The 6 Most Contagious Canine Diseases

Written and verified by biochemistry Luz Eduviges Thomas-Romero

Last update: 21 December, 2022

As a dog owner, getting to know some of the most contagious canine diseases is one of your most important duties. It’s only by having all the necessary information that you can guarantee your pet’s health and well-being.

Medicine is constantly evolving, for both humans and animals. This means that many diseases are no longer as common as they once were. Even so, it’s best to be aware of any disease your pet might catch, whether in the park, doggy day-care, or anywhere else.

1. Canine distemper – one of the most contagious canine disease

Also known as hardpad disease, canine distemper is a viral disease of the respiratory tract, and is the leading cause of infectious disease death in dogs. The virus that causes the disease belongs to the same family as the measles virus: paramyxovirus. Although there’s a vaccine, the disease hasn’t been eradicated and continues to be a risk.

Canine distemper is transmitted via bodily secretions, and causes gastrointestinal discomfort and upper respiratory issues before spreading to the neurological system. When this happens, the animal may experience seizures and die.

2. Canine parvovirus

We can’t talk about the most contagious canine diseases without talking about canine parvovirus. This viral disease is extremely serious, and advances rapidly. It has a 90% mortality rate if left untreated, but fortunately there’s a highly effective vaccine.

The infection causes severe diarrhea, vomiting and regurgitation, which can lead to dehydration and death. It’s transmitted orally, through direct or indirect contact with fecal matter.

3. Contagious canine diseases – canine influenza

This disease is caused by the canine influenza virus H3N8. It spreads in a similar way to human influenza, via coughing and sneezing.

Today, canine influenza is a controlled disease. It’s more common in animal shelters than in the general population. There’s a vaccine, which vets may prescribe to animals that are at risk.

4. Leptospirosis

This is a bacterial disease that is transmitted via contact with infected urine. It’s important to be aware that this disease can also infect humans. The microorganism first infects the mucous membranes or open wounds, before passing into the bloodstream. This stage can last 4 – 12 days. It then infects the renal epithelium and the liver parenchyma.

Leptospirosis can be either acute or chronic in nature, and is treated with antibiotics. Symptoms can vary from case to case, but may include fever, vomiting, increased thirst, jaundice, and frequent or lack of urination.

5. Contagious canine diseases – canine herpes virus

This is another viral disease. While it can affect dogs of any age, the canine herpes virus can be fatal in puppies. The infection may remain latent in tissues, meaning an animal may have it for life.

Canine herpes virus is very common in kennels. Many dogs can test positive for the infection without displaying any major symptoms. However, this means that they can still pass it to other dogs. It’s spread via nasal and oral secretions, as well as transplacental and venereal fluid.

Older dogs may have a mild fever or respiratory issues, but otherwise, the canine herpes virus often goes unnoticed.

A vaccine is available in the UK, but has not yet been legalized in the US. To prevent the infection in puppies, it’s important to avoid exposure and keep newborn puppies warm.

6. Rabies

Rabies is a well-known viral disease. The vaccination is so effective that it’s easy to forget just how deadly it is. In fact, rabies has a 100% mortality rate in humans, so owners need to make sure to keep their pets up-to-date on their rabies vaccine.

This disease is spread when an infected animal bites another. Dogs that come into regular contact with wild animals are at greater risk.

It’s important to note that if a dog bites a person, and there’s no evidence that the animal has been vaccinated against rabies, a quarantine period or even euthanasia may be necessary.