BCSE Medicine

Species-Specific Medicine – BCSE Study Guide

📅 March 28, 2026 ⏱ 30 min read

Domain 4 (Medicine) represents the LARGEST domain on the BCSE examination, comprising 50-55 questions (nearly 25% of all scored questions).

Overview and Clinical Importance

Domain 4 (Medicine) represents the LARGEST domain on the BCSE examination, comprising 50-55 questions (nearly 25% of all scored questions). This study guide focuses on species-specific medicine, covering the most high-yield conditions in canine, feline, and equine patients. Understanding species differences in disease presentation, diagnosis, and treatment is essential for BCSE success.

Small animal medicine (dogs and cats) forms the foundation of companion animal practice, while equine medicine tests your ability to manage large animal emergencies and chronic conditions. The BCSE expects integration of pathophysiology with clinical decision-making across species.

High-YieldMedicine questions often present clinical scenarios requiring you to identify the most likely diagnosis AND appropriate treatment. Know the classic presentations and first-line treatments for each species.

Breed	Clinical Presentation	Prognosis
Dobermann	Acute left-sided heart failure Ventricular arrhythmias common High incidence of sudden death	Poor - short clinical course, median survival 6-8 weeks after CHF onset
Boxer	Ventricular arrhythmias predominant May be asymptomatic initially Syncope from arrhythmias	Variable - arrhythmia control critical
Cocker Spaniel	Often longer clinical course Good response to therapy Taurine deficiency link	Better than Dobermanns with treatment
Giant Breeds	Great Danes, Irish Wolfhounds Atrial fibrillation common Subclinical phase may be prolonged	Guarded - progressive disease

ACVIM Stage	Description and Management
Stage A	At-risk breed, no murmur or structural changes. No treatment - monitor annually
Stage B1	Murmur present, no cardiomegaly. No treatment - echocardiogram every 6-12 months
Stage B2	Murmur with cardiomegaly but no clinical signs. START PIMOBENDAN (EPIC trial showed 15-month delay to CHF)
Stage C	Current or past CHF signs. Triple therapy: Pimobendan + Furosemide + ACE inhibitor. Add spironolactone if needed
Stage D	Refractory CHF. Maximize medications, consider torasemide, sildenafil for pulmonary hypertension

Diagnostic Feature	Details
Classic Radiographic Sign	'Double bubble' or 'Popeye arm' sign - compartmentalized stomach with soft tissue band separating pylorus from fundus
View Required	RIGHT LATERAL recumbent radiograph (dog's right side down) - best view to identify volvulus
Pylorus Location	Displaced cranially and dorsally, appearing on LEFT side of abdomen (normally on right)
Prognostic Indicators	Blood lactate greater than 6 mmol/L associated with gastric necrosis and worse prognosis

Aspect	Key Points
Pathogenesis	Virus targets rapidly dividing cells: intestinal crypt epithelium, bone marrow, lymphoid tissue. Results in villous collapse and severe enteritis
Diagnosis	Fecal ELISA (SNAP test) - false negatives possible early or with recent vaccination. PCR more sensitive
CBC Findings	Marked leukopenia with neutropenia (WBC often less than 2000/uL). Lymphopenia common. Thrombocytopenia possible
Treatment	Supportive care: aggressive IV fluids, antiemetics (maropitant), broad-spectrum antibiotics (sepsis risk), early enteral nutrition
Prognosis	With aggressive treatment: 85-90% survival. Without treatment: 10% survival. Young puppies and severe leukopenia have worse prognosis

Section 1: Canine Medicine

Dogs are the most commonly presented species in veterinary practice. The BCSE tests your knowledge of breed predispositions, classic presentations, and evidence-based treatment protocols.

Canine Cardiovascular Diseases

Dilated Cardiomyopathy (DCM)

Dilated cardiomyopathy is characterized by impaired ventricular function with progressive chamber dilation, typically affecting the left ventricle. It represents the most common acquired myocardial disease in large and giant breed dogs.

MEMORY TIP - DCM Breeds - 'DICE': Dobermanns, Irish Wolfhounds, Cocker Spaniels, English Springer Spaniels. These four breed groups account for most DCM cases with distinct presentations.

High-YieldDCM treatment mainstays: Pimobendan (inodilator - FIRST LINE), furosemide (diuretic), ACE inhibitor. Pimobendan has been shown to delay onset of CHF in preclinical DCM.

