Some Viral Diseases In Dogs : Part 2

VIRAL DISEASES

Viruses are disease-causing organisms that are even more basic than cells. They are simply packages of protein. 

INFECTIOUS CANINE HEPATITIS  

Infectious canine hepatitis is a highly contagious viral disease caused by canine adenovirus-1. In the United States the disease is rare and is seen almost exclusively in wild canids and unvaccinated dogs. Most cases occur in puppies under 1 year of age.

Following exposure, the virus multiplies in the dog’s tissues and is shed in all body secretions. During this stage, the dog is highly contagious and can spread infection to other dogs who make contact with his infected urine, stool, and saliva. After he has recovered, the dog remains infective and sheds the virus in the urine for up to nine months.

Infectious canine hepatitis affects the liver, kidneys, and lining of the blood vessels, producing a mild infection at one extreme to a rapidly fatal infection at the other. A dog with a mild or subclinical infection loses his appetite and simply appears lethargic. In the fatal form, the dog suddenly becomes ill, develops bloody diarrhea, collapses, and dies within hours. Puppies may die without obvious illness.

A dog with acute infection runs a fever up to 106°F (41.1°C), refuses to eat, passes bloody diarrhea, and, often, vomits blood. The dog has a tucked-up belly caused by painful swelling of the liver. Light is painful to the dog’s eyes and causes tearing and squinting. Tonsillitis, spontaneous bleeding beneath the gums and under the skin, and jaundice may occur.

Infectious hepatitis can be suspected by the signs and symptoms and confirmed by virus isolation tests. About 25 percent of dogs recovering from infectious canine hepatitis develop a characteristic clouding of the cornea of one or both eyes known as blue eye. In most cases blue eye disappears within a few days.

Treatment:

Acute cases must be hospitalized for intensive veterinary treatment.

RABIES 

Rabies is a fatal disease that occurs in nearly all warm-blooded animals, although rarely in rodents. In the United States, vaccination programs for dogs and other domestic animals have been remarkably effective. This has greatly reduced the risk of rabies in pets and their owners.

The major wildlife reservoirs for rabies (with substantial overlap) are the skunk in the Midwest, Southwest, and California; raccoons in New England and the East; foxes in New York, neighboring eastern Canada, Alaska, and the Southwest; and coyotes and foxes in Texas. Bats, which are distributed widely, also carry rabies.

The main source of infection for humans outside the United States continues to be a bite from an infected dog or cat. In India, for example, a country that lacks an effective rabies control program, it is estimated that several thousand people die of rabies each year. Travelers to countries where rabies is endemic should be aware of the risk of dog bites.

The rabies virus, which is present in infected saliva, enters the body at the site of a bite. Saliva on an open wound or disrupted mucous membrane also constitutes exposure. The average incubation period in dogs is two to eight weeks, but it can be as short as one week or as long as one year. The virus travels to the brain along the nerves. The more distant the bite is from the brain, the longer the period of incubation. The virus then travels back along the nerves to the mouth. Entry into the salivary glands occurs less than 10 days before symptoms appear—which means animals can be infectious before they show any signs of rabies (this is unusual but is possible).

Dogs can show either of two versions: the aggressive form, where they attack and act very boldly aggressive; or the “dumb” form, where they are ataxic (an inability to coordinate voluntary muscle movements) and may walk into objects. In both cases, you may notice extensive drooling due to paralysis of the muscles used for swallowing.

Any dog who is bitten by an animal who is not absolutely known to be free of rabies must be assumed to have been exposed to rabies, until proven otherwise. The National Association of State Public Health Veterinarians recommends that if the dog has previously been vaccinated against rabies, revaccinate immediately and observe the dog under leash confinement at home for 45 days. If the dog has not been vaccinated, either euthanize the animal or confine him under strict quarantine without direct handling by humans or contact with other animals for six months. Vaccinate him one month before he is released (that is, at five months after the bite). If this seems harsh, keep in mind that it would not have been necessary if the pet had been vaccinated. Different states may have their own specific quarantine and vaccination regulations for dogs who have been exposed to rabies.

Treatment:

 If you or your dog are bitten by any animal of unknown rabies status, it is extremely important to vigorously cleanse all wounds and scratches, washing them thoroughly with soap and water. Studies in animals have shown that prompt local wound cleansing greatly reduces the risk of rabies. The wound should not be sutured.

Prophylaxis in a previously vaccinated dog consists of a booster shot, which should be given as soon as possible (and certainly within 14 days of the lick or bite). Vaccination is not effective once signs of rabies infection appear.

The introduction of inactivated vaccines grown in human diploid cell cultures has improved the effectiveness and safety of postexposure vaccination for humans. Assuming the human bite victim did not have a preexposure rabies immunization, both passive rabies immune globulin and human origin active diploid cell vaccine should be given.