Digangi BA, Griffin B, Levy JK et al: Use of a commercially available relaxin test for detection of pregnancy in cats, J Am Vet Med Assoc 237:1267, 2010.
Relaxin is the only pregnancy-specific hormone reported in cats. In this study, investigators determined the earliest day of gestation at which relaxin could be detected in pregnant queens using a commercially available point-of-care test designed for use in dogs. They also calculated the sensitivity and specificity of the test for pregnancy detection on any specific day of gestation. The study looked at 162 female cats—24 queens from a breeding colony, 128 stray and feral queens undergoing ovariohysterectomy, and 10 ovariectomized cats. The 24 queens in the breeding colony were monitored for pregnancy while blood samples were taken daily to test for relaxin until 2 consecutive positive tests were obtained. Pregnancy was detected as early as gestational day 20 by use of the relaxin test kit. Maximum accuracy was achieved on day 29, when sensitivity reached 100%. False-positive tests were detected in 3 queens. Utilizing the test, pregnancy can be confirmed at an earlier date than with the use of radiography and without the safety concerns related to radiography. While ultrasonography is a more sensitive method for detection of pregnancy, it may not always be available and may be more expensive than blood sampling and point-of-care testing. When breeding dates are known, the predictive value and convenience of the relaxin test make it an excellent choice for diagnosis of pregnancy in cats. When breeding dates are unknown or when multiple dates are possible, interpretation of negative results becomes more complex and must be considered within the context of the patient’s history. [VT]Related articles:de Haas van Dorsser FJ, Lasano S, Steinetz BG: Pregnancy diagnosis in cats using a rapid, bench-top kit to detect relaxin in urine, Reprod Domest Anim 42:111, 2007.