Endocrine control of pregnancy and parturition in South American camelids and Old World camels and the resulting possibilities for hormonal pregnancy diagnostics.

For South American camelids (SAC) and, to a lesser extent, Old World camels (OWC), an increasing demand for veterinary services has developed in Central Europe in recent years, with specific knowledge of the reproductive endocrinology of this species being particularly in demand for the management of breeding farms. Compared to many other domestic animal species, relatively little reliable information is available on the endocrine control of pregnancy and parturition in camelids. However, some significant differences to other domestic ungulate species are evident. Knowledge of pregnancy-associated endocrine changes forms the basis for hormonal pregnancy diagnostics. Even though clinical pregnancy diagnostics using sonography is also of primary importance in camelids, hormonal methods, especially non-invasive methods, are potentially of considerable interest as they represent a less stressful or stress-free alternative. Non-invasive methods of pregnancy diagnostics are of particular interest in untrained OWC, where clinical diagnostics or blood sampling without sedation can be associated with unacceptable risks for the personnel involved. Experience with hormonal pregnancy diagnostics in camelids has so far only been published sporadically, with mostly progesterone, pregnancy-associated estrogens or relaxin being measured in the blood. Non-invasive measurement of progesterone or estrogen metabolites in feces and urine has also rarely been reported. The aim of this article is to summarize the current state of knowledge on the hormonal control of pregnancy and parturition in SAC and OWC and based on this, to show the possibilities for hormonal pregnancy diagnostics. Essential prerequisites for broader application, particularly of non-invasive methods in routine diagnostics, are the optimization of previously pursued methodological approaches, the commercial availability of the necessary reagents at reasonable cost, and the establishment of reliable reference values.