Interdigital cysts — also known as interdigital furuncles — are painful, fluid-filled swellings that develop in the skin between a dog’s toes. They are a common cause of paw licking, lameness, and general paw discomfort, and while they can appear suddenly and look alarming, they are treatable with appropriate veterinary care.
If your dog has been persistently licking their paws, limping on one foot, or you have noticed a swollen, red lump between their toes, contact Walker Lake Veterinary Centre at (587) 786-6771 for an assessment.
The term cyst is somewhat misleading — interdigital furuncles are not true cysts. They are inflammatory nodules that develop when hair follicles in the webbing between the toes become blocked, infected, or ruptured. Understanding this distinction explains both why they are painful and why they tend to recur.
Where Do Interdigital Cysts Develop?
Interdigital cysts develop in the interdigital spaces — the webbed skin between the toes. Dogs have webbing between each of their four main toes on all four feet, giving multiple potential sites for lesions to develop.
The front feet are more commonly affected than the hind feet, possibly because they bear more of the dog’s body weight and are subjected to greater repetitive trauma during normal movement. Lesions can affect a single interdigital space on one foot or multiple spaces across several feet simultaneously.
What Causes Interdigital Cysts?
Interdigital cysts rarely have a single clear cause. In most cases, multiple contributing factors interact to create the conditions for a lesion to develop.
Hair Follicle Trauma and Rupture
The most widely accepted mechanism involves short, stiff hairs in the interdigital skin being driven backward into the follicle — typically during normal walking on hard or rough surfaces. The inverted hair causes follicular inflammation, blockage, and eventually rupture of the follicle wall. When a hair follicle ruptures, the keratin and hair debris it releases into the surrounding tissue provokes a significant inflammatory response, producing the swollen, painful nodule characteristic of an interdigital furuncle.
Allergies
Environmental allergies and food allergies are strongly associated with interdigital cysts. Allergic dogs lick and chew their paws excessively — this repetitive trauma to the interdigital skin, combined with the chronic inflammation allergies cause in the skin, creates ideal conditions for follicular blockage and rupture.
Dogs with recurrent interdigital cysts — particularly those affecting multiple feet simultaneously — almost always have an underlying allergy driving the problem. Treating the cysts without addressing the allergy results in a cycle of resolution and recurrence.
Demodicosis
Demodex mites — which live in hair follicles — can trigger follicular inflammation and interdigital furuncle formation, particularly in young dogs or immunocompromised adults with generalised demodicosis. Any dog with recurrent interdigital cysts should have a skin scraping performed to assess for Demodex.
Bacterial Infection
Secondary bacterial infection is almost universally present in established interdigital furuncles. Staphylococcus pseudintermedius is the most common organism involved. The bacteria do not typically initiate the condition but rapidly colonise the inflamed, compromised follicle, compounding the inflammation and transforming a mild lesion into a painful abscess.
Anatomical Predisposition
Short-coated, heavily built dogs with broad, flat feet and tightly webbed toes are anatomically predisposed to interdigital cysts. The short, stiff coat hairs are more prone to follicular inversion, and the tight webbing creates more friction and less airflow between the toes.
Predisposed Breeds
- English Bulldogs — among the most commonly and severely affected
- French Bulldogs
- Labrador Retrievers
- Great Danes
- German Shepherds
- Boxers
- Basset Hounds
- Chinese Shar-Peis
Other Contributing Factors
- Obesity — excess body weight increases mechanical load on the feet and the degree of friction between the toes
- Walking on rough, abrasive, or hard surfaces — gravel, concrete, and rough terrain increase follicular trauma
- Moisture — wet feet that are not dried regularly create a moist environment that promotes bacterial growth
- Foreign bodies — grass awns and other foreign material embedded in the interdigital skin can trigger or perpetuate lesions
Signs and Symptoms
What Interdigital Cysts Look Like
- A smooth, round, reddish-brown or purple swelling between the toes — typically 0.5 to 2cm in diameter
- The lesion may be firm or fluctuant — soft and fluid-filled — depending on its stage
- Single or multiple lesions across one or more feet
- The surrounding interdigital skin is typically red and inflamed
- In more advanced cases the lesion ruptures, producing a draining tract with serosanguineous or purulent discharge
Signs of Discomfort
- Persistent licking and chewing of the affected paw — often the first sign the owner notices
- Lameness — favouring the affected foot, particularly on hard surfaces
- Reluctance to walk, run, or exercise
- Redness and brown saliva staining between the toes from chronic licking
- Pain when the paw is handled or when the interdigital space is gently palpated
Diagnosing Interdigital Cysts
Physical Examination
The diagnosis is typically made on physical examination — the characteristic location, appearance, and associated signs are usually sufficient. A thorough examination of all four feet is important to identify all affected sites.
Skin Cytology
A sample from the lesion — obtained by impression smear or fine needle aspiration — is examined microscopically for bacteria, yeast, and inflammatory cells. Cytology guides appropriate antibiotic selection and identifies concurrent yeast involvement.
Skin Scraping
Performed to detect Demodex mites — essential in dogs with multiple affected feet or recurrent lesions, particularly younger dogs.
Skin Biopsy
For recurrent or treatment-resistant lesions, biopsy provides definitive histological characterisation of the lesion and can identify foreign material, unusual organisms, or neoplastic change.
