Animal stress and training

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Stress usually involves situations of stimuli that we consider threatening, frustrating, or out of our control. The same can be said for animals. When most wild animals become threatened or frightened, they respond by "flight or fright." During the "flight or fright" response, a complex series of changes occurs in the body.

The brain's hypothalamus releases the hormone corticotrophin-releasing factor (CRF). CRF travels to the pituitary gland and triggers the release of adrenocorticotropic hormone (ACTH). This hormone travels in the blood to the adrenal glands and instructs them to release a third hormone, cortisol. The hormones rally the body systems and provide energy to enable dealing with a stressful situation. These changes appear as an increase in heart rate, increase in blood pressure, release of glucose from the liver, dilated bronchi, decrease in gut activity, and dilated pupils.

When a fight or flight response doesn't work, and the animal becomes very frustrated or distressed, it may adopt the conservation-withdrawal response. Changes from this response, in turn, has various side effects, such as suppression of inflammation, and changes in metabolism of carbohydrates, proteins and fats. An animal in conservation-withdrawal will appear quiet and depressed.

Long-term corticosteroid release suppresses the immune system, and allows for disease to occur more easily. For example, "Stress in livestock can lower productivity and possibly increase the risk of contamination from Salmonella and other bacterial pathogens," says Agricultural Research Service scientist Edward B. Knipling. Constant or long-term stress appears to be linked to hypertension (mainly due to permanent damage to the kidneys), arteriosclerosis, and other cardiovascular problems.

The animals in the zoo's collection may become threatened or frightened due to various situations-the most obvious would be loud noises, lightening, storms, etc. But they may also become stressed from normal veterinary routines, such as animal handling and blood collection. Physiological changes during these stressful situation may last at least 30 minutes or longer says American Association for Laboratory Animal Science. That is why training animals for basic husbandry and medical needs is so important.

The history of animal training has evolved tremendously over the past century. What once was considered revolutionary is now expected practice with a variety of animal species in captive situations. Via the use of 'operant conditioning' with an emphasis on positive reinforcement, animals have been trained to cooperate and/or accept a variety of previously potentially stressful circumstances.

Evidence of reduced stress in husbandry and medical procedures has been demonstrated many times. Denver Zoological Gardens measured blood parameters of bongo antelope (Tragelaphus eurycerus) after sedation via a dart or pole syringe. They also measured blood parameters on bongo conditioned with positive reinforcement for loading into a crate and a variety of other husbandry and veterinary procedures. Values for these blood parameters, commonly associated with stress, appeared to be lower in crate conditioned animals. By training an animal to cooperate in its own health care, life becomes less stressful for the animal and trainer. Some other examples of procedures trained with positive reinforcement include tigers sitting calmly for blood draws, lions allowing their teeth to be brushed, primates presenting their arms for tuberculosis testing, killer whales urinating on cue. Anesthetizing or restraining these animals for procedures seems impractical now.

Both the keepers and behavioral management staff at the Phoenix Zoo have made great strides in training for medical procedures. Training with positive reinforcement has allowed animals to learn to voluntarily participate in husbandry and medical behaviors and potentially avoid the stress associated with capture and restraint.

The Phoenix Zoo is located at 455 N. Galvin Parkway, Phoenix. Rain or shine, the zoo is open every day except Christmas Day (Dec. 25). Regular-season hours (Sept. 1-May 31) are 9 a.m.-5 p.m. Summer hours (June 1-Aug. 31) are 7 a.m.-1 p.m. during the week and 7 a.m.-4 p.m. on the weekends Admission is $14 for adults, $6 for children and $9 for seniors. For more information, call 602-273-1341 or visit .