Beagle dogs were readily infected by 1.3 × 108 colony forming units (cfu) of Brucella suis type 4 administered either on canned dog food, or intraperitoneally. Such infections were afebrile and otherwise asymptomatic and without any obvious gross lesions.
Inoculation of 108 cfu B. suis type 4 intraperitoneally into two gravid wolves (Canis lupus) resulted in infections in both animals. About 24 days later they gave birth, apparently at full-term, to two (both alive) and six (two alive and four dead) pups, respectively. Pups born alive died within 24 hours.
A black bear (Ursus americanus) infected with between 108 and 109 cfu yielded serologic and bacteriologic data similar to that derived from the observations on beagles and wolves. Two grizzly bears (Ursus arctos horribilis) were both infected by exposure to 1.3 × 109 cfu B. suis type 4 placed on canned dog food. Antibody titres reached very high levels within the first two months of infection.