Systematic Veterinary Virology

SYMPTOMS AND LESIONS

• The initial symptom is fever (103^ºF to 106^ºF), which usually peaks 3 to 6 days after infection. The fever often goes unnoticed and may peak again a few days later. Eye and nose discharge, depression, and loss of appetite (anorexia) are the associated symptoms during the period. After the fever, symptoms vary considerably, depending on the strain of the virus and the dog’s immunity.
• At initial stages gastrointestinal and respiratory symptoms are more common, which include conjunctivitis, diarrhoea, pneumonia (cough, labored breathing), rhinitis (runny nose)  and vomiting. These symptoms are often aggravated by secondary bacterial infections.
• Dogs develop encephalomyelitis (an inflammation of the brain and spinal cord), the symptoms of which are variable and progressive. Most dogs that die from distemper, die from neurological complications such as the following, ataxia (muscle incoordination), depression, hyperesthesia (increased sensitivity to sensory stimuli, such as pain or touch), myoclonus (muscle twitching or spasm), which can become disabling, paralysis, paresis (partial or incomplete paralysis), progressive deterioration of mental abilities, progressive deterioration of motor skills and seizures that can affect any part of the body (One type of seizure that affects the head, and is unique to distemper, is sometimes referred to as a “chewing gum fit” because the dog appears to be chewing gum).
• A variety of symptoms on the eye are also characteristic, which include keratoconjunctivitis, inflammation of the cornea and conjunctiva, or chorioretinitis, inflammation of the choroid and retina and optic neuritis (inflammation of the optic nerve which leads to blindness).
• Enamel hypoplasia (unenameled teeth that erode quickly in puppies whose permanent teeth haven’t erupted yet) and hyperkeratosis (hardening of the foot pads and nose) are seen in chronic infection. In utero infection of fetuses is rare.
• When it happens, this can lead to spontaneous abortion, persistent infection in newborn puppies, or the birth of normal looking puppies that rapidly develop symptoms and die within 4 to 6 weeks.