Save Your Fur Babies From Canine Distemper: 11 Things You Should Know

Distemper in dogs is a serious infectious illness that can strike your dog at any time. Hence, it is crucial to know more about this disease so that you can help protect your dog from it.

In this article, we’ll discuss all the things you must know about distemper in dogs. We’ll define what distemper is, how it affects a dog’s body, its signs and symptoms, and how is it diagnosed. We’ll also outline treatment plans and preventive measures to protect your dog from contracting distemper.

In this article, here are the 11 things we’ll tackle:

• What is distemper in dogs?
• Canine Distemper Virus Characteristics
• Canine Distemper Modes of Transmission
• How CDV attacks a Dog’s body
• Signs and Symptoms of Distemper in Dogs
• Dogs Susceptible to Canine Distemper
• Dogs with behavioral issues and canine distemper
• Diagnosing Canine Distemper
  • Laboratory Tests for CDV Detection
    • Reverse Transcription Polymerase Chain Reaction (RT-PCR)
    • Immunohistochemical staining
• Treatment Plans for Distemper in Dogs
• Is Medication for Canine Distemper on the way?
• Preventing Canine Distemper

What Is Distemper in Dogs?

Distemper in dogs, also known as canine distemper, is a viral disease caused by the canine distemper virus (CDV). It is a highly contagious disease that can be passed through coughing, sneezing, and direct contact with susceptible dogs.

Canine distemper causes serious problems affecting multiple systems in a dog’s body, such as:

• Respiratory system
• Gastrointestinal tract
• Spinal cord
• Brain

Since distemper in dogs is a multi-system disease, symptoms and the course of infection may vary widely depending on each dog’s case. Canine distemper may cause mild discomfort and illness in some dogs, while it can also be fatal for others.

Dogs that show no symptoms at all may have their diagnosis and treatment delayed. This is often because they don’t appear sick yet they are already harboring CDV. However, if canine distemper isn’t promptly diagnosed and treated in these dogs, it could cause devastating complications such as:

• Paralysis
• Increased vulnerability to other illnesses
• Impairments in vision and hearing

There is no known cure for canine distemper. Partial to full recovery may be possible for dogs with very strong immune systems. However, many dogs who contract the illness often fail to recover. Statistics show that 80% of puppies and 50% of adult dogs infected with distemper die.

Community outbreaks of canine distemper typically happen in places where unvaccinated dogs stay. These places may include pet stores and animal shelters.

Canine Distemper Virus Characteristics

Canine distemper virus (CDV) is part of the Morbillivirus genus. It also comes from the Paramyxoviridae family. This is the same virus family that causes human diseases such as mumps, parainfluenza, and measles.

Dogs are the primary reservoir of the virus. However, it can also be found in various wild animals such as ferrets, foxes, raccoons, coyotes, wolves, mink, and skunks.

CDV has an enveloped structure and a single strand of the RNA genome. Its enveloped nature makes it highly sensitive to humidity and temperature.

The virus lives longer in areas with cold temperatures. Specifically, it can live at 5 °C for 2 weeks (14 days). CDV tends to die down in hotter temperatures.

Certain chemical disinfectants can be used to kill the virus on hard surfaces. These include the following:

• 2% formalin
• 70% ethanol
• 05% quaternary ammonium chloride
• 100 ppm sodium hypochlorite

All these chemical disinfectants have shown an ability to reduce the infectivity of the virus when used on hard surfaces. It is recommended to use these disinfectants for at least 10 minutes to effectively clear the virus.

Canine Distemper Modes of Transmission

Canine distemper is primarily transmitted through infected respiratory droplets and aerosols in the air. A dog carrying the virus can pass it on by coughing or sneezing, releasing the virus particles in the air. Dogs near him may inhale these droplets, getting infected as a result.

CDV is shed in all kinds of body secretions from the affected dog. Hence, distemper in dogs can also spread through direct contact with all body secretions including eyes and nose secretions, saliva, urine, and feces.

The virus can also be passed on by sharing food and water bowls. It can live in containers that are not regularly disinfected or cleaned after use. However, aerosol and direct contact transmissions are still the most common ways an infected dog can pass on CDV.

How CDV Attacks a Dog’s Body

CDV mostly targets tissues making up a dog’s lymphatic, epithelial, and nervous systems. To put it simply, it chiefly attacks the lymphatic network, skin, brain, and spinal cord of a dog.

The canine distemper virus enters the dog’s body and attaches itself to the respiratory tract. It then creeps into the lymphatic tissues and starts multiplying itself from there. CDV often stays for around 2 days here, infecting the tonsils and bronchial lymph nodes.

On the 2^nd or 3^rd day of infection, CDV starts entering the dog’s bloodstream. The virus-containing blood now spreads throughout the dog’s body, infecting various tissues and systems including:

• Respiratory system (lungs)
• Digestive system (stomach, intestines, and related organs)
• Epithelial cells of the skin
• Optic nerves of the eyes
• Central nervous system (brain and spinal cord)
• Elimination organs (urinary tract and anus)

CDV continues to spread until the dog is already experiencing symptoms of brain and spinal cord inflammation (meningoencephalitis). These symptoms are painful and cause neuronal loss and immense suppression of the dog’s immune system.

