Evaluation of the embryo transfer procedure proposed by the International Embryo Transfer Society as a method of controlling vertical transmission of Neospora caninum in cattle.
OBJECTIVE
To evaluate efficacy of embryo transfer into seronegative recipients, using the procedure proposed by the International Embryo Transfer Society (IETS), for preventing vertical transmission of Neospora caninum in cattle.


METHODS
Prospective clinical trial.


METHODS
87 recipient cows and heifers and their embryo transfer calves from 22 donors originating from 9 dairy herds.


METHODS
Neospora caninum serologic status of donors and recipients was determined before collection and transfer of embryos. Viable embryos were washed and treated with trypsin. Recipients in experimental groups A (n = 50) and B (29) were seronegative and received embryos from seropositive and seronegative donors, respectively. Recipients in group C (n = 8) were seropositive and received embryos from seronegative or seropositive donors. Antibody titers against N caninum were determined monthly during pregnancy in recipients and in calf blood samples collected at birth. Tissues collected from stillborn calves and aborted fetuses were analyzed histologically and by immunohistochemical (IHC) methods.


RESULTS
76 calves and 11 fetuses and stillborn calves were examined. All calves from groups A and B were seronegative (n = 70) or lacked evidence of infection by use of tissue analysis (9). In group C, 5 of 6 calves were seropositive at birth, and IHC results were positive for 1 of 2 calves. Vertical transmission rate was significantly lower in groups A and B (0%) than in group C (75%).


CONCLUSIONS
Embryo transfer into seronegative recipients, using the procedure proposed by IETS, is an effective way to prevent vertical transmission of N caninum. Results provide support for pretransfer testing of all embryo transfer recipients.
Baillargeon
P
P
Clinique Vétérinaire St-Louis-Embryobec, St-Louis de Gonzague, QC, Canada.
Fecteau
G
G
Paré
J
J
Lamothe
P
P
Sauvé
R
R
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control* / Q000635:transmission; D003048:Coccidiosis / Q000517:prevention & control / Q000635:transmission / Q000662:veterinary*; D004624:Embryo Transfer / Q000662:veterinary*; D005260:Female; D007150:Immunohistochemistry / Q000662:veterinary; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control / Q000662:veterinary*; D008297:Male; D018688:Neospora; D011247:Pregnancy; D012698:Serologic Tests / Q000662:veterinary; D013480:Superovulation