Canine Distemper

While many owners will have heard of Canine Distemper Virus and may even know that it is one of the core diseases we vaccinate against, most would be hard-pushed to know what it is and to be able to describe the symptoms it causes. In fact, even a large number of vets will have only read about it in textbooks and will never have been presented with a case. This is largely thanks to the fact that the number of cases seen in the developed world has plummeted dramatically since the advent of the Distemper vaccination.

As Canine Distemper is not something that is seen much in the western world, there can be a temptation to become complacent about it and the devastation that it can potentially cause. A Distemper Virus outbreak can rapidly eradicate entire populations of dogs if unvaccinated. As an example, an outbreak that occurred in Greenland in the late 1980s had a high mortality rate, with about 80% of affected sled dogs passing away.

What Is Canine Distemper?

A viral disease that has the ability to affect several species of animals, including domesticated dogs, Canine Distemper has a high fatality rate. It is a single stranded RNA virus of the Paramyxoviridae family (the same family containing the virus responsible for Measles in humans).

This virus can affect a number of systems, including the gastrointestinal tract, respiratory tract and the central nervous system. Many animals will go on to develop significant secondary bacterial infections, which worsen their prognosis.

History of Canine Distemper

The first reported case of Canine Distemper virus within Europe was in the late 18th century. Though vaccines were first developed in the 1920s, it was not until the 1950s that they were made commercially available to the general public and their pet population.

In the past, there was little that could be done when it came to the Distemper Virus and as there is no treatment, it would claim the lives of many dogs every year. Thankfully, in the 1950s, an effective vaccination programme was introduced which has undoubtedly saved the lives of many. Nowadays, it is relatively rare for a dog to contract Distemper.

Unlike many other canine diseases, Distemper Virus can spread to dogs from wildlife, as well as undomesticated dogs. This includes foxes, coyotes, large cats (including lions), racoons and other animals. Historically, this has made it a hard disease to control. When there is an outbreak in the local wildlife population, any unvaccinated dogs living in the vicinity are put at risk.

What Are the Signs & Symptoms?

The severity of signs is variable and while some will only be mildly affected, with symptoms of an upper respiratory tract infection, others will become seriously ill and pass away. Some will refer to Canine Distemper as 'Hardpad Disease' because of the characteristic lesions that occur on paws, resulting in hardened, thickened skin (hyperkeratosis). Other common symptoms include:

• Ocular Discharge
• Nasal Discharge
• Cough
• Fever
• Vomiting
• Reduced Appetite
• Neurological signs (circling, tremors, seizures, etc.)
• Paralysis

Dogs will usually present with mild symptoms, which get progressively worse with time and neurological symptoms will become apparent towards the end of the disease process, although do not develop in every patient.

How Do Dogs Contract It?

An infectious disease that is spread through aerosol droplets, bodily fluids, including mucus, urine and faeces, can potentially contain the viral particles and transmit the disease from one animal to another. Most often, dogs are infected via direct contact, i.e. being coughed on by another animal.

While this is typically dog to dog spread, dogs can catch the disease from other animals, including foxes and coyotes. Other methods of transmission are possible, including via blood transfusion (although this would be very rare) and via the placenta of an infected mother to her pups.

Are Any Particular Dogs More at Risk?

Those that have never been vaccinated against the disease are at highest risk, particularly young dogs between the ages of three and six months. Those at the highest risk are puppies born to unvaccinated mothers, as mothers that have been vaccinated would pass on some level of protection within their milk.

Diagnosing Canine Distemper

It can be surprisingly difficult to make a definitive diagnosis of Distemper and though a vet may suspect the disease when an animal presents to them with the typical signs, it cannot be easily confirmed. While there are blood tests available, these tests can yield both false negatives and false positives so cannot be relied on.

Establishing a diagnosis of Distemper is important as any affected animal should be immediately isolated to prevent the disease spreading further. To be safe, any animal suspected of having Distemper should be assumed to have it until proven otherwise and quarantine procedures should be put in place.

Treatment Plan for Canine Distemper

Sadly, there is no specific treatment for Distemper, as is true of many similar viruses. Dogs are nursed intensively as their immune system attempts to fight off the infection. Typically, an animal will be hospitalised and given intravenous fluids to prevent dehydration, as well as anti-nausea medicine and antibiotics to treat secondary infections. Those that are not eating may require assistance in the form of syringe feeding, or even parenteral feeding.

Prognosis

The prognosis for those affected with Distemper Virus is dependent on the strain of virus they are exposed to, the age of the animal and their overall health and ability to mount a strong immune response.

Sadly, around half of infected animals will eventually pass away due to the disease and the statistics are even worse for puppies. In fact, even those that survive the initial viral infection can suffer from significant issues down the road.

Are There Any Lasting Symptoms for a Dog That Survives?

For those who manage to successfully fight off the initial infection and do not pass away, they may have chronic thickened pads and nose and they may also have enamel hypoplasia (especially if they were infected when very young).

Survivors of the disease can also go on to develop significant neurological issues several weeks to months later. These symptoms can include tremors, difficulty walking and seizures. Damage to the nervous system is permanent and can significantly impact an animal’s quality of life. Interestingly, in some dogs, these neurological symptoms have only been reported several years after the initial disease was first contracted.

Can Humans or Other Pets Catch Canine Distemper?

Luckily, humans will not develop Distemper and there have been no reported cases of a human being infected to date.

Other Pets

Though many wild animals can be affected with Distemper, only a small number of our domesticated pets are at risk. Domestic cats can potentially contract the disease but do not show symptoms and tend to clear the disease with ease. Ferrets are particularly prone to Distemper and there is 100% mortality rate within the species.

Preventative Methods

Vaccination is critical when it comes to preventing Distemper Virus, both for an individual and when it comes to the general population. All puppies should receive vaccines between six and eight weeks of age and vaccines will need to be boostered several weeks later. On top of this, repeated vaccinations to maintain immunity as an animal ages are advised. Vaccines can be effective in the face of an outbreak and if an unvaccinated animal is thought to have been exposed to the virus, they should receive the vaccine as soon as possible (ideally within the first few days).

If owners have previously had a dog with Distemper, they should wait at least one month before getting a new dog and should ensure the home and garden have been adequately disinfected before introducing the new dog. It would be prudent to not allow a young dog in the home until they have received their full vaccine course.

Ferrets that live with dogs should always be vaccinated (both for their own sakes and to prevent spreading the infection to dogs). It is also prudent to prevent contact with wildlife, which can harbour the infections, limiting any exposure to foxes, skunks, racoons, etc. This may mean implementing preventative measures, such as only allowing animals outdoors when supervised and/or on a lead, and having sturdy fences in back gardens.