Health
Itching summer and winter, chewed paws, ear infections that keep returning, three foods that changed nothing. Food allergy is confirmed by a trial diet run to the end.
Caution. A suddenly swollen muzzle or eyelids, hives, laboured breathing, repeated vomiting or collapse after a meal: call at once. Wet sores on the skin, swollen ears with discharge or itching that stops him sleeping: a vet within a day or two.
Do not look for the answer in a Facebook group, on TikTok or on a forum. Look for someone trained for this: your dog's own veterinarian, the only person who can examine, investigate and treat them.
Use this page to know what to observe, what to note and what to ask at the appointment, not to treat at home. If you still have doubts after a consultation, ask another vet or a specialist (dermatologist, internist) for a second opinion, not a group. And if you do not have a regular vet yet, find one now, while your dog is healthy: how to choose a veterinary clinic.
Your dog has been chewing his front paw for a year, summer and winter alike. The skin between his toes is red, his ears flare up every two or three months, he rubs his muzzle along the carpet and the skin under his tail is always sore. You have been through three bags of food: one "grain-free", one "with lamb", one "hypoallergenic" from the pet shop. Nothing changed. A friend told you "he's allergic to chicken". He may be. But food allergy in dogs is not something you work out from advice. It is confirmed in one way only, with a food trial run to the end, and below you will see how that is done, which signs need a vet quickly and which mistakes make the whole trial pointless.
A few things surprise almost everyone. Food allergy is rarer than people think: in an itchy dog, the commonest causes are fleas and allergy to what is in the air and the house (pollen, dust mites). Food allergy often comes alongside them. And "additives" are hardly ever to blame: dogs react to proteins, including the proteins in cereals. In the studies pooled by veterinary dermatologists, beef, dairy, chicken and wheat sit at the top; lamb, soya, pork and egg follow. In other words, exactly what dogs have eaten most, year after year.
Ordinary food allergy is a long story, with itching that goes on for months. A few situations, though, will not wait at all:
These are the signs of an acute allergic reaction. With food they are rare; we see them more often after an insect sting or a medicine. Call and head for the practice, without waiting for it to pass.
Other signs are not night-time emergencies, but you do not leave them until next month either. Call within a day or two if:
When he scratches. Note whether it is all year round or only from spring to autumn. Food allergy takes no notice of seasons; pollen allergy usually does. Write down the month it started and what changed then: new food, new treats, a house move.
Where he scratches. Draw a dog on a sheet of paper and colour in the areas: paws, ears, muzzle, eyes, armpits, belly, under the tail. In food allergy the usual pattern is the face, the ears, the paws and the area around the tail. One photo a week, in the same light, shows you after two months what you cannot see from one day to the next.
Stools. Dogs with food allergy sometimes pass more than three stools a day, softer, with mucus, even when the skin looks like the whole problem. Note vomiting, wind and a gurgling belly as well.
Everything he eats. The part almost everyone underestimates. Make the full list: the main food (brand, variety, every ingredient on the bag), treats, chews, scraps from the table, flavoured tablets, dog toothpaste, whatever he gets from the children, the grandparents or the neighbour across the landing. Every one of them contains protein.
Fleas. A fine comb along the back, near the tail, over a white tissue. Black specks that turn reddish when you wet them are flea dirt. Without up-to-date parasite protection, no diet tells you anything.
| What you see | More likely |
|---|---|
| Itching all year, on the face, ears, paws and around the tail, sometimes frequent stools | Food allergy (or a year-round environmental allergy) |
| Itching on the paws and face that starts in spring and eases in winter | Allergy to pollen and other things in the environment |
| Itching and crusts along the back, towards the tail | Flea allergy |
| Itching that appeared a few weeks after a new food | Possibly food; still confirmed only by an elimination diet |
| First-ever itching in an old dog | Another cause until proven otherwise: parasites, infections, other diseases |
One food, weighed, in two meals a day. Treats are pieces of the same food or of a wet version of it baked in the oven; for training they work as well as anything else, as long as you hand them over with real enthusiasm. Bowls are washed separately. The dog has no access to the cat's bowl, the other dogs' food, the bin or scraps in the street (a basket muzzle on walks if he scavenges). Flavoured medicines are swapped, with the vet's agreement. The diary goes on every evening: an itch score from 0 to 10, plus the weekly photos.
It is hard, but it is short. Eight weeks for an answer that tells you what he can safely eat for the rest of his life.
What dog owners search for most often on the internet about this problem, with the short answer. The answers are a guide only: the decision belongs to your dog's own vet, after an examination.
Only through an elimination diet: eight weeks on a single chicken-free food chosen by the vet, with no other treats at all, then you bring chicken back. If the itching drops on the diet and returns within days of the chicken, you have your answer. Blood, hair and saliva tests are not reliable for food allergy.
One with a protein the dog has never eaten, or a special one with the proteins broken down so finely that the body no longer recognises them. For the trial, your own vet chooses it. The 'hypoallergenic' label in pet shops is not regulated, and many foods carry traces of other proteins.
At least eight weeks. Many dogs improve sooner, some only towards the end. Then comes the challenge, when you bring the old food back: in allergic dogs the signs usually return within days, two weeks at most. Only then is the diagnosis certain.
Usually not. Grains are not the commonest cause; beef, dairy and chicken come up more often in studies. Some grain-free diets have also been linked with heart problems in dogs, a link still being studied. Talk to your vet before changing anything.
The information on this page is educational and does not replace an examination. For full details and a diagnosis, consult your dog's own veterinarian.
They often come together: the same causes, plans that complement each other.
Claws on the belly at midnight, paws licked red, an ear infection every summer. Behind the word "allergy" sit at least three diseases, each with its own plan.
Head shaking, scratching until he yelps, a yeasty smell. The ear is where it shows, the cause is usually elsewhere, and last time's drops will not find it.
The wet slurping every evening, rusty paws, a bald patch on the wrist. Licking is a symptom, and "he's bored" is the diagnosis that comes last, not first.
A puddle on the carpet at five in the morning, or three days of soft stool with mucus. Two different problems, and neither one gets solved from your medicine cabinet.
We work with your dog's behaviour, not its health. For any sign described here, book an appointment with your own vet; the related services page explains how to choose a clinic.