Distemper (Canine Distemper)
Canine distemper, sometimes referred to as hardpad disease, is a highly contagious and potentially lethal disease caused by a virus (canine distemper virus, or CDV) that attacks multiple systems within the body, including the respiratory, gastrointestinal, and nervous systems. This widespread infection throughout the body can make treatment difficult, which can be further complicated by subsequent bacterial infections as a result of the dog’s weakened immune system. Some dogs which appear to recover from canine distemper can develop neurologic signs months to years after initial infection. Young puppies develop CDV brain inflammation quite soon after infection. If CDV persists in the brain after the infection is cleared elsewhere in the body, progressive inflammation occurs in the brain and results in neurologic abnormalities. This syndrome is called old dog encephalitis and the damage to the nervous system is permanent.
Dogs are not the only species that can contract distemper – wild animals such as raccoons, skunks, foxes, wolves, coyotes, mink, ferrets, and some wild felids such as cheetahs, lions, and jaguars are all possible hosts to the virus. While humans are not at risk for contracting this disease, the canine distemper virus is closely related to the virus that causes measles in humans. CDV spreads through air droplets which are expelled when an animal sneezes or coughs. Dogs become infected either through direct contact with an infected animal or through airborne exposure. Mother dogs with the virus can also pass it along through the placenta to their puppies. Dogs with canine distemper can shed the virus for weeks to months after infection.
Puppies under four months of age or unvaccinated dogs are at an increased risk of contracting canine distemper. Canine distemper is a global disease, and as a large number of species are susceptible to infection, contact between wild animals and unvaccinated domestic dogs is another risk factor.
Initial signs of canine distemper include:
As the disease progresses and attacks the central nervous system, an infected dog may develop the following neurologic signs:
- Involuntary muscle twitching
- Partial or complete paralysis of the limbs
- Involuntary drooling or chewing motions (“chewing gum fit”)
- Walking in circles
- Head tilting
- Nystagmus (uncontrolled, rapid eye movements)
In addition to these neurologic signs, dogs may develop hyperkeratosis (thickening of the paw pads and nose) with gives distemper its colloquial name hardpad disease.
Canine distemper can last as little as 10 days, but the onset of neurologic signs can occur weeks to months after initial infection.
Physical examination findings of an upper respiratory infection or gastrointestinal signs increase suspicion for distemper, especially in a puppy or unvaccinated dog. Early in the course of infection, blood cells may contain large abnormalities which represent the distemper virus. Dogs with neurologic signs may have similar inclusions in the cells found in their spinal fluid. The presence of antibodies against CDV in the blood or spinal fluid are considered diagnostic criteria for distemper.
Unfortunately, canine distemper does not have a cure. Instead, treatment is focused on controlling the clinical signs associated with the disease and preventing secondary bacterial infections. Treatment can include:
- Fluid administration
- Supplemental feedings
- Medication to reduce fever
- Pain medication
- Seizure medication
Dogs suspected or diagnosed with canine distemper need to be separated from other dogs in order to prevent the disease from spreading. If a dog with distemper requires hospitalization, they will be housed in an isolation ward to protect other patients.
While some dogs with canine distemper recover completely, treatment of dogs with neurologic signs is frequently unsuccessful.
Vaccination is the best available method of preventing canine distemper. Canine distemper is a core vaccination, meaning it is a vaccine that veterinarians recommend for every dog. It is typically given in the form of a combination vaccine, alongside the vaccines for adenovirus and parvovirus. Puppies should be vaccinated starting at 6 weeks of age, and then every 3 to 4 weeks until they are 16 weeks old. A booster is given around one year, and then every three years afterwards. If you have a pet ferret in the home, it should be vaccinated for distemper as well.
Use caution when socializing your puppy or unvaccinated dog in areas where dogs congregate, such as dog parks, doggy day care, or obedience classes. As canine distemper is also found in wild animal populations, don’t allow your dog to interact with wildlife and keep your dog on a leash to prevent them from coming into contact with the remains of an animal that died from canine distemper virus.