About Author: Rachel Foster

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Tortoise: ‘Tis the Season for Hibernation

Research associate Daniel checks tortoise hatchling pens.

As we begin the new year at the San Diego Zoo Desert Tortoise Conservation Center (DTCC), almost all the tortoises have gone down into their burrows for their winter brumation (reptilian hibernation). During the winter months, we shift our responsibilities from feeding and processing tortoises (giving health assessments to those brought in to the DTCC) to doing surveillance in our assigned areas. We walk each section of pens looking for sick or injured tortoises and for damage that needs to be repaired in the pens.

Daniel checks tortoise pens to make sure the animals are in their burrows.

At this time of year, with consistently cool weather, all the tortoises should be pretty well entrenched in their burrows. After we are comfortable that the tortoises are down for the winter, we create a wall of earth in the opening of each burrow to provide an extra layer of protection against the elements. At this point, any tortoise found outside of their burrow is cause for concern. When we find tortoises out in cool weather, we bring them in for a complete health assessment.

All sick or injured tortoises are kept in the medical center for treatment, and the tortoises that appear healthy are put back in their pen and checked more frequently to monitor any change in their condition. Typically, tortoises that are awake and out of a burrow during the cold winter months usually have a health issue causing them to come out of brumation. Doing pen surveillance is the only way we can monitor the condition of the tortoises during the winter. Since it is not healthy to disturb the tortoises in their burrows, we have to closely monitor the behavior and condition of the tortoises that are active outside their burrows.

Rachel Foster is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Saving Tortoises, One Urolith at a Time.


Saving Tortoises, One Urolith at a Time

An x ray shows an adult desert tortoise with a large urolith on the left.

The tortoises have begun their fall slow-down and are preparing for their winter brumation (reptilian hibernation) here at the San Diego Zoo Desert Tortoise Conservation Center in Las Vegas. This means that the priorities in the medical center will shift a bit. We will have a few tortoises staying awake for the winter because they are either too sick or injured to brumate. However, we will also have a number of residents staying in the medical center waiting to have surgery at the state-of-the-art Harter Veterinary Medical Center, located at the San Diego Zoo Safari Park. All of these tortoises have dangerous uroliths that have developed in their bladder (uroliths are analogous to kidney and bladder stones in people).

A large stone removed from an adult tortoise carcass

Uroliths develop for various reasons, the most common being improper nutrition or prolonged dehydration. One of the adaptations that tortoises have that allows them to thrive in the arid desert environment is the ability to store large amounts of water in their bladder and to reabsorb it as the body needs it. As they reabsorb the water in their bladder, the solid particles in the bladder become more concentrated and can stick together. As time goes on more solids are deposited in the bladder and combine with those already present, forming a stone. Therefore, stones are more likely to form if a tortoise goes long periods of time without consuming fresh water to flush and replace the stored water.

Small stones that form can pass out of the bladder when the animal eliminates. However, once the stone becomes a certain size, it can be too big to pass and remains in the bladder where it can continue to get larger. If the stone is there long enough, it can adhere to the walls of the bladder, making it very difficult to surgically remove it without damaging the bladder. Eventually the stone can get large enough to take up most of the bladder space, thereby taking up very important water storage space. This compounds the problem by increasing dehydration in the tortoise. Eventually the stone can block the urethra, preventing the tortoise from eliminating at all and causing a build up of toxins in the tortoise. The long-term presence of uroliths can result in a prolonged, painful death.

A desert tortoise recovers from surgery to remove a stone.

We palpate every tortoise during its health assessment to see if we can feel a coelomic mass. Sand or gravel in the bowels or eggs can feel similar to uroliths during palpation, so we x-ray every tortoise in which we feel a mass to determine what the mass is. Once we have x-ray confirmation that it’s a urolith, we send the tortoise to the hospital, where veterinarian Nadine Lamberski has developed a less invasive technique to remove the stone. Traditionally, the most common stone removal technique used by veterinarians was to remove part of the plastron (the bottom part of the shell) to get to the stone. This procedure is very invasive and can take a very long time to heal since the bone of the plastron has to be removed. The veterinarians at the Safari Park use a technique in which they make an incision in the skin of the prefemoral area (just in front of the hindlimb) so they can access the stone and break it down and remove it without having to remove part of the shell. This surgery can take up to 6 hours to perform, but the recovery time for the tortoise is much quicker for this procedure. I am very excited to say that the veterinarians have performed a number of these surgeries successfully, and our tortoises have been able to return to us with a much better future in store for them.

