Domain 4 (Medicine) is the LARGEST domain on the BCSE, comprising nearly 25% of all exam questions (50-55 questions).
Overview and Clinical Importance
Domain 4 (Medicine) is the LARGEST domain on the BCSE, comprising nearly 25% of all exam questions (50-55 questions). This guide covers four critical body system categories that frequently appear on the examination: endocrine diseases, neurological disorders, musculoskeletal conditions, and dermatological diseases. These topics require integration of pathophysiology, clinical recognition, diagnostic approaches, and therapeutic management across multiple species.
High-YieldMedicine questions test your ability to integrate basic science knowledge with clinical application. Focus on etiology, pathophysiology, clinical signs, diagnosis, and treatment protocols across ALL species.
| Feature |
Canine DM |
Feline DM |
| Primary Type |
Type 1-like (insulin-dependent) - immune-mediated beta cell destruction |
Type 2-like (insulin resistance) - amyloid deposition, beta cell exhaustion |
| Risk Factors |
Genetics, pancreatitis, immune-mediated disease, obesity |
Obesity (number one risk), physical inactivity, certain breeds (Burmese), age greater than 6 years |
| Sex Predisposition |
Unspayed females (2x risk due to progesterone-induced insulin resistance) |
Male cats (1.5-2x more common) |
| Remission Potential |
Rare - most dogs are permanently insulin-dependent |
25-50% can achieve remission with early, aggressive treatment |
| Concurrent Disease |
Hypothyroidism, hyperadrenocorticism, pancreatitis |
Hypersomatotropism (acromegaly) causes 25% of feline DM cases in UK studies |
| Preferred Insulin |
Porcine lente (Vetsulin), NPH insulin |
Glargine (Lantus) or PZI - longer duration preferred |
| Diagnostic Test |
Interpretation |
| Blood Glucose |
Persistent hyperglycemia greater than 200 mg/dL (dogs) or greater than 250-300 mg/dL (cats - higher due to stress hyperglycemia) |
| Fructosamine |
Reflects average glucose over 2-3 weeks. Elevated values greater than 400 umol/L confirm persistent hyperglycemia. Not affected by stress. |
| Urinalysis |
Glucosuria (renal threshold: dogs approximately 180 mg/dL, cats approximately 280 mg/dL). Check for concurrent UTI. |
| Serum Chemistry |
Hypercholesterolemia, hypertriglyceridemia, elevated ALT/ALP. Rule out concurrent diseases. |
| Clinical Feature |
Details |
| Signalment |
Cats greater than 8 years old. No breed predisposition (Siamese and Himalayan may have decreased risk) |
| Physical Exam |
Palpable thyroid nodule (90%), tachycardia, weight loss, unkempt coat, hyperactivity, muscle wasting |
| Cardiovascular |
Systemic hypertension (15-20%), tachyarrhythmias, gallop rhythm, hypertrophic cardiomyopathy-like changes |
| Renal Masking |
CRITICAL: Hyperthyroidism increases GFR and can MASK underlying chronic kidney disease. Always reassess renal function after treating hyperthyroidism. |
| Treatment |
Advantages |
Disadvantages |
| Methimazole (medical) |
Reversible, relatively inexpensive, allows assessment of renal function during trial |
Lifelong therapy, GI side effects, potential hepatotoxicity, rare blood dyscrasias, requires monitoring |
| Radioactive Iodine (I-131) |
Curative in 95% with single treatment, no anesthesia, treats ectopic tissue, gold standard |
Expensive, requires specialized facility, radiation safety protocols, irreversible |
| Surgical Thyroidectomy |
Curative, immediate effect, allows histopathology |
Anesthesia risk in older cats, hypocalcemia risk (parathyroid damage), recurrence if ectopic tissue |
| Iodine-restricted diet (y/d) |
Non-invasive, no medication |
Strict compliance required (sole diet), may not control all cases, expensive |
| Clinical Feature |
Details |
| Predisposed Breeds |
Golden Retriever, Doberman Pinscher, Irish Setter, Dachshund, Cocker Spaniel, Boxer, Great Dane |
| Metabolic Signs |
Weight gain without polyphagia, lethargy, mental dullness, cold intolerance, exercise intolerance |
| Dermatologic Signs |
Bilateral symmetric non-pruritic alopecia, "rat tail," hyperpigmentation, seborrhea, recurrent pyoderma, myxedema |
| Cardiovascular |
Bradycardia, weak apex beat, decreased contractility |
| Neuromuscular (rare) |
Peripheral neuropathy, facial nerve paralysis, vestibular signs, megaesophagus, laryngeal paralysis |
| Test |
Interpretation |
| Total T4 |
Low T4 is sensitive but NOT specific. Many factors decrease T4 (illness, drugs like glucocorticoids, sulfonamides, phenobarbital). Normal T4 essentially rules OUT hypothyroidism. |
| Free T4 (fT4ed) |
More accurate than total T4, less affected by non-thyroidal illness. Free T4 by equilibrium dialysis (fT4ed) is preferred - avoid analog methods. |
| TSH |
Elevated TSH with low T4/fT4 strongly supports primary hypothyroidism. However, 25-40% of hypothyroid dogs have NORMAL TSH due to pituitary exhaustion or assay limitations. |
| Thyroglobulin Autoantibodies |
Positive in lymphocytic thyroiditis. Indicates immune-mediated disease but not necessarily current hypothyroid state. |
| Secondary Findings |
Fasting hypercholesterolemia, mild non-regenerative anemia (normocytic, normochromic), elevated CK |
Section 1: Endocrine Diseases
Endocrine diseases are among the most commonly tested topics on the BCSE due to their frequency in clinical practice and the integration of physiology, pathophysiology, and therapeutics required for their management.
Diabetes Mellitus
Diabetes mellitus (DM) is one of the most common endocrine diseases in both dogs and cats, with prevalence estimates ranging from 0.4% to 1.2% depending on the population studied. Understanding the species differences in pathophysiology is CRITICAL for exam success.
MEMORY AID - CANINE vs FELINE DIABETES
"Dogs are Type 1, Cats are Type 2" - Dogs typically have immune-mediated beta cell destruction (like human Type 1 DM), while cats have insulin resistance and beta cell dysfunction (like human Type 2 DM). Remember: "Cats Can Conquer" - with aggressive early treatment, some cats can achieve diabetic remission!
Species Comparison: Diabetes Mellitus
High-YieldThe "4 Ps" of diabetes mellitus: Polyuria, Polydipsia, Polyphagia, and weight loss (Pounds disappearing). Cataracts develop rapidly in diabetic DOGS but are RARE in diabetic cats.
[Include Image: Figure 1. Diabetic cataracts in a dog showing characteristic lens opacity]
Clinical Presentation and Diagnosis
Classic Clinical Signs: Polyuria, polydipsia, polyphagia with weight loss (PU/PD/PP/WL). In dogs, rapid cataract development is common. In cats, plantigrade stance (diabetic neuropathy) may be observed.
