Canine distemper

Canine distemper virusCanine distemper (sometimes termed hardpad disease) is a viral disease that affects a wide variety of animal families, including domestic and wild species of dogs, coyotes, foxes, pandas, wolves, ferrets, skunks, raccoons, and large cats, as well as pinnipeds, some primates, and a variety of other species. Animals in the family Felidae, including many species of large cat as well as domestic cats, were long believed to be resistant to canine distemper, until some researchers reported the prevalence of CDV infection in large felids. Both large Felidae and domestic cats are now known to be capable of infection, usually through close housing with dogs or possibly blood transfusion from infected cats, but such infections appear to be self-limiting and largely without symptoms. Canine distemper (sometimes termed hardpad disease) is a viral disease that affects a wide variety of animal families, including domestic and wild species of dogs, coyotes, foxes, pandas, wolves, ferrets, skunks, raccoons, and large cats, as well as pinnipeds, some primates, and a variety of other species. Animals in the family Felidae, including many species of large cat as well as domestic cats, were long believed to be resistant to canine distemper, until some researchers reported the prevalence of CDV infection in large felids. Both large Felidae and domestic cats are now known to be capable of infection, usually through close housing with dogs or possibly blood transfusion from infected cats, but such infections appear to be self-limiting and largely without symptoms. In canines, distemper affects several body systems, including the gastrointestinal and respiratory tracts and the spinal cord and brain, with common symptoms that include high fever, eye inflammation and eye/nose discharge, labored breathing and coughing, vomiting and diarrhea, loss of appetite and lethargy, and hardening of nose and footpads. The viral infection can be accompanied by secondary bacterial infections and can present eventual serious neurological symptoms. Canine distemper is caused by a single-stranded RNA virus of the family Paramyxoviridae (the same family of the viruses that causes measles, mumps, and bronchiolitis in humans). The disease is highly contagious via inhalation. Morbidity and mortality may vary greatly among animal species, with up to 100% mortality in unvaccinated populations of ferrets. In domestic dogs, while the acute generalized form of distemper has a high mortality rate, disease duration and severity depends mainly on the animal's age and immune status and virulence of the infecting strain of the virus. Despite extensive vaccination in many regions, it remains a major disease of dogs, and was the leading cause of infectious disease death in dogs, prior to a vaccine becoming available. The origin of the word 'distemper' is from the Middle English distemperen, meaning to upset the balance of the humors, which is from the Old French destemprer, meaning to disturb, which is from the Vulgar Latin distemperare: Latin dis- and Latin temperare, meaning to not mix properly. In dogs, signs of distemper vary widely from no signs, to mild respiratory signs indistinguishable from kennel cough, to severe pneumonia with vomiting, bloody diarrhea, and death. Commonly observed signs are a runny nose, vomiting and diarrhea, dehydration, excessive salivation, coughing and/or labored breathing, loss of appetite, and weight loss. If neurological signs develop, incontinence may ensue. Central nervous system signs include a localized involuntary twitching of muscles or groups of muscles, seizures with salivation and jaw movements commonly described as 'chewing-gum fits', or more appropriately as 'distemper myoclonus'. As the condition progresses, the seizures worsen and advance to grand mal convulsions followed by death of the animal. The animal may also show signs of sensitivity to light, incoordination, circling, increased sensitivity to sensory stimuli such as pain or touch, and deterioration of motor capabilities. Less commonly, they may lead to blindness and paralysis. The length of the systemic disease may be as short as 10 days, or the start of neurological signs may not occur until several weeks or months later. Those few that survive usually have a small tic or twitch of varying levels of severity. With time, this tic usually diminishes somewhat in its severity. A dog that survives distemper continues to have both nonlife-threatening and life-threatening signs throughout its lifespan. The most prevalent nonlife-threatening symptom is hard pad disease. This occurs when a dog experiences the thickening of the skin on the pads of its paws, as well as on the end of its nose. Another lasting symptom that is common is enamel hypoplasia. Puppies, especially, have damage to the enamel of teeth that are not completely formed or those that have not yet grown through the gums. This is a result of the virus killing the cells responsible for manufacturing the tooth enamel. These affected teeth tend to erode quickly. Life-threatening signs usually include those due to the degeneration of the nervous system. Dogs that have been infected with distemper tend to suffer a progressive deterioration of mental abilities and motor skills. With time, the dog can develop more severe seizures, paralysis, reduction in sight, and incoordination. These dogs are usually humanely euthanized because of the immense pain and suffering they face. Distemper is caused by a single-stranded RNA virus of the family Paramyxoviridae, which is a close relative of the viruses that cause measles in humans and rinderpest in animals.