When dog owners discover a lump between their pet’s toes, they often call it an interdigital cyst. This term, however, is a misnomer for what is more accurately known as interdigital furunculosis. These formations are not true cysts, which are fluid-filled sacs, but are instead painful inflammatory nodules. They are severe, boil-like lesions rooted in the skin of the paw webbing.
Signs and Underlying Causes
The first sign is often a change in the dog’s behavior, like persistent licking of the paw or lameness. Upon inspection, an owner might notice one or more raised, reddish-purple bumps in the webbing between the toes. These nodules can be smooth and shiny, ranging from 1 to 2 centimeters in diameter, and may rupture to release a bloody or pus-like fluid if a secondary infection is present. The area can be swollen and painful to the touch.
The development of these furuncles is an inflammatory response often triggered by trauma to hair follicles. Dogs with short, bristly hair coats and prominent paw webbing, such as English Bulldogs, Labrador Retrievers, and Chinese Shar-Peis, are particularly predisposed. The structure of their hair and paws makes it easier for short hair shafts to be forced backward into the follicles during movement, creating an ingrown hair. This embedded keratin from the hair shaft acts as a foreign body, provoking significant inflammation deep within the skin.
Other causes can also initiate this inflammatory cycle. Trauma from foreign bodies like splinters, thorns, or sharp grass seeds can become lodged in the skin, leading to a localized furuncle. Underlying allergic skin disease, where environmental or food allergies cause generalized inflammation and itching, is a common trigger. The resulting self-trauma from licking can damage follicles and lead to secondary bacterial infections. Obesity, which adds pressure to the paws, or mites can also contribute.
Veterinary Diagnosis and Professional Treatment
A veterinarian begins with a physical examination of the dog’s paws to assess the lesions. Diagnosis may be based on clinical signs, but further tests are common to identify the cause and rule out other conditions like tumors. A veterinarian may perform a skin scrape to check for mites or use cytology, where a small needle collects cells from the nodule to be examined under a microscope. This helps determine if the issue is primarily inflammatory or infectious.
For recurrent lesions, a bacterial culture can identify the specific bacteria and help select the most effective antibiotic. A biopsy, where a small piece of tissue is surgically removed for examination, provides the most definitive diagnosis and is used in persistent cases or when a tumor is suspected. This detailed examination of the tissue can confirm the presence of a furuncle.
Medical management is the most common approach, focusing on treating infection and reducing inflammation. This involves a long course of oral antibiotics, often for three to six weeks, to clear the deep infection. Topical treatments like medicated shampoos or wipes are also used to manage bacteria on the skin’s surface. Anti-inflammatory medications may also be prescribed to alleviate pain and swelling.
In some severe, chronic cases that do not respond to medical therapy, surgical options may be considered. This can involve lancing a single furuncle to remove a foreign object or, in extreme situations of recurrent disease, a procedure called fusion podoplasty. This surgery removes the affected web tissue to create a flat, unwebbed paw, preventing future furuncle formation.
At-Home Care and Prevention
While professional veterinary care is necessary for treatment, supportive at-home care can aid in recovery and help prevent recurrence. Under a vet’s guidance, owners may be instructed to perform regular paw soaks. Using a prescribed antiseptic solution or Epsom salts in warm water can help soothe the inflamed area, keep it clean, and encourage any abscesses to drain.
Managing the underlying cause is the best way to prevent recurrence. Owners should conduct regular paw inspections, especially after the dog has been walking on rough terrain, to check for foreign bodies, cuts, or initial signs of redness. Keeping the paws clean and dry is also beneficial. For dogs with conformational predispositions, protective boots can reduce friction and trauma during walks.
If allergies are the cause, strict adherence to an allergy management plan, which might include a special diet or medication, is needed. If obesity is a factor, weight management can reduce pressure on the paws.