[Include Image: Figure 1. Echocardiogram showing dilated left ventricle with poor contractility in a dog with DCM]

Myxomatous Mitral Valve Disease (MMVD)

MMVD is the most common acquired cardiac disease in dogs, affecting primarily small and medium breeds. Characterized by progressive myxomatous degeneration of the mitral valve leaflets leading to regurgitation.

MEMORY TIP - MMVD Breeds - 'CKCS Plus Small': Cavalier King Charles Spaniel (highest prevalence), plus Dachshund, Miniature/Toy Poodle, Chihuahua, and other small breeds. Remember: Small dogs = mitral valve, Large dogs = DCM.

High-YieldThe 'EPIC' study demonstrated pimobendan significantly delays onset of CHF in Stage B2 MMVD. Key diagnostic criteria for B2: Left atrial to aortic ratio greater than 1.6 AND normalized left ventricular internal diameter in diastole greater than 1.7.

Canine Gastrointestinal Emergencies

Gastric Dilatation-Volvulus (GDV)

GDV is a life-threatening emergency where the stomach dilates and rotates on its mesenteric axis (typically 180-270 degrees clockwise). This causes gastric outflow obstruction, vascular compromise, and systemic shock.

MEMORY TIP - GDV Risk Breeds - 'Great DOGS Get GDV': Great Danes, Dobermanns, Old German Shepherd Dogs, German Pointers, Standard Poodles. All large/giant, deep-chested breeds. Dogs greater than 30 kg have 38x higher risk than dogs less than 10 kg.

MEMORY TIP - GDV Clinical Signs - 'NRTS': Non-productive retching, Restlessness/anxiety, Tympanic abdomen, Shock (weak pulses, pale gums, tachycardia). This is the classic presentation you MUST recognize.

[Include Image: Figure 2. Right lateral abdominal radiograph showing classic 'double bubble' sign of GDV]

High-YieldGDV Treatment Sequence: (1) IV fluid resuscitation with crystalloids, (2) gastric decompression (trocarization or orogastric tube), (3) surgical correction with gastropexy. Prophylactic gastropexy in at-risk breeds is HIGHLY protective against recurrence.

MEMORY TIP - GDV Surgery Steps - 'DRG': Derotate (counterclockwise), Resect (if gastric necrosis present, splenectomy if needed), Gastropexy (right-sided incisional gastropexy most common). Surgery must occur promptly - survival drops significantly with cardiovascular compromise.

Canine Infectious Diseases

Canine Parvovirus (CPV-2)

Canine parvovirus is a highly contagious viral disease causing severe hemorrhagic gastroenteritis, primarily in unvaccinated puppies 6 weeks to 6 months of age. Certain breeds (Rottweiler, Doberman, American Pit Bull Terrier, German Shepherd) show increased susceptibility.

MEMORY TIP - Parvo Classic Triad: 'VLD' - Vomiting, Lethargy, Diarrhea (hemorrhagic, foul-smelling). Remember: severe leukopenia (neutropenia) on CBC supports diagnosis.

High-YieldParvoviral myocarditis (rare today due to maternal antibodies): affects puppies infected in utero or first weeks of life. NO GI signs - presents with acute respiratory distress and CHF. Usually fatal, survivors may develop DCM.

Canine Distemper Virus (CDV)

Canine distemper is a multisystemic viral disease caused by a morbillivirus. It affects respiratory, GI, and nervous systems with high morbidity and mortality in unvaccinated dogs.

MEMORY TIP - Distemper Progression - 'RING': Respiratory signs first (nasal/ocular discharge), then Intestinal (vomiting, diarrhea), then Neurologic (myoclonus, seizures), and finally Gangrene of footpads (hyperkeratosis = 'hard pad disease').

MEMORY TIP - Distemper Neurologic Signs - 'MCTS': Myoclonus (pathognomonic rhythmic muscle twitching), Circling/head tilt, Tremors/ataxia, Seizures. Neurologic signs may appear weeks after recovery from systemic illness.

High-Yield'Old dog encephalitis' - chronic progressive distemper encephalitis occurring years after infection. Presents as progressive dementia, ataxia, visual deficits in older dogs with unknown vaccination history.

Canine Endocrine Diseases

Hypothyroidism

Hypothyroidism is the most common endocrine disorder in dogs, typically caused by immune-mediated lymphocytic thyroiditis or idiopathic thyroid atrophy. It predominantly affects middle-aged, medium to large breed dogs.

MEMORY TIP - Hypothyroid Signs - 'SLOW COLD DOG': Sluggish/lethargy, Lipid elevation (hypercholesterolemia), Obesity/weight gain, Weight loss of hair (alopecia), Cold intolerance, Obtunded mentation (tragic facial expression), Low heart rate (bradycardia), Dry skin/seborrhea.

