Rabies Vaccine Induced Ischemic Dermatopathy (RVI-ID)

By Kathleen Wherley, Arcadian Norwich Terriers
Originally published in the AKC Gazette

NOTE: This article is compiled from medical information on a dog I bred, which was treated and diagnosed by Dr. Catherine Outerbridge, a Veterinary Dermatologist at UC Davis Veterinary Medical Teaching Hospital. Much of this information was obtained from Norwich owner, Wendy Larson.

There are evolving theories about the necessity and frequency of vaccinations for domestic dogs. State laws vary, but all require vaccinations against rabies. A little known and often misdiagnosed reaction to the rabies vaccine in Norwich Terriers is called "Rabies-Vaccine-Induced Ischemic Dermatopathy," or RVI-ID for short.

Rabies vaccines contain killed virus particles and also an "adjuvant," a substance that enhances antibody production. Some Norwich (perhaps 1-5%) have a reaction to the adjuvant ingredient which triggers an auto-immune response. Possible symptoms are: sores or lesions in the ear, hyperpigmentation (darkening) of the ear, sores on the tail or feet, dark lumps on the skin, or a lump at the injection site. Symptoms may appear immediately after a rabies vaccination, or may take days or even months to develop noticeably. These symptoms are not lethal, but can cause discomfort and/or disfigurement for your dog. Affected dogs show varying severity of symptoms, depending on their immune system and the conditions of the vaccination.

Most veterinarians are unfamiliar with RVI-ID and misdiagnose the problem. They often treat the symptoms with a steroid such as prednisone, and/or a cortisone ointment, which will alleviate the symptoms temporarily. Or they may prescribe antibiotics and anti-itch medications, which are ineffective. Some dogs resolve the symptoms on their own over time, but others will continue to worsen as the dog's immune system goes into overdrive, working against itself by attacking the vascular system.

If your dog shows symptoms of RVI-ID after receiving a rabies vaccine, consult with your vet or a veterinary dermatology specialist about using a vaccine from a different laboratory for future vaccinations.

Because the rabies vaccine is the most reacto-genic of the standard vaccinations given to dogs, it is advisable to space it out separately from other vaccinations. Leaving a two to three week interval between administering the rabies vaccine and other vaccinations (distemper) will lessen the chances of creating a reaction like RVI-ID. Administering an antihistamine medication such as Benedryl or diphenhydramine elixir will also dampen the reactive effect of the adjuvants without interfering with the immune response of the vaccine.

RVI-ID has become much more common now that most veterinarians give the rabies vaccine subcutaneously above the shoulders. Ask your veterinarian to administer the vaccine intramuscularly in the rear haunch muscle rather than subcutaneously.

If your dog does develop lesions in the ears or other symptoms of RVI-ID, Dr. Outerbridge recommends the following combined treatment: Pentoxyfylline, a pill that helps red blood cells to be more "flexible" and get through the capillaries and veins damaged by the autoimmune response, and Tacrolimus, an ointment that will help suppress the inflammation in the affected areas.

It is not an option at this time to discontinue vaccinating your dog against rabies. If your dog is not current on the required rabies vaccination and is ever thought to be exposed to rabies, it will mean immediate quarantine and perhaps even euthanization of your dog. But if your dog has an adverse reaction to the rabies vaccine, seek help in developing a vaccination protocol for your dog.