When your canine companion develops sudden, painful skin lesions, it can be a cause for significant concern. These eruptions might indicate a serious underlying condition: an autoimmune disorder. In these cases, the dog’s own immune system, which is designed to protect them from external threats, mistakenly attacks healthy body tissues, including the skin. This guide will delve into the causes, diagnosis, and treatment of autoimmune skin diseases in dogs, drawing insights from veterinary expertise.
The Manifestation of Autoimmune Skin Disease
Autoimmune skin conditions specifically target the epidermis and dermis, the outer and inner layers of the skin. When these layers separate due to the immune system’s attack, it can lead to the formation of painful blisters and pustules in the affected areas. These fragile lesions can easily erode, leading to crusting from discharge and fluid, and ultimately, hair loss. A significant concern with these conditions is the high likelihood of secondary bacterial infections due to the compromised skin barrier.
While severe, recurrent atopic dermatitis (environmental allergies) is often a suspected precursor to autoimmune skin problems, other factors can also be involved. Symptoms of atopic dermatitis itself can include persistent itching, sneezing, rashes, watery eyes, and excessive paw chewing. Unfortunately, by the time an autoimmune skin disease is diagnosed, the initial trigger may no longer be apparent, complicating the diagnostic and treatment process.
While viruses are known to trigger autoimmune skin conditions in humans, their role in dogs is less documented. Although a genetic predisposition is recognized in human autoimmune disorders, it hasn’t been definitively proven in dogs, though it is suspected. For instance, superficial pemphigus, an autoimmune skin disease, is observed more frequently in certain breeds like the Akita.
Occasionally, specific medications can act as triggers. This includes certain antibiotics like sulfonamide, penicillin, and cephalosporin. Topical medications used for flea and tick prevention, such as those containing fipronil, amitraz, S-methoprene, dinotefuran, pyriproxyfen, or permethrin, have also been implicated. In some instances, discontinuing the suspect medication may lead to the resolution of skin issues. However, other dogs will require ongoing treatment to manage and restore skin health. If you suspect a topical medication might be the cause, consult your veterinarian about safer alternatives like PetArmor flea & tick treatment for dogs.
Diagnosing Autoimmune Skin Diseases
Although not common, autoimmune skin diseases do occur in dogs. A comprehensive medical history is crucial to rule out any drug-induced conditions or parasitic infestations that could mimic autoimmune symptoms. When these possibilities are excluded and the cause remains unclear, a definitive diagnosis often requires a skin biopsy.
The biopsy process can be complex. Ideally, the sample should capture a vesicle or pustule before it erodes, but these lesions are often very delicate and rarely intact when the biopsy is performed. Furthermore, any treatment administered before the biopsy can interfere with the results. Dr. William H. Miller Jr., a professor emeritus of medicine, emphasizes that even with extensive experience, a biopsy is the only definitive way to diagnose an autoimmune skin problem.
This diagnostic path can be costly. In situations where financial constraints are a concern, a veterinarian might initially opt for a treatment trial with steroids. If steroids provide insufficient relief or the lesions recur after their use, a biopsy might then be considered. A significant challenge with this approach is that steroids cannot be administered for 14 to 21 days prior to the biopsy, as their use can alter the histological findings and lead to an incorrect diagnosis.
Treatment Strategies for Canine Autoimmune Skin Disease
A combination of medications often yields the fastest results in treating autoimmune skin diseases. By using lower doses of individual drugs, the risk of adverse side effects can be minimized. Most treatment protocols begin with glucocorticoids (steroids like prednisone), either alone or in conjunction with potent immunosuppressive drugs such as azathioprine or cyclosporine.
Steroids are readily available and easy for owners to administer at home. However, long-term use can lead to side effects, starting with increased thirst and urination, and potentially progressing to conditions like diabetes mellitus, liver disease, and Cushing’s disease. Pulse therapy, involving intermittent high doses rather than daily lower doses, may be recommended for dogs initially requiring high steroid levels. For milder or localized issues, topical steroids or immunomodulators like tacrolimus may help maintain remission.
Antibiotics are often necessary to combat secondary bacterial infections that flourish on compromised skin. A culture and sensitivity test is recommended to identify the most effective antibiotic. Concurrently treating underlying allergic dermatitis, such as atopy, is also beneficial. Similarly, addressing secondary yeast or fungal infections is important.
Emerging treatments for canine autoimmune skin disease include acupuncture, potentially combined with herbal therapies. Oclacitinib (Apoquel) shows promise, though further research is needed for widespread recommendation. A significant advantage of oclacitinib is its generally lower incidence of side effects and greater overall safety compared to long-term corticosteroid use.
Some dogs may experience remission for varying periods, allowing for a gradual reduction in medication or even a temporary cessation. However, in most cases, the disease is likely to recur.
It’s generally advisable to avoid shampooing affected dogs. Shampoos often contain low concentrations of hydrocortisone, which may not be potent enough. More importantly, the mechanical action involved in applying and rinsing shampoo can exacerbate fragile autoimmune skin, potentially worsening the condition.
If your dog is experiencing skin issues, exploring over-the-counter options for general skin health might be considered, such as a medicated dog shampoo for itchy skin, but always consult your veterinarian for a proper diagnosis and treatment plan for autoimmune conditions.
This article has been adapted with permission from the Cornell University College of Veterinary Medicine’s DogWatch newsletter, published by Belvoir Media Group.
