Canine distemper (distemper) is an infectious viral disease that affects animals of the family Canidae, Mustelidae, Mephitidae, Hyaenidae, Aileridae, Procyonidae, Pinnipedia, some Viverridae and Felidae (though not domestic cats suffering from other diseases, such as rhinotracheitis or calicivirus, presenting with respiratory symptoms). Of these, the most important for their relationship with humans, are the dog, brael ferret and mink. Canine distemper (distemper) is a negative single - stranded RNA virus of the Order Mononegavirales, family Paramyxoviridae, genus Morbillivirus. Despite a vaccine against the virus, the disease is still common in many regions of the world.
Canine distemper (distemper) is caused by a paramyxovirus closely related to measles virus and rinderpest. The virus is sensitive to lipid solvents and most disinfectants and is relatively unstable outside the host. The main route of infection is through aerosol droplets of secretions from infected animals. Some infected dogs can spread the virus for several months.
The virus initially replicates in the lymphatic tissue of the respiratory tract. Continuing with cell - associated viremia that results in infection of all lymphoid tissues, followed by infection of gastrointestinal epithelium, respiratory, and urogenital epithelium and CNS and optic nerves.
A transient fever usually occurs within 3-6 days after infection, and may be a leukopenia (lymphopenia, especially) at this time, these symptoms may go unnoticed or be accompanied by anorexia. Fever disappears for several days before a second fever, which lasts less than 1 week occur. This may be accompanied by serous nasal discharge, ocular discharge mucopurulenta and anorexia. GI and respiratory signs may follow and are often complicated by secondary bacterial infections. An acute encephalomyelitis may occur in association with or following systemic disease, or in the absence of systemic manifestations. Hyperkeratosis of the footpads and nasal epithelium plane can be seen. Neurological signs are common in dogs with hyperkeratosis, CNS signs are as follows: 1) involuntary contractions localized muscle or muscle group (myoclonus, chorea, flexor spasms, hyperkinesia), as in the leg or facial muscles, 2) paresis or paralysis, often most evident in the hindlimbs as ataxia, followed by quadriparesis tetraparalysis, and 3) is characterized by seizures and salivation often chewing movements of the jaw ( "chewing -Goma fits" ). Attacks become more frequent and severe, and the dog may fall on its side and paddle its legs; involuntary urination and defecation (bad great convulsion, epileptic seizure) often occur. A dog may have any of these neurological signs, as well as others in the course of the disease. Infection may be mild and asymptomatic or lead to severe disease manifested by most of the signs mentioned above. The course of systemic disease can be as short as 10 days, but the onset of neurological signs may take several weeks or months.
Chronic encephalitis canine distemper (distemper) (encephalitis old dog) is a condition characterized by ataxia, compulsive movements such as pressing the head against uncoordinated wall and hipermetría, can be seen in adult dogs with no history of signs related to canine distemper (distemper) systemic. Development of neurological signs is often more progressive. Although canine distemper antigen (distemper) has been detected in the brains of some dogs with old dog encephalitis fluorescent antibody staining, dogs with old dog encephalitis are not infectious and virus replication has not been demonstrated. Genetic methods may be necessary to document the infection. The disease is caused by an inflammatory reaction associated with the persistent infection with canine distemper virus (distemper) in the CNS.
The thymus atrophy is a postmortem consistent finding in infected young puppies. Hyperkeratosis of the nose and pads is often found in dogs with neurological manifestations. Depending on the degree of secondary bacterial infection, bronchopneumonia, enteritis, and pustules on the skin may also be present. Histologically, canine distemper virus (distemper) causes necrosis of the lymphoid tissues, interstitial pneumonia, and intranuclear inclusions and cytoplasmic organs, urinary, digestive and respiratory epithelium. Lesions are found in the brains of dogs with neurological complications include neuronal degeneration, gliosis, demyelination, nonsuppurative leptomeningitis and intranuclear inclusion bodies predominantly within glial cells.
Canine distemper (distemper) should be considered in the diagnosis of any febrile illness in puppies with multisystemic manifestations. While the typical clinical case is not difficult to diagnose, the characteristic signs sometimes do not appear until late in the disease. The clinical picture can be modified by concurrent toxoplasmosis, coccidiosis, parasitosis, and numerous bacteria and viral infections. Canine distemper (distemper) sometimes confused with other systemic infections such as leptospirosis, canine infectious hepatitis, or Rocky Mountain Spotted Fever. Catarrhal febrile illness with neurological sequelae justifying a clinical diagnosis of canine distemper (distemper).
At necropsy, the diagnosis is usually confirmed by histological lesions or immunofluorescence assay for the detection of viral antigen in tissues, or both. In dogs with multisystem signs, conjunctiva, trachea, vagina, other epithelia, or buffy coat blood can be examined by immunofluorescence. These samples usually negative when the dog is showing neurological manifestations or when circulating antibodies are present (or both).
Diagnosis can be made by serological demonstration of specific IgM virus or increased CSF regarding specific IgG serum virus.
Genetic detection of virus determined by PCR nucleic acid fragments of the viral structure. It is a qualitative reaction high sensitivity and specificity, it is always positive to the virus. It is the technique used as a reference method. The recommended test is the PCR analysis for canine distemper (distemper) and said sample is blood with EDTA anticoagulant. In IVAMI conventional RT-PCR is performed.
Recommended sample: Whole blood EDTA (3- 5 mL)