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Amphibian Medicine – Cold “Resurrects” Hellbender and Sick Frogs

HellbenderDuring my years with the Bronx Zoo, I have twice observed cold temperatures to revive salamanders (a Hellbender and a Greater Siren, please see photo) that seemed, by external appearances, to be quite dead.  A recent paper caused me to think back on these events, and to other examples of low temperatures being used to “treat” ailing Axolotls, Leopard Frogs and other amphibians …I would greatly appreciate your own observations and thoughts on this topic.

Cold Tolerant Amphibians

Many amphibians are well-adapted to surprisingly low temperatures.  On Long Island, NY, Eastern Tiger Salamanders may migrate to breeding ponds in February, and Spotted and Alpine Salamanders will cross snow for the same purpose.  Wood Frogs occur within the Arctic Circle, and I’ve found Gray Tree Frogs hibernating beneath a mere 2” of leaf litter in NYC.  Several Fire Salamanders under my care remained active at 38 F.

Early Experience with Cold Treatments

Back when I began keeping amphibians, little was known about treating their ailments.  As an eager 12-year-old “working” (largely without pay, other than an occasional slice of pizza!) for an animal importer in NYC, I was frustrated by the losses common in shipments of newts and frogs.

Calls to the Bronx Zoo and American Museum of Natural History were (uncharacteristically) not very productive.  I then contacted Wards and Carolina Biological, whose biological supply catalogs I had drooled over for years.  A kindly soul took the time to put me in touch with a lab that housed Leopard Frogs.  I learned that when bacterial diseases (“red leg”) struck, the frogs were refrigerated at 36-40 F for varying periods.  Chilled frogs often survived, while those kept a room temperature perished.  Neither my boss nor my mother appreciated the sickly amphibians stored in their refrigerators that followed this revelation, but both showed patience that I remain grateful for today!

Recent Experiences

The salamanders I mentioned as being “brought back to life” by the cold certainly did appear to be dead.  I believe the Hellbender went on to live for years after its “near-death experience”.

Other interesting experiences have involved Mexican Axolotls.  An individual in my collection became bloated and was unable to submerge.  A veterinarian who worked with me at the Bronx Zoo prescribed Itraconizole and other medications, but the infection proved resistant to all.  I refrigerated the animal at 40 F, whereupon the swelling abated.  I removed her for feeding once weekly, and left her out for 2 days following.  The swelling (gas from bacterial action) would recur after 2 days at room temperature.  A friend maintained an Axolotl under similar conditions for several months.

I also had some success while treating 100+ American Bullfrog tadpoles that had been stranded when their pond was drained.  Although most suffered severe abrasions, many recovered after being held at 40 F for several weeks.  They were initially treated with Methylene Blue as well; please see article below.

Conflicting Results: Cold Hinders Recovery

However, cool temperatures are not the answer to every amphibian health issue.  My veterinarian co-workers sometimes suggest keeping medicated animals at optimal temperatures for normal activity, the theory being that the immune system will function best under these conditions.  There may be a fine line, especially where cold-adapted species are concerned.  Perhaps certain micro-organisms do not cope well with low temperatures, and can be more easily killed by amphibian immune systems when the hosts are chilled.

In one study, mortalities increased when Australian Barred Frogs (Mixophys fasciolatus) suffering from Chytridiomycosis were chilled to 62 F.  And keeping American Bullfrogs at 38 F was found not to affect the survival of 4 species of harmful bacteria, but it did impede the frogs’ abilities to fight off infections.  Each species and health problem must be evaluated individually…please write in to discuss specific situations.

Observation: Snapping Turtle in February

smiling snapping turtleSlightly off-topic: just last week (February 17, 2012) I came across a large male Common Snapping Turtle who was out and about in a small woodland pool in northern New Jersey.  While this species is perhaps the most cold-tolerant of all turtles, I’ve not seen one active this early in the year.  As you can see from the photo, he tried to respond to the indignity of being photographed in true snapper fashion, but was too slow to scare my intrepid little hiking partner (please see photo).



Further Reading

Field Note: Alpine Salamanders active below snow

Video: frozen turtles

Methylene Blue as an Amphibian Medication

Temperature and Frog Declines

Fridging Amphibians

Discussion: Cold Treatment



  1. avatar

    I have a sick Newt Gingrich, but I’m gonna raise the room temperature

    • avatar

      Hello Robert,

      Thanks for the laugh! Nice to hear from you and glad to see you are, as always, doing such worthwhile work in NYC, placing thousands of reptiles, dogs, cats and just about every other type of abandoned creature in new homes. See you soon,

      Best regards, Frank Indiviglio.

