Acute moist dermatitis — a hot spot — is one of the fastest-developing skin problems in dogs. An owner can go to bed with a normal dog and wake to a hairless, raw, weeping patch that was not there the night before.
What happens
Something makes one small area itch. The dog licks, chews and scratches it. That trauma damages the skin surface, bacteria on the skin multiply in the damaged warm moist environment, and the resulting infection itches more.
The cycle self-accelerates. A dog can create a lesion several centimetres across in a few hours.
What they look like
- Red, moist, often weeping or oozing
- Hair loss over the area, with the surrounding hair matted and damp
- Well-defined edges, distinguishing it from more diffuse skin disease
- Hot to the touch
- Extremely painful. Dogs who are normally tolerant may snap when the area is approached
- Often on the cheek, neck, shoulder, hip or tail base
- Sometimes with a distinctive smell
What causes them
The hot spot is the result. Something started it, and if you do not find that something, it will happen again.
Common triggers:
- Fleas, and particularly flea allergy dermatitis
- Atopic dermatitis — environmental allergy
- A damp, unbrushed coat, especially in double-coated breeds after swimming or a bath. This is why they are more common in summer and in thick-coated dogs
- Ear infection, causing scratching at the head and neck
- Anal gland problems, causing chewing at the tail base
- Pain in a joint underneath, causing licking at one spot
- A foreign body — a grass seed
- Boredom or stress, producing repetitive licking
- Insect bites or stings
- Matted coat trapping moisture against the skin
What to do
Go to the vet. Hot spots are painful, they are infected, and they spread fast. Most need veterinary treatment and many need pain relief.
Treatment usually involves:
- Clipping the hair around and over the lesion, which is essential — you cannot treat what you cannot reach, and hair traps moisture and discharge. This often needs sedation, because the area is genuinely painful
- Cleaning with an antiseptic solution
- Topical treatment — a medicated spray, cream or powder, often containing an antibiotic and a steroid
- Systemic antibiotics for deeper or larger lesions
- Anti-inflammatories for pain and itch
- A cone or recovery suit, which is not optional. A dog who can reach the lesion will undo everything
What you can do at first aid level
If you cannot get to a vet immediately:
- Clip the hair around it if you can do so safely — blunt-nosed scissors or clippers, and only if your dog will tolerate it
- Clean gently with dilute chlorhexidine or plain saline
- Dry the area thoroughly
- Stop the dog reaching it — a cone, a recovery suit, or a t-shirt for a lesion on the body
- Keep it dry and open to the air. Do not bandage it
Do not:
- Apply human antiseptic creams, hydrocortisone or tea tree products
- Use hydrogen peroxide, which damages healing tissue
- Cover it with a dressing
- Let the dog swim or get wet
- Assume it will resolve on its own
Which dogs get them
More common in:
- Thick and double-coated breeds — Golden Retrievers, Labradors, German Shepherds, Newfoundlands, Saint Bernards, Rottweilers
- Dogs who swim
- Dogs with allergies
- Dogs with ear problems or hip pain
- Dogs in hot, humid weather
Preventing the next one
Find the underlying cause. A dog who has repeated hot spots has an ongoing problem — usually allergy, fleas, ear disease, or pain. Treating each hot spot individually without investigating the cause means treating them forever.
Keep the coat dry. Dry thoroughly after swimming and bathing, particularly down to the skin in double coats. A dog dryer on a cool setting is worth owning for a thick-coated dog.
Brush regularly. Matted coat traps moisture against the skin and prevents air circulation.
Some links on this page are affiliate links. If you buy through them we may earn a small commission at no extra cost to you — it helps keep this site free. We only recommend products we would use with our own dogs.
SleekEZ Deshedding Grooming Tool
For pulling dead undercoat out of a thick-coated dog. Loose undercoat holds moisture against the skin, which is exactly the environment hot spots form in — regular deshedding in summer is genuine prevention rather than tidiness.
Effective flea control, year round, on every animal in the house.
Manage allergies properly, with veterinary support.
Wipe and dry after walks, especially in wet weather.
Earth Rated Dog Wipes
For cleaning and drying paws and legs after a wet walk. For an allergic dog, removing pollen from the coat also removes one of the triggers that starts the scratching.
Address boredom and stress, which drive repetitive licking.
Check ears weekly, and deal with infections promptly.
When it is not a hot spot
Several things look similar and need different treatment:
- A bite or sting with localised swelling
- A puncture wound or abscess, which will be more swollen and may have a visible entry point
- Ringworm, which is typically circular, scaly and less moist
- Demodex or other mange
- A tumour, particularly a mast cell tumour, which can be red, swollen and variable
Which is another argument for having a vet look rather than treating a raw patch at home and hoping.
