The recent outbreak of measles in United States highlights the importance of vaccinations and prevention of diseases in this new global world. In veterinary medicine, we are extraordinarily fortunate to have a number of safe and effective vaccines to aid in the prevention of many life-threatening viral and bacterial diseases. One viral disease I would like to highlight today is Canine Distemper Virus (CDV). Like the measles virus, CDV belongs in the Paramyxoviridae family and the Morbillivirus genus. Despite Canine Distemper and Measles viruses sharing the same family and genus, neither virus can cross-infect the other species. Both viruses are highly contagious and present initially with fever, cough and red, runny eyes (conjunctivitis). Both viruses can invade the nervous system and cause life-threatening encephalitis. Thankfully, both viral diseases have a highly successful and safe vaccine to prevent the disease in their susceptible host. Another similarity, unfortunately, is that some people have become lax in their compliance with vaccinating their young children against measles and/or their pets against CDV. I’d like to sadly present a recent medical case of mine to convince those non-supporting vaccination policy individuals that they are foolishly playing Russian roulette with their loved one’s good health.
Meet Samurai, a massive pit bull with an amazingly sweet disposition. Samurai was recently rescued by Friends of Animal Care and Control in Chicago and is currently living in a temporary foster home. Samurai was first presented to my office three weeks ago after having six seizures in a 12-hour time period. After a complete physical examination and an extensive diagnostic work-up that included a visit to a veterinary neurologist for a MRI and cerebrospinal fluid analysis, I concluded that Samurai was suffering from CDV.
Some facts about Canine Distemper Virus:
Transmission: Most dogs acquire this viral disease after inhaling respiratory secretions from infectious dogs, foxes, weasels, and raccoons. The virus can also be transmitted from contaminated blood and urine. Young puppies and immune-compromised dogs are at high risk for acquiring CDV.
Clinical Signs: Once a dog is exposed to the CDV it usually takes about 10 to 14 days before the disease may clinically appear in the patient. It is during this critical time period that the pet’s immune system must try to mount an effective response against the virus. If the pet’s immune system is successful in destroying this virus, no clinical signs will appear. However, if the dog’s immune system is unsuccessful in these early days, the pet may show the following symptoms: cough, fever, runny eyes and decreased appetite. Occasionally pets will vomit or have diarrhea, form calluses on their nose and/or footpads. Many puppies that survive CDV have permanent damage to the enamel on their adult teeth, called enamel hypoplasia. This enamel defect encourages tooth decay as they age.
In more than 80% of puppies and 50% of adult dogs that fail to mount an early successful immune response to CDV, the virus will invade the nervous system and may cause retinal damage (vision loss), tremors in the jaw muscles (called “chewing gum fit”), rhythmic twitches of muscles (called myoclonus), imbalance, and/or generalized seizures. These neurological signs may appear within weeks or months after initial CDV exposure and may progress to death or cause permanent injury to the brain. In rare cases, seizures may occur many years later in apparently healthy distemper dog survivors.
Treatment: There is no cure for Canine Distemper Disease. As a veterinarian, my goal is to aid the patient in his/her struggle to survive. This may entail providing the patient with intravenous fluids to prevent dehydration, antibiotics to treat secondary bacterial infections, nutritional support, anti-vomiting or anti-diarrheal medication. If the patient seizes, anticonvulsant medications are given. A recovered CDV patient may shed the virus from their respiratory tract for a few weeks to months after the initial infection. It is very important to isolate this patient from other dogs during this recovery phase. Fortunately, the virus is very unstable in the environment and can be destroyed by 1:30 dilution of bleach in water and other cleaning detergents.
Prevention: At Animal Medical Center of Chicago, we vaccinate all eight-week old puppies with a series of three distemper-containing vaccines each separated by three to four weeks. After one year of age, we re-vaccinate every dog once every three years for distemper to help ensure future protection. Samurai’s illness is exceptionally tragic because it could have been completely prevented if he had received the distemper vaccines as a puppy.
Some pet owners avoid vaccines because they think the disease doesn’t exist in their neighborhood and/or they don’t want to “over-vaccinate” their pet. Others are afraid that their pet is going to have an allergic reaction to the vaccine or that the vaccine will cause cancer. I hope sharing Samurai’s unfortunate story today convinces historical non-believers that distemper is a real disease and still exists in our neighborhoods. The distemper vaccine is extraordinarily safe and effective. Vaccine reactions rarely happen, and if they do occur, it usually presents with non-life threatening symptoms like facial swelling, itching and vomiting which can all be successfully resolved by your veterinarian in a matter of hours. Finally, there exists no link today between the CDV vaccine and cancer.
Unfortunately, there is no cure once your pet is infected with the CDV. Samurai is currently on a cocktail of three different anticonvulsant medications to try to control his seizures. He went two weeks without a seizure and then, had three seizures just four days ago. We are still adjusting his anti-seizure medication and are hoping it’s just a matter of time before we find the right cocktail of drugs to successfully manage his disease. Tragically, most distemper dogs that show neurologic signs are euthanized within a year of diagnosis due to a combination of failure to control seizures and the emotional and economic toll it places on the family. I hope this story drives any pet owner who thought CDV did not exist straight to their veterinarian to get this lifesaving vaccine for their dog.