Hot spots (wet eczema, pyotraumatic dermatitis)

Sometimes dogs develop a sore spot on the skin which oozes and irritates. Often this develops over the space of just a few hours. The critical step in managing these spots is to stop the dog worrying them but veterinary attention should be sought to ensure there is no underlying condition that needs treatment. In most cases early treatment results in a rapid resolution of signs.

Wet eczema is also known as ‘hot spots’ and your vet may refer to it as ‘acute moist dermatitis’ or ‘pyotraumatic dermatitis’. It is caused by infection in the surface of the skin. Bacteria are present on all dogs’ skin but in order to cause infection they must break through the skin barrier. This can occur when there is damage to the skin either through changes in the skin itself or scratching by the dog.

Once the skin barrier is penetrated the bacteria can grow and this infection causes intense itchiness and the dog scratches the site resulting in further damage and spread of the sore.

It is normally clear when a dog has wet eczema. The sores are usually obvious as they most often develop on the face and the flanks. The skin sores in this condition are extremely itchy and affected dogs are unable to leave them alone. You will see your pet continually licking or scratching at the same site on their skin. The skin sores look red and ‘angry’ and exude a moist clear discharge which has a very unpleasant smell. If the sore is left alone then the exudates may dry and crust on the surface.

Some breeds of dog (especially Labrador retrievers and St Bernards) appear to be prone to developing wet eczema. However, it can be seen in any breed. Younger dogs also appear to be at greater risk of developing wet eczema, although once a dog has had one episode of wet eczema they are likely to be prone to subsequent episodes later in life too. Wet eczema is more common in summer months and particularly if dogs have dense or matted coats.

Wet eczema is triggered by an underlying skin problem and often it is caused by the dog scratching due to itchy skin. The itchy skin condition can be due to allergy (e.g. atopy), fleas, ticks or other parasites, irritation from an ear disease or anal sac disease or from the presence of a foreign body in the skin, e.g. a splinter, grass seed or thorn.

Irritation by a drop-on anti-flea treatment or other liquid that the skin was exposed to either intentionally or unintentionally is sometimes a cause. Continual wetting from bathing, swimming or drooling are possible causes. Damage from blades during clipping is also a consideration.

Wet eczema is usually caused by another skin disease so your vet will want to identify any potential cause – the condition will not clear up unless the underlying disease is properly treated. Your vet will check to see if an underlying disease is present and if so this can be treated at the same time as the wet eczema.

Sometimes, other skin diseases such as burns, deep bacterial infections, ringworm (dermatophytosis), calcinosis cutis or some tumours can have the appearance of wet eczema and so it is important to confirm the diagnosis in case a different treatment is needed. Clipping the surrounding fur, skin scrapes and cytological examinations and full-thickness skin biopsies are all useful tests that may often be helpful. Further tests are necessary in some situations.

The most important factor in management of wet eczema is to stop further trauma to the skin. The dog must be prevented from licking or scratching at the site – depending on the site of the sore a Buster or Elizabethan collar may be necessary. If the dog is scratching at the sore then bandaging the foot may help to reduce the amount of damage done. However, the affected area should be left open to the air whenever possible as this drying effect is very beneficial in the healing process.

Hair should be clipped from the sore skin and from the area surrounding the sore patch. Often the sores are much more extensive than they appear initially but clipping should be expanded continue until the whole affected area is exposed. The skin can then be bathed and dried.

Your vet may prescribe some antibacterial shampoo or cream to rub into the wound. but in most cases this is not necessary. However, in more severe cases, (particularly if the underlying skin disease is difficult to control), steroids or antihistamines may be required to reduce itchiness and antibiotic tablets given to control infection.

If your pet has had wet eczema it is quite likely that this will recur. Risks can be reduced by keeping the coat short and clean with regular bathing. Extra attention should be paid to flea control. Regular grooming will allow you to identify any skin diseases or wet eczema lesions early.