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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

Paul Baillargeon DMV, MSc1, Gilles Fecteau DMV, DACVIM2, Julie Paré DMV, PhD3, Pierre Lamothe DMV, MSc4, and Roger Sauvé DMV5
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  • 1 Clinique Vétérinaire St-Louis-Embryobec, 84 Principale, St-Louis de Gonzague, QC, Canada J0S 1T0.
  • | 2 Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada J2S 7C6
  • | 3 Biovet Inc, 2900 ave Vanier, St- Hyacinthe, QC, Canada J2S 6M2.
  • | 4 Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada J2S 7C6
  • | 5 Clinique Vétérinaire St-Louis-Embryobec, 84 Principale, St-Louis de Gonzague, QC, Canada J0S 1T0.

Abstract

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.

Design—Prospective clinical trial.

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

ProcedureNeospora 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%).

Conclusion and Clinical Relevance—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. (J Am Vet Med Assoc 2001;218: 1803–1806)

Abstract

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.

Design—Prospective clinical trial.

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

ProcedureNeospora 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%).

Conclusion and Clinical Relevance—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. (J Am Vet Med Assoc 2001;218: 1803–1806)