LAM: Exam 2

Soft Tissue Trauma of the oral cavity

• Lips, muzzle, cheek & tongue lacerations

• Superficial: second intention healing → lips/cheek/muzzle

• Deep mucosal: breaches oral mucosa → req closure 

  • 2-layer, absorbable mucosa-internal layer

• Tongue lacerations: suture; partial amp(frenulum)

Fractures of the oral cavity

• Et: kicks, collisions, cribbing, bit injuries

  • incisive bone, mandible, maxilla, teeth

• Cs: drooling, lack of feed intake, malalignment, instability, crepitus, swelling, odor

• Tx: soft feed, oral rinses, intraoral wiring, bone plates, screws, external fixation

Oropharyngeal Foreign Bodies

• Et: grass awns, splinters, wires

  • lingual/sublingual tissues, buccal recesses, palate, pharynx

• Cs: stomatitis, glossitis, cellulitis, quidding, abscess, salivation, halitosis, dysphagia

• Dt: speculum exam, palpation, rads, endoscopy

• Tx: removal + antibiotics/NSAIDs + oral lavage

Stomatitis & Glossitis

• Et:

  • Dental points: cheek/tongue lacerations

  • Parasites: Habronema, Gasterophilus(stomatitis), Helicocephalobus

  • Oral ulcers: blister beetles, VSV (report), NSAIDs, caustics, uremia : causes excessive drooling

  • Epulis: gingival hyperplasia, erupting teeth

  • Lampus: benign hard palate swelling with erupting incisors

• Tx: lavage, NSAIDs, antibiotics

Salivary Gland Diseases

• Sialoliths: obx, rupture, fistula

• Trauma: salivary fistula/trauma/laceration

• Obstruction: mucoceles; marsupialize

• Slaframine toxicity: herd outbreaks of ptyalism; remove source

  • red clover with Rhizoctonia fungus

Congenital Oropharyngeal Defects

• Cleft palate: nasal milk discharge, cough, FTT; Sx

• Wry nose: lateral deviation of maxilla; malocclusion, nasal obx

• Dental anomalies:

  • Parrot mouth: overbite, maxillary prognathism

  • Sow mouth: underbite, mandibular prognathism

  • Shear mouth, oligodontia, supernumerary teeth(delayed eruption)

• Dentigerous cysts: draining tracts @ ear base

Gastrointestinal Neoplasia

• Oropharyngeal

  • Melanoma: lip commissures; histopath

  • SCC: oral/pharyngeal tissues; histopath

  • Bone tumors: ossifying fibroma, osteoma, osteosarcoma; histopath

  • Dental tumors: odontoma, ameloblastoma; histopath

• Esophageal

  • Et: SCC

  • Cs: recurrent choke

  • Px: Poor

• Gastric

  • Et: SCC

  • Sig: Old

  • Cs: weight loss, chronic colic, poor appetite, choke

  • Dt: gastroscopy, biopsy, peritoneal cytology

  • Px: grave

• Intestinal

  • Et: Lymphosarcoma (#1), adenocarcinoma, leiomyosarcoma, GIST

  • Cs: weight loss, chronic diarrhea, colic

    • Mimics IBD

  • Dt: biopsy, US, cytology

  • Px: poor

Dental Anatomy & Physiology

• Hypsodont teeth: long crowns, short roots, enamel below gum line

  • Young: 24 teeth

    • @ 6m → 3 deciduous incisors & 3 premolars in each arcade

      • total 6 cheek teeth on each side

      • White: milk teeth

  • Adult: 36-44 teeth, canines present in males

  • P1 = wolf teeth

    • total 6 cheek teeth on each side

    • Hooks on P2, 3rd molar

• Growth: crowns until 6-9y; wear 2-3 mm/yr

  • Continuous eruption to match wear; reserve crown ↓ with age

Eruption times for permanent teeth

• Incisors: (I1-3) erupt at 2.5, 3.5, 4.5 years

• Canine (C1) at 4 to 5 years

• Premolars: 2.5, 3 & 4 years for P2-4

  • Wolf teeth (P1) at 5-6 months

• Molars (M1-3) at 1, 2, & 3.5 to 4 years

Dental Disease

• Et:

  • Points & hooks: sharp enamel lacerations; float regularly

  • Incisor abnormalities: retained, fractured, misaligned; extraction or stabilization

  • Canine teeth: unerupted (irritation), elongated (bit issues); file, extract

  • Wolf teeth: vestigial premolars; remove

  • Retained Premolar caps: impaction/infection (apical osteitis); remove + antibiotics 