MEMORY TIP - Hypothyroid Breeds - 'GOLD BERG': Golden Retriever, Old English Sheepdog, Labrador Retriever, Doberman, Boxer, English Setter, Rottweiler, Great Dane. All medium-large breeds with genetic predisposition.

High-YieldTreatment: Levothyroxine 0.02 mg/kg PO BID initially. Recheck T4 4-6 hours post-pill at 4-8 weeks. Target peak T4 in upper half of reference range. Clinical improvement in lethargy/activity within 1-2 weeks; skin/coat improvement takes 2-3 months.

Hyperadrenocorticism (Cushing Disease)

Hyperadrenocorticism results from chronic cortisol excess. Approximately 85% of cases are pituitary-dependent (PDH - ACTH-secreting pituitary tumor), and 15% are adrenal-dependent (functional adrenocortical tumor).

MEMORY TIP - Cushing Signs - 'PUPD HAM': Polyuria/Polydipsia (most common owner complaint), Urinary accidents/incontinence, Pot-bellied appearance, Dermatologic changes (thin skin, alopecia, calcinosis cutis), Hepatomegaly, Appetite increased (polyphagia), Muscle weakness/wasting.

MEMORY TIP - Cushing Breeds - 'PDST': Poodle, Dachshund, Small Terriers (Yorkshire, Jack Russell), These small breeds plus Boxers and Boston Terriers are predisposed. Think 'small dogs with big bellies.'

[Include Image: Figure 3. Dog with Cushing disease showing characteristic pot-bellied appearance, thin skin, and bilateral truncal alopecia]

High-YieldTreatment: PDH - Trilostane (preferred, reversible enzyme inhibitor) or mitotane. Adrenal tumor - adrenalectomy if no metastasis. Trilostane requires ACTH stim monitoring to avoid hypoadrenocorticism.

Diabetes Mellitus

Dogs typically develop insulin-dependent (Type 1-like) diabetes mellitus from immune-mediated beta cell destruction or pancreatitis. Unlike cats, diabetic remission is rare in dogs, requiring lifelong insulin therapy.

MEMORY TIP - Diabetes Classic Signs - 'The 4 Ps': Polyuria, Polydipsia, Polyphagia, and weight loss (Poor body condition despite good appetite). These are the hallmark clinical signs across species.

MEMORY TIP - Diabetic Dog Breeds - 'SAMP': Samoyeds, Australian Terriers, Miniature Schnauzers/Poodles, Pugs. Intact females have higher risk due to progesterone-induced insulin resistance during diestrus.

High-YieldDiabetic Ketoacidosis (DKA) is a life-threatening complication. Signs: severe dehydration, vomiting, Kussmaul respirations, fruity breath, ketonuria. Treatment priorities: (1) IV fluid resuscitation, (2) short-acting regular insulin (low-dose CRI 0.05-0.1 U/kg/hr), (3) electrolyte correction (potassium!), (4) identify/treat precipitating cause.

Diagnostic Test	Interpretation
Total T4 (TT4)	Screening test - LOW in hypothyroidism. If normal, hypothyroidism unlikely. If low, may be from non-thyroidal illness (euthyroid sick syndrome)
Free T4 by equilibrium dialysis	More accurate than TT4, less affected by non-thyroidal illness. LOW confirms diagnosis when TSH elevated
TSH	Elevated in primary hypothyroidism (negative feedback lost). Combined low T4 + elevated TSH = strong diagnosis
Thyroglobulin autoantibodies	Positive in lymphocytic thyroiditis (50-60% of cases). Useful for breeding decisions in predisposed breeds

Diagnostic Test	Interpretation
Urine Cortisol:Creatinine Ratio	Screening test - NORMAL ratio rules OUT Cushing with high negative predictive value. ELEVATED ratio requires confirmatory testing
Low-Dose Dexamethasone Suppression	GOLD STANDARD screening test. Normal dogs suppress cortisol less than 1.4 ug/dL at 8 hours. Cushing dogs fail to suppress. Some PDH cases show partial suppression at 4 hours
ACTH Stimulation Test	Best for iatrogenic Cushing (will show blunted response). Less sensitive than LDDS for natural disease. ONLY test to diagnose iatrogenic HAC
High-Dose Dexamethasone Suppression	DIFFERENTIATES PDH vs adrenal tumor. PDH usually suppresses (less than 50% baseline), adrenal tumors do NOT suppress
Abdominal Ultrasound	Bilaterally enlarged adrenals = PDH. Unilateral mass with contralateral atrophy = adrenal tumor

