Operant Conditioning of Diabetic Primates to Accept Insulin Injections
American Association of Zoo Veterinarians Conference 1998
Cynthia E. Stringfield, DVM; Jennifer K. McNary
Los Angeles Zoo, Los Angeles, CA, USA


Diabetes can affect a wide variety of primates.1 At the Los Angeles Zoo, we currently have two cases of diabetic primates that have been or are in the process of being trained, using operant conditioning methods, to accept insulin injections without any type of manual restraint.

Case Reports

“David,” a red-tailed moustached guenon (Cercopithecus cephus cephus), was found to be diabetic in May of 1997 after a routine preventive medicine exam. This animal was wild caught and estimated to be 24 years of age. The animal lived with two other animals, and when its diet was evaluated, it was determined that this guenon was eating primarily the grapes and bananas. The diet was altered; however, the keeper had difficulty getting the animal to eat other items in the exhibit environment. After three months of no improvement on an oral hypoglycemic agent, the guenon was brought to the health center to live in a large squeeze cage and undergo intensive training. According to its keepers, the guenon was very aggressive to people and other animals and “didn’t like anybody.” This monkey was high-strung, suspicious, cautious, and reacted quickly and instinctually. Operant conditioning was started, and the animal worked with one person for two sessions a day. A clicker and colored target were used with food rewards being given for the proper response. Diet was drastically altered to increase fiber and eliminate sugar and was accepted readily. This diet was used during training, then the remainder given after the training session. This initial training allowed the animal to become comfortable with the trainer and learn what was expected and how to successfully respond. Within two months it was expert at stationing and putting its arm through the bars to touch the target. The animal never became comfortable having its arm held or manipulated and would retreat when its arm was handled. However, when it would approach in a less formal manner, it became apparent that the animal liked to present by laying down with its back facing its trainer in a submissive manner. The animal would allow its back and other parts of its body to be scratched. Training was then altered to have the animal present in this manner. The animal was moved to a double dog run-type chain-link outdoor enclosure. Training rapidly progressed within another two months, from scratching its back, to pinching the skin, to poking with a needle, to administering a small amount of cold saline SC, to administering insulin. The animal is currently in the process of being regulated and since the animal does not allow blood collection, it is monitored via urine analysis for glucose. The next step will be to return the animal to the exhibit and work with it in the back holding area there.

“Tule,” an 18-year-old DeBrazza guenon, was being treated with prednisone for inflammatory bowel disease. Glucose and ketones were present in the animal’s urine; it was taken off the prednisone and then re-evaluated in November of 1997. The animal was severely compromised and diagnosed as a diabetic that needed immediate insulin therapy. (The animal was later diagnosed with Cushing’s disease as well.) The guenon was brought to the health center, housed in a large squeeze cage and given twice-daily insulin injections in the tail or rump by veterinary personnel with the use of the squeeze. Training was instituted in a similar manner as outlined above with the red-tailed moustached guenon; however, the initial goal was solely to get the animal to relax and provide it a positive experience with a person. The training was done at a separate time and by a different person so as not to associate the negative experience of being squeezed and getting injections with training. Initially, this animal was very ill and stressed but as it began to relax and its health improved, the training progressed to involve more touching and handling. The next step was to incorporate the injections. Progress was made very rapidly at this point; to date the animal allows injections with minimal squeezing and much less stress. This was an especially challenging case due to the animal’s medical condition necessitating treatment with restraint while simultaneously undergoing training.


These cases demonstrate that diabetic primates can be managed successfully and without stress with injectable insulin therapy long-term. The training required differs depending on the species and temperament of the animal. The animal gives the trainer cues as to what is the most comfortable and least threatening way to give the injections, and the manner of treatment and monitoring can then be tailor fit for the animal and its living environment.


The author would like to thank and commend the animal care and veterinary staff involved for their intense efforts, patience and perseverance that resulted in such positive outcomes for these animals.

Literature Cited

1.  Howard, Jr., C.F., M. Yasuda. 1990. Diabetes mellitus in nonhuman primates: recent research advances and current husbandry practices. J. Med. Primatol. 19:609–625.


Speaker Information
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Cynthia E. Stringfield, DVM
Los Angeles Zoo
Los Angeles, CA, USA

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