canine-medicine

# Canine Medicine ## Overview Canine-specific clinical medicine covering breed predispositions, common disease presentations, normal physiologic parameters, and species-specific diagnostic and treatment approaches for dogs. Dogs are the most commonly treated veterinary species with the deepest evidence base, but significant breed variation means "canine medicine" is not monolithic. ## When to Use - Patient is a dog of any breed, age, or size - User asks about canine-specific disease presentations, diagnostics, or treatments - User asks about breed-specific considerations in dogs - Keywords: dog, canine, puppy, breed, K9 ## Clinical Reference Values (Adult Dog) | Parameter | Normal Range | | --- | --- | | Temperature | 100.5-102.5°F (38.1-39.2°C) | | Heart rate | 60-140 bpm (size-dependent: large dogs lower, small dogs higher) | | Respiratory rate | 10-30 bpm | | CRT (capillary refill time) | < 2 seconds | | Systolic blood pressure | 110-160 mmHg | | PCV | 37-55% | | Total protein | 5.0-7.5 g/dL | | Blood glucose | 74-143 mg/dL | | BUN | 7-27 mg/dL | | Creatinine | 0.5-1.8 mg/dL (sighthounds: up to 2.2 mg/dL normal) | ## Key Canine-Specific Considerations - **Breed diversity creates enormous clinical variation.** A 2 kg Chihuahua and a 70 kg Great Dane are the same species but have dramatically different disease profiles, drug dosing, anesthetic risk, and life expectancy (5-7 years for giant breeds vs. 14-16 years for small breeds). - **Sighthound normals differ:** Greyhounds and related breeds have lower WBC, platelet counts, and T4, higher PCV (55-65%), and higher creatinine (up to 2.2 mg/dL). These are physiologic, not pathologic. - **MDR1 mutation:** Primarily affects herding breeds (Collie, Australian Shepherd, Shetland Sheepdog, Old English Sheepdog, and crosses). Causes sensitivity to ivermectin (high dose), loperamide, acepromazine, and some chemotherapy agents. Test before prescribing P-glycoprotein substrates. - **Brachycephalic breeds** (Bulldogs, Pugs, French Bulldogs): Brachycephalic obstructive airway syndrome (BOAS), higher anesthesia risk, corneal ulceration, spinal malformations, heat stroke susceptibility. - **Large/Giant breeds:** Higher incidence of orthopedic disease (hip/elbow dysplasia, OCD), osteosarcoma, DCM, GDV. Shorter life expectancy. Prophylactic gastropexy may be recommended for GDV-prone breeds. ## Common Canine Diseases (No Feline Equivalent) - **GDV (gastric dilatation-volvulus):** Surgical emergency. Deep-chested breeds (Great Dane, German Shepherd, Standard Poodle, Weimaraner). Mortality 10-45% even with treatment. - **CCL rupture (cranial cruciate ligament):** Most common orthopedic surgery in dogs. Breeds: Labrador, Rottweiler, Newfoundland. TPLO is gold standard surgical correction. - **Canine cognitive dysfunction (CCD):** Age-related dementia. Prevalence >50% in dogs over 11 years. Disorientation, altered sleep cycles, loss of housetraining. - **Idiopathic epilepsy:** Breed-dependent prevalence (Border Collie, Belgian Tervuren, Labrador, Golden Retriever). Onset typically 1-5 years. First-line: phenobarbital or levetiracetam. ## Canine-Specific Diagnostics | Test | Purpose | Notes | | --- | --- | --- | | 4Dx SNAP | Heartworm + tick-borne disease (Ehrlichia, Anaplasma, Lyme) | Annual screening in endemic areas | | cPLI / Spec cPL | Canine pancreatitis | More specific than lipase/amylase | | NT-proBNP | Cardiac biomarker | Screening for occult heart disease | | SDMA | Early renal disease | Rises before creatinine in CKD | | Thyroxine (T4) | Hypothyroidism screening | Common in middle-aged large breeds | | Cortisol (LDDS/ACTH stim) | Cushing's disease | Common in older small breeds | ## Drug Safety Notes - Dogs tolerate acetaminophen (with caution, 10 mg/kg PO q12h) but cats cannot. - Chocolate (theobromine) toxicity: dogs metabolize theobromine slowly (~17.5 hour half-life). Dose-dependent: mild GI at 20 mg/kg, cardiac at 40 mg/kg, seizures/death at 60+ mg/kg. - Xylitol: Profoundly hypoglycemic in dogs (0.1 g/kg), hepatotoxic at higher doses. - Grape/raisin toxicity: Idiosyncratic nephrotoxicity. No established safe dose. Treat all exposures as potentially lethal. - NSAIDs: Carprofen, meloxicam, deracoxib, firocoxib all FDA-approved for canine use. Always check renal function and avoid concurrent corticosteroid use. ## Workflow 1. Identify breed, age, sex, reproductive status, and weight. 2. Apply breed-specific disease predispositions to differential ranking. 3. Use canine-specific reference ranges for lab interpretation. Note sighthound exceptions. 4. Check MDR1 status for herding breeds before prescribing P-glycoprotein substrates. 5. Select canine-approved drugs at species-appropriate doses. 6. Consider size-category differences (toy, small, medium, large, giant) for drug dosing, anesthetic protocols, and disease risk. ## Limitations - Canine medicine is the best-evidenced area of veterinary medicine, but many conditions still lack RCT-level evidence. - Mixed breed dogs may carry predispositions from any contributing breed. DNA testing (Embark, Wisdom Panel) can help but is not comprehensive. - Regional disease prevalence varies significantly (heartworm, tick-borne diseases, Valley Fever, blastomycosis, leptospirosis). - Breed-specific reference ranges are only well-established for sighthounds; other breeds may have uncharacterized normals.