  • Dental caries/decay: infundibular defects, pulp exposure, fractures

  • Apical osteitis: infection, sinus, draining tracts; extraction, curettage, antibiotics

  • Malocclusions: Wave mouth (older horses), step mouth (missing opposing tooth), shear mouth (angled occlusion, narrow mandible), smooth mouth (aged, worn down); diastema, spaces between teeth that trap feed

  • Periodontal dz: malocclusion/diastema, gingivitis, bone loss, tooth loss

• Cs: Weight loss, quidding, reluctance to eat, bitting problems, tilting head, drooling, bloody saliva, halitosis, unilateral malodorous nasal discharge

• Tx: sinus trephination, buccotomy, repulsion, intraoral tooth extraction

Routine Dental Care

• Exams: at birth, then 1-2x/year

  • Observation: body condition, drooling, swelling, quids

  • Feed test: observe mastication

  • Oral exam: requires sedation, irrigation, manual & visual exam

  • Full exam: full mouth speculum + good light

  • Ancillary diagnostics: radiography, CT/MRI, endoscopy

• Floating: remove points/hooks

• Wolf teeth: removal at 1-2y

• Retained caps: extract if causing problems

• Canine teeth: file sharp edges

Extraction of cheek teeth

• infection, fracture, loose tooth, malposition, dental tumors

• Standing intraoral extraction preferred

  • lateral buccotomy → more challenging

Esophageal Obstruction (Choke)

• Et: intraluminal feed impaction at cervical, thoracic inlet, heart base, cardia

  • Poor dentition, coarse feed, feeding after exercise, pharyngeal dysfunction, neuro dx, previous choke, stricture, diverticulum, scaring, mass, megaesophagus

• Cs: Saliva/ feed from nostrils, anxious, extended neck, gagging, retching, coughing, perforation, esophagitis

• Dt: NG tube, endoscopy, US, rads

• Tx: Remove feed/water 48h (aspiration), xylazine, acepromazine, lavage stomach w/ warm h2o, esophagotomy (refract)

  • Mild choke may resolve w/ sedation

  • Can cause Esophagitis

  • Chronic: complications are stricture, diverticulum, megaesophagus, recurrent obstruction

Esophageal Lavage

• Why: choke

• How: 

  • NG tube, head lowered.

    • Never force tube past obx.

  • Warm water flush, drain repeatedly.

  • Massage bolus (if cervical)

Esophagotomy

• Why: refractory choke, FB retrieval

• How: 

  • Longitudinal incision, primary closure if healthy tissue

  • Place NG prior esophagostomy tube for feeding

  • Longitudinal esophagotomy over or below obstruction​

• Rx: antibiotics

Esophageal Perforation

• Et: prolonged choke, FB, NG tube, trauma.

• Tx: Feeding via esophagostomy tube below perforation

  • Cervical: drainage/closure

  • Thoracic: usually fatal 

Esophageal Strictures

• Et: sequela of choke, trauma, reflux esophagitis, congenital

• Cs: recurrent choke

• Dt: endoscopy, contrast rads

• Tx: balloon dilation, bougienage, esophagomyotomy, resection, grafts, soft diet

Esophageal Diverticulum

• Pulsion: defect in the muscular wall

  • mucosa/submucosa herniates through muscle defect

    • Sig: post-choke, narrow neck

    • Tx: Sx

• Traction: scar pulls wall out 

  • Sig: wide neck, shallow

  • Tx: minimal clinical impact

Megaesophagus

• Usually aquired

• Et: obx, stricture, diverticulum, idiopathic, neuro dz, dysautonomia/grass sickness

• Sig: Friesians(idiopathic)

• Cs: dilated, hypomotile esophagus

• Dt: endoscopy 

• Tx: feed slurry with horse’s head elevated

Esophagitis

• Et: Choke, reflux esophagitis, NSAIDs, cantharidin

  • gastro-duodenal ulceration in foals (mostly)

• Cs: progress to stricture/megaesophagus

Mechanisms of Intestinal Injury and Colic

• Distension/stretching and Mesenteric tension

  • Simple: intraluminal blockage, non-strangulating displacement → distention, mesenteric tension

• Ischemia

  • Strangulating: lumen + bld supply occlusion → ischemia, necrosis, perforation

  • Non-strangulating: Verminous arteritis (S. vulgaris) → arterial spasm, stenosis, embolism.

