The itchy dog

1. Fleas — always rule out first: Always rule these out first, even if you have never seen one. Flea allergy dermatitis is the most common skin disease in dogs, and an allergic dog reacts to a handful of bites you will never find. Comb over a damp white paper towel — black specks that turn rust red are flea dirt, which is digested blood.

2. Environmental (atopy): Pollen, dust mites, mold. Usually seasonal at first and year-round later, and typically starts between one and three years old. Classic pattern: paws, belly, armpits, face and ears — the thin-skinned places.

3. Food: Less common than the internet suggests, perhaps 10 to 15 percent of allergic skin disease. Usually a PROTEIN, not grain. Diagnosed only by a strict elimination diet for eight to twelve weeks with nothing else passing their lips — no treats, no flavored medication, no scraps. Blood and saliva allergy tests for food are not reliable.

4. Infection: Bacterial or yeast, usually secondary to one of the above. This is why the itch often improves on antibiotics and returns after — the infection was treated and the cause was not.

· WHERE they scratch — paws and belly suggest atopy, tail base suggests fleas, ears alone can be either
· WHEN it happens — seasonal points to environmental, year-round points to food or indoor allergens
· Photograph the skin monthly. Redness is hard to remember accurately.
· Note any diet change, new bedding, new cleaning product or new walk route

· Rigorous flea prevention on every animal in the house, year round, for at least three months before concluding it is not fleas
· Omega-3 fatty acids — the best-evidenced supplement for skin, and it takes 8 to 12 weeks
· Wiping paws and belly after walks, which physically removes pollen and is genuinely underrated
· A gentle soap-free or medicated shampoo, with the contact time the label says — usually ten minutes, not a rinse
· Modern prescription medications. There are now options that control itch far better than steroids and with fewer side effects, and no reason to leave a dog miserable.

This is a chronic condition, not a one-off. Managing it well usually costs less than repeatedly treating flare-ups badly, and the single most expensive approach is guessing for two years.

Hair loss in patches, crusting, a bad smell, thickened or blackened skin, open sores, or itching that stops them sleeping. Those are infection or advanced disease, not a scratch.

· American College of Veterinary Dermatology (acvd.org)
· Merck Veterinary Manual (merckvetmanual.com) — the standard clinical reference, free online
· Cornell Riney Canine Health Center (vet.cornell.edu)
· Nationwide pet insurance annual claims reports (nationwide.com) — skin allergies as the most common claim, year after year

The flea comb test, the photo record, and paw wiping cost nothing and narrow it down faster than anything else.