Pregnancy diagnosis in wild canids using a commercially available relaxin assay

Accurate detection of pregnancy is a useful tool in zoo management and husbandry, conservation breeding programs and research settings. Our study evaluated the ability of a commercial relaxin hormone assay used in domestic dogs (ReproCHEK(TM)) to accurately detect pregnancy through plasma analysis in two wolf and two fox species. The relaxin assay detected all of the pregnancies greater than 25 days gestation for island foxes, fennec foxes, gray wolves, and Mexican gray wolves. For island foxes, three negative relaxin results were attributed to using the test earlier postconception than manufacturer recommendation (before day 20). Five other negative results were found for females estimated at 15-25 days gestation, spanning the early and intermediate period (21-30 days gestation) when relaxin may be detected but less reliably. There were no false-positive results in nonmated negative control animals. Relaxin assay results were highly correlated with ultrasound results and the intra-assay replicate agreement was 100%. Our results show that the ReproCHEK(TM) commercial relaxin assay is a minimally invasive and reliable method for pregnancy detection in these wild species when used after 25 days gestation and might be applied to other canids as well. Furthermore, this assay is easy to run and requires no specialized equipment, making it extremely useful for zoo and field research applications. Zoo Biol 27:406-413, 2008. (c) 2008 Wiley-Liss, Inc.