Cornell University College of Veterinary Medicine alumnus, Zachary Dvornicky-Raymond ’15, DVM ’19, recently published a study in the Journal of Zoo and Wildlife Medicine regarding validation of a portable, point-of-care test for pregnancy diagnosis in wild ungulates (hoofed mammals).

Cornell veterinary students spend the final year of the four-year Doctor of Veterinary Medicine (DVM) program participating in clinical rotations in the Cornell University Hospital for Animals (CUHA). Students also have the opportunity to travel elsewhere for externships to broaden their clinical experience.

During his clinical year, Dvornicky-Raymond spent 6 weeks at the White Oak Conservation Center in Yulee, Florida. White Oak Conservation partners with domestic and international wildlife agencies to promote the conservation of endangered and threatened species, including many species of wild ungulates. The Center’s 17,000 acres are home to okapi, bongo antelope, dama gazelles, zebras, and gerenuk, among others. 

Challenges of early pregnancy detection in wild ungulates

For many species of endangered and threatened wild ungulates, captive breeding programs are a cornerstone of conservation. Early, accurate pregnancy detection is important for herd health and genetic management, particularly in a conservation setting with a risk of inbreeding depression. For example, the North American captive breeding population of gerenuk – a slender gazelle native to East Africa – was derived from only 28 founder individuals.

Conventional pregnancy diagnosis tools commonly utilized for domestic ruminants, such as ultrasonography, have variable application within captive populations of non-domestic ruminants. Ultrasound requires specialized equipment and an experienced operator, and non-domestic species often require physical or chemical restraint for such procedures. Fecal progestin analysis, in which a fecal sample is evaluated for the presence of hormones that rise during pregnancy, is a common, non-invasive method of pregnancy detection and monitoring in non-domestic ruminants. However, fecal progestin analysis is less effective in early pregnancy, has been shown to be ineffective in some species, and has yet to be validated in many wild ungulate species. Other non-invasive methods of pregnancy detection are therefore needed.

Point-of-care blood test successfully detects pregnancy in gerenuk and eland

Pregnancy-associated glycoproteins (PAGs) are produced by the mammalian placenta. A commercial point-of-care test for the presence of PAGs in maternal blood has been validated for use in cattle, sheep, goats, and water buffalo. The test is portable, simple to use, and can be conducted without specialized equipment. “Since it requires less than a milliliter of blood, this test could be incorporated into a screening/research tool for wild ungulates that are immobilized for other reasons such as collaring, health assessments, and translocations,” said Dr. Dvornicky-Raymond. “You could also use this in some captive breeding situations where an individual is conditioned to collect blood – many are.” For other individuals, the duration of chemical or physical restraint required to collect blood for the test is significantly shorter than would be required for ultrasound.

Dr. Dvornicky-Raymond analyzed serum samples from four species of ungulates housed at the White Oak Conservation Center - gerenuk, eastern giant eland, dama gazelle, and okapi - using the PAG test. The PAG test was found to be 100% specific (no false positives detected) and 100% sensitive (no false negatives detected) for pregnancy detection in gerenuk and eland. The assay was not effective at detecting pregnancy in okapi or dama gazelle. The results were published in the Journal of Zoo and Wildlife Medicine in January 2021.

“My vision for this test is that it will be assessed and utilized for many ungulate species,” said Dvornicky-Raymond. Since the test is rapid and requires only a tiny volume of blood, it could prove extremely useful for earlier pregnancy detection, herd health monitoring, and genetic management, particularly in th field, and for species for which fecal progestin assays are not validated. “You could determine if an individual is pregnant in a matter of minutes, and make life-saving decisions not to move or stress that animal.”

Dr. Dvornicky-Raymond is currently a specialty intern in Zoological Medicine and Surgery at Colorado State University, and is pursuing a career in conservation medicine. Dvornicky-Raymond developed an interest in reproductive physiology through his undergraduate work with Cornell’s Dr. Alexander Travis at the Baker Institute for Animal Health, studying canine assisted reproductive technologies. Dvornicky-Raymond credits his time at White Oak for sparking his interest in ungulate and megavertebrate conservation and medicine, and continuing to inspire his path forward as an aspiring conservationist. “I would go back in a heartbeat if I could,” he said.

Written by Isabel Jimenez, DVM ‘19