    • mesenteric artery

• Acute inflam

  • SI (enteritis): ileus, distention, reflux, endotoxemia, hypovolemia

  • LI (colitis): ileus, diarrhea, fluid loss, PLE, endotoxemia.

Colic

• Et: Distension, stretching, tension, ischemia, inflam

• Cs: fever, pain, tachycardia, weak pulse, hemoconcentration, left shift, thrombocytopenia, prolonged clotting times, dogsitting, restless, no gastric sounds 

• Dt: 

  • Nasogastric intubation: reflux suggests SI obx or gastritis

  • Rectal exam: distention, displacement, impaction, mesenteric bands, masses

  • Abd. US: distention, thick walls, displacement, sand, intussusception, hernia, colitis, peritonitis

  • Paracentesis: peritonitis, bowel compromise

• Tx: xylazine, butorphanol, flunixin, detomidine, laparotomy, NG tube, cecal trocharization, fluids, plasma, polymyxin B, cathartics, laxities

  • Restore fxn, decompress, pain relief, stabilize

Predispositions for Colic in Horses

• Foals: meconium impaction, enterocolitis, uroperitoneum

• Weanlings/yearlings: gastric ulcers, ascarid impaction, intussusception, FBs

• Adults: spasmodic, flatulent, gastric ulcers, LI impactions/displacements/volvulus, SI strangulations, typhlocolitis, verminous arteritis

• Broodmares: uterine torsion, colon displacement/torsion

• Stallions: inguinal hernia, testicular torsion

• Older/obese horses: strangulating pedunculated lipomas

• Miniatures/young: sand/hair/FB impactions

Peritoneal fluid analysis

• Normal: clear, yellow, WBC <5,000/µL, protein <2.5 g/dL

• Early obstruction: normal

• Vascular compromise: serosanguinous, ↑ protein/WBC, toxic neutrophils

• Necrosis: dark, degen neutrophils

• Rupture: brown/green, bacteria, plant matter

Colic Surgery

• What: Laparotomy

• Why: Progressive/unrelenting pain, surgical lesions, progressive peritoneal fluid changes, CV deterioration, unresponsive to Rx 

• Pre-op: stabilize CV, penicillin + gentamicin, anti-inflam, NG tube, xylazine-ketamine-GG/diazepam, gas anesthesia

• How: 

  • Ventral midline incision

  • Inspect and palpate cecum, colon, peritoneal fluid

  • Correct displacements/volvulus, decompress, resect

  • Closure with absorbable suture, belly bandage

• Px: 

  • LI simple obx: good

  • SI obx: gaurded 

  • LI torsion/volvulus: variable

Equine Gastric Ulcer Syndrome

• Et: fasting, high concentrates, stress, exercise, NSAIDs

  • Squamous ulcers: near margo plicatus, lesser curvature; acid exposure : Omeprazole

  • Glandular ulcers: pyloric antrum, proximal duodenum; mucus barrier fail : Omeprazole, sucralfate

• Cs: poor performance, girthy, cranky, inappatance, colic, bruxism, ptyalism, recumbency, diarrhea

  • foals have more CS than adults

• Dt: endoscopy, Hyperkeratosis

• Cs: ↓ stress, turnout, free-choice hay, stop grain/NSAIDs, rest, omeprazole, H2 antagonists, sucralfate, misoprostol, gastroenterostomy

  • Ranitidine: great inj in foals; H 2 blocker

• Px: Squamous > glandular

Gastric Dilatation

• Et: 

  • Primary: grain overload, excessive fermentation, gas, fluid. : increased grains(Carbs)

  • Secondary: SI obstruction,  reflux.

• Cs: colic, reflux, splenic displacement, distended SI(2ndary), rupture

• Dt: NG intubation, rectal exam, US

• Tx: decompression w/NG tube

  • leave in place if secondary

Grain Overload..