Aspect	Key Information
Diagnosis	Persistent fasting hyperglycemia (greater than 200 mg/dL) WITH glucosuria. Rule out stress hyperglycemia with fructosamine (elevated if chronic)
Initial Insulin	Start with intermediate-acting insulin (NPH, Vetsulin/Caninsulin) at 0.25-0.5 U/kg BID with meals. Adjust based on glucose curves
Monitoring Goal	Blood glucose between 100-250 mg/dL throughout day. Avoid hypoglycemia (less than 80 mg/dL) - more dangerous than mild hyperglycemia
Concurrent Disease	ALWAYS evaluate for Cushing disease, UTI, and pancreatitis. These cause insulin resistance and must be addressed

Diagnostic Test	Clinical Interpretation
Total T4 (TT4)	Elevated in most cases - the primary screening test. HOWEVER, may be normal in early disease or with concurrent non-thyroidal illness
Free T4 (fT4)	More sensitive than TT4, helpful when TT4 is borderline high-normal in a clinically suspicious cat. May be falsely elevated in euthyroid sick cats
TSH	Suppressed in hyperthyroidism. Useful when combined with TT4 for equivocal cases
Technetium scan	Gold standard for localization before surgery/I-131. Identifies unilateral vs bilateral, ectopic tissue, possible carcinoma (asymmetric/large uptake)
Blood pressure	Check in ALL hyperthyroid cats - 15-20% are hypertensive. Target BP less than 160 mmHg systolic. Treat with amlodipine if elevated

Section 2: Feline Medicine

Cats are unique patients with distinct disease presentations and drug sensitivities. The BCSE tests your understanding of feline-specific conditions and species differences in treatment protocols. Remember: cats are NOT small dogs!

MEMORY TIP - Feline Drug Sensitivities - 'FATE': Fluoroquinolones (retinal toxicity), Acetaminophen (TOXIC - avoid!), Tetracyclines (esophageal strictures - give with food/water), Essential oils (hepatotoxic). These are critical safety concerns unique to cats.

Feline Endocrine Diseases

Hyperthyroidism

Hyperthyroidism is THE most common endocrine disorder of cats, affecting primarily middle-aged to older cats (greater than 8 years). It is caused by functional benign adenomatous hyperplasia or adenoma of the thyroid gland (bilateral in 70% of cases). Thyroid carcinoma accounts for less than 3% of cases.

MEMORY TIP - Hyperthyroid Cat Signs - 'THIN HUNGRY CAT': Tachycardia/heart murmur, Hyperactive/restless, Increased appetite (polyphagia), Neck mass (palpable thyroid), Hypertension possible, Unkempt coat, Nervous behavior, GI signs (vomiting/diarrhea), Racing heart, Yowling (especially at night), Cachexia (weight loss despite eating), Anxious, Thirst increased (PU/PD).

High-YieldTHE CRITICAL COMPLICATION: Hyperthyroidism MASKS chronic kidney disease (CKD). Elevated GFR from hyperthyroidism artificially lowers creatinine. After treatment, GFR normalizes and CKD may be unmasked. ALWAYS recheck renal values 2-4 weeks post-treatment.

MEMORY TIP - Hyperthyroid Treatment Options - 'MAIDS': Methimazole (medical management - most common first-line), Antithyroid diet (Hill's y/d - iodine restricted), I-131 radioiodine (CURATIVE, gold standard), Diet modification, Surgery (thyroidectomy - curative but anesthesia risk).

[Include Image: Figure 4. Cat with hyperthyroidism showing weight loss, unkempt coat, and palpable thyroid nodule]

Chronic Kidney Disease (CKD)

CKD is extremely common in older cats, affecting approximately 30% of cats over 15 years of age. It is characterized by irreversible structural and functional loss of nephrons with progressive decline in GFR.

MEMORY TIP - CKD Signs - 'WET CAT': Weight loss, Excessive thirst (polydipsia), Tiredness/lethargy, Changes in appetite (decreased), Altered urination (polyuria), Thin/poor body condition.

High-YieldSDMA (symmetric dimethylarginine) increases earlier than creatinine in CKD - can detect 40% loss of renal function. Use SDMA for early detection, especially in geriatric screenings.

MEMORY TIP - CKD Management - 'FLUID CARE': Fluid therapy (SC fluids at home for dehydration), Limit phosphorus (renal diets, phosphate binders), Urinary protein assessment (UPC ratio), Investigate for hypertension, Diet modification (renal-specific), Correct anemia (if needed with ESAs), Address nausea (antiemetics), Rehydrate when needed, Electrolyte monitoring.

