Establishment of a Chinese hamster breeding colony.

A colony of outbred Chinese hamsters, Cricetulus griseus, was established. Attempts to use previously published methods of physically protecting the males were unsatisfactory. Rather, females were selected for nonaggressive behavior. Breeding was among pairs allowed to cohabit for 5 1/2 days. Production was typically in excess of 180 offspring per month, with an average breeder population of 44 females and 30 males. Litters were weaned at 3 weeks of age. At that time, appropriate numbers of offspring of female parents with a history including nonaggressive behavior, fecundity and freedom from seizures were retained for use as future breeders. Females were first bred at 8-12 weeks of age and males at 8-12 months. The remaining animals were maintained in groups of like-sex littermates until used. With these methods, mortality among breeder males due to overly aggressive female behavior was reduced to 3%. Animal husbandry procedures and record keeping requirements were relatively simple, not labor intensive and would be easily adaptable to most facilities.

Streptococcal enteropathy in infant rats.

A spontaneous outbreak of enteric disease with high morbidity and mortality occurred in preweanling rats on a multigeneration toxicity study. The rats had a large number of gram-positive cocci on the surface of villi in the small intestine without associated inflammatory change. Ultrastructural study identified filamentous attachments between adjacent bacteria, and between bacteria and morphologically normal microvilli. The organism was isolated and identified as Streptococcus sp. The disease was reproduced in rat pups by inoculating dams and newborn rats with pure cultures of the Streptococcus. Streptococcal enteropathy is a previously unreported disease in rats.

Interspecies transmission of Cytauxzoon felis.

The causative agent of feline cytauxzoonosis was experimentally inoculated into 4 species of domestic farm animals, 9 species of laboratory animals, and 17 wildlife species. The inoculum consisted of freshly collected or deep-frozen blood and/or tissue homogenates from domestic cats euthanatized in extremis with experimentally transmitted feline cytauxzoonosis. A bobcat, Lynx rufus floridanus (Florida bobcat), developed cytauxzoonosis typical of the disease observed in domestic cats and died of the disease 2 weeks after inoculation. A persistent parasitemia, but no overt signs of illness, developed in another bobcat, Lynx rufus rufus (eastern bobcat). The sheep developed a low persistent parasitemia, but no clinical signs of illness. There was no clear evidence of cytauxzoonosis demonstrated by necropsy or histopathologic or blood smear examinations in all other species. Additionally, freshly collected blood and/or tissue homogenates from animals of various species, except bobcats, failed to produce evidence of cytauxzoonosis when subinoculated into domestic cats.

Experimental transmission of Syphacia muris among rats, mice, hamsters and gerbils.

Rats infected with Syphacia muris were allowed to cohabit with uninfected Mongolian gerbils, Syrian hamsters and mice. These uninfected animals subsequently became infected with Syphacia muris and when were removed and allowed to cohabit with uninfected rats. Syphacia muris was readily transmitted back to the rat from the gerbil, hamster and mouse. Transmission of Syphacia muris to the gerbil and hamster expands the host range of this parasite.

Dihydrostreptomycin toxicity in the Mongolian gerbil, Meriones unguiculatus.

A fatal syndrome of acute toxicity was produced in Mongolian gerbils following the injection of a penicillin-dihydrostreptomycin-procaine combination. The toxicity was determined to be due to the dihydrostreptomycin component. Fifty milligrams of dihydrostreptomycin produced 80-100% mortality in 55-65 g gerbils.

Dentostomella translucida in the Mongolian gerbil (Meriones unguiculatus).

Dentostomella translucida, an oxyurid, was found in the small intestine of 39 out of 43 Mongolian gerbils from a research colony and in five pet gerbils in Columbia, Missouri. This discovery established a new host record and a new georgraphic locality for the parasite. Diagnosis of parasitism was best made by direct observation of the nematodes in the host's intestine af necropsy. The average length of males was 10.3 mm, and that of females was 20.3 mm. Parasite numbers in infected animals ranged from to 11, with an average of four. No clinical manifestations of disease were associated with the parasitisms. The prepatent period of infection was determined to be determined to be between 25 and 29 days.

Syphacia obvelata in the Mongolian gerbil (Meriones unguiculatus): natural occurrence and experimental transmission.

An adult from a research colony and a litter of 5-week-old Mongolian gerbils (Meriones unguiculatus) from a pet store were found to have pinworms identified as Syphacia obvelata. The infected gerbils were allowed to cohabitate with uninfected gerbils. Similarly, infected gerbils were caged with uninfected mice and infected mice with uninfected gerbils. Results of these studies showed that Syphacia obvelata can be transmitted from gerbil to gerbil, gerbil to mouse, and mouse to gerbil.