I came across a brief report in a local Michigan paper (thanks to the internet) of an outbreak of distemper in Manistee County, Michigan. The short report said that “Police said they’ve recently shot at least a dozen foxes and raccoons wandering around backyards and golf courses. A local veterinarian was reported to have said that “household pets could become infected if exposed to bodily fluids of animals with distemper”. The versatility of the law enforcers in dealing with this wildlife reservoir of disease is impressive. This prompted me to check up on the research on this well known dog disease, and I was surprised to discover that the virus may be linked to human disease, and that keeping up the dog’s vaccinations could be important to the owner’s health as well as to the dog’s.
Canine distemper is viral disease caused by a Morbillivirus (similar to the measles virus – in fact the measles vaccine can protect pups against distemper). The disease can affect all Canidae (dogs, wolves and foxes), as well as Mustelidae (such as ferrets, mink, and skunk), most Procyonidae (including raccoons), and some Viveridae. It is highly infectious in dogs and other susceptible species and symptoms can range from being mild to severe, and can be fatal in some cases. Young puppies and dogs that have not been vaccinated are most susceptible.
The virus is relatively labile and unstable outside of the host. Distemper can be endemic in urban areas, and the infection is transmitted by inhalation and by direct contact and via fomites. Infected animals shed large numbers of viral particles in secretions and excretions during the active stage of the disease. The presence of maternal antibody can result in many infections being sub-clinical. The incubation period for the virus is 3 to 7 days but may be as long as 4 weeks.
The disease usually causes nasal and eye discharge, twitching, coughing, diarrhoea, vomiting and seizures. The infected dog often refuses its food. Signs of the disease usually include fever, respiratory and gastrointestinal signs, encephalomyelitis, and hyperkeratosis of the footpads (which is why it is sometimes called hardpad disease), and neurological signs. The neurological signs can include muscle twitching, paralysis and ataxia, and convulsions. A chronic course of the disease called old-dog encephalitis usually includes ataxia and compulsive movements, with the neurological signs being progressive.
A number of vaccines are available including modified live vaccine, recombinant vaccines. The 2006 American Animal Hospital Guidelines (2006) recommend that puppies should be given 3 doses of vaccine between 6-16 weeks of age, with a booster dose one year after the end of the first series of injections with revaccination at intervals of 3 years or longer. There is no specific treatment of the disease but is easily prevented by vaccination.
There are more than 2000 records on canine distemper on the CAB Abstracts database and these can be found using the keyword descriptor canine distemper:su.
Canine distemper is not usually thought of as a disease of humans, however there is some evidence to link the canine distemper virus with Paget’s disease of bone. Paget’s disease of bone (osteitis deformans) is a chronic condition that affects bone growth, causing the bones to expand and become deformed. The deformed bones then weaken and are more likely to fracture. The spine, the pelvis, the legs, the skull (head) and the collarbone are most often affected. There are 11 references on the CAB Abstracts Database on Paget’s disease and distemper. One reference concludes that there is conclusive proof that canine distemper virus "can infect and replicate in human osteoclast precursors, raising possible zoonotic implications for CDV. This study provides further evidence for the possible role of paramyxoviruses in the pathogenesis of Paget’s disease.
More work would need to be done on the epidemiology of the Paget’s disease and canine distemper virus, before any conclusions can be made on whether it is a zoonotic disease, but it might be wise to keep the dog’s vaccinations up to date.
A comparison of in situ hybridisation, reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ-RT-PCR for the detection of canine distemper virus RNA in Paget’s disease. Hoyland, J. A.; Dixon, J. A.; Berry, J. L.; Davies, M.; Selby, P. L.; Mee, A. P. Journal of Virological Methods, 109, (2) 2003, 253-259
Canine distemper virus induces human osteoclastogenesis through NF-κB and sequestosome 1/P62 activation. Selby, P. L.;Davies, M.; Mee, A. P. Journal of Bone and Mineral Research, 2006, 21, (11). 1750-1756
Other useful sources of online information on the canine distemper disease are:
Merck Veterinary Manual
UC Davis Koret Shelter Medicine Program. Information sheet