Perianal fistula in dogs is an uncomfortable and potentially serious condition. It occurs when the tissue around a dog’s anus becomes inflamed and secondarily infected. This can lead to a great deal of pain and discomfort. Symptoms may include licking at the area around their anus, scooting along the floor on their hindquarters, straining during bowel movements, and general discomfort or lethargy. While perianal fistulas are not typically life-threatening if treated promptly by a veterinarian they can be difficult to manage once established. In this comprehensive guide, we will discuss what causes a perianal fistula in dogs and how it can be treated so your furry friend can get back to feeling its best again!
What is a perianal fistula?
Perianal fistula in dogs is a chronic inflammatory condition affecting the tissues surrounding the anus and rectum. This disease is marked by the development of abnormal passageways, or fistulous tracts, between the deeper tissue layers and the skin's surface. These tracts often exhibit an unpleasant odor and are typically characterized by ulceration, discharge of pus, and significant pain.
Perianal fistulas predominantly affect middle-aged dogs, with intact males being more susceptible to the condition. Although German Shepherd dogs have a predisposition to developing perianal fistulas, it can occur in any breed. The average age of affected dogs is around 7 years; however, the age at diagnosis can vary considerably, ranging from 2 to 12 years.
What causes a perianal fistula in dogs?
Immune-mediated pathogenesis is believed to be a contributing factor in the development of perianal fistulas in dogs. This means that the dog's own immune system may play a role in causing the condition. In such cases, an overactive or dysregulated immune response targets the perianal and perirectal tissues, leading to inflammation and the formation of fistulous tracts.
While the exact cause of this immune dysregulation remains unclear, understanding its potential involvement in the pathogenesis of perianal fistulas is crucial for developing targeted treatment strategies aimed at reducing inflammation and managing the immune response to promote healing and alleviate discomfort in affected dogs.
What are the symptoms of a perianal fistula in dogs?
Common symptoms of perianal fistulae in dogs include:
- Tenesmus (straining to defecate)
- Dyschezia (difficulty defecating)
- Malodorous and purulent perianal discharge
- Low tail carriage
- Perianal licking
- Hematochezia (blood in stool)
- Scooting
- Weight loss
- Lethargy
Perianal fistulas tend to develop gradually and progressively, which means the condition can often go unnoticed for some time, especially if the dog has long hair covering the perianal region.
How is a perianal fistula diagnosed?
Diagnosis of a perianal fistula in dogs relies on evaluating the dog's medical history, and findings from physical examinations, and excluding other possible conditions that may present similar symptoms, such as tumours, abscesses, and adverse reactions to food.
Your veterinarian will start with a thorough physical examination and a careful review of your dog’s medical history. A rectal examination is often necessary to evaluate the extent and severity of the condition. In some cases, due to the pain and sensitivity associated with perianal fistulas, a dog may need to be sedated or anesthetized for a more thorough examination of the affected area.
Your veterinarian may recommend a biopsy of the affected tissue to confirm the diagnosis and rule out other conditions, such as cancer.
What are the treatment options for perianal fistula in dogs?
The preferred treatment approach for perianal fistula involves the use of immune-modulating medications. Typically, systemic antibiotics are administered during the initial few weeks of treatment to address any secondary bacterial infections that may be present.
Medical management can be categorized into two distinct phases:
- Induction phase: This initial phase of treatment aims to alleviate the clinical signs of perianal fistulas. During this phase, higher doses of medication are typically administered, and it generally lasts for up to 4 months.
- Maintenance phase: The objective of this phase is to keep the clinical signs in check and prevent them from reappearing. Similar to other immune-mediated skin conditions, lifelong therapy may be necessary for effective management. Additionally, it is essential to control any secondary bacterial infections that may arise during this phase.
Treatment options for perianal fistula can be topical, systemic, or both. Topical treatments use tacrolimus as it is a potent immunomodulatory medication. If the dog's clinical signs are relatively mild and they tolerate topical therapy, tacrolimus can be utilized as the sole treatment. Tacrolimus is typically applied to the affected areas once to twice daily and can be used as a maintenance therapy.
Systemic therapy can be utilized either on its own or in tandem with topical treatment. Cyclosporine is the preferred systemic medication and has been studied thoroughly over multiple studies.
Furthermore, perianal fistula in dogs often shows significant improvement within 1-2 weeks after initiating treatment with cyclosporine. In a particular study, a vast majority of cases (85%) experienced resolution within 4 months. It is essential not to suddenly stop administering cyclosporine. Instead, once the clinical signs have notably improved or entered remission, the dosage should be gradually reduced. The goal is to taper the medication over a period of 3-5 months, allowing for a smooth transition and sustained recovery.
Combining cyclosporine with ketoconazole has been found to be a cost-effective treatment strategy for perianal fistula in dogs. Ketoconazole, an antifungal medication, is known to inhibit the enzyme responsible for breaking down cyclosporine in the liver. This interaction effectively increases cyclosporine's blood concentration, allowing for a reduced dosage of cyclosporine while maintaining its therapeutic benefits.
By using lower doses of cyclosporine in combination with ketoconazole, the overall cost of treatment can be significantly reduced. This approach makes the therapy more affordable for pet owners without compromising the efficacy of the treatment. It is essential to consult with your veterinarian before initiating this combination therapy, as they will carefully monitor your dog's response and adjust dosages accordingly to ensure optimal results and minimize the risk of side effects.
What is the prognosis for dogs with perianal fistulas?
Perianal fistulas are generally a chronic condition. While the overall prognosis for managing the symptoms is quite favorable, completely curing the disease can be challenging. It is crucial to understand that perianal fistulas may relapse or recur over time. In cases where the initial treatment is not highly effective, various drug regimens may be necessary to achieve the desired results. If your dog remains comfortable, you may opt to accept the presence of small fistulas, allowing for the use of lower medication doses and reducing the risk of drug-related side effects.
In conclusion, perianal fistula in dogs can be effectively managed with a combination of topical and systemic medications. Cyclosporine is the preferred systemic medication, however, combining it with ketoconazole has been found to reduce overall treatment costs without compromising efficacy. Although there is no definitive cure for this condition, with proper management and monitoring from your veterinarian, you may be able to keep your dog comfortable while minimizing the risk of relapse or recurrence. Ultimately, understanding how best to manage this chronic disease will help ensure that your dog remains happy and healthy for years to come.