Health
Nothing in the morning, a red wet patch under the ear by evening, the size of your palm next day. Hot spots spread fast and nearly always have another cause.
Caution. The red, wet patch is growing by the hour, it is on his face or near an eye, he will not let you touch it, there is smelly pus or he has a temperature: ring your dog's vet today. Until then, a protective collar and nothing on the wound.
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.
His coat looked fine this morning. This evening, just under his ear, there is a red, wet, shiny patch the size of a jam-jar lid, with the hair stuck down around it, and when you reach for it he flinches or growls. By tomorrow it is the size of your palm. Maybe he is a retriever who swam in the lake on Sunday and was left to dry off on his own, or a shepherd with a dense undercoat in late August. This is a hot spot, a moist dermatitis that appears and spreads within hours, nearly always because something else set him off licking or scratching. Below: when to ring the vet today, what to note down, what the vet will do, and what you should never put on it.
A hot spot will not kill him. It is an open wound, though, it hurts and it keeps getting bigger. Ring the same day if:
Ring straight away, too, if he also shows signs of an ear infection: shaking his head, holding it on one side, an ear that is red and smells. A hot spot on the cheek very often starts at the ear.
A photo with a ruler next to it. Take one now and another six hours later, ruler beside the patch both times. The vet can tell from them how fast it is spreading.
Where it is. He cannot tell you what is itching, but where the patch sits often can:
| Where the patch is | What may be behind it |
|---|---|
| Cheek, under the ear, neck | An ear infection or an itchy ear; he scratches it with a back paw |
| Rump, above the tail, thighs | Fleas (flea allergy), full anal glands |
| Near a joint (hip, knee) | Pain: he licks the place that hurts |
| Anywhere, after a bath or a swim | A thick coat that stayed wet against the skin for hours |
| Paws, belly, armpits | Allergies, environmental or food |
Fleas. Stand him on a white towel and run a fine flea comb through the base of his tail. Black specks that go reddish on damp kitchen paper are flea dirt. In an allergic dog, one flea is enough.
What happened in the days before. A swim, a bath with no proper drying, a heatwave, a stay in kennels, a short clip, a new food, a missed parasite treatment. Write down when the scratching started and where.
The coat. In breeds with a dense undercoat, such as golden retrievers, Labradors, German shepherds, huskies and Newfoundlands, check whether dead undercoat has balled up against the skin. That is where the damp sits.
Until you get to the vet, if you have a protective collar at home (the cone from a previous visit), put it on him so he cannot reach the patch. That is as far as it goes. Nothing goes on the wound.
If hot spots keep coming back, the vet will suggest an allergy plan. That might mean strict flea control all year, an elimination diet if a food allergy is suspected, or tests for environmental allergies.
The collar stays on day and night, including when he seems to be sleeping peacefully. Take it off "just for an hour" and the next morning you will find the patch open again. Raise his food and water bowls on a step, or use wider ones, so the cone does not catch on the rim. Walks carry on. Swimming and pushing through undergrowth wait until the patch has closed. If it is on his neck, leave the collar off for a few days and use a harness that keeps clear of the spot.
Look at the patch twice a day without touching it. Good signs: it dries, goes matt, then scabs. Bad signs: it gets wet again, spreads, or yellow dots appear around it, and then you ring the vet without waiting for the check-up.
After every swim or bath, dry him right down to the skin, not just the top layer. On dogs with a thick undercoat, a towel followed by a dryer on a cool setting makes a big difference. Brush him often while he is moulting so dead undercoat cannot pack against the skin. Keep up flea protection all year, and look in his ears once a week. And when you see him scratching hard at the same place, look there first, before a patch has a chance to appear.
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.
A wet, painful inflammation on the surface of the skin, which vets call acute moist dermatitis. It starts when a dog licks, scratches or chews at one place over and over: the damaged skin gets damp, infected and spreads. Within a few hours it can grow from the size of a fingernail to the size of a palm.
Because something itches or hurts: fleas, especially in allergic dogs, an ear infection, full anal glands, environmental or food allergies, a sore joint. A thick coat left wet after a swim or a bath, and hot weather, give the patch a head start. Breeds with a dense undercoat, such as golden retrievers and German shepherds, get them more often.
Rarely, because the itching and licking keep it open. More often it gets bigger day by day. Caught on the first day, with the hair clipped, the wound cleaned by the vet, a protective collar and the cause treated, it dries out within days and the hair grows back in two or three weeks. Left alone, the infection can go deeper.
Nothing. Human creams, surgical spirit, vinegar and essential oils sting, seal the damp in or are toxic when the dog licks them off. What you can do is put a protective collar on him so he cannot reach the patch, and get him to the vet the same day with a photo taken with a ruler beside it.
Dry him thoroughly after swimming and bathing, right down to the skin. Brush him often while he is moulting so dead undercoat does not sit against the skin. Keep up flea protection all year and look in his ears once a week. If hot spots keep coming back, ask your vet for an allergy plan.
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.
A hard bead with legs on his neck after the woods, or black specks on the sofa that turn red when wet. Both can be sorted out, and neither with oil or garlic.
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.
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.