Feline False Pregnancies: Using a Novel Approach to Diagnose Pregnancy  

clouded leopard at Brookfield Zoo

As mentioned in a previous blog (September 2017), one of the most unique phenomenon faced in monitoring reproduction in felids are false-positive pregnancy results due to pseudo (false) pregnancies. Looking at only progesterone and estrogen isn’t enough, levels will go up indicating pregnancy, but in reality, the individual is not pregnant! False-positive results can occur from larger felids (e.g. tiger, leopard) to smaller (e.g. black-footed cat, domestic cat).  With no clear answer as to why false pregnancies occur, researchers have to find ways to still diagnose pregnancies with certainty.

How do we overcome this hurdle? Thanks to the development of a new assay created by the Institute for Wildlife and Zoo Research in Berlin, monitoring PGFM in felids has given us a tool to accurately test for pregnancy. Unlike our typical progesterone and estrogen tests, PGFM will only be detected if a fetus is present.

We tested this new hormone assay on Amur tiger, clouded leopard, and black-footed cats and the results were very optimistic! In each case, progesterone levels increased which would normally alert us of a pregnancy, but PGFM only increased if the individual was truly pregnant. The following graphically represents our findings (clouded leopard Cirrus).


Graph A


Graph B

Graph A shows an increase in progesterone levels during an actual pregnancy. PGFM levels begin to increase approximately halfway through the gestation length. The presence of PGFM confirms a positive pregnancy diagnosis. Graph B shows an increase in progesterone levels during a false pregnancy. PGFM levels remain low, never rising confirming a false pregnancy, no fetus is present.

Thanks to the development of this new assay, we now can distinguish between pregnancy and false pregnancy! This will help our talented animal care professionals prepare truly pregnant females for birth and know when to expect the arrival of young. Successful breeding is vital in zoological institutions in order to maintain a healthy sustainable population as well as keeping track of successful breeding individuals.

Please stayed tuned for future updates from the Endocrine Lab!

-Jocelyn Bryant, Endocrinology Lab Manager

Posted: 6/18/2018 1:24:08 PM by Bryan Todd Oakley

CZS & Brookfield Zoo

Since the opening of Brookfield Zoo in 1934, the Chicago Zoological Society has had an international reputation for taking a cutting-edge role in animal care and conservation of the natural world. Learn more about the animals, people, and research that make up CZS here at our blog.


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