Feline Infectious Diseases

Feline Leukemia Virus (FeLV)

FeLV is a retrovirus causing immunosuppression, anemia, lymphoma, and other neoplasias. Transmitted through prolonged close contact (grooming, shared food/water), bites, and in utero. Progressively infected cats have a median survival of 2-3 years.

MEMORY TIP - FeLV Testing Strategy - 'SNAP then PCR': SNAP tests detect p27 antigen in blood (screening test). If positive, confirm with PCR (identifies proviral DNA in blood cells). Discordant results suggest regressive infection. Retest in 30 days if initial positive.

MEMORY TIP - FeLV Outcomes - 'RIPA': Regressive infection (virus eliminated, antibodies present), Incomplete infection (latent, may reactivate), Progressive infection (persistent viremia, disease develops), Abortive infection (never viremic, exposure only).

Feline Immunodeficiency Virus (FIV)

FIV is a lentivirus (similar to HIV) causing progressive immune dysfunction. Primary transmission is through bite wounds, making intact male outdoor cats at highest risk. Unlike FeLV, FIV-positive cats may live normal lifespans with proper care.

MEMORY TIP - FIV Risk Profile - 'BITING TOM': Think intact male cats that fight - outdoor, unneutered, territorial males are the classic FIV patient. B = Bites transmit virus, T = Tom cats (intact males), O = Outdoor lifestyle, M = Male predominance.

High-YieldTest ALL cats for FeLV and FIV at time of acquisition and after potential exposure. FIV antibody tests may be positive in vaccinated cats or kittens with maternal antibodies - retest kittens at 6 months of age.

Feline Urinary Disorders

Feline Lower Urinary Tract Disease (FLUTD)

FLUTD is an umbrella term for disorders affecting the bladder and urethra of cats. Feline idiopathic cystitis (FIC) accounts for 55-65% of cases in cats under 10 years old. Urethral obstruction ('blocked cat') is a life-threatening emergency.

MEMORY TIP - FLUTD Causes - 'STUPIN': Stones (urolithiasis - 15-25%), Tumor (rare), Urethral plug/obstruction, Plugs (mucous/crystalline), Idiopathic cystitis (FIC - most common), iNfection (UTI - rare in young cats, more common in older/female cats).

MEMORY TIP - Blocked Cat Emergency Signs - 'STRAINING MALE': Male cats (98% of obstructions are male due to longer, narrower urethra). Signs: Straining to urinate, Tense painful bladder, Repeated trips to litterbox, Absent or small urine output, In distress/vocalizing, No appetite, Groggy/depressed if prolonged.

High-YieldUrethral obstruction treatment sequence: (1) Stabilize cardiovascular status, (2) Treat hyperkalemia if present, (3) Relieve obstruction (urinary catheter - always use closed collection), (4) IV fluids for post-obstructive diuresis, (5) Maintain catheter 24-72 hours, (6) Long-term management of underlying cause.

Treatment	Key Points
Methimazole	Start 2.5 mg PO BID, recheck TT4 and renal values in 2-4 weeks. Side effects: GI upset, facial pruritus, hepatotoxicity, bone marrow suppression. Requires lifelong treatment
Radioiodine (I-131)	Single injection destroys hyperactive thyroid tissue. 95% cure rate. Requires specialized facility and 1-2 week isolation. PREFERRED CURATIVE OPTION
Thyroidectomy	Surgical removal of affected lobe(s). Risk of parathyroid damage leading to hypocalcemia. Monitor calcium for 5-7 days post-op
Diet (Hill's y/d)	Iodine-restricted diet as sole food source. Effective but requires strict compliance - no treats or other foods. Not curative

IRIS Stage	Creatinine (mg/dL)	SDMA (ug/dL)	Clinical Status
Stage 1	Less than 1.6	Less than 18	Non-azotemic, other abnormalities present
Stage 2	1.6-2.8	18-25	Mild azotemia, may be subclinical
Stage 3	2.9-5.0	26-38	Moderate azotemia, clinical signs common
Stage 4	Greater than 5.0	Greater than 38	Severe azotemia, uremia, poor prognosis

Feature	FeLV	FIV
Virus type	Gammaretrovirus	Lentivirus
Primary transmission	Prolonged close contact, vertical transmission	Bite wounds (fighting)
At-risk population	Young cats, multi-cat households	Adult intact males, outdoor cats
Associated neoplasia	Lymphoma, leukemia (much higher risk)	B-cell lymphoma (lower risk than FeLV)
Prognosis	Progressive infection: 2-3 year median survival	Often live normal lifespan with indoor care
Vaccine available	Yes - recommended for at-risk cats	Yes - but testing before vaccination important

