CANINE DISTEMPER

CANINE DISTEMPER

Canine distemper is a highly contagious and serious viral illness of dogs with no known cure. The disease has a worldwide distribution and is often fatal. The disease affects dogs, and certain species of wildlife, such as raccoons, wolves, foxes and skunks. The common house pet, the ferret, is also a carrier of this virus. It is caused by the Canine distemper virus (CDV) which is similar to the measles virus, and is a member of the genus Morbillivirus within the family Paramyxoviridae. Canine distemper virus is an enveloped negative- sense, single-stranded RNA virus that produces a multi- systemic disease and results in immunosuppression in the host. The disease is sometimes called “hard pad disease” because certain strains of the virus can cause an abnormal enlargement or thickening of the pads of an animal’s feet.

Risk Factors

Presence of Dogs with incomplete vaccination or no vaccination

Young, unvaccinated puppies and non-immunized older dogs tend to be more susceptible to the disease.

Transmission and Spread

Canine distemper virus is spread most frequently by direct contact with respiratory tract secretions from an infected dog or wildlife. Other potential sources of infection include contact with infected body tissues and secretions such as urine. Pregnant dogs that contract the virus can infect their unborn puppies.  The virus initially attacks a dog’s tonsils and lymph nodes and replicates there for about one week. It then attacks the respiratory, urogenital, gastrointestinal, and nervous systems.

Clinical Presentation

CD is a multisystemic disease that can present with one or more of the following: In the initial stages; high fever (≥39.7° C), reddened eyes, and a watery discharge from the nose and eyes. An infected dog will become lethargic and tired, and will usually become anorexic. Persistent coughing, vomiting, and diarrhoea may also occur. The respiratory signs may be complicated by secondary bacterial infection (purulent nasal discharge, coughing, dyspnoea, pneumonia). In the later stages of the disease, the virus starts attacking the other systems of the dog’s body, particularly the nervous system. The brain and spinal cord are affected and the dog may start having fits, seizures, paralysis, and attacks of hysteria. This may result in death 2-5 weeks after initial infection.

Diagnosis

 Canine distemper is diagnosed with biochemical tests and urine analysis, which may also reveal a reduced number of lymphocytes in the initial stages of the disease (lymphopenia). A serology test may identify positive antibodies, but this test cannot distinguish between vaccination antibodies and an exposure to a virulent virus. Viral antigens may be detected in urine sediment or vaginal imprints. Haired skin, nasal mucous, and the footpad epithelium may be tested for antibodies as well. Radiographs can only be used to determine whether an infected animal has contracted pneumonia. Computed tomography (CT) and magnetic resonance imaging (MRI) scans can be used to examine the brain for any lesions that may have developed.

Treatment

Unfortunately, there is no cure for Canine Distemper. Treatment for the disease, therefore, is heavily focused on alleviating the symptoms. If the animal has become anorexic or has diarrhoea, intravenous supportive fluids may be given. Discharge from the eyes and nose must be cleaned away regularly. Antibiotics may be prescribed to control the symptoms caused by a secondary bacterial infection, and Phenobarbitals and Potassium Bromide may be needed to control convulsions and seizures. There are no antiviral drugs that are effective in treating the disease.

Prognosis

The prospect of survival depends on the dog’s immune system and its individual ability to kill the virus. Generally, 50 percent of dogs that contract the virus will develop the clinical signs and symptoms associated with distemper, but the illness can range from mild clinical signs to death. Death may occur from one or two weeks to three months following infection with the virus. Once an animal develops neurological symptoms of the disease, such as seizures or paralysis, its chances of surviving are slim and its quality of life is bound to become progressively worse. Thus, these animals are usually “put to sleep,” or euthanized, in order to ensure a humane death.

Prevention

Vaccination with the DHLP vaccine is an excellent preventive measure as it provides a prolonged immunity in a high percentage of dogs that receive the vaccine at 9-16 weeks of age. Canine distemper is therefore a vaccine preventable disease.

Keep puppies that have not had all their vaccinations away from unvaccinated and wild animals. The use of appropriate disinfectants such as Quaternary ammonium disinfectants is effective in killing the canine distemper virus in kennels, hospitals, or other potentially infected areas. Sanitation is very important in preventing the spread of any infectious disease. The owner should consult with a veterinarian about the best vaccination schedule for an individual dog.

Dr. Moses Bwana

Post-grad at the University of Nairobi [Applied Microbiology]

Department of Veterinary Pathology, Microbiology andParasitology

Faculty of Veterinary Medicine