  2. avatar


    During the late 70’s I worked after school at a pet shop on Bleecker and Morton Streets in the West village of Manhattan, called Exotic Aquatics. We once received a large shipment of Fire-bellied Toads that I was told arrived dead due to over-icing during transport. The boss said that they came in frozen solid, so she put them in the refrigerator in order to preserve and return them to the shipper the following week when he made his rounds.
    The next week, I was told to retrieve the bin of toads and discovered to everyone’s delight that they were not only alive, but were beaming after their weeklong winter vacation!

    Nearly 10 years ago, in mid-August, while arriving by my hotel lobby during the International Reptile Breeders Expo in Daytona Beach, Florida, I was forced to do some accidental herping.
    There is a tradition at these shows for all of the serious herpetophiles to congregate the night before the exhibit opens, in the main hotel lobby and bar area, which was located right on the beach. These affairs can go well into the night, and are often more edifying than the actual show, when the experts are often too busy hawking their wares to chat. Upon dropping my bag at the bar, I began to admire the delicate sculpted pale grey tree frogs that were mounted beneath the bar, approximately three feet from each other, but I wondered why they were placed there, since people sitting on the bar stools would surely hit them with their knees. Upon close investigation, I discovered that these three inch beauties were alive!
    I immediately removed all three adults and placed them into plastic deli containers that I brought with me for the show. Since there was nothing for them to eat at the bar, plus the fact that they can be considered an invasive species, my plan was to bring them back to New York, and give them to my good friend Frank Indiviglio at the Bronx Zoo, so that he could release them into a tropical rainforest exhibit there. The frogs would reside predator-free in a jungle paradise, for the rest of their lives.
    When I got back to my room, I put a ball of wet paper towel in the corner of each container, which already had a few air holes poked out, and kept them away from any sunlight. They remained in perfect condition for the entire weekend, and when I got them home, I called Frank and he said he would be happy to take them. When he came that day to pick them up, we discovered that my cat had opened one of the containers, and it was empty. We searched high and low for the third frog, but we never found it. Frank eventually left and released the remaining two frogs into Eden, yet it was a bitter sweet triumph.
    That was in August. Six months later, while I was sweeping the floor, I dislodged what looked like a flat, dirty piece of paper from under the front door threshold. I picked it up, and it was completely without weight and as dry as a cracker; the remains of my lost frog. In addition, since it was at the front door during a 20 degree January day, it was also frozen. I looked at this ice cold, skeletal, transparent piece of paper and decided to throw it into my turtle tank so at least the poor thing’s life would contribute a bit of calcium to another life form. It was so desiccated and odorless, that after a quick sniff, the turtles completely ignored it.
    A half hour later, when I entered the room where the turtles resided, I saw something that initially led me to believe that someone lost their pet frog, because clinging to the rim of the turtle’s aquarium was a Large Cuban Tree Frog! If I didn’t witness this exhibition of amphibian prowess, I would never have believed it, but the frog now resides with his friends at the Bronx Zoo. (I hope I didn’t get Frank in trouble for confessing to our unorthodox re-homing method!)

    • avatar

      Hello Robert,

      Thanks for reminding me of that…I remember the frogs well; they were Cuban Treefrogs. Considering their origins, it’s especially amazing that the escapee survived such cold weather. They adjusted very well to life in a huge green-house type area behind one of our croc exhibits at the Bx Zoo, along with a number of anoles of various species (which they likely consumed from time to time!). I’m confident that they are still fat and happy.

      Very interesting note on the Fire-bellies, thanks for that, and for reminding me of Exotic Aquatics.

      Keep up the great work at Social Tees Animal Rescue and see you soon,

      Best regards, Frank Indiviglio.

  3. avatar

    I have 2 recent experiences in treating Chinese fire belly newts with low temperatures. I received a shipment of newts. One arrived bloated and died the next day. Another was not feeding during the 1st week. After reading about low temperature treatment I placed the newt in a quarantine container. I placed a standard 16oz bottle of water, frozen solid in the tank twice a day. One in the morning and one in the evening. In 2 days the newt was accepting food readily and was placed into its designated enclosure shortly after.

    Several weeks later I purchased a single newt that had not been eating. I placed the newt in a quarantine container and decided to experiment with the treatment by adding ice cubes directly to the water from our ice machine. Just a few cubes to bring down the water temperature. I did this twice per day for a week of quarantine.

    Both newts are thriving today and eating at every feeding. I am considering making some form of low temperature treatment a standard procedure for new arrivals if I continue to learn of more experiences of success with this technique.

    • avatar

      Hi Mark,

      Thanks so much for the useful feedback. Great to hear, and very important. I’ll be sure to pass it on to others. If you decide to use on a regular basis, it might be safest to slowly lower temps. I’ve had luck with rapid cooling, for obviously sick animals, but no sense in adding undue stress if they look well (“Ick”, which is more commonly seen in fish, and other micro-organisms can infect amphibians under temperature-change stress).

      Good luck and enjoy, Frank

About Frank Indiviglio

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
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