Finding	Clinical Significance
Hyperkalemia	Life-threatening - K greater than 7-8 mEq/L causes cardiac arrhythmias/arrest. ECG changes: peaked T waves, bradycardia, absent P waves. TREAT FIRST with calcium gluconate (cardioprotection) and insulin/dextrose
Post-obstructive diuresis	After relief, massive diuresis occurs. May lose 50-100 mL/hr urine. Requires aggressive IV fluid replacement (2-3x maintenance) for 24-48 hours
Azotemia (postrenal)	BUN and creatinine elevated from obstruction. Should normalize rapidly (24-48 hours) after relief. Persistent elevation suggests concurrent renal injury
Re-obstruction risk	20-40% of cats re-obstruct within 6 months. Environmental modification and stress reduction critical. Consider perineal urethrostomy for recurrent obstruction

Section 3: Equine Medicine

Equine medicine presents unique challenges due to the horse's large size, hindgut fermentation physiology, and high-performance demands. The BCSE tests your ability to manage equine emergencies (particularly colic) and common chronic conditions.

High-YieldColic is THE most important equine topic for the BCSE. It is the leading cause of death in horses aged 1-20 years. Master the clinical assessment, differentiation of medical vs surgical cases, and emergency stabilization.

Equine Gastrointestinal Emergencies

Equine Colic - Overview

Colic is a clinical sign of abdominal pain, not a diagnosis. It represents numerous potential conditions from simple gas distension to life-threatening strangulating lesions. The primary practitioner must rapidly determine if medical management is appropriate or if surgical referral is indicated.

MEMORY TIP - Colic Assessment - 'PRNS' Physical Exam: Pulse (heart rate - most important single parameter), Rectal exam (essential - feel for displacement, impaction, distension), Nasogastric intubation (reflux indicates proximal obstruction), Sound (gut sounds - absent or hypermotile).

MEMORY TIP - Surgical Colic Indicators - 'SURGICAL': Severe unrelenting pain, Unresponsive to analgesia, Reflux (more than 4L nasogastric), Gut sounds absent, Increased heart rate (greater than 60), Cardiovascular deterioration, Abdominocentesis abnormal (serosanguinous fluid, elevated lactate), Lack of fecal output.

[Include Image: Figure 5. Lateral abdominal radiograph of horse showing large colon distension with gas-fluid interface typical of colonic displacement]

Common Colic Types

High-YieldNasogastric reflux greater than 4 liters indicates proximal GI obstruction (stomach, duodenum, jejunum). This is a surgical indicator - DO NOT administer oral fluids or allow the horse to eat/drink. Decompress stomach and refer.

MEMORY TIP - Peritoneal Fluid in Colic - 'COLOR TELLS': Clear yellow = normal or early. Serosanguinous = intestinal compromise/strangulation. Orange/turbid = peritonitis. Feculent = bowel rupture (grave prognosis). Lactate greater than 2.0 mmol/L in peritoneal fluid suggests intestinal ischemia.

Equine Laminitis

Laminitis is inflammation of the sensitive laminae of the hoof, resulting in failure of the bond between the hoof wall and the third phalanx (P3/coffin bone). It represents one of the most significant welfare concerns in equine medicine and can be career-ending or fatal.

MEMORY TIP - Laminitis Causes - 'SECS': Sepsis/Systemic inflammation (grain overload, retained placenta, colitis), Endocrine disease (Equine Metabolic Syndrome, PPID/Cushing), Contralateral limb overload (supporting limb laminitis), Steroid administration (controversial but possible contributor).

MEMORY TIP - Laminitis Stance - 'ROCKED BACK': The classic laminitis stance - horse rocks weight back onto hindquarters to relieve pressure on painful front feet. Front feet placed forward, hind feet underneath body. Reluctant to move, may be recumbent in severe cases.

[Include Image: Figure 6. Lateral radiograph of equine foot showing P3 rotation and increased founder distance in chronic laminitis]

High-YieldEndocrinopathic laminitis (from EMS or PPID) is now the MOST COMMON cause of laminitis. Hyperinsulinemia is the key driver - insulin greater than 188 uU/mL is a poor prognostic indicator. Always test for underlying endocrine disease in laminitis cases.