MEMORY AID - STRESS HYPERGLYCEMIA IN CATS
"Frightened Felines Fake it" - Cats can have stress-induced blood glucose up to 300-400 mg/dL! Always confirm with fructosamine or glycosuria if suspicious. Dogs do NOT typically show significant stress hyperglycemia.
Diabetic Ketoacidosis (DKA)
DKA is a life-threatening complication of diabetes mellitus requiring emergency intervention. It occurs when severe insulin deficiency leads to uncontrolled lipolysis and ketone body production.
MEMORY AID - DKA TREATMENT - "FISK"
F = Fluids (0.9% NaCl initially, correct dehydration)
I = Insulin (regular insulin CRI after 1-2 hours of fluids)
S = Serum electrolytes (monitor K+ - add KCl when needed)
K = Ketones (monitor resolution with urine dipstick or blood beta-hydroxybutyrate)
High-YieldIn DKA, total body potassium is DEPLETED even if serum K+ appears normal or elevated. Insulin administration drives K+ intracellularly - always supplement potassium and monitor closely!
Hyperthyroidism
Hyperthyroidism is the most common endocrine disorder of middle-aged to older cats, caused by autonomous thyroid hormone production from benign adenomatous hyperplasia (98%) or thyroid carcinoma (2%).
MEMORY AID - FELINE HYPERTHYROIDISM - "WATCH"
W = Weight loss (despite polyphagia)
A = Appetite increased (ravenous)
T = Tachycardia and thyroid nodule palpable
C = Cardiac changes (gallop rhythm, murmur, hypertrophic cardiomyopathy)
H = Hyperactivity, hypertension, vomiting (GI signs)
High-YieldWhen treating feline hyperthyroidism, ALWAYS assess kidney function before and 2-4 weeks after initiating therapy. The increased GFR from hyperthyroidism may be masking concurrent CKD - treating the hyperthyroidism can unmask renal disease!
[Include Image: Figure 2. Palpation technique for thyroid nodules in cats - ventral cervical region]
Treatment Options for Feline Hyperthyroidism
MEMORY AID - METHIMAZOLE SIDE EFFECTS - "VIGS"
V = Vomiting (most common - give with food)
I = Immune-mediated reactions (rare but serious: hepatopathy, blood dyscrasias)
G = GI upset, facial pruritus (self-excoriation)
S = Serum ALT elevation - monitor liver enzymes
Hypothyroidism
Hypothyroidism is one of the most common endocrine disorders in dogs, typically resulting from immune-mediated thyroiditis (lymphocytic thyroiditis) or idiopathic thyroid atrophy. It is RARE in cats (usually iatrogenic or post-radioiodine therapy).
MEMORY AID - CANINE HYPOTHYROIDISM - "SLOW DOG"
S = Skin changes (bilateral symmetric alopecia, "rat tail," seborrhea, pyoderma)
L = Lethargy, mental dullness ("tragic facial expression")
O = Obesity/weight gain (without increased appetite)
W = Weakness, cold intolerance
D = Dermatological problems (hyperpigmentation, poor wound healing)
O = Often middle-aged, medium to large breeds
G = Gain weight easily, bradycardia
[Include Image: Figure 3. Bilateral symmetric alopecia and "rat tail" in a hypothyroid dog]
Diagnosis of Canine Hypothyroidism
Diagnosis requires integration of clinical signs with appropriate laboratory testing. Beware of "euthyroid sick syndrome" (non-thyroidal illness) causing low T4 without true hypothyroidism.
High-YieldThe gold standard diagnosis of hypothyroidism requires BOTH compatible clinical signs AND appropriate laboratory findings. A low T4 alone is NOT sufficient for diagnosis due to the high prevalence of euthyroid sick syndrome.
MEMORY AID - DRUGS THAT LOWER T4 - "GPS"
G = Glucocorticoids (and other steroids)
P = Phenobarbital (anticonvulsants)
S = Sulfonamides (trimethoprim-sulfa especially)
Hyperadrenocorticism (Cushing's Disease)
Hyperadrenocorticism (HAC) results from chronic cortisol excess. In dogs, 80-85% of cases are pituitary-dependent (PDH) due to ACTH-secreting pituitary adenomas, while 15-20% are adrenal-dependent (ADH) due to adrenal tumors. HAC is common in dogs but RARE in cats.
MEMORY AID - CUSHING'S CLINICAL SIGNS - "PUPPY HEADS"
P = Polyuria/Polydipsia (most common - 80-90%)
U = Urinary accidents (losing house training)
P = Pot-bellied appearance (hepatomegaly, muscle wasting)
P = Panting (even at rest)
Y = "Your dog looks different" (owners notice)
H = Hair loss (bilateral symmetric, trunk)
E = Elevated liver enzymes (ALP 90%)
A = Appetite increased
D = Dermatologic changes (thin skin, calcinosis cutis)
S = Skin changes, slow wound healing, susceptibility to infection
[Include Image: Figure 4. Pot-bellied appearance and bilateral symmetric alopecia in a dog with Cushing's disease]
Diagnostic Testing for Hyperadrenocorticism
MEMORY AID - HAC TESTING STRATEGY - "LUCAS"
L = LDDS (Low-Dose Dexamethasone Suppression) - best screening test, 90-95% sensitive
U = UCCR (Urine Cortisol:Creatinine Ratio) - high sensitivity, low specificity - rules OUT disease if negative
C = ACTH Stimulation - less sensitive (60-85%) but specific, also detects iatrogenic HAC
A = Adrenal imaging (ultrasound) - helps differentiate PDH from ADH
S = HDDS (High-Dose Dex Suppression) - helps differentiate PDH from ADH after diagnosis confirmed
High-YieldACTH stimulation test is the ONLY way to diagnose IATROGENIC Cushing's (from glucocorticoid administration). These patients show NO cortisol response to ACTH because their adrenals have atrophied. LDDS cannot detect iatrogenic HAC.
Treatment of Canine Hyperadrenocorticism
Hypoadrenocorticism (Addison's Disease)
Hypoadrenocorticism results from deficient adrenocortical hormone production, typically from immune-mediated destruction of the adrenal cortex. Often called "the great pretender" due to its vague, waxing-waning clinical signs.
MEMORY AID - ADDISON'S - "THE GREAT PRETENDER"
Typical presentation: Young adult female dog with vague, waxing-waning signs that improve with IV fluids and stress (because stress triggers ACTH release, but damaged adrenals cannot respond). Classic breeds: Standard Poodle, Portuguese Water Dog, Nova Scotia Duck Tolling Retriever, Great Dane, Bearded Collie, West Highland White Terrier
High-YieldThe absence of a stress leukogram in a sick dog is a major clue to Addison's! Normally, stress/illness causes lymphopenia and eosinopenia due to cortisol release. In Addison's, the lymphocyte and eosinophil counts are often normal or elevated.
