By Dr. Jennifer Coates
Veterinarians have a saying, “when you hear hoof beats, think horses not zebras,” which serves to remind us all that rare diseases are… rare. But zebras are sometimes responsible for the sound of hoof beats. These five rare dog diseases are worth knowing about.
Alopecia is the medical term meaning an abnormal absence of hair. The “X” in Alopecia X simply indicates that the veterinary community doesn’t completely understand what is going on with this condition. Dogs with Alopecia X experience gradual, symmetrical hair loss over the sides of their bodies. At first the areas are covered with a fuzzy “puppy” coat, but eventually, all the hair falls out.
No treatment is necessary since Alopecia X is a strictly a cosmetic concern, but some dogs do respond to castration, medications that suppress adrenal function, or hormone supplements.
Dogs with malignant hyperthermia develop dangerously high body temperatures in response to a variety of stimuli, including stress, excitement, activity, and anesthetic agents. These individuals have faulty channels in their muscle cells that cause them to contract and then fail to relax normally. This causes muscle twitches and spasms. The high body temperature that results can lead to severe metabolic changes, a rapid and uneven heart rhythm, organ failure, and sometimes death. Episodes can be treated with intravenous administration of the drug dantrolene. Prevention is limited to avoiding the situations that initiate an attack, and keeping dogs in a cool environment.
Urinary tract infections or inadequate housetraining are the first things that come to mind when a young dog is leaving behind dribbles (or puddles) of urine on the floor. Once these conditions are ruled out, however, the possibility of an ectopic ureter should be considered. Ureters are the tubes that carry urine from the kidneys to the bladder. A relatively rare canine birth defect sometimes results in one or both of these tubes emptying away from their normal location in the bladder. Surgery is the most effective way to treat ectopic ureters in dogs, but sometimes medications or other therapies can be useful as well.
Myasthenia gravis is a disorder affecting the connection between nerves and muscles. Most cases develop as a result of the dog’s own immune system attacking this neuromuscular junction, but cancer, disorders of the thyroid gland or thymus, birth defects, and other conditions may also be to blame. Muscle weakness is the classic sign of myasthenia. Sometimes this weakness is limited to a small group of muscles (e.g., those of the esophagus), but in other cases the entire body seems to be affected. Supportive care and medications that prevent the breakdown of the neurotransmitter acetylcholine can help many dogs with myasthenia lead a relatively normal life.
Vogt-Koyanagi-Harada (VKH) Syndrome (also known as uveodermatologic syndrome) is an immune-mediated disease that results in eye problems (red eyes, tearing, poor vision, blindness, squinting, discomfort in bright light, etc.) and an abnormal whitening of tissues and hair around the eyes, lips, nose, and sometimes other parts of the body. Treatment typically involves a combination of medications that reduce inflammation and suppress the immune system in the eyes and affected skin. Other therapies may also be necessary depending on the severity of a dog’s VKH.