We have a number of tortoises ready for surgery this winter. Once they recover, they will be able to be released to the wild Mojave Desert in the healthiest condition possible next year to live out their long lives in a natural environment.

Rachel Foster is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Desert Tortoise Hibernation: Not for All.


Desert Tortoise Hibernation: Not for All

An ill desert tortoise enjoys the heat lamp this winter.

As our second season ends here at the San Diego Zoo’s Desert Tortoise Conservation Center in Las Vegas, the tortoises have gone deep into their burrows for brumation (winter hibernation). For the most part, this means we get to take a bit of a breather as well. However, there are a few tortoises that are not brumating this year due to health issues that we hope can be resolved over the winter months. These special tortoises are staying with me in the medical center until the spring. Although in most cases it is better (and necessary) for any species that would normally hibernate to do so, there are some instances in which it may be better for individuals with certain types of medical conditions to stay awake through the winter.

We have a few tortoises undergoing treatment for severe upper respiratory symptoms (cloudy nasal and ocular discharge and labored breathing). Although the treatment takes about two weeks, by the time their treatment ends, it is too cold for them to safely go out into a pen. Instead, they are staying in the medical center where their immune systems will have time to recover from their illnesses so that by spring, they will be strong and healthy again.

We also have a few very emaciated tortoises that we felt were too skinny to survive hibernation this year. Our goal is to fatten them up over the winter! With daily feedings, we hope to get their weight stabilized enough so that they will be ready to go back out in the spring.

The last few tortoises we have in the medical center are waiting to go to the Paul Harter Veterinary Medical Center at the San Diego Zoo Safari Park to have urolith (bladder stone) surgery. We get a number of tortoises each year that have uroliths that are too large for them to pass. This can result in a very long and painful death if they are not removed surgically. Our amazing veterinarian, Nadine Lamberski, has developed surgical techniques to safely remove these stones.

Since Dr. Lamberski has to work these unexpected surgeries into her normally very busy schedule, these tortoises are hanging out with me in the medical center until they can be transferred to the Safari Park. Don’t worry, though, that we are not acting fast enough to remove these uroliths; although tortoises can eventually die from them, they can actually live for years with them, which is one of the reasons that most pet owners don’t realize their tortoise even has one!  As they wait for their surgeries, they are happily munching away on hay and tortoise chow and spend most of their time comfortably basking under their combination heat and UVB lamps. The first two of these urolith tortoises will be headed to the hospital next week!

Rachel Foster is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Tortoises Need Heat and Light.


Tortoises Need Heat and Light

This healthy desert tortoise enjoys the warm sun.

We are reaching the mid-point of our second season here at the San Diego Zoo Desert Tortoise Conservation Center in Las Vegas, and we are seeing an increase in the number of calls to the Pet Tortoise Hotline! However, a large number of these pet tortoises arrive with a number of different health issues, most resulting from improper housing and diet. These can lead to a number of different conditions ranging from upper respiratory conditions to metabolic bone disease.

Since the entire shell of a tortoise is made up of bone and keratin, it is very important to feed them foods high in calcium to maintain the shell’s rigidity. As tortoises bask in the sun, they are not only soaking up the UV rays needed for calcium metabolism, but they are also warming themselves so that they can properly digest their food. Without the heat, even if they are eating, they are not digesting or getting the nutrients they need.

Rachel examines a tortoise at the Center.

In one case we saw this year, three tortoises were surrendered to the hotline. They had been living in an aquarium without any heat or light and were fed lettuce for several years before finally being surrendered. By the time they came to us, their condition was so severe that they were only barely alive. Their shells were flat and so soft that they bent inward with the most gentle touch. In addition, their beaks didn’t develop properly, they had severe edema all over their bodies, and they were very ill. These conditions are the direct result of nothing more than the tortoises being housed indoors and not being fed properly.

In another case, a tortoise came to us severely emaciated with old dog bite wounds all over her carapace (see a post about this problem: Family Dog Loves Pet Tortoise Too Much?). Because the family dog kept trying to use her as a chew toy, she was kept in a closet without heat or light where she was fed lettuce and fruit (not ideal for tortoises). Today, that tortoise is emaciated because, even though she was given food, she was unable to digest it without heat and light. She is just one of a number of tortoises we are rehabilitating so that some day they will be healthy enough to be released to the wild where they will contribute to the recovery of wild populations.