MEMORY AID - ADDISONIAN CRISIS TREATMENT - "SAFE"
S = Saline (0.9% NaCl IV - addresses hypovolemia and hyponatremia)
A = Address hyperkalemia if severe (calcium gluconate for cardioprotection, dextrose +/- insulin)
F = Fluids continued until stabilized
E = Emergency glucocorticoid (dexamethasone SP - does not interfere with ACTH stim test, OR hydrocortisone if not testing)
Insulinoma
Insulinoma is a functional beta cell tumor of the pancreas that secretes insulin independent of blood glucose levels. Most common in middle-aged to older, large breed dogs. Malignancy rate is high (greater than 95%).
MEMORY AID - INSULINOMA CLINICAL SIGNS - "SEEN"
S = Seizures (hypoglycemia-induced)
E = Exercise intolerance, collapse, weakness (episodic)
E = Eating relieves signs temporarily
N = Neurologic signs (ataxia, behavior changes, tremors)
Whipple's Triad (diagnostic criteria for insulinoma): (1) Clinical signs consistent with hypoglycemia, (2) Documented hypoglycemia at the time of clinical signs (blood glucose less than 60 mg/dL), (3) Resolution of signs with glucose administration.
High-YieldThe key diagnostic finding in insulinoma is INAPPROPRIATE insulin secretion: normal or elevated insulin in the face of hypoglycemia. Calculate the Amended Insulin:Glucose Ratio (AIGR) - values greater than 30 are highly suspicious. Imaging (ultrasound, CT) may miss small tumors.
Medical Management: Frequent small meals, avoid fasting, avoid strenuous exercise. Prednisone (promotes gluconeogenesis, increases insulin resistance). Diazoxide (inhibits insulin secretion). Octreotide (somatostatin analog) for refractory cases.
| Clinical Feature |
Details |
| Signalment |
Middle-aged to older dogs. Predisposed breeds: Poodle, Dachshund, Boston Terrier, Boxer, Beagle |
| PU/PD |
Most common sign (80-90%). Cortisol inhibits ADH action and release (nephrogenic diabetes insipidus effect) |
| Skin/Coat |
Bilaterally symmetric alopecia, thin skin, comedones, calcinosis cutis (pathognomonic), recurrent pyoderma |
| Body Changes |
Pot-bellied appearance (hepatomegaly, abdominal muscle weakness), muscle wasting, weakness |
| Laboratory |
Stress leukogram, elevated ALP (steroid-induced isoenzyme - 90%), hypercholesterolemia, dilute urine (USG less than 1.020) |
| Test |
Best For |
Interpretation |
| LDDS Test |
Screening - most sensitive (90-95%) |
Normal dogs suppress cortisol at 4 and 8 hours. Failure to suppress equals positive. May help differentiate PDH if suppression at 4h but not 8h. |
| ACTH Stimulation |
Detecting iatrogenic HAC, monitoring therapy |
Exaggerated response to ACTH. Less sensitive (60-85%) but very specific. The ONLY test to detect iatrogenic HAC (which shows NO response to ACTH). |
| Urine Cortisol: Creatinine Ratio |
Screening at home (low stress) |
Very sensitive - a NEGATIVE result essentially rules out HAC. Positive results require further testing (low specificity). |
| Abdominal Ultrasound |
Differentiating PDH from ADH |
PDH: bilateral adrenomegaly. ADH: unilateral adrenal mass with contralateral atrophy. Also assess for other complications. |
| Endogenous ACTH |
Differentiating PDH from ADH |
PDH: normal to elevated ACTH. ADH: low/undetectable ACTH (tumor secretes cortisol independent of ACTH) |
| Treatment |
Details |
| Trilostane |
Competitive inhibitor of 3-beta-hydroxysteroid dehydrogenase. First-line medical therapy. Give with food. Monitor with ACTH stimulation (target post-ACTH cortisol 1.5-5 ug/dL). Risk of adrenal necrosis. |
| Mitotane (o,p'-DDD) |
Adrenolytic - destroys adrenal cortex. Effective but more adverse effects. Used less frequently now. Requires careful monitoring. |
| Adrenalectomy |
Treatment of choice for ADH. Unilateral for adenoma. Risk of thromboembolism, hemorrhage. Requires careful perioperative management. |
| Pituitary Radiation |
Option for PDH, especially with neurologic signs from macroadenoma. Specialized facilities required. |
| Feature |
Details |
| Signalment |
Young to middle-aged dogs (median 4 years), female predisposition (70%) |
| Clinical Signs |
Lethargy, weakness, anorexia, vomiting, diarrhea, weight loss, shaking, collapse. Signs wax and wane. |
| Classic Electrolytes |
Hyponatremia, hyperkalemia (Na:K ratio less than 27:1). NOT present in "atypical" glucocorticoid-deficient cases. |
| Other Lab Findings |
Hypoglycemia, azotemia (prerenal), absence of stress leukogram (lymphocytes NOT decreased), hypercalcemia (25-30%) |
| ECG Changes |
Bradycardia, peaked T waves, widened QRS, absent P waves (hyperkalemia effects) |
| Seizure Type |
Description |
| Generalized Tonic-Clonic |
Loss of consciousness, bilateral motor activity, paddling, opisthotonus, salivation, urination/defecation. Post-ictal phase follows. |
| Focal (Partial) |
Asymmetric motor activity, facial twitching, chewing movements ("fly-biting"), behavioral changes. May or may not progress to generalized. |
| Cluster Seizures |
Two or more seizures within 24 hours with recovery between. Emergency - requires intervention. |
| Status Epilepticus |
Continuous seizure activity greater than 5 minutes OR repeated seizures without recovery. EMERGENCY - life-threatening. |
| Diagnostic Tier |
Requirements |
| Tier 1 (Suspected) |
Age 6 months to 6 years, normal interictal neurological exam, normal CBC/chemistry, no evidence of toxin exposure |
| Tier 2 (Probable) |
Tier 1 criteria PLUS normal brain MRI and normal CSF analysis |
| Tier 3 (Definitive) |
Tier 2 criteria PLUS EEG confirmation of epileptiform activity |
Section 2: Neurological Diseases
Neurological diseases require systematic neurolocalization followed by appropriate diagnostic testing. The BCSE emphasizes the ability to localize lesions anatomically and correlate clinical signs with underlying pathology.
Seizures and Epilepsy
Epilepsy is one of the most common chronic neurological conditions in dogs, with prevalence estimated at 1-2% of the canine population. Understanding seizure classification and the diagnostic approach is essential for the BCSE.
MEMORY AID - SEIZURE CLASSIFICATION - "IF ReSt"
I = Idiopathic epilepsy (unknown cause, presumed genetic)
F = Focal seizures (partial - one hemisphere)
Re = Reactive seizures (metabolic: hypoglycemia, hepatic encephalopathy, toxins, electrolyte disturbances)
St = Structural epilepsy (intracranial lesion: tumor, infection, trauma, vascular)
Idiopathic Epilepsy
Idiopathic epilepsy is a diagnosis of exclusion when no underlying cause is identified. Typical presentation: onset between 6 months to 6 years of age, normal interictal neurological examination, normal MRI and CSF analysis.