Equine Endocrine Diseases

Equine Metabolic Syndrome (EMS)

EMS is characterized by insulin dysregulation (hyperinsulinemia and/or tissue insulin resistance), obesity or regional adiposity, and a predisposition to laminitis. It typically affects middle-aged (5-15 years) horses and ponies.

MEMORY TIP - EMS Features - 'FAT CRESTY PONY': Think of the classic 'easy keeper' with a cresty neck and fat pads despite little feed. Breeds: Ponies, Morgans, Paso Finos, Arabians. Fat deposits: nuchal ligament (cresty neck), tailhead, sheath/mammary.

Pituitary Pars Intermedia Dysfunction (PPID/Cushing Disease)

PPID results from degeneration of dopaminergic neurons in the hypothalamus, leading to loss of inhibition of the pituitary pars intermedia. This causes overproduction of POMC-derived peptides (ACTH, alpha-MSH, beta-endorphin). It affects primarily horses over 15 years of age.

MEMORY TIP - PPID Signs - 'HIRSUTE OLD HORSE': Hirsutism (long curly coat that fails to shed - PATHOGNOMONIC), Infections (recurrent, delayed healing), Regional/generalized muscle wasting, Sweating (hyperhidrosis), Urination increased (PU/PD), Infertility, Tiredness/lethargy, Eyes (supraorbital fat loss gives aged appearance).

[Include Image: Figure 7. Horse with PPID showing characteristic hirsutism with long, curly coat that has failed to shed]

High-YieldPPID and EMS can occur concurrently. Horses with PPID have higher laminitis risk when concurrent hyperinsulinemia is present. Always assess insulin status in PPID patients. Control both conditions to minimize laminitis risk.

Equine Respiratory Diseases

Equine Asthma (formerly RAO/COPD/Heaves)

Equine asthma is a spectrum of inflammatory airway disease, ranging from mild/moderate (previously IAD) to severe (previously RAO/heaves). It is characterized by airway inflammation, bronchoconstriction, and mucus accumulation, triggered by environmental allergens.

MEMORY TIP - Equine Asthma Signs - 'HEAVES': Heave line (hypertrophied external abdominal oblique muscles from expiratory effort), Expiratory dyspnea with abdominal push, Audible wheezes, Visible nasal flare, Exercise intolerance, Seasonal or environmental triggers.

High-YieldStrangles (Streptococcus equi subsp. equi) - highly contagious upper respiratory infection with lymph node abscessation. Signs: fever, nasal discharge, submandibular/retropharyngeal lymph node swelling and abscessation. Treatment: supportive care, allow abscesses to drain. DO NOT give antibiotics unless signs of complications (bastard strangles). Strict isolation required.

Species Comparison Overview

Critical Memory Tips Summary

DCM Breeds (DICE): Dobermanns, Irish Wolfhounds, Cocker Spaniels, English Springer Spaniels
GDV Risk (Great DOGS Get GDV): Great Danes, Dobermanns, Old German Shepherds, German Pointers, Standard Poodles
Hypothyroid Signs (SLOW COLD DOG): Sluggish, Lipid elevation, Obesity, Weight loss of hair, Cold intolerance, Obtunded, Low HR, Dry skin
Cushing Signs (PUPD HAM): Polyuria/Polydipsia, Urinary accidents, Pot-belly, Dermatologic changes, Hepatomegaly, Appetite increased, Muscle weakness
Hyperthyroid Cat (THIN HUNGRY CAT): Tachycardia, Hyperactive, Increased appetite, Neck mass, Hypertension, Unkempt coat, Nervous, GI signs, Racing heart, Yowling, Cachexia, Anxious, Thirst increased
Blocked Cat (STRAINING MALE): Male cats, Straining, Tense bladder, Repeated trips, Absent urine output, In distress, No appetite, Groggy/depressed
PPID Signs (HIRSUTE OLD HORSE): Hirsutism (pathognomonic), Infections, Regional muscle wasting, Sweating, Urination increased, Infertility, Tiredness, Eyes (aged appearance)
Surgical Colic Indicators (SURGICAL): Severe pain, Unresponsive to analgesia, Reflux greater than 4L, Gut sounds absent, Increased HR greater than 60, Cardiovascular deterioration, Abdominocentesis abnormal, Lack of fecal output

Heart Rate	Clinical Interpretation
Less than 40 bpm	Normal range - mild colic, good prognosis with medical management
40-60 bpm	Moderate pain - requires close monitoring, may need surgical evaluation
60-80 bpm	Severe pain - concerning for surgical lesion, cardiovascular compromise beginning
Greater than 80 bpm	Cardiovascular shock - likely strangulating lesion, emergency surgery indicated, guarded prognosis

