Canine Distemper Virus

Overview of Canine Distemper Virus

Canine distemper is a highly contagious disease caused by canine distemper virus (CDV). It may affect the respiratory, gastrointestinal and neurologic systems in the body. It is generally transmitted through contact with mucous and watery secretions discharged from the eyes and noses of infected dogs. However, it can also be transmitted by contact with urine and other bodily fluids of infected dogs, so your dog may become infected without coming into contact with an infected dog. Air currents and inanimate objects can also carry the virus.

Distemper was a common infection in dogs many years ago, but the incidence has been significantly decreased through widespread vaccination of dogs. Canine distemper is now most commonly seen in young, unvaccinated or immune-compromised dogs. More than 50 percent of dogs that contract the disease die from it. Even if a dog doesn’t die, canine distemper can cause irreparable damage to the nervous system, leaving the dog with partial or total paralysis or seizures.

Canine distemper can strike any dog of any breed or any sex, although it is most common in young dogs.

What To Watch For

While some affected individuals have only a few mild clinical signs, others may exhibit more severe signs. The first noticeable signs might be discharge from the eyes and nose, mild cough, and mild lethargy. Other common signs are:

  • Depression, malaise
  • Anorexia, dehydration
  • Vomiting
  • Diarrhea
  • Seizures
  • Lack of coordination
  • Involuntary muscle tremors or tics
  • Paralysis or weakness
  • Blindness
  • Hardening of the footpads
  • Discoloration and pitting of the teeth of growing dogs
  • Diagnosis of Canine Distemper Virus

    Diagnosis is often difficult, since there is no one reliable test for the disease. Diagnosis is usually suspected from the history and clinical signs. Your veterinarian may also recommend the following tests:

  • A complete blood count (CBC), biochemical profile, and urinalysis
  • X-rays of the chest and abdomen
  • Cerebrospinal fluid (CSF) testing if neurologic signs are present
  • Examination of buffy coat smears (the layer of white blood cells formed when blood is spun down) and/or conjunctival scrapings from under the eyelid for distemper viral particles)
  • Measurement of distemper antibody titers in blood or the cerebrospinal fluid
  • Treatment of Canine Distemper

    There is no treatment available that kills the virus once it infects the dog. The disease is often progressive despite therapy. Therapy is supportive and aims to strengthen and nourish the body, allowing the dog time to fight off the infection themselves. Dogs with distemper may need to be hospitalized and must be kept in isolation, so as not to infect other dogs. Therapy usually includes:

  • Intravenous fluid and electrolyte therapy, and in some cases, parenteral (intravenous) nutrition for patients who are severely ill.
  • Antibiotic therapy for secondary bacterial infections
  • Symptomatic therapy for respiratory, gastrointestinal, and/or neurologic signs
  • Home Care and Prevention

    At home, administer all medications, and return for follow-up examinations as directed by your veterinarian.

    It is important to disinfect contaminated areas by cleaning food and water bowls and other contaminated items with a mixture of one cup of chlorine bleach to a gallon of water.

    Fortunately, canine distemper is preventable. Puppies should receive a series of vaccinations beginning when they are six to eight weeks old and repeated at three to four week intervals until a high state of immunity is achieved, usually around 16 to 20 weeks of age. Vaccines are then usually repeated on annual basis for several more years to maintain the dog’s immunity to the virus.

    Until your puppy is vaccinated, keep him away from areas where he may be exposed to the virus, like parks or kennels. Keep him away from other dogs that may not have been vaccinated.

    In-depth Information on Distemper Virus in Dogs

    Canine distemper virus (CDV) causes a highly contagious disease of dogs and also affects other species such as the fox, coyote, wolf, ferret, skunk, and raccoon. The incidence of disease is greatest in young dogs three to six months of age. Young dogs are most susceptible because the protection against distemper that is passed on from mother to newborn has decreased or disappeared by 9 to12 weeks of age.

    Distemper is caused by a virus similar to the one that causes measles in people. It is transmitted through the air via droplets originating from many bodily fluids of an infected animal. Because the virus does not affect people or cats, there is no concern for dogs transmitting it to these species.

    Different stages of the disease are associated with various clinical signs, usually involving some combination of the respiratory and/or gastrointestinal tract signs in the early stages, and the nervous system several weeks later. Not all stages occur in all dogs. Distemper is much less common than it was years ago, prior to the introduction of the distemper vaccination. The prognosis for dogs with distemper ranges from good to guarded. Some patients recover; some patients recover but have additional manifestations of the disease later in life; some dogs die from the disease or have such severe persistent signs that they must be euthanized.

    Differential Diagnosis

    Several diseases and disorders can appear similar to canine distemper.

    The respiratory form of canine distemper must be differentiated from the following:

  • Kennel cough, or infectious tracheobronchitis, is a contagious respiratory disease of dogs that is manifested by coughing. This is a transient disease, and most dogs recover without severe complications.
  • Pneumonia due to other infections (bacterial, fungal) can present similarly to dogs with distemper.