MEMORY AID - IDIOPATHIC EPILEPSY CRITERIA - "AGE"
A = Age at first seizure: 6 months to 6 years
G = Genetic predisposition (breeds: Beagle, German Shepherd, Golden Retriever, Labrador, Belgian Tervuren, Border Collie)
E = Exclusion of reactive and structural causes (normal bloodwork, imaging, CSF)
High-YieldIf a dog presents with first seizure under 6 months of age, suspect congenital abnormalities, metabolic disease, or infectious causes. If over 6 years at first seizure, brain tumor becomes a more likely differential.
Anticonvulsant Therapy
MEMORY AID - WHEN TO START ANTICONVULSANTS - "SERIOUS"
S = Status epilepticus or cluster seizures
E = Epilepsy confirmed (after diagnostic workup)
R = Recurrent seizures (greater than 2 in 6 months)
I = Increasing frequency or severity
O = Owner safety concerns or quality of life issues
U = Underlying cause requires treatment
S = Severe post-ictal phase
High-YieldNEVER abruptly discontinue phenobarbital or potassium bromide - can precipitate status epilepticus! Always wean slowly over weeks to months.
Emergency Management: Status Epilepticus
MEMORY AID - STATUS EPILEPTICUS TREATMENT - "BIG DAM"
B = Benzodiazepine first (diazepam IV 0.5-2 mg/kg, or midazolam IM if no IV access)
I = IV catheter and fluids
G = Glucose check and correct hypoglycemia if present
D = Diazepam can be repeated up to 3 times
A = Add phenobarbital IV if diazepam fails (2-4 mg/kg slow IV)
M = Monitor vitals, consider propofol or pentobarbital CRI if refractory
[Include Image: Figure 5. Algorithm for emergency seizure management in dogs]
Intervertebral Disc Disease (IVDD)
IVDD is one of the most common causes of spinal cord dysfunction in dogs. It is classified as Hansen Type I (acute disc extrusion) or Hansen Type II (chronic disc protrusion). Understanding the difference is critical for prognosis and treatment.
MEMORY AID - HANSEN TYPES - "I = IMPACT, II = INSIDIOUS"
Type I (Extrusion): Acute nuclear extrusion through ruptured annulus. Chondrodystrophic breeds (Dachshund, Beagle, Cocker Spaniel, Corgi, Basset Hound). Young to middle-aged (3-6 years). Sudden onset paralysis possible.
Type II (Protrusion): Gradual annular bulging, nucleus stays contained. Non-chondrodystrophic large breeds. Older dogs (greater than 5 years). Slowly progressive, chronic course.
Neurological Grading of Thoracolumbar IVDD
MEMORY AID - IVDD GRADING - "1-5 SCALE"
Grade 1: Pain only, no neurological deficits
Grade 2: Ambulatory paraparesis (walking but wobbly), mild ataxia
Grade 3: Non-ambulatory paraparesis (cannot walk but has voluntary movement)
Grade 4: Paraplegia (no voluntary movement) WITH deep pain sensation
Grade 5: Paraplegia WITHOUT deep pain sensation (worst prognosis)
High-YieldDeep pain perception is the MOST IMPORTANT prognostic indicator in IVDD. Test by applying hemostats to the toe - a CONSCIOUS response (turning head, trying to bite, vocalization) indicates intact deep pain. Withdrawal reflex ALONE is NOT deep pain (spinal reflex only)!
[Include Image: Figure 6. MRI showing thoracolumbar disc extrusion with spinal cord compression]
Vestibular Disease
Vestibular disease presents with head tilt, nystagmus, and ataxia. The key clinical challenge is differentiating peripheral (ear/CN VIII) from central (brainstem) vestibular disease, as they have vastly different prognoses and treatments.
MEMORY AID - PERIPHERAL vs CENTRAL VESTIBULAR - "PC FINDER"
PERIPHERAL (better prognosis):
- Horizontal or rotary nystagmus (fast phase AWAY from lesion)
- Nystagmus direction does NOT change with head position
- NO proprioceptive deficits
- Facial paralysis and Horner's syndrome MAY be present (CN VII/sympathetic)
CENTRAL (worse prognosis):
- May have vertical or direction-changing nystagmus
- Proprioceptive deficits PRESENT (indicates brainstem)
- Other cranial nerve deficits possible
- Mental status changes possible
High-YieldPROPRIOCEPTIVE DEFICITS are the KEY differentiator between peripheral and central vestibular disease. If paw positioning or placing reactions are abnormal, the lesion is CENTRAL until proven otherwise.
Idiopathic (Geriatric) Vestibular Disease
Idiopathic vestibular disease is the most common cause of acute peripheral vestibular signs in older dogs. Typical patient: older dog with peracute onset of head tilt, nystagmus, ataxia, and often severe nausea. No identifiable cause found. Prognosis is EXCELLENT with supportive care - most improve dramatically within 72 hours and recover fully within 2-3 weeks.
MEMORY AID - GERIATRIC VESTIBULAR - "OLD DOG"
O = Older dogs (usually greater than 8 years)
L = Looks like a stroke but isn't
D = Dramatic improvement within 3-7 days
D = Diagnosis of exclusion (rule out otitis, tumor)
O = Often complete recovery in 2-3 weeks
G = Good prognosis - reassure worried owners!