• Et: access to grain bin, rich alfalfa, lush pasture

  • Corn, barley, oats, sweet feed, commercial pellets​

• Cs: acute gastric dilation, rupture, colitis, acidosis, endotoxemia, laminitis

• Tx: gastric lavage, mineral oil, fluxin, decompress (once CS)

Gastric Impaction

• uncommon

• Et: poor dentition, coarse forage, beet pulp, persimmon seeds (phytobezoars), grain overload

  • Frisians

• Dt: US, gastroscopy, laparotomy

• Tx: crystalloid fluids, cola lavage (persimmon), massage, sx

• Px: fair to poor

Gastric Rupture

• Et: dilation, impaction

• Cs: Rapid septic peritonitis, endotoxemia, death

• Dt: US, paracentesis (feed material), necropsy

• Tx: euthanasia

Small Intestinal Adynamic Ileus

• Et: poor propulsive motility
  Dt: Enterogastric reflux (NG tube), imaging w/ distended loops

• Cs: Abdominal pain, post-op ileus, enteritis, peritonitis, neonatal weakness

• Tx: NG decompression, prokinetics, Sx

Small Intestinal Obstructions

• Abd. pain, Nasogastric reflux, SI distention 

• Simple Intraluminal 

  • Ascarid: foals (post-deworming heavy burden)

  • Ilea: Bermuda hay & tapeworms

  • FB: baling twine, plastic

• Strangulating

  • Pedunculated lipoma: old, overweight horses

  • SI volvulus: all ages

• Meckel’s diverticulum complications

  • Cs: Abdominal pain

  • Dt: Enterogastric reflux (NG tube), imaging w/ distended loops

  • Tx: Sx emerg

Adynamic Ileus

• Inhibition of propulsive bowel → functional obstruction 

• Sx complication, Enteritis

• Tx: underlying dz, supportive care: NG tube decompression, ± motility drugs

Small Intestinal Incarcerations (Entrapments)

• Et: Epiploic foramen entrapment

  • Mesenteric rents / gastrosplenic lig tears

  • Umbilical/body wall/diaphragmatic/ inguinal hernia

• Sig: cribbing

• Cs: Abdominal pain

• Dt: Enterogastric reflux (NG tube), imaging w/ distended loops

• Tx: Sx

Intussusceptions & Intestinal Adhesions

• Small Intestinal: Jejunum, jejunal-ileal, ileo-ileal, ileo-cecal 

  • Ileal-cecal: tapeworms.

  • Adhesions: post-surgery or peritonitis

  • Sig: young, hypermotility or enteritis

  • Dt: Enterogastric reflux (NG tube), imaging w/ distended loops

  • Cs: Abdominal pain

  • Tx: Sx resection/anastomosis

• Large Intestinal

  • Et: Cecal-cecal or ceco-colic.

  • Sig: young

  • Cs: severe pain, weight loss, diarrhea, mass

  • Tx: surgery

  • Px: fair-poor

Large Intestinal Impaction

• Most common: pelvic flexure or transverse colon

• Colon

  • Et: dehydration, poor teeth, coarse hay, sand, NSAIDs

  • Cs: intermittent mild colic, palpable mass(left side involved)

  • Tx: fluids, hypotonic saline, fluxin, laxatives, cathartics, psyllium, MgSO4, Sx

• Cecal: abd. rectal palpation

  • Et: ortho Sx, stall rest, NSAIDs, motility dz

  • Cs: rupture

  • Tx: aggressive fluids and laxatives!!, typhlotomy, bypass (ileocolostomy)

Sand Accumulation

• Et: sandy soil, feeding on ground

  • right dorsal colon

• Cs: colic, diarrhea, impaction, abd. pain

• Dt: sand in feces, US, rads

• Tx: psyllium, fluids, analgesics, Sx, avoid ground feeding

Enterolithiasis

• Et: Struvite (Mg-ammonium phosphate) stones in large colon

• Sig: CA, AZ, FL, IN, alfalfa diet, high mineral

• Cs: chronic colic, acute obx

• Dt: rads

• Tx: Sx removal

Dorsal Displacement of Large Intestine

• Left → can move freely “floating colon”

  • Et: Colon trapped between spleen & left kidney, nephrosplenic lig.

