When opportunistic infection does occur, treatment with antibiotics is very successful at clearing the disease and preventing mortality due to the low levels of resistance in this species.

In other mammals, the pathogen can cause lymphadenitis, arthritis, fever, mastitis, wound infections, and other conditions that vary depending on the host species.

The development of disease can occur rapidly, and symptoms in cats include skin ulceration, chronic respiratory infection, and necrotizing sinusitis.

The persistence and spread of these bacteria in a confined area can lead to both sepsis and death, quickly resulting in extremely high levels of mortality among susceptible cats.

[citation needed] "Up to 70–100% of young queens in breeding catteries may carry this bacterium in the vagina, resulting in infection of the kittens, but also in the transfer of passive immunity against S. canis via colostrum.

[citation needed] The occurrence of S. canis was thought for years to be limited to cats and dogs with rare instances of infection in cattle and other animals.

In another case of human infection, an elderly woman was initially admitted to the hospital after slight bruising of her eyebrow, and readmitted a few days later with a high fever.

Additional support for the possibility of S. canis infections in humans has been provided by multiple cases linking the occurrence of the disease to dog ownership in elderly men.

[15] In these cases, all men had a history of ulcers on their lower limbs, which acted as an entry point for the transmission of bacteria from the respiratory tract of the dogs.

This history, in combination with continued exposure from household dogs, led to the transfer of the disease and the expression of symptoms that required medical attention.