| Drug |
Mechanism |
Key Points |
Monitoring |
| Phenobarbital |
Enhances GABA-A receptor activity |
First-line in dogs, inexpensive, effective. Hepatotoxicity risk with chronic use. PU/PD, polyphagia, sedation initially. |
Serum levels, liver enzymes q6mo |
| Potassium Bromide |
Hyperpolarizes neurons (chloride substitute) |
Add-on therapy or monotherapy if hepatic disease. Long half-life (25 days) - takes weeks to reach steady state. Bromism toxicity possible. |
Serum levels q3-6mo |
| Levetiracetam (Keppra) |
SV2A protein binding |
Excellent safety profile, minimal hepatic metabolism, good add-on. Short half-life requires TID dosing or extended-release. More expensive. |
Generally not needed |
| Zonisamide |
Multiple (sodium channels, carbonic anhydrase) |
Add-on or alternative if phenobarbital not tolerated. BID dosing. Generally well tolerated. |
Serum levels optional |
| Feature |
Hansen Type I |
Hansen Type II |
| Mechanism |
Chondroid degeneration with acute nuclear extrusion |
Fibroid degeneration with chronic annular protrusion |
| Typical Breeds |
Chondrodystrophic: Dachshund (most common), Beagle, Cocker Spaniel, Pekingese, French Bulldog |
Large non-chondrodystrophic: German Shepherd, Labrador, Doberman |
| Age of Onset |
3-6 years (degeneration starts at 1-2 years) |
Greater than 5-8 years |
| Presentation |
Acute onset, often sudden paralysis. Can be severe. |
Chronic, slowly progressive. Waxing-waning course. |
| Common Locations |
Thoracolumbar (T11-L2 most common), cervical |
Lumbosacral, caudal cervical |
| Grade |
Neurological Status |
Treatment and Prognosis |
| Grade 1 |
Pain only, neurologically normal |
Conservative: strict cage rest 4-6 weeks, anti-inflammatory medications, analgesics. Good prognosis (greater than 90% recover). |
| Grade 2 |
Ambulatory paraparesis, ataxia |
Conservative or surgical. Surgery recommended if recurrent or severe. Good prognosis (greater than 85%). |
| Grade 3 |
Non-ambulatory paraparesis |
Surgery recommended (hemilaminectomy). Good prognosis with surgery (greater than 90%). |
| Grade 4 |
Paraplegic WITH deep pain |
Surgery recommended urgently. Good prognosis with timely surgery (85-95%). |
| Grade 5 |
Paraplegic WITHOUT deep pain |
Emergency surgery within 24-48 hours if any chance of recovery. Guarded to poor prognosis (less than 50-60% even with surgery). |
| Feature |
Peripheral |
Central |
| Nystagmus Type |
Horizontal or rotary only. Fast phase away from lesion. Direction consistent. |
May be vertical, positional, or direction-changing (pathognomonic for central) |
| Proprioception |
NORMAL |
ABNORMAL (ipsilateral deficits) |
| Head Tilt |
Toward the lesion side |
Usually toward lesion (paradoxical away if cerebellum) |
| Other CN Deficits |
CN VII (facial), Horner's syndrome possible |
Multiple cranial nerves may be affected |
| Mentation |
Normal |
May be altered (obtunded, stuporous) |
| Common Causes |
Otitis media/interna, idiopathic (geriatric), hypothyroidism, ototoxicity |
Brainstem tumor, encephalitis, infarct, trauma |
| Feature |
Details |
| Primary Causes in Dogs |
Hip dysplasia, elbow dysplasia, cranial cruciate ligament rupture, patellar luxation, OCD, trauma |
| Clinical Signs |
Lameness (worse after rest, improves with mild activity), stiffness, decreased activity, reluctance to jump/climb stairs, muscle atrophy, joint thickening, crepitus, decreased range of motion |
| Radiographic Findings |
Osteophytes (bone spurs), subchondral sclerosis, joint space narrowing, soft tissue swelling, enthesophytes |
| Key Point |
Radiographic severity often does NOT correlate with clinical signs. Some dogs with severe radiographic changes are minimally affected, while others with mild changes have significant pain. |
| Intervention |
Details |
| NSAIDs |
First-line pharmacological therapy. Inhibit COX enzymes, reduce inflammation and pain. Monitor renal and hepatic function. Avoid in dehydrated patients or those with pre-existing renal disease. Examples: carprofen, meloxicam, deracoxib, firocoxib, grapiprant (EP4 receptor antagonist). |
| Weight Management |
The MOST effective single intervention. Even 6-8% weight loss significantly improves clinical signs. Reduces mechanical stress on joints. |
| Disease-Modifying Agents |
Injectable polysulfated glycosaminoglycans (Adequan), oral supplements (glucosamine, chondroitin, omega-3 fatty acids). Evidence is variable but generally safe. |
| Adjunct Analgesics |
Gabapentin (neuropathic pain component), amantadine (NMDA antagonist for central sensitization), tramadol (less effective than previously thought for dogs). |
| Physical Rehabilitation |
Controlled exercise, swimming/underwater treadmill, range of motion exercises, therapeutic ultrasound, laser therapy. Maintains muscle mass and joint mobility. |
| Monoclonal Antibodies |
Bedinvetmab (dogs) and frunevetmab (cats) - anti-nerve growth factor (NGF) antibodies. Monthly injections. Newer option with good efficacy. |
Section 3: Musculoskeletal Diseases
Musculoskeletal diseases are extremely common in veterinary practice. Osteoarthritis affects approximately 20% of the adult dog population, and developmental orthopedic diseases are among the most frequent reasons for surgical referral.
Osteoarthritis (Degenerative Joint Disease)
Osteoarthritis (OA) is a chronic, progressive degenerative joint disease characterized by cartilage degradation, subchondral bone changes, osteophyte formation, and synovial inflammation. In dogs, it is usually SECONDARY to developmental disease (hip/elbow dysplasia, cruciate rupture) rather than primary age-related degeneration.
MEMORY AID - OA PATHOPHYSIOLOGY - "DISCO"
D = Damage to articular cartilage (initiating event)
I = Inflammation (synovitis releases cytokines: IL-1, TNF-alpha)
S = Subchondral bone sclerosis and remodeling
C = Cartilage degradation (MMPs break down proteoglycans and collagen)
O = Osteophyte formation (body's attempt to stabilize joint)
High-YieldOA in dogs should be considered a "young dog disease" because it typically starts from developmental orthopedic disease early in life. By the time clinical signs are obvious, significant joint damage has already occurred.
[Include Image: Figure 7. Radiograph showing osteophyte formation and joint space changes in canine osteoarthritis]
Multimodal Management of Osteoarthritis
MEMORY AID - OA TREATMENT - "PAWSOME"
P = Pain management (NSAIDs as first-line: meloxicam, carprofen, deracoxib, grapiprant)
A = Activity modification (controlled exercise, avoid high-impact activities)
W = Weight management (CRITICAL - weight loss is the most impactful single intervention)
S = Supplements (omega-3 fatty acids, glucosamine/chondroitin - modest evidence)
O = Other therapies (physical rehabilitation, laser therapy, acupuncture)
M = Medical adjuncts (gabapentin, amantadine for chronic/neuropathic pain)
E = Environmental modifications (ramps, orthopedic beds, raised food bowls)
Hip Dysplasia
Canine hip dysplasia (CHD) is a polygenic developmental disorder characterized by hip joint laxity leading to subluxation, abnormal wear, and secondary osteoarthritis. It is one of the most common inherited orthopedic diseases in dogs.
MEMORY AID - HIP DYSPLASIA BREEDS - "LARGE DOGS HURT"
L = Labrador Retriever (very common)
A = Also German Shepherd, Golden Retriever
R = Rottweiler, Saint Bernard
G = Great Dane
E = English Bulldogs and other giant breeds
Note: Greyhounds and other sighthounds have very LOW incidence
MEMORY AID - ORTOLANI TEST
With dog in lateral recumbency, flex hip to 90 degrees, apply axial pressure on femur (subluxates femoral head), then slowly abduct the limb. A POSITIVE test = palpable "clunk" as femoral head reduces back into acetabulum. Indicates joint laxity.