The virus can spread rapidly in a few days to weeks. The incubation period is typically 1-2 weeks after initial exposure to CDV. Clinical signs may show up after the incubation period, but some dogs don’t show symptoms until after 4-5 weeks or even more.

Signs and Symptoms of Distemper in Dogs

Initially, a dog with canine distemper presents with the following symptoms:

• Fever, one episode 3-8 days upon exposure to the virus; another episode 11-12 days into the disease
• Clear to greenish discharge from the eyes and nose
• Lethargy
• Depression and listlessness
• Sneezing and coughing
• Eye inflammation

These symptoms are then followed by changes in the gastrointestinal system. The dog experiences the following symptoms:

• Vomiting
• Suppressed appetite
• Diarrhea
• Pus blisters on the abdominal area
• Dehydration
• Weight loss

As CDV further spreads inside a dog’s body, it can cause symptoms highly similar to rabies. These neurological symptoms appear around 1-3 weeks after recovering from the earlier symptoms:

• Muscle twitches
• Seizures
• Head shaking
• Convulsions with salivation and jaw-chewing movements, as if the dog is chewing a gum
• Sensitivity to pain or touch
• Weakness or paralysis
• Confusion
• Rhythmic muscle jerking when resting or sleeping, typically affecting the head and neck

Hardening and thickening of the footpads may also occur. This is why distemper in dogs is also nicknamed “hard pad disease”. The skin on the nose may thicken as well.

All the mentioned symptoms make a dog so sick he becomes especially vulnerable to secondary bacterial infections such as pneumonia. When a dog contracts a secondary infection, his immune system further weakens and fails to fight off the canine distemper virus spreading through his body.

Most of the neurological symptoms are fatal to dogs. A dog surviving these symptoms often gets irreversible and permanent damage to his nervous system.

Dogs Susceptible to Canine Distemper

Here are the dog populations that are most susceptible to canine distemper:

• Puppies below seven weeks and born to mothers who were not immunized against CDV
• Puppies 3-6 months old
• Mixed-breed dogs
• Unvaccinated dogs
• Rescue dogs
• Shelter dogs living in communities with plenty of unvaccinated dogs
• Dogs with weak immune systems due to pre-existing infections

Note that all dogs may contract canine distemper, regardless of age or breed. However, these susceptible populations have higher chances of mortality when infected with CDV.

Dogs with Behavioral Issues and Canine Distemper

Dogs who are aggressive or present with behavioral problems may also run the risk of passing the canine distemper virus to another dog. For instance, an asymptomatic dog with CDV breaks outside your home and runs towards other dogs in a park, coming into direct contact with them. He can shed the virus into the air and pass the virus to other dogs without anyone knowing it.

Or perhaps your dog is currently doing well on a dog training program founded on positive reinforcement (1). Then suddenly, you noticed more aggressive behavior from your otherwise well-behaved dog. It could be that your dog is feeling unwell most of the time due to an infection. Hence, you must immediately check him for signs of illness, especially distemper.

Diagnosing Canine Distemper

Diagnosing distemper in dogs is quite complicated. This is due to various factors such as:

• Signs and symptoms are highly variable depending on the dog infected
• Symptoms take time to appear
• Secondary infections often come with the disease
• Symptoms of other dog infections look similar to that of canine distemper

Veterinarians combine physical examination and laboratory testing to check for canine distemper. The vet will look for the symptoms and signs of distemper in dogs, then order for additional lab tests to rule out other infections and confirm the canine distemper diagnosis. Biopsies, x-rays, bacterial cultures, and complete blood cell counts may be done to rule out other infections.

Laboratory Tests for CDV Detection

There are two specific tests that a veterinarian may order for a dog suspected with canine distemper. These tests are RT-PCR and immunohistochemical staining.

1. RT-PCR

Reverse Transcription Polymerase Chain Reaction (RT-PCR) is the main test carried out to detect distemper in dogs. RT-PCR detects the virus by looking for its nucleoprotein RNA in either blood, respiratory secretions, urine, feces, and cerebrospinal fluid.

In an RT-PCR test, the virus’ RNA is extracted from the specimen using a special chemical extraction kit. Once the RNA is isolated, the virus is identified by decoding the nucleoprotein gene sequences in the RNA. This is done through amplification using oligonucleotides through polymerase chain reaction (PCR).

The samples to be taken from the dog for RT-PCR testing vary depending on the presentation of canine distemper and its symptoms on that particular dog. However, whole blood and serum are the samples routinely used in most dogs. Cerebrospinal fluid is typically taken if the dog presents with systemic and/or neurological symptoms already.

A German study done in 1999 confirmed that RT-PCR is a specific, fast, and sensitive method in determining the presence of canine distemper virus in dogs. Hence, it is a good way to check if a dog truly has canine distemper.

2. Immunohistochemical Staining

Immunohistochemical staining is done to look for CDV antigens in a specific tissue or whole blood. Samples taken from the dog may include lung, brain, nasal mucosa, haired skin, footpad epithelium, or eye discharges.

