By Dr. Tyler Charbonneau,
DVM Dermatology and Allergy
PVESC
Transmission or Cause: Vasculitis is inflammation of blood vessels resulting in compromised blood flow to the affected areas. The inflammation is due to overstimulation of the patient’s own immune system. There are many possible causes including infection (bacterial, viral, fungal, or tick-transmitted illnesses), adverse drug or vaccine reactions, malignancies, and autoimmune (“self-attack”) disorders such as systemic lupus. In many cases, the exact cause cannot be determined.
Animals Affected: Vasculitis is uncommon in canines and rare in felines. Patients can be of any age, breed or gender, although some breeds may be overrepresented such as Jack Russell terriers. In cases of vaccine-related vasculitis, it is more common in small-breed, silky-coated dogs such as Poodles and Yorkshire terriers.
Clinical Signs: Symptoms include bruising of the skin, localized area of necrotic (dead) skin and skin ulceration. The commonly affected areas include ear pinnae, lips, mouth, paws, tail, and scrotum. Patients that have vasculitis induced by rabies vaccination may have localized hair loss at the injection site, occurring 1-3 months post-vaccination. Some patients progress to a more generalized form of vasculitis causing symptoms of lethargy, decreased appetite, fever, muscle disease, joint inflammation and swelling of extremities.
Diagnosis: The diagnosis of vasculitis is determined by the patient’s medical history, clinical signs (symptoms), and diagnostics to identify causes of vasculitis. Diagnostics may include full routine blood work/testing for autoimmune and/or infectious diseases, and skin biopsies. Skin biopsies may demonstrate inflammation of blood vessels with resultant damage to skin glands and hair follicles.
Prognosis: The prognosis depends on the underlying cause, severity of symptoms, and extent, if any, of internal organ involvement.
Treatment: Treatment of vasculitis involves identifying and treating underlying causes if possible and using medications to suppress blood vessel inflammation. Medications include corticosteroids, pentoxifylline, combined use of tetracycline and niacinamide, dapsone, sulfasalazine, cyclosporine, and azathioprine. In some patients, medication(s) can be weaned over time while some animals require lifelong medication for disease control. Most patients are very tolerant of such medications, even long term.
Prevention: Because there are many potential underlying causes of vasculitis, prevention per se is not usually possible. However, in dogs with rabies vaccine-induced vasculitis, further vaccinations should be avoided, if possible, as they may exacerbate the disease.