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Deadly Dog Virus Looms


Last updated 2/15/2024 at 10:38am

A respiratory illness and corresponding bacterial infection affecting dogs is looming among the nation, and owners are urged to take precautions.

The dogs are being attacked by a disease called Streptococcus Equi subspecies zooepidemicus, which is also known as Strep zoo, and the bacterial infection Mycoplasma. The two in combination has led to “more severe disease than what the shelter might see with just one of these pathogens.”

Strep zoo is a bacteria that is primarily spread through direct contact and fomites.

The illness typically is found within animal shelters and poses little threat to the public canine population. The fomites are inanimate objects on which the disease can be transferred, such as flooring, doorknobs, clothing and shoes, for example.

Scientists are trying to figure out what’s causing the current outbreak, how widespread it is, and how many previously healthy pups have become seriously ill or died.

Canine respiratory infections, especially dog flu, are common, often causing outbreaks in shelters and doggy day cares. The current surge has been spreading in areas of the U.S. and Canada over the last year. This outbreak is different from garden-variety respiratory illness, experts say, because of the large number of cases serious enough to lead to pneumonia.

More dogs may be getting severely ill because they have been infected with multiple pathogens at the same time – including canine influenza, Bordetella (kennel cough) and mycoplasma pneumonia – said Dr. Deborah Silverstein, section chief of emergency medicine and critical care at the Ryan Veterinary Hospital at the University of Pennsylvania –similar to the tripledemic of Covid-19, influenza and RSV that affected people last fall and winter.

Many dogs may have lower resistance to infections because pandemic-era restrictions kept them out of day cares or boarding facilities and they weren’t exposed to circulating viruses or bacteria, experts note. There have also been reported decreases in canine vaccination rates. A recent study found that nearly half of dog owners are hesitant about vaccinations for their pets.

Silverstein said it’s possible that any of these factors could explain the increased incidence of a disease making some dogs deathly ill.

Still, there is a possibility there is a new bacteria circulating.

One big factor slowing down research in the U.S. is that there is no single group keeping track of pet illnesses.

Another hurdle is that many owners can’t afford to take a sick dog to a veterinary hospital or specialty center or even pay for diagnostic testing. In fact, the treatment cost for the sickest dogs can range from $15,000 to $20,000, Steve Weinrauch, chief veterinary product officer at Trupanion, said.

Which dogs are at increased risk?

Usually, brachycephalic or flat-faced dog breeds such as French bulldogs or pugs, senior dogs or dogs with underlying lung disease are more at risk of developing pneumonia from a respiratory infection.

But at Texas A&M School of Veterinary Medicine, Dr. Kate Aicher treated a cluster of cases of atypical canine respiratory disease in young, vaccinated dogs in March and April of this year. What Aicher and her colleagues were seeing was a sudden onset of fever and a wide range of severity.

“You don’t expect 1- and 2-year-old dogs who are well conditioned and healthy to end up with pneumonia so severe that they need to be put on a ventilator and then die,” said Aicher. “You don’t expect dogs to die despite aggressive care.”

About 75% of the dogs at Texas A&M tested positive for a known pathogen. But in 25% there was nothing at all on the tests, Aicher said.

Symptoms of canine respiratory infection include:



Red, runny eyes.

Many dogs will recover on their own. But if the dog has difficulty breathing or stops eating, it could be a more serious problem and the dog should be taken to a vet.

With all the attention the unidentified illness is getting in the news, and especially on social media, Dr. Cynda Crawford, a chair in shelter medicine at the University of Florida College of Veterinary Medicine, worries that owners will panic when there don’t yet seem to be that many cases overall.

Nevertheless, “vets working on the front lines in private practice are seeing higher numbers of dogs with respiratory illness, and some of those dogs are progressing to pneumonia,” Crawford said. “They are reporting that the dogs are not responding as well or as quickly to the normal standard of care.”

Four dogs have died from Strep zoo at the San Diego Humane Society’s San Diego Campus. To prevent the spread of the disease, all dogs at the organization’s San Diego Campus are being treated, and staff working with the dogs are required to wear personal protective equipment.

To prevent the spread of disease, San Diego Humane Society is urging everyone to help keep dogs out of the shelter. Finders of lost animals are strongly encouraged to participate in their Wait 48 or StrayCare programs, which allow community members to care for stray pets in their homes while we actively work to find their owner. Through the Wait 48 program, you can keep a lost pet in your home for a few days while seeking the pet’s owner. In many cases, animals reunite with their families without ever needing to enter a shelter! Through the StrayCare Program, you can keep a lost pet in your home during their legally required 72-hour stray hold period while we seek their owner. If the owner can’t be found, you can choose to adopt, continue fostering or return the pet to the shelter at a prescheduled appointment time.

San Diego Humane Society’s medical team has reached out to community members who adopted dogs that may have been exposed to Strep zoo and offered treatment and testing.