Category — Animal Sciences
Many visitors to the Zoo have met our two African lions, John and Imani, in the new Africa exhibit. These two young cats were paired up earlier this year with the hope that they would breed and produce their first litter of cubs in the near future. The good news is that breeding activity has been observed on several occasions this past year, and, after at least one pseudopregnancy, it appears that Imani is now pregnant and due to give birth within the next month. Which raises the question – how do you diagnose pregnancy in a lion anyway?
Scientists at the Zoo’s Center for Conservation and Research of Endangered Wildlife (CREW) commonly use three methods for pregnancy diagnosis in wildlife species: ultrasonography, fecal progesterone analysis, and urine relaxin analysis. Ultrasonography remains the gold standard since visualization of a fetus with a strong heartbeat is the definitive proof of pregnancy. CREW frequently uses abdominal ultrasonography to diagnose and monitor pregnancies in our domestic cats (see below). However, this method can be challenging to apply with a potentially dangerous carnivore, like Imani. Through the Zoo’s operant conditioning program, Imani eventually may be trained to allow voluntary abdominal ultrasound exams, but this method is currently not an option with her.
The second approach for pregnancy diagnosis is the use of fecal progesterone analysis. Lions, like other felids, show an increase in fecal progesterone levels shortly after ovulation that is detectable using CREW’s hormone assays. If lions ovulate but don’t conceive, they will have a pseudopregnancy that lasts 50 to 60 days and then progesterone will decline back to baseline levels. If progesterone concentrations stay elevated beyond 60 days post-breeding, then the female is most likely pregnant. Imani’s fecal hormone profile (below) shows progesterone levels increasing coincident with her last breeding activity and staying elevated through at least 66 days post-breeding (the last fecal sample tested).
The third option for pregnancy diagnosis involves measurement of another hormone, relaxin, that is produced by the placenta and excreted in the urine. CREW has helped to pioneer the use of a bench-top relaxin test for pregnancy diagnosis with urine from cats. Our previous research has found that pregnant domestic cats and Pallas’ cats produce high levels of urinary relaxin that are detectable with the bench-top test, but pregnant cheetahs and clouded leopards apparently do not. Imani is the first lion that we have evaluated late in a suspected pregnancy. Urine samples collected from Imani at day 73 and 74 post-breeding were both positive for relaxin (below, circled line in window #2), providing further presumptive evidence of an ongoing pregnancy. In the absence of a sonogram showing a viable fetus, the positive results from the progesterone and relaxin assays provide our best evidence that Imani is pregnant.
Hopefully, Imani will confirm our diagnosis in the next few weeks with the anticipated birth of her first litter of cubs. Since Imani will be a first-time mom, she will be provided with a quiet, off-exhibit den area to give birth and bond with her cubs, and likely will remain off-exhibit until early spring when the cubs are a bit older.
October 28, 2014 No Comments
You probably already know that the Cincinnati Zoo is committed to the conservation of lions, tigers and cheetahs, but did you know that we are also leading the way in small cat conservation? And our Small Cat Signature Project just got bigger! Our Center for Conservation and Research of Endangered Wildlife (CREW) recently received a Museums for America Grant from the Institute of Museum and Library Services to improve our ability to maintain healthy captive populations of five small cat species across the country—the Brazilian ocelot, the Pallas’ cat, the black-footed cat, the Arabian sand cat and the fishing cat.
Unfortunately, none of these small cat populations are considered sustainable through natural breeding alone. That’s where Dr. Bill Swanson, CREW’s Director of Animal Research and the world’s leading expert on small cat reproduction, comes in. Working in partnership with Dr. Jason Herrick of the National Foundation for Fertility Research and the Species Survival Plan coordinators for each species, Dr. Swanson will direct the project with a focus on three goals: 1) Collect and freeze semen from the most valuable cats for each species, 2) Produce viable offspring using artificial insemination in recommended breeding pairs that fail to reproduce naturally, 3) Produce offspring with frozen-thawed semen from genetically valuable or under-represented males.
Building on CREW’s decades of ground-breaking research on small cat reproduction, successful completion of this project will greatly enhance the sustainability and stewardship of small cat collections in AZA zoos. Now that’s big news!
October 9, 2014 1 Comment
Written by Crissi Lanier & Shasta Bray
It’s not as easy as one would think. Dr. Erin Curry with our Center for Conservation and Research of Endangered Wildlife (CREW) is committed to finding a way.