To do this, a sample of tissue or whole blood is smeared on slides, then stained with a fluorescent substance. CDV antigens will show up illuminated on its own by the fluorescent dye or as a result of enzymatic color change reactions.

CDV antigens in tissues and whole blood confirm the presence of the virus in a dog’s body. Hence, immunohistochemical staining is another definitive way to detect distemper in dogs.

However, there may be times that the amount of CDV antigens is insufficient and therefore does not show up in the staining, of which a false negative result may occur. If this happens, another testing method like RT-PCR is recommended.

Treatment Plans for Distemper in Dogs

There is no known treatment for distemper in dogs. Hence, veterinarians turn to supportive care to manage canine distemper. Interventions given to a dog may vary depending on his symptoms and possible secondary infections.

Antibiotics offer no direct effect since they don’t kill viruses. These medications are only given to treat any secondary bacterial infections a dog with distemper may have, such as pneumonia.

Treatment plans for dogs with distemper often include the following:

• Admission to a vet hospital and isolation from other dogs
• Intravenous fluids to beat dehydration
• Medications to control vomiting and diarrhea
• Medications to address specific neurologic symptoms such as muscle twitches and chewing fits
• Anticonvulsants for seizures
• Antibiotics for dogs that developed secondary bacterial infections

Most dogs who reached neurological symptoms but survived canine distemper have irreversible changes in their brain function. This leads to partial or full paralysis for some dogs. Others may have lifelong problems in coordination and muscle tone.

Dogs who are diagnosed or who have recovered from canine distemper should be isolated from other dogs at least 2 weeks after the disappearance of any clinical signs.

Is a Medication for Canine Distemper on the Way?

Many research efforts have been undertaken to create a new drug for canine distemper. Most ideas did not make it to the trial phase, but there are a few optimistic veterinarians and laboratories who believe a cure will finally be at hand for distemper in dogs.

One veterinarian from California came upon an experimental drug used by holistic doctors to treat different kinds of viral infections. The result was indeed promising. The distemper-infected dog he treated recovered well enough. The only remains of distemper on the dog was an occasional involuntary movement in one paw.

Since then, plenty of veterinarians have tried using the drug with a whopping 80% success rate in dogs with canine distemper. More research is underway, though, and with this early success, veterinarians are highly optimistic for a definite cure to distemper.

Preventing Canine Distemper

Canine distemper is such a contagious and life-threatening disease. Hence, all dog owners are strongly advised to have their dogs or puppies vaccinated against the disease. Proper vaccination is the key to effectively preventing distemper in dogs.

Canine distemper vaccination falls into two types – modified-live virus (MLV) and recombinant CDV (rCDV) vaccines. Your veterinarian will determine which type of CDV vaccine is suited to your puppy or dog. Rest assured that both types of vaccines can effectively provide immunity against distemper.

The initial dosages of CDV vaccination are given between 6-16 weeks of age. Your puppy will receive distemper vaccination in three doses during this time frame, namely:

• At 6-8 weeks
• At 10-12 weeks
• At 14-16 weeks

The next distemper shot will be given at 12-16 months. Subsequent shots must continuously be given every 1-2 years to provide effective protection against distemper in dogs.

Other ways to prevent canine distemper include the following:

• Be cautious when socializing your puppy or dog. Exercise caution when you take your dog to areas with unvaccinated animals or areas where lots of dogs congregate often, such as parks, classes, and doggy daycare.

• Do not let your dog come into contact with infected dogs or wildlife.

• If you have a pet ferret at home with your dog, have it vaccinated against distemper as well. A USDA-approved ferret vaccine is available for these animals.

• Thoroughly disinfect all food and water bowls before and after use. CDV is highly-susceptible to common household disinfectants containing sodium hypochlorite or ethanol.

• Immediately bring your dog to your veterinarian if you suspect signs or symptoms of canine distemper. Early diagnosis and treatment prevent life-threatening complications to develop.

Wrapping It All Up

Distemper in dogs is an illness that is highly contagious and fatal. It comes from the canine distemper virus. Signs and symptoms vary per dog, but the disease generally infects multiple body systems including the respiratory, gastrointestinal, and neurological systems.

Dogs infected with the disease have high chances of not making it through. Those with strong immune systems may be able to fight off the virus, though. But still, distemper in dogs may leave lifelong complications such as paralysis or impaired muscle function.

RT-PCR and immunohistochemical tests are done to confirm the presence of the virus in a dog’s body. Veterinarians also check for secondary bacterial infections contracted as a result of a severely weakened immune system from the distemper infection.

No direct medication is available for distemper. Supportive care according to a dog’s symptoms is often done to help the dog heal from the virus.

Vaccination is the primary method of canine distemper prevention. Other measures such as cautious dog socialization, disinfection, and immunization of other pets like ferrets can also be helpful.

To wrap it all up, canine distemper is a serious illness. You must protect your dog from it through regular vaccination. After all, no dog deserves to contract such a painful and life-threatening condition.

References:

(1) Volhard, J. & Volhard, W. (2010). Dog training for dummies. 3^rd Edition. Wiley Publishing Inc.