Thursday, October 6, 2016



This 4-part series on the top 20 equine conditions will set you up for NAVLE® success.


Click here if you missed parts 1, 2, or 3.


Check out the new “Top 20 Topics” archive homepage!


5 more of Zuku's top 20 equine conditions to know for NAVLE® success:

  1. Atrial fibrillation (AF)

                    ECG from a horse with atrial fibrillation

    • Classic case:
      • Athletic horses: exercise intolerance, exercise-induced epistaxis
      • Pleasure or idle horses: incidental finding
    • Dx:
      • Irregularly irregular heartbeat ausculted
      • Electrocardiogram (ECG) confirms diagnosis
        • No P waves; instead fibrillation (f) waves with relatively normal-appearing QRS complexes
        • Irregular R–R interval
    • Rx:
      • Don't treat arrhythmia if underlying cardiac disease (it won't work and increased risk of fatal arrhythmia) or horse is retired
      • Do treat if no underlying cardiac disease ("lone" AF) & desire athletic performance
        • Medical cardioversion: quinidine IV or PO
        • Transvenous electrical cardioversion: requires general anesthesia
    • Pearls:
      • Prognosis good if "lone" AF, poor for athletic performance if AF is secondary to underlying cardiac disease
      • Large atrial size & high vagal tone predisposes normal horses

  2. Equine gastric ulcer syndrome (EGUS)

                    Pyloric glandular gastric ulceration (note hyperemic areas around central pylorus)

    • Classic case:
      • Can be inapparent
      • Colic, inappetance
      • Weight loss
      • Ill thrift
      • "Grumpiness," especially during girthing
    • Dx: Only definitive diagnostic is fasting gastroscopy
      • Grading systems based on number and severity of ulcers
      • Squamous ulceration: most common site is squamous mucosa of lesser curvature just proximal to margo plicatus
      • Glandular ulceration: most common site is pylorus
    • Rx:
      • Proton pump inhibitors (omeprazole) = gold standard
      • H2-receptor antagonists (ranitidine)
      • Frequent feeding (turnout) & decrease stress
    • Pearls:
      • Prognosis: excellent with appropriate Rx and management changes
      • Glandular ulcers more difficult to treat than squamous
      • Very common! At least 60% performance horses have EGUS
      • Performance horses under constant transport & training stress may require prophylactic Rx

  3. Esophageal obstruction

                    Bilateral feed/salivary nasal discharge may be seen with esophageal obstruction

    • Classic case:
      • Ptyalism
      • Feed material /saliva out of nostrils
      • Retching, coughing
      • Palpable lump in esophageal area
    • Dx:
      • Clinical signs usually diagnostic
      • Unable to gently pass nasogastric tube
      • Advanced cases: esophageal endoscopy, ultrasound
    • Rx:
      • Withhold feed & water
      • Sedation, spasmolytic agents (e.g., Buscopan®), NSAIDs
      • Pass nasogastric tube & lavage esophagus (make sure head low) if not resolved in 4–6 h
      • Prophylactic antimicrobials against aspiration pneumonia
      • Severe, prolonged cases may require IV fluids, anesthesia, or surgical intervention (esophagotomy)
    • Pearls:
      • Prognosis excellent for 1st-time/uncomplicated cases
      • Older horses with dental issues prone to this problem
      • Complications: aspiration pneumonia; esophageal stricture, diverticulum, or rupture
      • Improper layperson's term is "choke"

  4. Lower airway inflammatory diseases

                    Administering inhaled medication to a horse with lower airway inflammatory disease

    • Classic case:
      • 2 most common types have similar clinical signs: chronic cough, mucoid/mucopurulent nasal discharge, exercise intolerance
      • Recurrent airway obstruction (RAO, heaves):
        • Older horse with a "heave line" (muscle definition from abdominal expiration)
        • Wheezing
        • Tachypnea at rest during episodes
      • Inflammatory airway disease (IAD):
        • Any age horse but usually younger performance horse
        • NO tachypnea at rest
    • Dx:
      • Bronchoalveolar lavage (BAL): increased percentage of inflammatory cells (neutrophils for RAO, neutrophils/mast cells/eosinophils for IAD)
      • Endoscopy is supportive: shows increased tracheal mucus
    • Rx:
      • Environmental management = most important!
        • Decrease dust and allergens
      • Medications: systemic or inhaled, 2-pronged:
        • Corticosteroids: antiinflammatory
        • Bronchodilators: open airways
    • Pearls:
      • Prognosis good with environmental modification
        • Guarded prognosis if chronic, poorly managed RAO
      • RAO is similar to human asthma
      • 3 components of RAO: mucus production, bronchospasm, and neutrophil accumulation