The Cincinnati Zoo is currently home to two polar bears, Little One and Berit. Little One is a 24-year-old male and, despite his name, is the taller of the two bears. Berit is a 16-year-old female. She has a longer and leader body and face and sharper features than Little One. Plus her ears tend to stick out a little more. Polar bears can reproduce until about 26 years old and Berit is at a prime age for reproduction. She and Little One have been together since 2007 and are observed breeding every year, yet Berit has never had cubs. We aren’t giving up yet.
In the meantime, Dr. Erin Curry has been working very hard in the CREW lab to develop a non-invasive pregnancy test for polar bears. It’s important for zoos to know when their polar bears are pregnant to be able to properly care for and monitor them. It is very difficult to determine if a female polar bear is pregnant because there is a period of time between mating and implantation of about 4 to 7 months, making it extremely difficult to know if breeding successfully resulted in a pregnant female. Polar bears also go through a period called pseudo-pregnancy, in which females show an increase in progesterone level similar to that of a pregnant female, but in the end there is no cub born. Pseudo-pregnancy also occurs in otters, wolverines, red pandas and some cat species. These factors make it extremely difficult to determine if a bear is pregnant. While there is not a definitive test yet, she has multiple projects underway that look promising.
Maybe the answer can be found in feces. Feces samples are very easy to collect without requiring invasive procedures. Samples from about 55 bears from 24 different institutions across North America and Canada are sent to Dr. Curry three times a year, packed in dry ice, to research any possible chemicals that may be present in pregnant bears but absent in others. She is also examining various protein levels in the feces and has identified five proteins that are higher in pregnant bears than in non-pregnant or male bears. More research is needed and it is a very expensive test. The goal would be to develop a cost-effective and user-friendly test.
You may have heard about Elvis, the polar bear poo-sniffing dog. Elvis has been pretty successful so far in distinguishing between feces from pregnant and non-pregnant bears. Dr. Curry continues to try to determine what exactly Elvis smells that alerts him to the pregnancy. Read more about Elvis’ story here.
Another way to determine if a bear is pregnant could be through an ultrasound, but conducting one on a polar bear has its challenges. Dr. Curry along with Megan-Kate Ferguson (Curator of Animal Development and Training) and the bear keepers have been working with Berit to desensitize her to being touched so she can undergo medical procedures, such as ultrasounds, without sedation. Desensitization is a process by which the animal is touched through a training wall with an instrument, such as an ultrasound probe, over a period of time as the animal becomes less reactive to it and it becomes like a routine practice. The animal is rewarded throughout the process, called operant conditioning, to associate positive rewards with being touched. As the animal becomes more used to being touched, more actions and commands are added to eventually complete the behavior necessary for the procedure. It is a multi-step process that takes time and patience to develop an animal’s level of trust and comfort. Megan-Kate explains this process further in previous blog posts here.
Now that Berit is conditioned to being touched through the training wall while standing with her abdomen pressed up against it, the next step is to perform exploratory ultrasounds to find her uterus. Even though we know Berit is not currently pregnant, the ability to even find the uterus at all is important if performing ultrasounds is to become a reliable way of detecting pregnancy. Despite a polar bear’s large size, the uterus is small and very difficult to find. Polar bears have two uterine horns, each of which (in a non-pregnant state) is roughly the size of a pencil.
First, Berit is called in to the training area and asked to stand up at the training wall. When she completes this, she is immediately rewarded with ground meat treats. Megan-Kate then hoses her lower abdomen down through the wall; performing an ultrasound is more successful on a wet bear because a more solid connection is made between the bear’s skin and the probe. There can’t be any air or space between the probe and the skin, which is difficult due to her thick, fur coat. Once Berit is sufficiently wet, Dr. Curry uses the probe to search for the uterus. A transducer on the probe emits sound waves into the body and picks up the echoes as they bounce back from organs. The ultrasound machine then translates the information into a two-dimensional image of the bear’s insides that Dr. Curry interprets. During this time, Berit receives treats and constant positive reinforcement as she stands very still and calm.
On this day, Berit cooperated like a champ and Dr. Curry was able to find the bowels, but not the uterus. Maybe next time! Even so, it was a successful day of continued training with Berit.
Solving the problems facing polar bear reproduction in zoos isn’t going to happen overnight, but it’s an ongoing challenge that Dr. Curry and the rest of the Zoo are committed to seeing through. Learn more here.
September 1, 2014 2 Comments