Treatment Options for Hip Dysplasia
Cranial Cruciate Ligament Disease
Cranial cruciate ligament (CCL) rupture is the most common cause of hindlimb lameness in dogs and a leading cause of degenerative joint disease in the stifle. Unlike in humans where ACL tears are typically traumatic, canine CCL disease is usually a chronic degenerative process.
MEMORY AID - CCL RUPTURE - "CATCH IT"
C = Chronic degeneration (not acute trauma usually)
A = Affects 40-60% bilaterally (check other leg!)
T = Tibial thrust and cranial drawer positive
C = Concurrent meniscal injury common (50%+)
H = History of hindlimb lameness, "toe-touching" at rest
I = Inflammation and effusion palpable (medial buttress)
T = Treatment usually surgical for best outcomes
High-Yield50-60% of dogs with CCL rupture in one stifle will rupture the contralateral CCL within 1-2 years. Always evaluate both stifles and counsel owners about this risk.
[Include Image: Figure 8. Demonstration of cranial drawer test in a dog]
Surgical Treatment Options for CCL Rupture
Patellar Luxation
Patellar luxation is displacement of the patella from the trochlear groove. It is one of the most common orthopedic conditions in dogs, particularly affecting small and toy breeds. Medial luxation is most common (75% of cases).
MEMORY AID - PATELLAR LUXATION - "TINY DOGS SLIP"
Medial luxation (most common): Toy and small breeds (Pomeranian, Yorkshire Terrier, Chihuahua, Toy Poodle, Boston Terrier)
Lateral luxation (less common): Large breeds (more often associated with trauma or severe dysplasia)
Grading System for Patellar Luxation
MEMORY AID - PATELLAR LUXATION GRADES - "1234"
Grade 1: Patella can be manually luxated but spontaneously returns. Dog is usually asymptomatic.
Grade 2: Patella luxates spontaneously with flexion but can be manually reduced. Intermittent lameness ("skipping").
Grade 3: Patella is permanently luxated but can be manually reduced (will reluxate). Consistent lameness.
Grade 4: Patella is permanently luxated and CANNOT be reduced manually. Severe limb deformity, non-weight bearing.
High-YieldCCL rupture and patellar luxation often occur together! Chronic patellar luxation changes stifle biomechanics, predisposing to CCL disease. Always assess both structures.
| Feature |
Details |
| Pathophysiology |
Joint laxity leads to abnormal femoral head and acetabulum development. Subluxation causes abnormal wear, cartilage damage, and progressive OA. |
| Clinical Signs (young) |
Bunny-hopping gait, reluctance to exercise, difficulty rising, hip pain on extension. Signs may appear at 5-10 months. |
| Clinical Signs (adult) |
Chronic hindlimb lameness, muscle atrophy, exercise intolerance, difficulty rising. Secondary OA signs. |
| Physical Exam |
Pain on hip extension, positive Ortolani sign (subluxation and reduction), decreased range of motion, thigh muscle atrophy |
| Radiographic Signs |
Shallow acetabulum, femoral head subluxation, incongruent joint, osteophytes, subchondral sclerosis. Extended hip view standard. |
| Treatment |
Best Candidates |
Details |
| Conservative/Medical |
Mild cases, older dogs, financial constraints |
Weight management, NSAIDs, controlled exercise, physical therapy, joint supplements. Can provide good quality of life for many dogs. |
| Juvenile Pubic Symphysiodesis (JPS) |
Young puppies less than 16-20 weeks with laxity |
Early intervention to increase acetabular coverage. Minimally invasive. Must be done before growth plates close. |
| Triple/Double Pelvic Osteotomy (TPO/DPO) |
Young dogs (less than 10-12 months) with minimal OA |
Rotates acetabulum to increase femoral head coverage. Requires good cartilage. Salvage procedure. |
| Total Hip Replacement (THR) |
Skeletally mature dogs, severe dysplasia/OA |
Gold standard for severe cases. Eliminates pain, restores function. Expensive. Best outcomes when done by specialists. |
| Femoral Head and Neck Ostectomy (FHO) |
Smaller dogs (less than 20 kg), financial constraints |
Salvage procedure - removes femoral head. Creates fibrous "false joint." Better results in smaller patients. |
| Feature |
Details |
| Predisposing Factors |
Obesity, poor physical condition, steep tibial plateau angle, genetics. Breeds: Labrador, Rottweiler, Newfoundland, American Staffordshire Terrier |
| Clinical Signs |
Acute or chronic hindlimb lameness, stifle effusion, muscle atrophy, "sitting to the side" (leg held out), toe-touching at rest |
| Cranial Drawer Test |
With stifle in slight flexion, stabilize femur and attempt to move tibia cranially. Positive test = cranial movement of tibia relative to femur. |
| Tibial Thrust Test |
With stifle in slight flexion, flex the hock. Positive test = tibia thrusts cranially when hock is flexed (more reliable in awake patients). |
| Meniscal Injury |
Medial meniscus commonly damaged (50%+). May hear/feel "meniscal click." Important to assess during surgery. |
| Technique |
Description |
| Extracapsular Repair (Lateral Suture) |
Heavy suture placed outside joint to mimic CCL function. Less expensive, shorter surgery. Good results in dogs less than 15-20 kg. Higher failure rate in larger dogs. |
| Tibial Plateau Leveling Osteotomy (TPLO) |
Osteotomy of proximal tibia rotated to level tibial plateau, eliminating tibial thrust. Most common procedure for larger dogs. Excellent outcomes. |
| Tibial Tuberosity Advancement (TTA) |
Advances tibial tuberosity to neutralize cranial tibial thrust by changing patellar tendon angle. Alternative to TPLO with similar outcomes. |
| Conservative Management |
May be considered for dogs less than 10 kg, poor surgical candidates, or financial constraints. Involves weight management, activity restriction, physical therapy, NSAIDs. OA progression is expected. |
| Grade |
Physical Exam Findings |
Treatment Recommendation |
| 1 |
Patella in groove at rest, can be manually luxated, spontaneously reduces |
Usually no treatment needed. Monitor for progression. |
| 2 |
Patella luxates spontaneously with flexion, can be manually reduced, intermittent skipping gait |
Surgery recommended if clinical signs present or worsening. Soft tissue and bone procedures. |
| 3 |
Patella permanently luxated, can be manually reduced but immediately reluxates, moderate limb deformity |
Surgery recommended. Trochleoplasty, tibial tuberosity transposition, soft tissue procedures. |
| 4 |
Patella permanently luxated, CANNOT be manually reduced, severe skeletal deformity |
Surgery challenging. May require corrective osteotomies. Guarded prognosis. |
| Feature |
Details |
| Age of Onset |
Typically 6 months to 3 years (rarely under 6 months) |
| Predisposed Breeds |
West Highland White Terrier, Bulldog, Labrador Retriever, Golden Retriever, German Shepherd, Boxer, Shar-Pei, Dalmatian |
| Primary Lesions |
Erythema, papules (early). Pruritus is often "pre-lesional" - itching before visible skin changes. |
| Secondary Lesions |
Excoriations, alopecia, lichenification, hyperpigmentation (chronic changes from self-trauma) |
| Common Complications |
Recurrent pyoderma (Staphylococcus pseudintermedius), Malassezia dermatitis, otitis externa (80% of atopic dogs) |
| Seasonality |
May be seasonal (pollen allergies) or non-seasonal (dust mites, mold). Often becomes perennial over time. |
Section 4: Dermatological Diseases
Dermatological diseases are among the most common presentations in small animal practice, with integumentary conditions accounting for approximately 20-25% of all veterinary visits. A systematic approach to pruritic and non-pruritic skin disease is essential for BCSE success.
