Degenerative

  • Et: Systemic CT disease

  • Cs: Bilateral, dropped fetlocks, progressive pain

  • Tx: euth

Inferior Check Ligament Desmitis

• Et: Athletic strain

• Cs: Palpable painful swelling between DDF and suspensory lig

• Dt: Perineural anesthesia, US

• Tx: Rest, NSAIDs, controlled exercise

• Px: Guarded