    • Non-strangulating 

  • Cs: mild pain

  • Dt: rectal exam, US

  • Tx: rolling, phenylephrine, controlled exercise, Sx

• Right

  • Et: Colon wrapped around cecum, displaced to right body wall

    • Non-strangulating

  • Cs: Progressive pain, distention, cardiovascular compermise 

  • Dt: rectal exam, US

  • Tx: Sx

Large Colon Volvulus/Torsion

• Et: 360° twist, ischemia

  • Twist LC at mesenteric attachment near base of the cecum

  • Twist LC at mesenteric attachment at sternal and diaphragmatic flexures

• Cs: Severe pain, rapid CV compromise

• Tx: Sx emerg

• Px: poor

Simple Obstructions of Small Colon & Rectum

• Et: impaction, Fecaliths, FB

• Sig: foals, minis

• Cs: Meconium retention

• Dt: rectal “snake”, rads

• Tx: fluids, laxatives, cathartics, pain med, decompression, Sx

Congenital Disorders affecting the Colon and Rectum

• Atresia coli: rare, fatal

• Intestinal aganglionosis

  • Aka: Lethal White Syndrome

  • Et: foals homozygous overo Paint mutation 

  • Cs: fail to pass meconium, severe colic, fatal

Rectal Conditions in Horses

• Prolapse

  • Mild (I/II): submucosa, conservative tx, osmotics, kneading

  • Severe (III/IV): insusseption of rectal wall, Sx

• Tears

  • Et: Iatrogenic

  • Id: Grades I–IV depth-based

    • I/II: mucosal, Laxatives, feed restriction, low residue feed

    • III: muscoa and serosa into mesorectum, Sx

    • IV: muscoa and serosa into peritoneum, Sx

• Strangulating/Trauma: Pedunculated lipoma, mesocolic tears, cervical tear prolapse, intramural hematoma

Proximal Enteritis

• Et: acute inflam of duodenum/proximal jejunum

  • C. difficile toxins in adults → Infection suspected

• Cs: edema, hemorrhage, trans-mural inflam, ileus, depression, fever, colic, distended SI, large gastric reflux, toxemia, hypovolemia

  • laminitis

• DDx: SI obstruction/strangulation = explore lap

• Tx: NG decompression, fluids, flunixin, plasma, antibiotics, lidocaine CRI

Acute Colitis / Typhlocolitis

• Common

• Et: bacti, viral, grain overload, antibiotics 

  • LPS translocation (100%), bacti translocation (30%)

• Cs: fever, tachycardia, injected MM, diarrhea (cowpie → watery → hemorrhagic), hypovolemia, shock, PLE, endotoxemia, acute fibrinous necrotizing colitis

  •  laminitis, renal failure, bowel infarction, peritonitis, thrombophlebitis

• Dt: hemoconcentration, left shift w/ toxic chnage, thrombocytopenia, azotemia, acidosis, ↓ protein

• Tx: Fluids, Flunixin, Antibiotics, polymyxin B, plasma, smectite, metronidazole, bismuth, digital hypothermia, frog support, sand bedding, transfaunation, hay

Salmonellosis

• Salmonella enterica enterica​ → sporatic

• Et: G-, many serovars, zoonotic 

  • nosocomial major concern

  • Invades L1 mucosa

• Cs: inapparent, fever, neutropenia, acute colitis, neonatal septicemia

• Dt: fecal PCR, culture

  • major DDx for acute typhlocolitis​

• Tx: fluids, NSAIDs, antibiotics (septicemia), biosecurity!

Clostridia-associated colitis in adults​

• Necrotizing, often hemorrhagic typhlocolitis; exotoxins

• Clostridium perfringens ​

  • Type A: sporadic & antibiotic-associated

• Clostridioides difficile (formerly Clostridium difficile)​

  • Sporadic & antibiotic-associated forms ​

  • Nosocomial infections

• Dx: fecal toxin assays

• Maintenance: Treat endotoxemia, shock, hypoproteinemia​

  • Oral metronidazole

Potomac Horse Fever

• Seasonal

• Et: Neorickettsia risticii

  • fluke larvae, bugs/aquatic snails, waterways

• Sig: Mid-Atlantic, Midwest, CA, TX, Summer

• Cs: Acute Colitis

  • Fibrinous, necrotizing typhlocolitis​

• Dt: PCR (bld, feces), paired sera

• Tx: tetracyclines, killed vaccines

Equine Coronavirus

• self-limiting

• Cs: anorexia, fever, depression, leukopenia, diarrhea, acute colitis 

• Dt: fecal PCR

• Tx: supportive

Larval Cyathostomiasis

• Et: Encysted larvae in LI mucosa mass emergence

  • small strongyles (cyathostomins)

