Intestinal Viral Infection (Rotavirus) in Dogs

Most dogs are exposed to rotavirus at some point in their lives. Canine rotavirus is part of a large group of RNA viruses from the family Reoviridae. Different strains of rotavirus affect many types of animals, including humans, cats, cattle, pigs and birds as well as dogs, and they are one of the leading causes of diarrhea based illness around the world, primarily in children. Strains of rotavirus are species specific, but the RNA strands have the ability to mutate easily and can jump species fairly often. The virus is most prevalent in third world countries where humans live in close proximity to cattle and other animals. The effect of canine rotavirus is generally mild. Puppies under 12 weeks of age commonly have symptoms of watery diarrhea. This is rarely fatal, unless the puppy is especially weak or the infection is combined with another disease such as canine parvovirus or coronavirus. In adult dogs, rotavirus is not usually symptomatic and dogs that have been exposed to the disease carry antibodies in their feces, so secondary infection is less serious. Occasionally a particularly virulent strain of the virus can cause a problem, or dogs with weakened immune symptoms may be especially susceptible. Although canine rotavirus does not typically affect humans, the virus can be zoonotic (communicable to humans), so good hygiene practices are essential, especially around large populations of infected dogs. There is currently no vaccine for rotavirus in dogs.

Rotaviruses can cause infection in many animals including humans. The virus is rarely symptomatic in dogs, but puppies may experience mild diarrhea and occasionally other symptoms as well. Veterinarians call this canine rotavirus. The disease is usually not serious and most symptoms resolve themselves in 8-10 days.

Symptoms of rotavirus in puppies are typical of many viral and bacterial infections. These always have the potential to be serious, so the puppy should be evaluated by a veterinarian.

• Watery diarrhea
• Mucus in the feces
• Low-grade fever
• Nausea or vomiting
• Poor appetite
• Low energy

Types

There are eight different types of rotavirus, categorized from A-H. Rotaviruses that affect dogs belong to Group A. This is also the group that most commonly affects humans, although B and C have been known to cause outbreaks. Each group is further divided into serotypes or strains. G3 and P3 are the serotypes that have been most commonly found in dogs. These serotypes can affect humans, but this is rare.

Causes of Intestinal Viral Infection (Rotavirus) in Dogs

Rotavirus is spread through contact with feces and other infected fluids. Dogs do not need to show symptoms to be carrying the disease. These conditions make infection more likely.

• Puppies
• Weak immune system
• Combination with another virus
• Conditions of poor hygiene
• Overcrowding
• Large populations of stray or feral dogs

The veterinarian will physically examine puppies that are showing symptoms. Mild enteritis (intestinal infection) is the most common sign. The virus infects the tips of the villi in the small intestine. These cells normally absorb nutrients, so when they are infected, proper digestion becomes impossible and ingested food passes quickly through the intestine causing diarrhea. Lack of essential nutrients can also cause weight loss and low energy.

Rotavirus is sometimes difficult to distinguish from coronavirus and parvovirus since all three viruses cause diarrhea in puppies; however parvovirus is usually responsible for more serious fatal illness than either of the other two infections. The virus can be definitively diagnosed by examining a prepared feces sample under a microscope. This is rarely done for mild cases of rotavirus or coronavirus since there is no cure for either disease and symptoms must be treated supportively. The veterinarian will try to eliminate other more serious causes of infection, such as canine parvovirus, hookworm, or a bacterial infection.

The most common problem with rotavirus is dehydration. Puppies with severe diarrhea will need to be given extra fluids and electrolytes. Pedialyte can be a good fluid to ensure hydration. If the puppy is unable to drink on its own, or symptoms are severe, the veterinarian may give fluids intravenously. This is rare with rotavirus and suggests that the virus is combined with another infection.  Symptoms usually resolve themselves within 10 days and are rarely fatal.

Rotavirus infection secondary to another disease is more common, and in fact, may be responsible for all but about 2% of cases. Antibiotics could be prescribed to limit bacterial infection resulting from a weakened immune system, although these wouldn’t have any effect against rotavirus. If the puppy also has hookworm, this condition would also need to be treated with medication.

Most puppies will recover from the disease and likely be protected against further infection. Puppies that are ill should be quarantined to avoid spreading the virus. Adult dogs do not usually show symptoms, but they can still carry the disease. Regular cleaning and disinfectant use can help to limit infection and the virus’s zoonotic potential should always be a concern. Virulent strains are possible since the virus mutates quickly, but this isn’t commonly reported in dogs.