Atopic Dermatitis
Canine atopic dermatitis (CAD) is a hereditary, chronic inflammatory and pruritic skin disease associated with IgE antibodies to environmental allergens. It is one of the most common causes of chronic pruritus in dogs, second only to flea allergy dermatitis.
MEMORY AID - ATOPIC DERMATITIS - "FLAPPS"
F = Face (periocular, muzzle)
L = Limbs (distal extremities, interdigital)
A = Axillae and groin (flexural surfaces)
P = Pinnae (concave surface, otitis externa)
P = Perianal region
S = Secondary infections COMMON (pyoderma, Malassezia)
Note: Dorsum is typically SPARED (unlike flea allergy)
[Include Image: Figure 9. Typical distribution of lesions in canine atopic dermatitis - face, paws, flexural surfaces]
Diagnostic Approach to Canine Atopic Dermatitis
Atopic dermatitis is a CLINICAL DIAGNOSIS based on history and physical examination after ruling out other pruritic diseases. There is no definitive diagnostic test for atopy itself - allergy testing is used to identify specific allergens for immunotherapy, NOT to diagnose the condition.
MEMORY AID - FAVROT'S CRITERIA FOR CAD
Meet 5 or more of 8 criteria = 85% sensitive, 79% specific for CAD:
1. Age less than 3 years at onset
2. Mostly indoor dog
3. Glucocorticoid-responsive pruritus
4. Chronic or recurrent yeast infections
5. Affected front feet
6. Affected ear pinnae
7. Non-affected ear margins
8. Non-affected dorsolumbar area
High-YieldALWAYS treat secondary infections BEFORE evaluating response to anti-pruritic therapy. Bacterial pyoderma and Malassezia dermatitis cause significant pruritus and confound assessment of underlying allergic disease.
Management of Canine Atopic Dermatitis
MEMORY AID - CAD TREATMENT - "ASIT FIRST"
A = Allergen-specific immunotherapy (only treatment that can change immune response - 50-80% effective)
S = Secondary infections - treat and prevent (antiseptic shampoos, ear cleaners)
I = Immediate relief with symptomatic therapy
T = Topical therapies (steroids for flares, moisturizers for barrier support)
F = Flea control year-round
I = Immunomodulatory drugs (oclacitinib, lokivetmab, cyclosporine)
R = Reduce inflammation (steroids for flares only - not long-term)
S = Supplements (omega-3 fatty acids, ceramide products)
T = Tailored to patient (multimodal approach required)
Pyoderma (Bacterial Skin Infection)
Pyoderma ("pus in the skin") is bacterial infection of the skin, most commonly caused by Staphylococcus pseudintermedius. It is almost always SECONDARY to an underlying disease process. Identifying and treating the primary cause is essential for preventing recurrence.
MEMORY AID - PYODERMA CLASSIFICATION - "SSD"
S = Surface pyoderma (hot spots, fold pyoderma, bacterial overgrowth) - bacteria on surface only
S = Superficial pyoderma (folliculitis, impetigo) - involves epidermis and hair follicles
D = Deep pyoderma (furunculosis, cellulitis) - extends into dermis, more serious
[Include Image: Figure 10. Epidermal collarettes and "moth-eaten" alopecia typical of superficial pyoderma in a dog]
Underlying Causes of Recurrent Pyoderma
MEMORY AID - RECURRENT PYODERMA - "ACHED"
A = Allergies (atopy, food allergy, flea allergy - most common!)
C = Conformational issues (skin folds, lip folds)
H = Hormonal/endocrine (hypothyroidism, Cushing's, diabetes)
E = Ectoparasites (Demodex, Sarcoptes)
D = Drug-induced immunosuppression, keratinization disorders
High-YieldIf pyoderma recurs after appropriate antibiotic therapy, ALWAYS investigate for an underlying cause. The most common underlying causes are allergies (especially atopic dermatitis) and endocrine diseases.
Diagnosis and Treatment of Pyoderma
Diagnosis: Cytology is ESSENTIAL for every suspected pyoderma case. Collect samples from pustules, under collarettes, or by impression smear. Look for bacteria (cocci usually - S. pseudintermedius) and inflammatory cells (neutrophils). Culture and sensitivity recommended for deep pyoderma, recurrent cases, or poor response to empirical therapy.
High-YieldMethicillin-resistant Staphylococcus pseudintermedius (MRSP) is an emerging concern. Risk factors include prior antibiotic exposure, hospitalization, and chronic skin disease. Culture-guided therapy is essential for MRSP cases.
Other High-Yield Dermatological Conditions
Demodicosis
Demodicosis is caused by overgrowth of Demodex mites in hair follicles. Demodex canis (dogs) and Demodex cati (cats) are normal skin flora; disease occurs when immune suppression allows overgrowth.
MEMORY AID - DEMODICOSIS - "SCABBY BUT NOT"
Demodicosis is NOT contagious (unlike Sarcoptes)!
Localized: less than 4 lesions, young dogs (3-6 months), 90% resolve spontaneously
Generalized: greater than 4 lesions, extensive, requires treatment
Adult-onset: ALWAYS look for underlying immunosuppression (Cushing's, cancer, immunosuppressive drugs)
Diagnosis: DEEP skin scrapings (squeeze skin to express mites from follicles). See cigar-shaped mites.
Dermatophytosis (Ringworm)
Dermatophytosis is a superficial fungal infection of keratinized tissues (hair, skin, nails). Most commonly caused by Microsporum canis in dogs and cats. ZOONOTIC - can infect humans.
MEMORY AID - DERMATOPHYTOSIS DIAGNOSIS - "WITCH"
W = Wood's lamp (50% of M. canis fluoresces apple-green - but NOT other species)
I = Identify infected hairs (broken hairs at lesion edges)
T = Trichogram (direct microscopy - see hyphae and spores on hair shaft)
C = Culture (gold standard - DTM media turns red with growth)
H = Histopathology (if culture-negative but still suspicious)
High-YieldDERMATOPHYTOSIS IS ZOONOTIC! Educate owners about transmission risk, especially to children, elderly, and immunocompromised individuals. Strict hygiene and environmental decontamination are essential.