• Sig: 2-3y, seasonal, deworming

• Cs: acute colitis

  • mass emergence of L4

• Tx: fluids, larvicidal deworming

  • moxidectin, high-dose fenbendazole

Antibiotic-associated diarrhea

• Disruption of normal flora

• Et: Dysbiosis, Salmonella, C. difficile/perfringens overgrowth

• Cs: acute colitis 

• Tx: stop antibiotics → then test, transfaunation

Grain overload

• Et: CHO fermentation

• Cs: enteric acidosis, dysbiosis, endotoxemia, acute colitis

  • acute gastritis & gastric dilatation &/or enterocolitis; med. emergency​ 

    • Laminitis = common sequelae  

• Tx: critical care + herd prophylaxis, oil, NSAIDs

Blister beetle toxicosis

• Cantharidin is a vesicant toxin

• Et: beetles or cantharidin in alfalfa hay

• Cs: colic, diarrhea, shock, hematuria, hypocalcemia, lamanitis, myocarditis

  • Multisystemic toxicosis and acute colitis 

• Dt: ↓ Ca, urine cantharidin

• Tx: fluids, mineral oil/charcoal, shock therapy

• Px: guarded

Right dorsal colitis

• Et: NSAID, PBZ, localized ulcerative dz of right dorsal colon

• Cs: chronic colic, diarrhea, ↓ protein, edema

  • Acute colitis 

• Dt: NSAID history, fecal occult blood, US thickening

• Tx: ↓ residue/psyllium/oil diet, sucralfate, misoprostol, metronidazole

Infiltrative & Inflam Bowel Disease

• Et: cellular infiltration of intestinal wall

  • Granulomatous enteritis, Lymphocytic–plasmacytic enteritis, Idiopathic focal eosinophilic enteritis, multisystemic eosinophilic dz

• Cs: weight loss, thickened bowel wall, ↓ protein, chronic diarrhea, colic

  • malabsorption and maldigestion

• Dt: Rectal palpation, US, glucose/D-xylose, biopsy

• Tx: steroids, azathioprine, larvicidal deworming, Sx (IFEE)

• Px: poor (GE, LPE, MEED), fair (IFEE)

Clostridial enterocolitis

• Et: C. perfringens A, C, C. difficile, antibiotic-associated

• Sig: Foals <1 week

• Cs: Hemorrhagic diarrhea, colic, rapid shock

• Dt: toxins assay, culture, cytology

• Tx: NPO, IV fluids, antibiotics, metronidazole, plasma, husbandry change 

• Px: poor

Foal heat diarrhea

• Sig: Healthy foals, 9-14d

• Cs: Mild diarrhea

• Tx: self-limiting

Equine Rotavirus

• The major viral diarrhea in foals

• Et: Destroys villi

• Sig: foals <2m

• Cs: Profuse watery diarrhea, malabsorption, osmotic diarrhea

• Dt: ELISA, EM

• Tx: supportive; vax mares

Rhodococcus equi enterocolitis

• Primarily causes respiratory disease

• Sig: weanlings

• Cs: pneumonia, SI/LI ulcerative enteritis, abscesses, peritonitis, diharrhea 

• Dt: US, culture/PCR

• Tx: macrolide + rifampin (long-term)

Lawsonia intracellularis

• Et: Proliferative enteropathy

• Sig: Weanlings 6m

• Cs: weight loss, edema, ↓ protein, diarrhea, thick ileum/jejunum (hose gut)

• Dt: US, PCR, serology

• Tx: tetracyclines, supportive care

Ascarids (Parascaris equorum/univalens)

• Adult Round worm → jejunum

• Et: Prepatent 10-12w

• Sig: Foals, pasture

• Cs: SI obx post-deworming, pot belly, liver/lung pathology, abd. pain!!

• Dt: US

• Tx: prevention: benzimidazoles q 60d until 12-18m

  • Macrocyclic lactone resistance

Large Strongyles

• GI bug

• Et: S. vulgaris, extra-intestinal migration

  • Rare but re-emerging

  • migrate via intestinal arterioles to the walls of mesenteric

• Cs: arteritis, infarction, peritonitis, mesenteric artery thrombosis

• Tx:  Resection, routine ivermectin

Small Strongyles

• Et: Encyst in LI mucosa, Cyathostomins

• Sig: yearling horses

• Cs: diarrhea, ill thrift

• Tx: larvicidal deworming

  • moxidectin, high-dose fenbendazole

    • resistance common

Tapeworms

• Et: At ileocecal valve, Anoplocephala perfoliata

  • oribatid mite : intermediate host

  • distal small intestine and cecum, at the ileocecal valve ​

• Cs: impaction, intussusception

• Tx: annual praziquantel, high-dose pyrantel in fall/winter

The Equine Peritoneum

• Structure:

  • Parietal: lines abdominal wall & diaphragm

  • Visceral: covers abdominal organs

  • Fluid: Clear, slightly amber, low protein (<2.5 g/dL), low cellularity (<5,000/µL)

