The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is primarily known as the cause of the human pandemic. Global surveillance has documented that dogs are susceptible to infection with this virus, though contracting SARS-CoV-2 is considered an uncommon event. Infections have typically been identified in companion animals living in close proximity to infected human household members.
Susceptibility of Dogs to the Virus
Dogs become infected with SARS-CoV-2 almost exclusively through human-to-dog transmission, meaning the virus spills over from a sick owner or caregiver. The mechanism involves the virus’s spike protein binding to the angiotensin-converting enzyme 2 (ACE2) receptor on host cells. The canine ACE2 receptor shares sufficient structural similarity with the human receptor to allow this viral attachment.
However, the biological susceptibility of dogs is lower than that of other species, such as cats or ferrets. This difference is attributed to the distribution and concentration of ACE2 receptors within the canine respiratory tract. Research suggests that while the virus can replicate in the nasal mucosa, the expression of entry factors is more limited in dogs.
Despite this lower biological susceptibility, infection is common when exposure is high. Studies show that dogs in households with confirmed human COVID-19 cases have an elevated seroprevalence, indicating prior infection. Up to 68% of exposed dogs developed antibodies, even without showing outward signs of illness. Most confirmed infections are subclinical, meaning the dog does not appear sick, or they experience only mild, transient symptoms.
Recognizing Symptoms and Testing
The clinical signs of SARS-CoV-2 infection in dogs are often vague and mild, making them difficult to distinguish from other common canine ailments. Symptoms can include mild respiratory issues such as coughing, sneezing, and nasal discharge. Some dogs may also exhibit non-respiratory signs, including lethargy, decreased appetite, vomiting, or diarrhea.
Most infected dogs recover completely without requiring specialized treatment. Serious illness is extremely rare in dogs, but owners should monitor for any worsening signs like difficulty breathing or persistent fever. If an exposed dog displays these symptoms, the owner should contact their veterinarian immediately.
Routine testing of dogs for SARS-CoV-2 is not recommended by veterinary public health organizations. Testing is reserved for specific scenarios, often requiring a collaborative decision between the veterinarian and public health officials. This typically involves a symptomatic pet with known close contact with a human COVID-19 patient, especially when common causes have been ruled out. The diagnostic method is a polymerase chain reaction (PCR) test, which detects the viral genetic material in samples collected from the dog.
The Risk of Animal-to-Human Transmission
A primary concern for many pet owners is the potential for their dog to transmit the virus back to people. Scientific consensus, supported by organizations like the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO), indicates that the risk of dogs spreading SARS-CoV-2 to humans is extremely low. The transmission chain is overwhelmingly one-directional: from infected people to their pets.
There is no evidence that dogs play a significant role in spreading the virus to people or establishing new outbreaks. Instances of animal-to-human spread have been primarily linked to farmed mink and some other species, but not domestic dogs. This reassurance is based on extensive epidemiological data collected throughout the pandemic.
People are far more likely to contract SARS-CoV-2 from other people than from their pets. While an infected dog can temporarily shed the virus, the amount and duration of shedding appear insufficient to drive a public health concern. Public health guidelines focus on preventing human-to-animal transmission rather than the reverse. Owners should continue to practice good hygiene, such as washing hands after handling their pet.
Current Veterinary Management and Care
If a dog is suspected or confirmed to have SARS-CoV-2, veterinary care is supportive, as there is no specific antiviral medication licensed for canines. Treatment focuses on managing symptoms, which involves ensuring adequate rest, hydration, and nutrition. For dogs with severe gastrointestinal issues or dehydration, a veterinarian might recommend intravenous fluids.
If a human household member is infected with COVID-19, they should limit contact with their dog to prevent viral spread. An uninfected person in the household should provide care, feeding, and walking for the pet. If the infected owner must care for the dog, they should wear a mask, practice hand hygiene before and after interacting, and avoid close contact like snuggling or sharing a bed.
Owners should be aware that established canine coronavirus vaccines (CCoV), which protect against common enteric or respiratory strains, do not provide protection against SARS-CoV-2. These vaccines are designed for genetically distinct viruses and should not be relied upon for cross-protection. There is no SARS-CoV-2 vaccine widely available or routinely recommended for dogs in most regions.