Diagnosis of early pregnancy in the throughbred mare by the toad test - Resulte of its utilization during fifteen breeding seasons

Abstract

The results with the utilization of the male toad test for the diagnosis of pregnancy in the Thoroughbred mare, during fifteen breeding season, were described. The experiments were performed on male toads (Bufo morinus L. and Bufo paracnemis Lutz) varying in weight from 90 to 320 g. Galli Mainini's technique with some modification was used. Blood serum samples were drawn from 313 mares thirty-six to 120 days following the date of the last breeding. A single mare-serum injection of 12 to 15 ml was given subcutaneously into the latero-caudal lymph sac of the toad. Two toads were used for each test. Positive reactions, caracterized by spermatozoa found in toad's urine, had resulted mainly within three to six hours. As reasonable but not strict aseptic procedures followed the collection of the blood-serum samples, some investigations were undertaken, (a) with putrid positive serum and (b) with positive serum sample preserved by the addition of sodium mertiolate in the proposition of 1:10.000 or sodium sulfatiazol in the concentration of 0,2 per cent. In (a) all the toads gave positive results and a great number of them died about 24 hours after the injection. In (b), after 13 months of conservation, all the samples gave also positive results, and were not toxic for the toads. Of the 782 test that were performed, 593 positive and 150 negative reactions were in agreement. Among the results not in agreement, 15 were false positives and 24 were false negatives. Eleven of these false negatives reactions resulted from blood-serum samples collected to early (before the 43rd day), or too late (after the 98th day), for detecting gonadotroph'-hormone, and the early reactions could not be retested. The accuracy of the toad test realized with serum samples collected between 45 to 90 days - the proper time for the test-was of 96,35 per cent. In this period both 11 false positives and false negatives reaction were observed. So, if the false positives reactions were not computed as an error of the test, its efficiency would be of 98.17 per cent. An efficiency of 91.55 per cent were obtained with the reactions performed with blood samples collected between 36 to 45 days after the last breeding, that is at an early time, during which a pregnant mare could give a false negative test. In this period, of the 154 tests performed, ten were false negatives, and could not be also retested. However, the percentage of accuracy would be higher if the toad test had been better managed, and the blood samples collected at the proper time. So, of the 263 male toad tests wich have been well performed during the last five years, from blood samples of 83 mares, pertaining to the same stud, the following results were obtained: 258 in agreement, one false positive and four false negative. In this case the efficiency of the test was of 98,09 per cent.