    • Contains fibrinolytic activity, phagocytic defense

• Histo: single layer mesothelial cells + CT stroma, vessels, lymphatics, nerves

• Fxn: produces peritoneal fluid for lubrication + defense

Peritonitis

• Et: secondary dz (#1), Iatrogenic, mixed bacti (Hem/Lymph)

  • neutrophil recruitment + fibrin-rich exudate (seals defect)

• Cs: 

  • Local: min signs

  • Acute: Fever, depression, toxemia, dehydration, pain, stilted gait, septic

  • Chronic: abscesses/adhesions, recurrent colic, weight loss, fever

• Dt: Abdominocentesis

  • neutrophils, degen changes, intracellular bacti, ↓ glucose, ↑ lactate

• Tx: fluids, NSAIDs, antibiotics (sing bacti), laparotomy, lavage 

  • Acute septic = emerg Tx

  • chronic/primary = Rx

General Hepatic Injury

• subclinical dz → common

• No gallbladder, constant flow of bile into duodenum

  • Holds 10% of BV

  • Considerable regeneration potential

  • large reserve capacity → sig. liver dz w/out CS

• Et: Disruption in protein, carb, lipid metabolism

  • poor detoxification, ↓ vit/mineral storage, ↑ ammonia & toxins, hepatic encephalopathy

• Cs: Lethargy, anorexia, fever, depression, colic, endotoxemia, diarrhea, encephalopathy, jaundice, photosensitization, ventral edema, hemolysis, laryngeal paralysis, loss of BCS(chronic)

  • Ddx: biliary obx w/ R colon disp = no fever

• Dt: ↑ SDH/AST (hepatocellular injury), ↑ GGT (biliary dz),      ↑ billirubin(jaundice), ↑ bile acids, ↓ glucose, ↓ BUN, ↑ ammonia, ↓ albumin, ↑ globulins, prolonged clotting times, ↑ fibrinogen, ↑ PCV, imaging/US, biopsy

  • ↑ AST alone = mm injury / rhabdomyolysis

  • Hemolysis & hemoglobinuria = end stage!

• Tx: tx specific dz!, out of sunlight, Fluids (K+, dextrose), propofol, detomidine, ↓ protein + ↑ CHO diet, lactulose, neomycin, mineral oil, sedation as needed

• Reactive hepatopathy = 2ndary hepatopathy 

Bacterial Cholangiohepatitis & Cholelithiasis

• Calcium bilirubinate concentrations in biliary tree

• Et: Ascending G – bacteria, 2ndary SI obstruction

  • E. coli, Actinobacillus

• Cs: Fever, colic, jaundice, depression, icterus, inflammatory leukogram, abd pain, dilated bile ducts

  • Ddx: biliary obx w/ R colon disp = no fever

• Dt: Biopsy (neutrophilic periportal inflam), inflam leukogram,      ↑ GGT > ↑ AST & SDH

• Tx: medical support, Prolonged pentoxifylline, ursodiol, NSAID, Sx

• Px: Good if early; recurrent if stones remain.

Tyzzer’s Disease

• Et: Clostridium piliforme; Gram–, spore-forming

  • portal circulation / bacteremia

  • Spores: soil and adult feces

    • → sporulation in GI→ liver

• Sig: foals 1-6w

• Cs: Peracute fever, depression, diarrhea, encephalopathy

  • SEVERE Necrotizing hepatitis, myocarditis, enteritis

• Dt: Necropsy with silver stain, acidosis, low glucose, high AST

• Tx: tetracyclines 

• Px: Grave, highly fatal

Theiler’s Disease / EqPV-H 

• Et: Equine Parvovirus-Hepatitis

  • 4-12w: antitoxins, plasma, blood + horizontal transmission

• Sig: adult - most asymptomatic 

• Cs: subclinical, fulminant necrosis, encephalopathy, jaundice, “dish rag” liver, small liver

• Dt: PCR (serum = supportive, liver = diagnostic)

• Tx: Supportive 

• Px: guarded, recover or die in 7d

  • highly fatal

Equine Hepacivirus (EqHV)

• Similar to hepatitis C

• Et: Mild transient hepatitis vs persistent infection 

  • foals maintain high viremia

• Cs: 1)chronic active hepatitis / 2)fibrosis/progressive inflammation

• Dt: dont seroconvert, no ↑ liver enzymes

Pyrrolizidine Alkaloid Toxicosis

• Et: ragwort, rattleweed, houndstongue → baled into hay

  • flower + seeds (most) > leaves> stems> roots

• Path: alkaloid exposure→ pyrroles → DNA cross-linking → megalocytosis, biliary hyperplasia, bridging progressive fibrosis

