Interdigital Cysts in Dogs

Interdigital Cysts form in between a dog's paws in the webbing that’s found there and are extremely painful which makes it difficult for dogs to move about or walk. They are in fact, called Interdigital Furuncles and they are nodular lesions and not cysts at all. However, cysts found between a dog's toes could well be a type of furuncle or they could be a totally different type of problem altogether.

The Causes

One of the most common causes of dogs developing interdigital furuncles is because they have developed some sort of bacterial infection that's deeply embedded in the tissue found in between their toes. It could be that a foreign object has lodged itself in the tissue and this has then become infected. Dogs will lick and chew at the affected area of their foot which just makes the condition that much worse.

The reason they are more prone to developing the furuncles between their toes is because the hair that grows in the webbing can easily get pushed back into hair follicles when dogs are running along. When the hair gets trapped in skin, it can cause an inflammation which can then lead to a bacterial infection flaring up. Occasionally, a foreign object might become embedded in the webbing, but this is quite rare. A primary cause of the condition is typically Demodicosis (mange) and sometimes Canine atopic dermatitis can be the cause of dogs suffering from the problem again and again. As previously mentioned, there is some evidence that the condition could be linked to trauma which leads to hair being retained beneath the skin found between a dog's toes.

Breeds Most at Risk

Some breeds seem to be more at risk of developing bacterial interdigital furunculosis than others and this is mainly due to the fact they have bristly, short hair growing in the webbing found between their toes or because the webbing is quite prominent. They may well develop the condition as result of both. The breeds known to suffer from the condition the most include the following:

• English Bulldog
• Shar Pei
• Labrador Retriever

Signs to Watch Out For

When a dog starts developing an interdigital furuncle they typically show signs of being lame on the affected foot. In the early stages, the problem may be localised in one area in and if left untreated, this can quickly spread to other areas with multiple nodules forming. These nodules become inflamed, swollen and sore before they burst exuding a bloody fluid. They generally form on the upper side of a dog's paw, but they can also develop on the underside too. Because they are so painful, a dog suffering from interdigital furuncles will typically do the following:

• Be lame on an affected foot
• Lick and chew on their paws excessively
• Bite at the lesion on their paw

If the problem is caused by a foreign object becoming embedded in a dog's paw, removing it would typically solve the problem and unless another foreign object embeds itself again, the problem is not usually recurring. However, if it’s a bacteria problem, new lesions could well form and develop even when other lesions have been treated and cured. Research has found that the presence of free keratin in the tissue could be the trigger for dogs developing interdigital furuncles and why they keep recurring.

Diagnosing the Problem

A vet would examine a dog's foot to determine if they are suffering from the condition. They would establish if the cause is traumatic lesion or whether a foreign body has become lodged in between a dog's toes. They would also check to see if the dog has developed follicular comedone cysts and neoplasia which luckily, is very rarely seen in dogs.

The sort of tests a vet would do to establish a correct diagnosis may well include the following:

• Skin scrapings - this would check for Demodex mites
• Impression smears
• Fine-needle aspirates

If it is found that a foreign body is responsible, a vet would surgically remove this which is generally the case if the culprit is a grass seed or something similar. Should the vet suspect the problem is palmar and plantar follicular cysts, they would recommend doing a skin biopsy. However, it's worth noting that lesions found in dog's paw are very often complicated because of secondary infections setting in which includes Malassezia spp.

Treatment Options

In most instances, the condition can be treated with topical antibiotic ointments and antibiotics. However, any treatment would depend on how deep an infection has gone which could see a dog needing longer term treatment. Warm compresses and foot soaks have been found to be effective at treating interdigital furuncles. If lesions keep recurring, a vet would need to find out if there is an underlying cause which could well include the following:

• Atopy
• Hypothyroidism
• Concurrent Malassezia infections

With this said, antibiotic ointments although useful, cannot penetrate deep enough which is why vets prescribe a course of oral antibiotics. Owners must ensure a dog completes the recommended course for the antibiotic to be effective because all too often a dog might develop an interdigital furuncle again because the course of antibiotics was not completed or the doses were incorrect.