Six weeks of scratching, and still no answer.
Itchy skin is the most common reason dogs and cats end up at the vet, and the hardest thing to get a straight answer about. These guides walk the diagnostic path in the order a vet would.
We don't sell food, so we've nothing to talk you into.
Four things most pet-food sites won't tell you
- Blood allergy tests don't work
- Serum and saliva "food allergy tests" don't reliably predict what an animal reacts to when fed. They are not a shortcut around the trial.
- "Hypoallergenic" is not a regulated word
- Any manufacturer may use it. Over-the-counter diets have repeatedly been found to contain proteins not named on the label.
- Changing food first is usually the wrong move
- Parasites and environmental allergy come first. Switching early wastes weeks and corrupts the diet history a real trial depends on.
- Years on a food proves nothing
- Allergy needs prior exposure, so reactions build to familiar foods rather than new ones. Five years of the same kibble is not a defence.
The order a vet works through
Cheapest and most treatable first. Working in this order isn't caution, it's that each step changes what the next one means.
- 01
Parasites
Fleas and mites first, always. Flea allergy needs very few bites, so "I have never seen one" rules nothing out.
- 02
Secondary infection
Broken skin turns bacterial or yeasty, and that itches on its own. Usually needs clearing before anything under it can be judged.
- 03
Environmental allergy
Pollen, dust mites, mould. The tell is seasonality: worse in spring and summer, easier in winter.
- 04
Food allergy
Usually year-round, sometimes with digestive signs. Confirmed only by an elimination trial and rechallenge.
Most owners start at step four. That's why it drags on for months.
Start here
The 8-week elimination diet trial, step by step
It is the only reliable way to diagnose a food allergy in a dog or cat. It is also the protocol owners most often abandon halfway. Here is what the eight weeks actually involve.
Read the guide
How the eight weeks run
- Wk 0–1Transition on, remove every other food source
- Wk 1–8Strict elimination, log daily
- Wk 8Assess against week one
- Wk 8–9Rechallenge, the step that confirms it
- Wk 9+Single ingredients, one at a time
The rest of the path
Why is my dog itching? Working through the causes in order
Itching is the single most common reason dogs are taken to the vet. It is also the symptom most often treated in the wrong order, which is why it drags on for months.
9 minWhy is my cat itching, scratching, or overgrooming?
Cats rarely scratch in front of you. They groom it away in private, which is why feline itch is usually spotted weeks late, and often mistaken for fussy grooming.
8 minFood allergy or environmental allergy? How to tell them apart
They look almost identical on the skin and are treated completely differently. A few pieces of history usually separate them.
7 minHow to read a pet food label when you are avoiding an ingredient
Once you know what your animal reacts to, the task becomes avoiding it — which is harder than it should be, because the same ingredient appears under many names.
6 minWhat to record during a food trial (and what your vet actually reads)
Eight weeks is longer than memory is reliable, and the improvement you are watching for is gradual by nature.
5 min
What it might be
The 25 ingredients most often behind food reactions. Each page lists every alternative name it hides under on a label, which is why "chicken-free" is harder to shop for than it sounds.
Free, no account
The 8-week trial tracker, free
A printable daily log built to hand straight to your vet: meals and medications, itch score, ears and digestion, and the weekly photo prompts that make gradual improvement visible.
The tracker, and occasionally a new guide. Nothing else, and you can leave any time. How we handle your data .
- Daily meals, treats and flavoured medications
- Itch score, ears, digestion, scratch locations
- Weekly photo prompts, same spot and light
- A rechallenge section for weeks 8–9