Canine Coronavirus Infection in Dogs

Canine coronavirus (CCoV) is a relatively new intestinal disease in dogs. It was first identified in England in 1971, but it has since spread all around the world. Coronaviruses are found in many different animals including pigs, cows, cats, and humans, as well as dogs. They are an RNA virus, so named because of the corona like halo that appears under a microscope. Viruses will first only affect one species, but new strains do develop quickly and may occasionally jump species to form a new disease. CCoV is believed to have come originally from pigs, while another, more recent, canine respiratory coronavirus (CRCoV) may have jumped from cows. Typically, CCoV causes enteritis, inflammation of the small intestine. It is rarely symptomatic in adult dogs, but puppies have diarrhea and sometimes other symptoms as well. It affects weak puppies most commonly. In puppies under three months of age, it can be fatal, but usually because it is combined with another infection. The virus invades the upper intestinal tract within 2 to 3 days and continues to be passed in the feces for 9 days, and sometimes longer. The disease is highly contagious and spreads easily through the feces of infected animals; many dogs can be carriers without actually showing symptoms. Adult dogs that have been exposed develop antibodies to the disease. Puppies can be vaccinated at 6 and 9 weeks of age and should be protected against most forms for life. The respiratory version, CRCoV, is a separate virus that is not responsive to the same antibodies or vaccination.

Coronavirus causes a range of infectious diseases and is found in many animals. Typically, coronavirus causes an intestinal infection in dogs. Veterinarians call this canine coronavirus infection. Symptoms are usually only apparent in puppies and dogs with a weakened immune system and the disease is rarely fatal.

Adult dogs often have few or very mild symptoms. The disease is much more noticeable in puppies. Dogs or puppies with the following symptoms should be taken to see a veterinarian:

• Watery diarrhea
• Nausea
• Lack of appetite
• Vomiting
• Hard or bloated belly
• Fever
• Cough, sneezing and other respiratory symptoms

Types

Coronaviruses can mutate quickly and a number of different types are found in dogs.

• Coronavirus enteritis (CCoV) – this is by far the most common. It is rarely serious, even for puppies and most adult dogs have almost no symptoms.
• Canine respiratory coronavirus (CRCoV) – this is a new version of the virus that was discovered in 2003, probably a variant of a bovine coronavirus. It infects the lungs and causes coughing and mild respiratory symptoms similar to the human cold. It is rarely diagnosed, but is probably one of several infectious respiratory conditions responsible for the disease known as ‘kennel cough.’ Cases are more common in Europe and Japan, but American and Canadian dogs have also been found to have antibodies.
• Pantropic variants of canine coronavirus – this is a rare version of the disease that can cause potentially fatal infection throughout the body.

Coronavirus is spread through contact with other infected animals. Many factors can make it more likely to catch a serious infection.

• Staying in a kennel
• A crowded dog show
• Any condition of overcrowding
• Dog with a weakened immune system
• Puppies
• Combination with another infection

Most cases of coronavirus are diagnosed symptomatically. CCoV will be suspected in ill puppies, and also dogs that live in overcrowded situations. Watery diarrhea in puppies is the most common symptom, but some cases also have vomiting and occasionally fever. The puppy’s belly may be swollen and hard. Adult dogs can occasionally show similar symptoms.

Coronavirus is sometimes confused with canine parvovirus which typically causes more severe illness in puppies. Definitive diagnoses can be made by performing PCR tests, but the procedure is complicated and rarely performed. There is no specific cure for either condition, so the symptoms must be treated supportively in both cases.

Canine respiratory coronavirus is difficult to diagnose as many types of respiratory infections present with the same symptoms. A tissue swab may be sent for testing, but this would most likely only be done for a virus causing a serious epidemic at a kennel.

Dehydration is the most common problem with puppies that have CCoV. The puppy should be encouraged to drink independently if possible. Pedialyte can be a good fluid to hydrate puppies. If the puppy will not or cannot drink, fluids and electrolytes will need to be given intravenously.

Various medications may be prescribed based on the symptoms. Metoclopramide can relax the intestine, and famotidine or another acid-blocker can help to coat the intestinal walls and protect them against inflammation.  With puppies that are also vomiting, anti-emetics may be given. Antibiotics are commonly prescribed to control any concurrent bacterial infection which could present a bigger problem with a weakened immune system. Some puppies have hookworm (or other parasitic infestations) at the same time and need treatment for this as well. A heating pad may be helpful to maintain the proper temperature for young puppies.

CCoV is also treated supportively. Antibiotics are given to prevent bacterial infections. Dogs who develop pneumonia along with the virus could need oxygen, but this is rare.

All infected dogs should be quarantined for several weeks to avoid spreading the disease. This helps to contain the virus somewhat, even though dogs that are asymptomatic can still carry infection. Cleaning stool away with bleach or another disinfectant can effectively kill the virus, however, so maintaining sanitary conditions is the best way to stop an outbreak. Keeping dogs and puppies in good health also makes them less susceptible to infection. Puppies and dogs that are at high risk (such as kennel or show dogs) should be vaccinated against CCoV.