Pinnal Vasculitis: Why are my dog's ears crusty?
Vasculitis is a general term that is used to describe skin diseases that are caused by inflammation of the blood vessel walls. It is an uncommon disorder that can occur anywhere in the body of cats and dogs. If the condition affects the blood vessels of the ear flaps (pinna), it is referred to as “pinnal vasculitis”. It should be noted that vasculitis is not a disease in itself but a reaction to an underlying trigger. Keep reading to learn about the causes, symptoms, and treatment of pinnal vasculitis in dogs.
What causes pinnal vasculitis in dogs?
When inflammatory cells attack the walls of the blood vessels, it will result in the disruption of blood flow and eventually hypoxia (lack of oxygen) of the affected tissues, and death of tissues (necrosis). The inflammation is believed to be the result of the body’s abnormal immune response. Different factors can trigger this abnormal response. These include the following:
- Adverse reactions to drugs such as antibiotics and non-steroidal anti-inflammatory medications (NSAIDs)
- Vaccines - Cases of vasculitis have been reported following rabies vaccination. Certain breeds of dogs have been observed to be more prone to develop vaccine-related vasculitis. Vaccine-induced vasculitis is mainly seen in small breed dogs such as Toy Poodles, Silky Terriers, Yorkshire Terriers, Pekingese, Maltese, and Bichons.
- Infections - certain bacterial, viral, and protozoal infections have been implicated in cases of vasculitis.
- Certain types of cancer or neoplasia
- Autoimmune diseases such as Systemic Lupus Erythematosus (SLE)
- Idiopathic causes - The trigger factor cannot be identified.
Symptoms of Pinnal Vasculitis in Dogs
Pinnal vasculitis is one of the most common forms of vasculitis. The skin covering the pinna (ear flaps) is more susceptible to cold and other environmental factors. The lesions usually start to develop on the tip of the pinna and spread along the pinnal surface.
An ulcer is often found in the center of the lesion. The ulcer is surrounded by a thick layer of crust and scaling. The skin may take on a darker color (hyperpigmentation). The skin of an affected area develops purple spots, redness, sores, and scabs. Shedding of dead tissue can also occur. Without proper veterinary intervention, the tissues will die from a lack of oxygen and the dog will end up with a deformed ear flap margin.
Acute vasculitis commonly occurs in the dog’s legs and feet, ears, lips, the tip of the tail, scrotum, and oral mucosa. These areas are more vulnerable as their blood supply has limited collateral circulation.
Two Common Types of Pinnal Vasculitis in Dogs
- Vasculitis with cartilage necrosis of the pinnal fold is characterized by the formation of crusts, exudates, and ulcers on the middle part of the pinna or ear flap. The lesions are also present along the pinnal fold of dogs whose ears have been cropped.
- Proliferative thrombovascular necrosis of the pinna is a progressive condition characterized by painful wedge-shaped lesions and death of the tissues of the outer margins of the ear flap. Tissue death is caused by the decrease in blood flow to the area as a result of blot clot formation within blood vessels. Changes to the skin generally start at the tip of the ear flap and then spread toward the inner surface.
Most cases of vasculitis in dogs are associated with the antigen-antibody response of the immune system. Take note that any foreign antigen (trigger factor) can provoke an immune response. The list of trigger factors is quite long and may include bacteria, viruses, protozoa, drugs, cancer, food, or autoimmune disease (like lupus erythematosus).
How Pinnal Vasculitis in Dogs is Diagnosed
Several factors should be considered to arrive at a definite diagnosis. These factors include the history and clinical findings coupled with results of histopathology (biopsy) tests.
A biopsy is necessary to arrive at a definitive diagnosis. The results of the biopsy are reviewed by a dermatohistopathologist (veterinarian specialized in skin pathology). Once the diagnosis has been established, the next step would be to identify the underlying cause.
Your vet may recommend blood work and urinalysis for further evaluation. Serological tests can help rule out infectious causes. If serology results are negative, bacterial cultures and specific auto-antibody tests may be considered. Medications given or vaccinations administered within the last 4-5 months may also have to be considered. There are cases, however, when the cause cannot be fully established and are termed as ‘idiopathic”.
Treatment of Pinnal Vasculitis in Dogs
The treatment protocol for pinnal vasculitis must be tailored to the individual dog based on the extent and severity of the skin lesions. It involves correcting the underlying cause or triggering factor(s) and administering medications that support immune system integrity and function. These may include:
- Immunomodulatory agents (Pentoxyfylline, Tacrolimus)
- Immunosuppressive medications (Prednisone, Cyclosporine, Chlorambucil)
- Tetracycline-Niacinamide combination
- High-dose fatty acid therapy
- Surgery may be necessary to remove the dead and diseased tissues.
Considering that these medications can have potential side effects, administering any drug to your dog without veterinary advice can be counter-productive and could only lead to more serious health issues.
Treating pinnal vasculitis in dogs can entail time and lots of patience. Many cases can be a challenge to control and different treatment regimens may be necessary. Treatment may take as long as 3-4 months to get the problem under control and the dog may require life-long medication to minimize or altogether prevent a recurrence.
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