  5. Colic

                    Obtaining nasogastric reflux from a colicky horse

    • Classic case:
      • Abdominal pain: rolling, pawing, looking at side, stretching, kicking at abdomen, recumbency, groaning
      • Tachycardia & tachypnea
      • Decreased appetite & fecal passage
      • Shock in severe cases
    • Dx: Goal = ID part of the GI tract involved & type of colic
      • Physical exam: pain level, HR, RR, GI sounds, mucous membrane color & hydration
      • Abdominal palpation per rectum: location and dilation of GI tract
      • Pass nasogastric tube (NGT): abnormal if > 2 L net reflux
      • Abdominal ultrasound: location, motility, and dilation of GI tract; peritoneal fluid evaluation
      • Abdominocentesis: increased total protein, serosanguineous color, and high lactate suggest need for surgery
    • Rx:
      • Sedatives and analgesics: alpha-2 agonists and opioids, NSAIDs
      • Parasympatholytics (Buscopan®): for spasmodic colic
      • NGT: decompression +/- enteral fluids (+/- electrolytes, laxatives) if no significant reflux
      • IV fluids
      • Surgery: exploratory laparotomy if pain repeatedly refractory to analgesics and/or exam suggests strangulating lesion
    • Pearls:
      • Prognosis variable depending on lesion: e.g., good for basic medical colic vs. guarded for strangulating lesion in shocky horse with large amount of small intestine resected
      • Colic types divided into:
        • Medical vs. surgical
        • Small intestinal vs. large intestinal
        • Strangulating vs. nonstrangulating
      • 3 most common types encountered in practice:
        • Spasmodic/gas colic
        • Impaction colic
        • Strangulating obstruction (e.g., large colon volvulus, strangulating lipoma)
      • Specific types common in certain horses:
        • Large colon volvulus in broodmares
        • Fecaliths in miniature horses
        • Lipomas in old horses
        • Enteroliths in Arabians

owl    Zuku-certified bodacious websites on equine conditions:

The Equine Heart: Power Plant Unequaled!

Courtesy of UC Davis School of Vet Med.

Terrific comprehensive overview of equine cardiology with great gross images and ECGs.

 ACVIM Consensus Statements

Learn about IAD, equine cardiovascular diseases, and EGUS.

The MOST current and comprehensive information on these common equine conditions from the specialists!

Current treatment options for small airway inflammatory disease

Courtesy of Tufts University Cummings School of Vet Med.

Excellent practical overview of Rx for heaves and IAD.

The Glass Horse

A brief free look at this very cool 3-D way to learn equine anatomy.

"A horse doesn't care how much you know, until he knows how much you care."

– Pat Parelli



Example of NAVLE®-format equine question:

A 4-year-old Standardbred gelding is presented with a 4-week history of exercise intolerance and recent history of pulling up abruptly in a race. An irregularly irregular heart rhythm was auscultated during a physical exam.
Temp = 100.7°F (38.1°C) [Normal = 99.0–100.6°F, 37.2–38.1°C]
HR=32 bpm [Normal = 28-40 bpm]
BR=12 brpm [Normal = 10-14 brpm]
An echocardiogram does not reveal any abnormalities.
An electrocardiogram (ECG) is performed and shown below.
Which one of the following choices is the correct prognosis for this patient?


   A. Unknown without further workup

   B. Good

   C. Fair

   D. Poor

   E. Grave

Click here for the answer and explanatory text…




Images courtesy of Dr. Stephanie Brault (ECG, horse with inhaler), Dr. Diana Hassel (nasal discharge), Paul (race horses), Dr. Nora Grenager (nasogastric reflux, glandular ulceration), 4028mdk09 (rolling horse).