Effect of Cross-Fostering on a Variety of Viral Agents in Conventionally Bred Rats

We aimed to compare the serological profiles of the pups that were housed with their biological mothers and the ones which were transferred to foster-dams after birth, with regard to certain viral agents. The day of delivery for the pregnant rat is recognized as the postnatal day 0 (P0). The pups born from Group 1 [P(0), P(21), P(60)] pregnant rats were housed with their biological mothers. In Group 2 [P(1), P(21), P(60)], however, P(1) consisted of pups housed with their biological mother for 24 hours while P(21) and P(60) consisted of pups transferred from the their biological mother immediately at birth. Antibody response against Lymphocytic Choriomeningitis Virus (LCMV), Rat Parvo Virus (RPV), Sendai Virus (SV) and Toolan's H1 viruses was not detected in dams and pups of all the groups, whereas high rate (45%) of antibody positivity was observed in response to Kilham' Rat Virus (KRV). No statistically significant difference was determined between the pups left with their biological mother and with the foster mothers, except for Murine Adeno Virus type 1, type 2 (MAD 1 and 2), Reovirus type 3 (REO-3) and Theiler's Murine Encephalomyelitis Virus (TMEV). It was conspicuous in terms of REO-3 that for the pups it was essential to stay with their biological mothers and nursed during the first 24 hours. As a result, foster mother usage in breeding laboratory animals is found to be beneficial against a variety of viral agents for the pups particularly in the later period of their lives and we suggest to continue this implementation in routine laboratory practice whenever necessary.