Canine and Feline Companion Animal Practice
Start with a species-first framework
Companion-animal questions reward structure: identify species, age, presenting complaint, then work through a problem list. Know core preventive medicine cold - puppy/kitten series finishing at ~16 weeks, rabies per local law, adult boosters, heartworm antigen testing plus year-round prevention (feline diagnostics are insensitive; occult infection is common and antigen may be negative), and fecal/parasite control including zoonotic roundworms and hookworms.
High-yield disease clusters
Expect endocrinology, cardiology, urinary, GI, and toxicology. Diabetes mellitus needs insulin, diet, and monitoring (glucose curve, fructosamine); distinguish uncomplicated regulation from DKA (ketones, acidosis, dehydration, vomiting). Feline hyperthyroidism presents as weight loss with polyphagia and a palpable thyroid; it frequently masks chronic kidney disease - recheck renal values 2–4 weeks after starting methimazole, because lowering thyroid hormone can unmask CKD. Hypothyroidism is fundamentally a dog disease (middle-aged, weight gain, dermatopathy) and is over-diagnosed in cats. Cardiac staples: myxomatous mitral valve disease in small-breed dogs (left apical murmur, left atrial enlargement, cough - pimobendan once cardiomegaly is documented) and hypertrophic cardiomyopathy in cats (gallop rhythm, murmur may be absent, thromboembolism risk).
Traps that decide questions
Species-specific drug toxicity: permethrin spot-ons are lethal to cats; acetaminophen and ibuprofen are toxic to cats; lilies cause acute kidney injury in cats; xylitol, grapes/raisins, and chocolate are canine toxins. Never extrapolate a dog dose to a cat, and avoid NSAID/ACE-inhibitor combinations in dehydrated patients.
Worked example
A 12-year-old cat with weight loss, ravenous appetite, T4 elevated, creatinine 1.8 mg/dL. Start methimazole (or refer for radioiodine), then recheck T4 and renal panel in 2–4 weeks. Declining renal function after treatment reveals underlying CKD and may require dose reduction. Rule of thumb: treat the thyroid, but watch the kidney.