Endocrine Diseases
- Diabetes mellitus: Dogs = Type 1-like (insulin-dependent), Cats = Type 2-like (may achieve remission). Cataracts in dogs, plantigrade stance in cats.
- Hyperthyroidism: Common in older cats. Reassess renal function after treatment (may unmask CKD).
- Hypothyroidism: Common in dogs. Diagnosis requires clinical signs + low T4/fT4 + elevated TSH. Beware euthyroid sick syndrome.
- Cushing's: LDDS is most sensitive screening test. ACTH stim is ONLY test that detects iatrogenic Cushing's.
- Addison's: The "great pretender." Look for absent stress leukogram, electrolyte changes (low Na:K), hypercalcemia.
Neurological Diseases
- Idiopathic epilepsy: Onset 6 months to 6 years, normal interictal exam. Diagnosis of exclusion.
- IVDD: Type I = acute (chondrodystrophic breeds), Type II = chronic (large breeds). Deep pain perception is the MOST important prognostic indicator.
- Vestibular disease: Proprioceptive deficits = CENTRAL (brainstem). No proprioceptive deficits = peripheral (better prognosis).
Musculoskeletal Diseases
- Osteoarthritis: Usually SECONDARY to developmental disease in dogs. Weight management is the single most effective intervention.
- Hip dysplasia: Ortolani test indicates joint laxity. Treatment ranges from conservative to THR depending on severity.
- CCL rupture: Degenerative (not traumatic) in dogs. 50-60% bilateral within 1-2 years. Cranial drawer and tibial thrust tests.
- Patellar luxation: Medial most common (small breeds). Grade 1-4 based on reducibility.
Dermatological Diseases
- Atopic dermatitis: Clinical diagnosis (Favrot's criteria). Distribution: face, ears, paws, flexural surfaces. Dorsum SPARED.
- Pyoderma: Almost always SECONDARY. Treat infection FIRST before assessing anti-pruritic response. S. pseudintermedius is primary pathogen.
- Demodicosis: NOT contagious. Diagnose with DEEP skin scrapings. Isoxazolines are now first-line treatment.
- Dermatophytosis: ZOONOTIC. Wood's lamp only 50% sensitive for M. canis. Fungal culture is gold standard. Treat until 2 negative cultures.
| Diagnostic Step |
Purpose |
| Rule Out Ectoparasites |
Flea combing, skin scrapings for Demodex/Sarcoptes. Treat all pets with flea preventive regardless of findings. |
| Cytology |
Identify secondary pyoderma (bacteria) and Malassezia. MUST treat secondary infections before assessing response to other treatments. |
| Diet Trial |
8-12 week elimination diet (novel protein or hydrolyzed) to rule out food allergy. STRICT compliance essential. |
| Allergy Testing |
Intradermal testing (gold standard) or serum IgE testing. Used to select allergens for immunotherapy - NOT diagnostic for atopy. |
| Treatment |
Details |
| Oclacitinib (Apoquel) |
JAK inhibitor - blocks itch and inflammation pathways. Rapid onset (within 24 hours). BID for 14 days, then SID. Monitor CBC. Avoid in dogs less than 12 months or with serious infections. |
| Lokivetmab (Cytopoint) |
Monoclonal antibody against IL-31 (key itch cytokine). Monthly injection. Very safe, minimal drug interactions. Excellent for pruritus control. |
| Cyclosporine (Atopica) |
Calcineurin inhibitor - immunomodulatory. Slower onset (4-6 weeks). GI side effects common initially. May increase papilloma risk. |
| Glucocorticoids |
Effective but NOT for long-term use. Reserve for acute flares. Significant side effects with chronic use (PU/PD, iatrogenic Cushing's). |
| Allergen-Specific Immunotherapy (ASIT) |
Only treatment that can modify disease course. Based on allergy testing results. 50-80% show improvement. Takes 6-12 months to assess efficacy. |
| Topical Therapy |
Antiseptic shampoos (chlorhexidine), moisturizers, topical steroids for localized lesions. Essential adjunct therapy. |
| Type |
Clinical Features |
Treatment Approach |
| Surface Pyoderma |
Hot spots (acute moist dermatitis), skin fold dermatitis (intertrigo), bacterial overgrowth. Red, moist, pruritic. |
Topical therapy often sufficient. Clip hair, clean, topical antimicrobials. Address underlying cause. |
| Superficial Pyoderma (Folliculitis) |
Papules, pustules, epidermal collarettes, "moth-eaten" alopecia. Most common form. |
Topical for localized. Systemic antibiotics 3-4 weeks for generalized (minimum 1 week past clinical resolution). |
| Deep Pyoderma |
Nodules, draining tracts, hemorrhagic bullae, pain. Furunculosis (ruptured hair follicles). Can cause cellulitis. |
Systemic antibiotics 6-8 weeks MINIMUM. Culture and sensitivity recommended. May need longer treatment. |
| Treatment Approach |
Details |
| Topical Therapy |
First-line for surface and localized superficial pyoderma. Chlorhexidine (2-4%) shampoos, sprays, or mousses. Benzoyl peroxide for follicular flushing. 2-3 times weekly bathing. |
| Systemic Antibiotics |
First-line empirical: cephalexin, amoxicillin-clavulanate, or clindamycin. Duration: superficial 3-4 weeks (1 week past clinical cure); deep 6-8 weeks minimum. |
| Culture and Sensitivity |
Indicated for: deep pyoderma, recurrent pyoderma, treatment failure, cytology showing rods (gram-negative). Guides antibiotic selection, especially for MRSP. |
| Address Underlying Cause |
CRITICAL for preventing recurrence. Investigate allergies, endocrine disease, parasites. Without addressing the primary cause, pyoderma will recur. |
| Treatment |
Details |
| Isoxazolines (First-line) |
Fluralaner (Bravecto), afoxolaner (NexGard), sarolaner (Simparica). Highly effective, easy to administer. Now considered first-line treatment. |
| Ivermectin |
Effective but AVOID in MDR1-mutant breeds (Collies, Australian Shepherds, etc.). Daily dosing required. |
| Treatment Duration |
Continue until 2 consecutive negative skin scrapings 1 month apart. Usually 2-4 months total. |
| Clinical Features |
Details |
| Typical Lesions |
Circular areas of alopecia with scaling, often with peripheral erythema. "Classic" ringworm appearance. Variable pruritus (often minimal). |
| Predisposed Animals |
Young animals, immunocompromised, Persian cats (may be asymptomatic carriers), shelter/cattery environments |
| Treatment |
Systemic antifungals (itraconazole, terbinafine) for 6-8 weeks minimum. Topical therapy (lime sulfur dips, miconazole/chlorhexidine) as adjunct. Environmental decontamination essential. |
| Resolution Criteria |
Two consecutive negative fungal cultures 2-4 weeks apart. Do not stop treatment based on clinical appearance alone. |