Ron Hines DVM PhD
Diarrhea is very common in puppies. Sometimes it is due to the things they eat and chew on ( read here ); but sometimes it is due to organisms that have take up residence in your dog’s intestines. The most serious of them is the canine parvovirus. Read about canine parvovirus here. Another much less lethal virus, the enteric form (=confined to the intestines) of the coronavirus of dogs.
When the enteric form of canine coronavirus acts alone, diarrhea lasts only a few days (if symptoms occur at all). Your puppy might be uncomfortable and have a tummy ache for a time. It might pass soft stools and occasionally some true diarrhea that messes up your house. When coronavirus diarrhea occurs, it rarely if ever contains blood. Your pup’s appetite might drop off for a few days as well. When symptoms are more severe, it is usually because your dog was co-infected with other intestinal pathogens (even parvovirus) and/or intestinal parasites at the same time. Environmental and nutritional stress the puppy is or was under tend to accentuate symptoms.
Canine coronavirus is highly contagious. When diarrhea occurs, it generally begins 1-4 days after exposure to the stool of a carrier dog. Few of the dogs that are most likely to spread coronavirus show any signs that they are ill. These recovered or resistant dogs are thought to be able to continue shedding the virus for up to 6 months.
Your dog is most likely to catch coronavirus at locations where lots of dogs congregate. Doggy daycare centers, dog parks, grooming establishments, mass vaccination clinics and animal shelters. The more crowded the animals, the poorer the sanitation, the more likely it is that cross infection will occur. It is particularly common in puppy mill puppies and pups supplied by large commercial dog-breeding operations (more than 3 breeding dams). The coronavirus can infect dogs of any age. But most dogs will have already been exposed and immune by the time they are one year old. The virus causes inflammation of the upper intestines (enteritis). The inflamed intestines, moving more rapidly to expel their contents, produce the diarrhea. Something I will mention frequently as I go along is that coronavirus of dogs rarely if ever acts alone. It produces enteritis and diarrhea as one player among many players that have taken up residence in your dog – all at the same time. ( read here )
A fatty (phospholipid) protective envelope surrounds coronavirus. Unlike the parvovirus that has no envelope but is highly stable in the environment, coronavirus are quite easy to kill with bleach, ammonia or hydrogen peroxide; as well as with dish and laundry detergents that effecctively dissolves their fatty protective phospholipid coating.
Is There Confusion Regarding The illness that Canine Coronavirus Is Capable Of Causing?
Yes there is quite a bit of confusion.
I mention in a number of my articles, it is rare for dog feces from a disease-contaminated source to contain only one pathogen. When your dog’s sniffing nose comes in contact with poop, it is likely to be exposed to quite a few different pathogens all at the same time. A lot of the earlier canine coronavirus studies assumed that if a dog developed diarrhea when no parasites could be seen microscopically in its stool and tests came back negative for parvovirus but positive for coronavirus, that the coronavirus must be the cause of the dog’s diarrhea. But now that veterinarians have access to more sophisticated tests, we know that a multitude of different potentially disease causing viral and bacterial organism – usually working together – are found in the intestinal tract of coronavirus-positive dogs with diarrhea. It is still impossible to know how much each one of those other organisms contributes to a diarrhea problem.
To compound matters, new viral pathogens, capable of causing diarrhea in young dogs, are being discovered every year. They often co-infect the same dogs infected with coronavirus. The older studies that attributed a sick dog’s symptoms to coronavirus did not check for these more recently discovered pathogens. The most recent I know of are the Astroviruses. Read about these new discoveries here.
Respiratory Coronavirus Of Dogs
The AVMA put out an advisory in 2008 regarding a “new” coronavirus that had the ability to cause severe respiratory (lung) infections in dogs. That coronavirus (CRCoV) is a different virus from the traditional intestinal coronavirus of dogs (CCoV). The newly discovered coronavirus appears to be a much closer relative to the coronaviruses that cause respiratory infections in humans (SARS & MERS ) and others varieties that causes respiratory problems in pigs and cows than it does to the coronavirus associated with diarrhea in young dogs. ( read here ) The fact that intestinal tract CCoV and respiratory tract CRCoV are not the same virus is something not everyone immediately grasped. ( see here )
If My Puppy Catches Coronavirus What Symptoms Might I See?
I mentioned the diarrhea in young dogs and puppies. As opposed to the diarrhea caused by dietary indiscretions (eating trash) or that of intestinal hookworms or giardia, the diarrhea associated with coronavirus generally contains little mucus. Blood is rarely seen in coronavirus diarrhea. Some associate coronavirus diarrhea with a fetid odor or orange tint, but that is not something to be relied upon.
Older dogs often overcome the virus (seroconvert) without experiencing diarrhea. We know they were exposed to coronavirus because antibodies against the virus now appear in their blood. Veterinarians call those subclinical cases.
Some dogs also vomit early in enteric coronavirus infections.