Rachel Foster is a research associate at the San Diego Zoo Desert Tortoise Conservation Center.


Family Dog Loves Pet Tortoise Too Much?

An adult tortoise with its right forelimb chewed off by a dog.

An adult tortoise with its right forelimb chewed off by a dog.

Greetings to my fellow tortoise lovers!

As I go about my daily duties caring for the tortoises in the medical pavilion at the San Diego Zoo’s Desert Tortoise Conservation Center (DTCC), I am constantly reminded about how fragile these seemingly tough little critters can be. Thousands of years of evolution have made these guys the highly adapted desert burrowers that they are today, but there are just some things that their strong shells and tough skin cannot protect them from.

Since my arrival here at the DTCC in April 2009, I have cared for a number of tortoises that have been injured by dogs. A few of them were wild tortoises that were caught by pet dogs that were out roaming the desert unsupervised by their owners, and some were predated by wild coyotes and kit foxes. However, a number of the cases I’ve worked with have been pet tortoises that were housed in areas that were easily accessed by, or even shared with, the family dog.

As a tortoise lover and a dog lover, I have to say that this is not a good thing. Dogs love to chew, and when they get bored, they are very likely to chew on anything they can get their mouths on. Since tortoises are pretty slow moving animals, they make easy targets, and chewing on them can be a fun, interactive game for a dog while the tortoise tries to push and wiggle its way out of the dog’s grip. No matter how old, docile, well trained, or well mannered your dog is, there is always the risk of it one day deciding that your tortoise would make a nice chew toy.

We had to humanely euthanize this poor tortoise.

A juvenile tortoise, chewed on by a dog, was euthanized because of the severity of the wounds (really deep punctures).

At the DTCC, we have received tortoises with injuries ranging from minor shell punctures and abrasions to severe shell damage and missing limbs. A few cases had to be humanely euthanized due to the severity of their injuries. In every case in which I have spoken to the injured tortoise’s owner, they all say the same thing: “Our dog is so gentle and friendly, we never thought it would hurt the tortoise,” and “My dog and tortoise have lived together for so long, I don’t know what made him decide to chew on the tortoise now.”

Of all the issues we deal with on a day-to-day basis concerning the health and well being of the tortoises, I think that these cases involving family pets are among the saddest, because the situation is so easily preventable. If you are a tortoise owner that also has dogs, please recognize the potential danger that your dog poses to your tortoise and take the necessary steps to protect him/her. Also, if you live in southern Nevada, please remember that you are always welcome to surrender your tortoise to us at the Desert Tortoise Conservation Center no matter what condition the tortoise is in, and you can be assured that we will provide him/her with the best possible care.

Rachel Foster is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read her previous post, More Tortoise Hatchlings.


More Tortoise Hatchlings

dtcc_4hatchlingsGreetings to my fellow tortoise lovers!

We’ve finally finished up with our busy season here at the San Diego Zoo’s Desert Tortoise Conservation Center (DTCC) in Las Vegas, and the tortoises have gone into hibernation for the winter. Now that we have time to reflect on everything we did last season, I want to share with you one of our success stories.

We are very excited about the productive hatchling season we had this year. Many of the babies are now living in our new predator-proof hatchling enclosures. As part of our herd management plan to ensure that diseases do not get transmitted among our animals, we disinfect and sterilize the quarantine pens and then install a new artificial burrow whenever a current tortoise moves out and a new tortoise moves in. This requires a lot of digging. One day, while out preparing a burrow for a newly arrived tortoise, Daniel Essary (a research associate at the DTCC) accidentally hit a nest of eggs deep in the soil at the far end of the burrow. As careful as we are while digging new burrows, it is impossible for us to know if a previous female resident left eggs behind, especially when they are left in an unexpected location like the back of a burrow.

dtcc_hatchlings_in_eggsDaniel immediately stopped shoveling and started carefully scooping the dirt away with his hands to reveal five damaged eggs. The outer, hard part of each shell was badly cracked and missing in some places, but the inner lining was still intact. He gently scooped them up and brought them to me to see if anything could be done for the unhatched babies. The first egg he found was damaged beyond saving, but I thought maybe the others would have a chance if they were protected in the incubator. We put them in an uncovered plastic container with some soil from the burrow and placed a damp cloth over the eggs to keep them from drying out. We didn’t know if this would work since the eggs were pretty badly damaged, and we didn’t know how developed the embryos might be.