    The gastrointestinal (GI) form of canine distemper must be differentiated from the following:

  • Other GI viral diseases including parvovirus and coronavirus
  • Bacterial enteritis including Campylobacter, Salmonella and Clostridia
  • Protozoal infections, specifically, Giardia
  • Ingestion of foreign bodies and toxins
  • Any non-infectious disorder that causes vomiting and diarrhea in dogs

    The central nervous system (CNS) form of canine distemper must be differentiated from the following:

  • Granulomatous meningoencephalitis is a progressive, inflammatory disease of the central nervous system of dogs. Many signs seen in this disorder may mimic the neurologic form of canine distemper.
  • Protozoal encephalitis is an inflammation of the brain, caused by one of the protozoal organisms (neosporosis, toxoplasmosis).
  • Cryptococcosis is a systemic fungal infection that affects particularly the respiratory and neurologic systems.
  • Lead poisoning commonly produces clinical signs that involve both the gastrointestinal tract and nervous system.

    In-depth Information on Diagnosis of Canine Distemper

    Certain diagnostic tests must be performed for a definitive diagnosis of canine distemper and to exclude other disease processes that may cause similar symptoms. A complete history (vaccination status, travel pattern, environment, etc.), description of clinical signs, and thorough physical examination are all important to obtaining a diagnosis.

    There are certain characteristic changes that may be apparent on the physical examination that lead to a presumptive diagnosis of canine distemper. These include the following:

  • Pitting and discoloration of the enamel (white surface coating) of the teeth
  • Presence of rhythmic jerking of a single muscle or a group of associated muscles, called tics or myoclonus
  • Abnormally thickened and hard foot pads
  • Inflammatory changes in the retinas of the eyes that are compatible with distemper

    The following tests are recommended to confirm a diagnosis:

  • A complete blood count (CBC) may reveal a mild lymphopenia (a decrease in the number of lymphocyte white blood cells), particularly during the early stage of infection. Occasionally, thrombocytopenia (decreased platelets) is seen also.
  • A biochemical profile is usually within normal limits, although it may reveal changes in kidney and/or liver enzymes, electrolytes, blood sugar, and protein levels, depending on the stage of disease and degree of severity of disease present.
  • A urinalysis is helpful in determining the level of hydration on the patient.
  • Chest and abdominal X-rays are an important part of any baseline work-up. They may be normal, they may show evidence of pneumonia, and they may help rule out other causes of similar clinical signs.

    Your veterinarian may recommend additional tests to exclude or diagnose concurrent conditions. These tests are not always necessary in every case; however, they may be of benefit in certain individuals and are selected on a case-by-case basis. These include the following:

  • The ultimate diagnosis is based on demonstration of viral antigens (proteins) in scrapings and body fluids such as conjunctival smears, transtracheal washings, urine sediment, buffy coat (layer of white blood cells formed after blood is spun down), and cerebrospinal fluid (CSF). Their absence does not rule out infection, however.
  • Analysis and testing CSF obtained from individuals exhibiting neurologic signs may be useful in diagnosing distemper. Microscopic analysis of CSF may show increased numbers of lymphocytes and protein. Detection of high antibody titers for distemper in the CSF can provide supportive evidence of an active infection. Comparing the antibody titers found in the CSF to antibody titers found in the serum (blood) may also help support the diagnosis of distemper.
  • The measurement of antibodies to the distemper virus in blood may be helpful. Dogs that are able to mount an antibody response to the virus usually have titers that increase over a 2- to 4-week time period. A single elevated antibody titer taken at the beginning of the illness may be difficult to interpret, because it could represent antibodies produced by prior vaccination.
  • In-depth Information on Therapy

    Dogs with distemper may need to be hospitalized and must always be kept in isolation to prevent infection of other dogs. Therapy is mainly supportive and symptomatic, as there are no antiviral drugs that are effective against distemper. Because there are several clinical manifestations of distemper, there is no single treatment plan that can be recommended for all dogs. The pet owner whose dog has distemper should also understand that even with the best of care, up to 50 percent of dogs infected with canine distemper succumb to the disease.

  • Intravenous fluid and electrolyte therapy may be recommended in the patient who has severe gastrointestinal signs, is unable or unwilling to eat, and is dehydrated.
  • Parenteral (intravenous) nutrition may be indicated in the debilitated patient, especially when protracted vomiting and diarrhea are present.
  • Administration of antiemetic drugs to stop vomiting may be of benefit.
  • Antibiotics are indicated to control secondary bacterial infections. Many dogs with severe distemper infections are immunocompromised, which means their immune system is functioning less than optimally, and they are susceptible to other infections.
  • In dogs that develop seizures, anticonvulsant therapy may be administered.
  • There is no effective treatment available for the myoclonus or tics that are produced in some dogs by distemper.
  • Follow-up Care for Dogs with Distemper Virus

    Optimal treatment for your dogs requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not rapidly improve.

  • Dogs should be closely monitored, as pneumonia and/or dehydration from vomiting and diarrhea in the acute phase could debilitate an animal quickly.
  • Administer all prescribed medication as directed. Alert your veterinarian if you are experiencing problems treating your pet.
  • Depending on the circumstances, distemper may range from a subclinical infection (having no clinical signs) to a fatal infection. Death may occur from two weeks to three months post-infection.
  • Euthanasia may be recommended for dogs with severe, unresponsive pneumonia, debilitating myoclonus, paralysis or inability to walk, unrelenting vomiting or diarrhea, or seizures.
  • Recovered dogs are not carriers of infection, and usually have good immunity against the disease.
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