  • Exposure over weeks to months

• Cs: #1 cause of liver failure, neuro, photosensitivity, colic

• Dt: Megalocytosis, biopisy, assess herd, biochem 

• Tx: no tx, eliminate source, ↑ protein diet, fluids, pentoxifylline

 Hyperlipemia & Hepatic Lipidosis

• Complication of hyperlipemia

• Et: Triglyceride mobilization → fatty infiltration of liver → failure

  • Negative energy balance

• Sig: Ponies, donkeys, obese pregnant mares

• Dt: ↑ triglycerides + hepatic signs

• Tx: manage ↑ lipids, pergolide, fluids, diet, reverse neg energy balance

Chronic Active Hepatitis / Cirrhosis

• Chronic/sustained inflammation response

• Et: Bacti (neutrophilic), immune/EqHV (lymphoplasmacytic), toxins

• Cs: acute hepatic encephalopathy, gradual/progressive fibrosis

• Dt: ↑ GGT, ↓ BUN, ↓ albumin, ↑ globulins, ↑ bile acids, polycythemia, liver biopsy

• Tx: underlying dz, antibiotics, steroids, azathioprine, ursodiol, pentoxifylline, nutrition

• Px: Poor if persistent encephalopathy, bile acids >20, severe fibrosis

Non-hepatic Hyperammonemia

• Et: Acute colitis,  bacti overgrowth, ammonia absorption

  • common in adult horses

• Cs: Diarrhea, colic, feed refusal, encephalopathy, bindless, mania

  • no liver dz

• Dt: ↑ ammonia, acidosis, ↑ lactate, ↑ glucose

  • metabolic acidosis, elevated l-lactate, hyperglycemia

Tx: Supportive, neomycin, lactulose, detomidine, propofol, crystalloid fluids (no bicarb, add KCL), sodium benzonate

Anatomical Biliary Obstructions

• Et: R dorsal displacement of colon, duodenal strictures (foals)

  • DDX cholangitis/cholelithiasis 

• Cs: Colic, jaundice, ↑ GGT/bilirubin

  • No fever

• Tx: Surgical correction

  • Duodenal strictures in foals w/ ulcerated duodenitis

Pituitary Pars Intermedia Dysfunction (“Equine Cushing’s”)

• Et: ↓ dopamine, ↑ ACTH & POMC peptides

• Middle aged - older ~ 19y over weight

  • unregulated release ACTH

  • hyperplasia Melanotropes of pituitary pars intermedia (PI) normally secrete of pro-opiomelanocortin (POMC)

    • controlled by dopaminergic neurons in the hypothalamus

• Cs: hypertrichosis, muscle wasting, PU/PD, laminitis, infections, lethargic, hair coat change, delayed shedding, insulin dysregulation

• Dt: resting ACTH, TRH stim test.

  • stress leukogram & possible steroid hepatopathy

• Tx: Pergolide (Prascend®) → dopamine agonist, low carb/high fat diet, clipping, preventive care

  • no cure 

Equine Metabolic Syndrome

• Sig: “easy keepers,” ponies, Arabians, Morgans, Mustangs

• Cs: obesity, insulin dysregulation, laminitis

• Dt: ↑ resting insulin, dynamic insulin testing

• Tx: ↓ CHO diet, restricted pasture, hay at 1.5% BW, exercise, thyroxine, metformin

  • type 2 DM

Hyperlipemia / Hyperlipidemia

• Et: fat mobilization → TG >500 mg/dL → hepatic lipidosis

  • negative energy balance

• Sig: ponies, minis, donkeys

  • Measure/monitor TGs in all sick minis

• Cs: depression, anorexia, diarrhea, colic, lipemic plasma

• Tx: dextrose, NG feeding, insulin

• Px: guarded if advanced

Misc Endocrine Disorders

• Thyroid disease: congenital goiter, iatrogenic hyperthyroidism, thyroid neoplasia.

• Parathyroid: nutritional secondary hyperparathyroidism (“big head disease”), hypocalcemia (lactation tetany, blister beetle).

• Adrenal: rare Addison’s, pheochromocytoma, anhidrosis.

• Pancreas: Type I DM rare, Type II (EMS/PPID overlap), islet cell tumors rare.