Colic Type	Key Features	Diagnosis	Treatment
Spasmodic Colic	Mild-moderate intermittent pain, hypermotile gut sounds, rapid response to analgesics	Clinical signs, response to treatment, exclusion of others	Buscopan, flunixin, walk horse. Most resolve quickly
Large Colon Impaction	Mild-moderate pain, decreased fecal output, palpable impaction at pelvic flexure on rectal	Rectal palpation, transabdominal ultrasound	Enteral fluids via NG tube, IV fluids, analgesics. Surgery if medical fails
Left Dorsal Displacement	Large colon trapped over nephrosplenic ligament, mild-moderate recurrent pain	Rectal: colon missing from normal position. Ultrasound: colon dorsal to spleen	Phenylephrine + jogging, rolling under anesthesia, or surgery
Right Dorsal Displacement	Large colon between cecum and body wall, moderate-severe pain, more serious	Rectal: tight gas-distended bands. Ultrasound helpful	Usually requires surgical correction
Large Colon Volvulus	EMERGENCY - severe unrelenting pain, rapid cardiovascular deterioration, 180-360 degree rotation	Clinical signs, nasogastric reflux, serosanguinous peritoneal fluid	Emergency surgery. Prognosis guarded - survival 55-75% with surgery
Small Intestinal Strangulation	Severe pain, nasogastric reflux (greater than 4L), small intestine distension on rectal/ultrasound	Reflux, ultrasound shows multiple distended SI loops, abdominocentesis	Emergency surgery - resection/anastomosis if needed

Clinical Sign	Description
Bounding digital pulses	Easily palpable, strong pulses in digital arteries at fetlock or pastern. Present bilaterally in most cases
Heat in hoof wall	Increased temperature of hoof wall, especially at coronary band. Compare to a normal horse or unaffected feet
Pain to hoof testers	Positive response, especially at toe region. Compare to heel region which is often less painful
Obel lameness grade	Grade 1: shifts weight, walks normally. Grade 2: walks willingly but stilted gait. Grade 3: reluctant to move, resists lifting feet. Grade 4: refuses to move, may be recumbent
Radiographic changes	Rotation: P3 rotates away from hoof wall (angle greater than 5 degrees). Sinking: entire P3 moves distally. Founder distance increased. Look for gas lines in severe cases (poor prognosis)

Feature	EMS	PPID
Typical age	5-15 years (middle-aged)	Greater than 15 years (geriatric)
Body condition	Obese with regional adiposity (cresty neck, fat pads)	Often thin with muscle wasting despite normal/increased appetite
Hair coat	Normal	Hirsutism - long, curly coat that fails to shed (pathognomonic)
Primary diagnostic test	Oral sugar test or IV insulin tolerance test (assess insulin response)	Basal ACTH (seasonal variation - highest in autumn) or TRH stimulation test
Laminitis risk	High - hyperinsulinemia directly causes laminitis	High - especially if concurrent hyperinsulinemia present
Treatment	Diet (low NSC hay, no grain), exercise, weight loss. Metformin may help some cases	Pergolide (dopamine agonist) - start low (0.5-1 mg/day) and titrate to effect

Treatment Component	Details
Environmental management	MOST IMPORTANT - remove from dusty environment. Turnout is ideal. Low-dust bedding, soaked/steamed hay, good ventilation. May need complete pasture turnout
Corticosteroids	Systemic (dexamethasone) for acute severe cases. Inhaled (fluticasone, beclomethasone) for long-term management using spacer devices
Bronchodilators	Clenbuterol (oral) or albuterol (inhaled) for bronchoconstriction. Often used with corticosteroids for acute episodes

Condition	Canine	Feline	Equine
Most common heart disease	MMVD (small breeds), DCM (large breeds)	Hypertrophic cardiomyopathy (HCM)	Mitral valve disease, atrial fibrillation
Thyroid disorder	Hypothyroidism (common)	Hyperthyroidism (common)	Rare - PPID affects pituitary
Adrenal disorder	Hyperadrenocorticism/Cushing (common)	Rare	PPID (pituitary-based, similar to Cushing)
Diabetes pattern	Type 1-like, insulin-dependent, no remission	Type 2-like, may achieve remission with diet/glargine	Rare - EMS causes insulin dysregulation
GI emergency	GDV (gastric dilatation-volvulus)	Urethral obstruction, linear foreign body	Colic (many types)

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Species-Specific Medicine &ndash; BCSE Study Guide