While there wasn’t anything we could do to save the first egg, we were very excited when the other four eggs all hatched naturally after a couple of days in the incubator. Three of them hatched with no problem, but the fourth had a damaged yolk sac. Since the yolk sac provides nutrients to a newly hatched tortoise and it is somewhat vascular (it has blood vessels in it), we didn’t know if this would adversely affect the hatchling’s survival. However, we didn’t give up on the baby. We soaked all four hatchlings several times a day in order to keep them hydrated and to help remove the inner egg membrane that had dried to their shell. We kept their handling time to a minimum to avoid stress and to prevent further damage to what was left of the yolk sac of the last hatchling.

Rachel wrapped this little one with gauze to make sure that no further damage would be caused to the broken yolk sac.

Rachel wrapped this little one with gauze to make sure that no further damage would be caused to the broken yolk sac.

Happily, after spending a few weeks in the medical pavilion, all four hatchlings made it through. The one with the damaged yolk sac developed a bit slower, and we were unsure at first if he would make it, but he survived and quickly caught up to his clutchmates. It was a very exciting day when they were finally ready to go into their own outdoor hatchling enclosure, and they took to their new home as if they had lived there forever.

You may wonder why we would allow new hatchlings to hibernate since they seem so fragile, but we have found that if you allow hatchlings to hibernate for their first winter after hatching, they become stronger and healthier adults than those that are not allowed to hibernate. I will be sure to give you an update of their condition when they wake up in the spring!

Rachel Foster is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read a previous post about the DTCC, We Love Volunteers.


Desert Tortoises: Lucy and Ethel

Greetings to my fellow tortoise lovers.

Last week we updated you on some of the challenges we face at the Desert Tortoise Conservation Center (DTCC) in Las Vegas with regard to the condition many of the tortoises are in when they arrive here (see post, Desert Tortoises: A Sad Week). Whether out of ignorance or just sheer neglect on the part of their previous guardians, many of these tortoises arrive with a wide variety of conditions that range from metabolic bone disease and upper respiratory tract infection to severe body deformities and traumatic injuries, which are most commonly caused by dog bites or being hit by a vehicle. Despite these daily challenges, great things happen here as well, so this week I’d like to share with you one of our success stories.

Lucy and Ethel arrived at the DTCC on my second day at work, and I immediately fell in love. Okay, so I fall in love with all of my patients, but these two girls really hold a special place in my heart. When they arrived, we immediately noted their flattened carapaces (top shell), called pancaking, and they had quite a bit of pyramiding (raising) of their scutes (indivudal pieces of the shell). A normal healthy desert tortoise should have a nicely rounded carapace, and the scutes should all lay flat along the surface. In addition to the severe shell deformities, their skin was very yellow and flaking off, and their eyes were swollen so severely that they could barely open them. They were also so weak that they could not support their own weight enough to move about their enclosure. All of these signs indicate to us that these tortoises were definitely kept indoors for the majority of their lives so they didn’t get the proper heat and light and were not fed a well-balanced diet. It is quite miraculous that they have lived as long as they have and that their organs have not completely shut down.

So at this point you must be asking yourself, When will she get to the good part? Well, here it is: after weeks of providing them with the proper food, allowing them to bask outside daily in the sun’s natural rays and soaking them every other day in a tub of water to help them establish and maintain hydration, they look like new girls, so much so that our DTCC manager, Paula Kahn, refers to them as the Lovely Ladies! In these past few months they have gone from being marginally alive to interactive, beautiful eating machines, and even their skin and shell color is approaching normal. Of course, they will always be very recognizable because no amount of good food, light, and heat will fix the carapace deformities they have, but their skin looks 100 percent better, and we can finally see their beautiful eyes!

In addition to their physical improvements, they have also greatly improved in behavior. Like most sisters, they fight over the best spots in their enclosure, and, of course, they squabble over their food. They have changed from two very sick and depressed little girls that I worried wouldn’t make it to two very energetic and healthy (though a bit deformed) big girls (they’ve also gained quite a bit of weight). Due to the severe deformities of their carapaces, they cannot be released back to the wild but rather will be used as education animals to show students and visitors the proper way to care for a tortoise…a valuable lesson for all.

Rachel Foster is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center.