Allergy Investigation
For dogs with recurrent interdigital cysts — particularly involving multiple feet — allergy investigation should be discussed with your veterinarian. This may include a food elimination diet trial and assessment for environmental allergies.
Treating Interdigital Cysts
Treatment addresses both the acute lesion and the underlying predisposing factors.
Topical Treatment
For mild, early lesions, topical treatment alone may be sufficient. This includes:
- Daily foot soaks in dilute chlorhexidine solution — reduces bacterial load and softens the lesion
- Topical antimicrobial sprays or wipes applied to the interdigital spaces
- Keeping the feet clean and thoroughly dried after outdoor walks and bathing
Systemic Antibiotics
Most established interdigital furuncles require a course of systemic antibiotics to address the bacterial component. Treatment duration is typically 4 to 6 weeks — shorter courses frequently result in incomplete resolution and recurrence. Culture and sensitivity testing is recommended for recurrent or non-responsive cases to ensure the correct antibiotic is being used.
Anti-Inflammatory Medication
Oral anti-inflammatory medication — typically an NSAID — reduces the pain and inflammation associated with the lesion and helps break the licking cycle.
E-Collar
An Elizabethan collar prevents the dog from licking and chewing the affected paw during treatment. Interrupting the licking cycle is essential for resolution — continued licking perpetuates the inflammation and introduces additional bacteria to the site.
Surgical Treatment
For individual chronic or recurrent lesions that fail to respond to medical management, surgical options include:
- CO2 laser ablation — highly effective for destroying the abnormal tissue and reducing recurrence
- Surgical excision of the lesion
- Surgical fusion of the interdigital web — removing the webbing between affected toes eliminates the tight interdigital space that predisposes to lesion formation. This is typically reserved for dogs with severe, recurrent disease affecting a specific interdigital space
Addressing the Underlying Cause
As with most recurrent skin conditions in dogs, long-term resolution requires identifying and managing the underlying cause:
- Allergy management — if allergies are driving the problem, implementing appropriate allergy treatment significantly reduces recurrence
- Weight management — achieving a healthy body weight reduces mechanical foot stress
- Demodicosis treatment — if Demodex is identified, specific antiparasitic treatment is required
- Surface modification — where possible, reducing the dog’s exposure to rough, abrasive surfaces
If your dog has swollen, painful toes or has been persistently licking their paws, book an appointment at Walker Lake Veterinary Centre. Call (587) 786-6771 or book online. Located at 5109 22 Avenue SW, Southwest Edmonton.
Preventing Recurrence
For dogs prone to interdigital cysts, ongoing preventive care reduces the frequency and severity of recurrence:
- Dry the feet thoroughly after every walk — particularly between the toes
- Regular foot soaks with dilute chlorhexidine solution during periods of active skin disease
- Keep nails trimmed — long nails alter foot posture and increase interdigital pressure
- Booties during walks on rough or abrasive surfaces — can significantly reduce follicular trauma in predisposed dogs
- Maintain a healthy body weight
- Year-round flea and parasite prevention — reduces one potential inflammatory trigger
- Manage any underlying allergies consistently
Book an Appointment at Walker Lake Veterinary Centre
Walker Lake Veterinary Centre provides skin assessment, cytology, and treatment for interdigital cysts and other paw conditions in dogs across Walker Lake, Summerside, Ellerslie, Heritage Valley, and Southwest Edmonton.
Call us at (587) 786-6771 or book online. We are located at 5109 22 Avenue SW, Edmonton.
Clinic hours:
- Monday, Tuesday & Thursday: 9:00 AM – 7:00 PM
- Wednesday & Friday: 9:00 AM – 6:00 PM
- Saturday: 9:00 AM – 3:00 PM
- Sunday: Closed
Frequently Asked Questions
Can interdigital cysts resolve on their own?
Very mild early lesions occasionally resolve with improved foot hygiene alone. However, most established interdigital furuncles require veterinary treatment to resolve completely. Without treatment, lesions typically worsen — the bacteria multiply, the lesion enlarges, and it becomes increasingly painful and difficult to treat.
Are interdigital cysts contagious to other dogs or humans?
Interdigital cysts themselves are not contagious. However, if the underlying cause is demodicosis or a bacterial skin infection, appropriate precautions are warranted. Discuss this with your veterinarian if you have multiple dogs in the household.
Why does my dog keep getting interdigital cysts?
Recurrent interdigital cysts almost always have an underlying cause — most commonly allergies, but also demodicosis, obesity, or anatomical predisposition. Repeated short courses of antibiotics that resolve each episode without investigating the root cause leads to an ongoing cycle. A thorough dermatological investigation is warranted for any dog with more than two episodes.
Can I treat my dog’s interdigital cyst at home?
Daily foot soaks in dilute chlorhexidine solution and keeping the feet clean and dry are appropriate supportive measures at home. However, most established lesions require prescription antibiotics and anti-inflammatory medication from a veterinarian for complete resolution. Do not attempt to lance or squeeze the lesion at home — this introduces further bacteria and significantly worsens the inflammation.
How long does treatment take?
Most interdigital furuncles require 4 to 6 weeks of antibiotic treatment for complete resolution. Dogs that respond well to treatment typically show meaningful improvement within 2 weeks. Lesions that are not improving after 3 to 4 weeks of appropriate treatment should be re-evaluated — culture and sensitivity testing and biopsy may be indicated.
