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Distemper in dogs: Vet's guide to signs and treatment

sad dog sitting on rug
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Distemper in dogs is a highly contagious viral disease that can cause respiratory, gastrointestinal, and neurological symptoms and even death. 

It is always best to take out pet insurance when you get a dog to offset the costs associated with treating serious diseases that they may pick up such as distemper. 

Let’s take a closer look at what distemper is, how to spot it, and the benefits of vaccination. 

What is distemper in dogs?

Distemper in dogs is caused by canine distemper virus, which is closely related to the viruses that cause measles and rinderpest in humans. 

Behind rabies, it is the second most deadly virus in dogs, with a mortality rate of approximately 50%—in puppies, this may even be as high as 80%. Although any dog can be affected by distemper, puppies under 4 months of age and unvaccinated dogs are at an increased risk of infection. 

How is distemper in dogs spread?

Because canine distemper virus is present in high concentrations in the respiratory secretions of infected dogs, distemper is usually spread via respiratory droplets in the air (i.e., by coughing or sneezing) or by direct contact. Less commonly, distemper can be transmitted in urine and feces. Distemper can also be passed down to the fetus in utero through the placenta.

It’s not only dogs who are affected by canine distemper virus—ferrets and wildlife such as raccoons, skunks, foxes, coyotes, and wolves can also develop infection. This is one of the many reasons why it’s best to prevent any contact between your pooch and wild animals.

What happens to a dog with distemper?

Upon exposure to canine distemper virus, the virus replicates in the immune cells and lymphoid tissues of affected dogs. It can then travel via the blood to the respiratory and gastrointestinal tracts, and in some cases, it may eventually spread to the central nervous system.

The severity of disease depends on the strain of the virus, the amount of virus the dog is exposed to, and the dog’s immune system. The prognosis of distemper is worse in dogs who show neurological signs. 

Owners should be aware that it may take weeks or even months for neurological symptoms to develop following initial infection, so they should monitor their dog closely following a distemper diagnosis. Dogs who survive may have irreversible damage to the nervous system and subsequent lifelong neurological impairment.

Sick dog lying on the couch

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What are the first signs of distemper in dogs? 

The clinical signs of distemper can vary from dog to dog. Early symptoms of the disease may include:

  •  Discharge from the eyes and nose, which may range in consistency from a watery fluid to pus-like material 
  • Lethargy 
  • Reduced appetite 
  • Vomiting 
  • Coughing 
  • Fever 

Once distemper has progressed further, it may spread to the nervous system and cause symptoms such as:

  • Incoordination 
  • Tremors 
  • Circling 
  • Head tilt 
  • Blindness 
  • Seizures, including focal seizures of the jaw (sometimes referred to as “chewing gum fits”) 
  • Partial or complete paralysis 

Distemper occasionally causes the footpads and/or nose to thicken and harden (“hard pad disease”). It also suppresses the immune system of infected dogs, leaving them prone to developing secondary bacterial infections.

In pregnant dogs, infection with canine distemper virus can lead to miscarriage or stillbirth. Puppies who develop infection before their adult teeth come in often have enamel defects.

The symptoms of distemper can be similar to those of other infectious diseases like kennel cough, parvovirus, and meningitis, so an accurate diagnosis is important to ensure that appropriate treatment is given.

How is distemper diagnosed and treated in dogs?

Distemper is diagnosed based on a dog’s clinical history (i.e., age, vaccination status, and exposure history) and symptoms in combination with laboratory test results. Dogs with distemper may show a severe reduction in white blood cells, clusters of protein on blood smears, and biochemical changes related to dehydration or an increased production of antibodies. 

Samples of blood, respiratory secretions, and/or cerebrospinal fluid can also be sent away to the lab to be tested for antibodies against canine distemper virus or the virus itself.

There is no cure for distemper in dogs, so treatment mainly involves supportive care. Intravenous fluid therapy can be given to address dehydration, and antibiotics are prescribed in cases with secondary bacterial infections. 

Other medications can be used to control an individual dog’s symptoms—for example, vomiting dogs benefit from antinausea and gastroprotectant medications, and dogs experiencing seizures will be treated with anticonvulsants.

Vet examining dog

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Dr Diana Hasler
Dr. Diana Hasler BVM&S MRCVS

Dr. Diana Hasler (opens in new tab) graduated with distinction from the University of Edinburgh Royal (Dick) School of Veterinary Studies in 2018. She has experience working as a small animal veterinarian in general practice, where she has treated many dogs, cats, rabbits, and rodents. She has also recently branched out into the field of medical communications, doing freelance work as a medical editor and writer.

Vaccinations against distemper in dogs 

Although distemper is still seen all over the world, infection has become much less common in the domestic dog due to the development of effective vaccines against canine distemper virus. The vaccine that protects against canine distemper virus is a core vaccine and is therefore one of the most important puppy shots.

The American Animal Hospital Association (opens in new tab) (AAHA) recommends that puppies are vaccinated against canine distemper virus as early as 6 weeks of age, receiving additional doses every 2-4 weeks until they are 16 weeks old. Boosters should be given 1 year later and every 1-3 years thereafter according to the protocol set by the vaccine manufacturer.

Although pet insurance generally doesn’t cover the cost of vaccines, many veterinary clinics offer affordable preventative healthcare plans that provide regular vaccinations and flea and worm treatment, often along with other perks. Your vet can answer any questions you have about the distemper vaccine, including its protocol and how much it costs.

Side effects of the distemper vaccine in dogs 

Although the canine distemper vaccine is very safe, some dogs may experience side effects following vaccination. The most common side effects are mild, appear within a few hours, and include lethargy, reduced appetite, mild fever, and discomfort and/or local swelling where the vaccine was injected. These signs typically resolve within 1 or 2 days.

If your dog shows more severe side effects that could be indicative of a life-threatening allergic reaction like skin rash, hives, itchiness, facial swelling, difficulty breathing, persistent vomiting or diarrhea, or collapse, veterinary attention should be sought immediately.