Overcrowding a factor in San Diego shelter outbreak of Strep zoo

Updated November 20, 2023

The San Diego Humane Society (SDHS) is dealing with a canine respiratory illness outbreak exacerbated by overcrowding. The organization said that four of its dogs died after being infected with Streptococcus equi subsp. zooepidemicus (also known as Strep zoo), which was complicated by infection with bacterial agent in some cases.

“The two in combination have led to more severe disease than what the shelter might see with just one of these pathogens,” the SHDS wrote in a November 13 statement.

Dr. Laura Bunke, San Diego Humane Society’s John R. Peterson Foundation shelter medicine resident, said they first noticed severe cases around November 10 when two dogs were bleeding from the nose and mouth and in acute respiratory distress, which resulted in them being euthanized.

A puppy dog stands behind an animal shelter cage

Canine infectious respiratory disease complex (CIRDC), or “kennel cough,” is commonplace at the shelter, and Dr. Bunke said they usually treat it with doxycycline and leave the dogs in place. However, if they see dogs with more severe clinical signs or more dogs with CIRDC than expected, the shelter initiates testing. That’s what happened in this case. After submitting samples for a full respiratory PCR panel, results came back positive for Strep zoo, and some samples were also positive for Mycoplasma or Bordetella spp.

At that time, ill dogs were present in only one of the four buildings on one of the four campuses the shelter maintains. All dogs in that building were started on control doses of antimicrobials. But then this past week, the shelter had two more dogs that tested positive for Strep zoo and required euthanasia. All 280 dogs at the San Diego campus were then given antimicrobials preventively. Since then, they haven’t had any more cases.

Because strep can live longer in the environment, shelter staff members are providing temporary housing for dogs and going building by building to deep clean, Dr. Bunke said.

The shelter is 178% overcapacity for dogs based on housing. She says the dogs are more susceptible to CIRDC because of the overcrowding, which can increase stress in the dogs as well as hinder the staff’s ability to sanitize and disinfect.

The organization is limiting its dog intake to only stray animals through December 1, as well as waiving reclaim fees and adoption fees. Plus, they are putting out a plea out for people to foster dogs, even temporarily. The organization has over 400 dogs available for adoption between all four locations of the organization.

“Our biggest plea … for the dogs is to get them out of the shelter,” Dr. Bunke said. “We’re over capacity and really want to get the dogs in a loving home.”