Many dogs experience 1-3 days of diminished appetite and lethargy.
A few run fevers.
The chief danger associated with diarrhea are dehydration and blood electrolyte imbalances. You can read more about the signs of dehydration that you might observe and how veterinarians deal with it in my article on parvovirus.
Might There More Severe Strains Of Canine Intestinal Corona Virus (CCoV)?
Medical scientists know that coronavirus, as a group, have a reputation for mutation to more (and less) pathogenic forms owing to their ability to recombine in the body with other strains of coronavirus that they encounter. They also have a high rate of spontaneous mutations. ( read here ) Although no one has studied these attributes in dogs; some propose that this is the case with canine enteric coronavirus as well.
The possibility that canine coronavirus mutated into a more dangerous (more pathogenic) form rests on a single report of what occurred at a pet shop in Bari, Italy in 2005. Three miniature pinscher and one cocker spaniel, 1.5 –1.8 month old, developed fever, lethargy, vomiting, bloody diarrhea and neurological signs. They died 2 days later. Three to four days after the first four, two more pinschers and a Pekingese of the same general ages also died. ( read here ) A variant of coronavirus was detected in these dogs (CCoV type II) and tests for common alternative explanations for the diarrhea (parvo, distemper, adenovirus and bacteria) were negative. The authors announced that they had discovered a highly pathogenic form of canine coronavirus. They gave it the name, Pantropic Canine Coronavirus. ( read here ) However, to the best of my knowledge, no attempts were ever made to reproduce the disease using the specific virus they had isolated.
Subsequently Cornell University published another review of this particular corona virus strain. But they mentioned no cases as having occurred in North America nor did they make attempts to reproduce the disease. ( read here ) They did suggest that perhaps the canine coronavirus combined with the coronavirus of cats and/or swine to produce a more pathogenic mutant. That theory had been presented earlier. (read here)
Whether this mutant canine coronavirus represents a greater threat to your dog than the traditional canine enteric coronavirus veterinarians have dealt with is still an open question. None of the studies checked for the presence of astrovirus. Astrovirus are known to accompany coronavirus in diarrhea outbreaks in beagles. ( read here & here ) It is impossible to positively attribute a disease to one organism unless you give only that organism to an animal and produce the disease. That has been known for a long time. ( read here )
Are There Tests My Veterinarian Can Run To Diagnose Coronavirus?
University and large commercial veterinary diagnostic laboratories can check your dog’s stool for coronavirus. They can also run blood antibody tests that tell them if your dog was ever exposed to the virus. However, those tests are rarely run on samples from individual pets. They are generally reserved for scientific studies and animal shelters facing an unacceptable number of diarrhea cases. (eg see here:)
What Treatment Might My Dog Receive?
There is no specific treatment for dogs with a digestive tract coronavirus infections. TLC (loving care) and whatever supportive care that is indicated are usually all that are required. In a typical mild case, the diarrhea resolves in a few days without any medications being dispensed. Many veterinarians would suggest oral fluids (eg electrolytes) and a bland diet given in small amounts throughout the day. Others might suggest withholding food for 24 hours. Both are valid approaches. But still other vets might send you home with a basket full of products, i/d™, a/d™ or EN™ dog food, Pro-Pectalin®, probiotics like Proviable-KP™ ,etc. I do not believe that any of those products will speed a coronavirus recovery. Antibiotics would be counter productive since they kill no virus but do kill off the protective bacteria that normally reside in your dog’s intestines.
Should the diarrhea be severe, the primary treatment would be to correct dehydration and electrolyte imbalances. The rest would be selected from the same treatments suggested for parvovirus infections. You can read about those medications in detail here.
Are Vaccines Available Against Coronavirus Infection?
There are currently two that I know of: Boehringer Ingelheim ’s Recombitek Corona MLV® a weakened (attenuated) live virus product and Zoetis’ Vanguard CV® which is a killed (inactivated) product. Both companies, plus Merck, incorporate coronavirus in their “8-way” carpet bomb formulas marketed to protect dogs against everything. I never recommend them because I believe that the more ingredients a vaccine contains, the more likely it is to confuse the immune system. None of the vaccines currently on the market are believed to provide complete (“sterile”) protection against coronavirus. ( read here2 + product inserts).
The American Animal Hospital Association, AAHA no longer recommends coronavirus-containing vaccines, based on their opinion that the disease is usually mild or subclinical and that it generally occurs in dogs 6 weeks of age or younger (too young to be successfully vaccinated).
The central pharmacy at the Vet School, University of California, Davis no longer stocks coronavirus-containing vaccines. Their rational is: “It is not possible to reproduce disease with coronavirus unless the dog is immunosuppressed with steroids. Antibodies do not correlate with resistance to infection and the length of time these vaccines might make a dog resistant to coronavirus is unknown.” ( see here ) Nevertheless, some boarding kennels and other commercial establishments might still insist that your dog receive a coronavirus-containing vaccination before they provide services.