PAWS Magazine


Issue 46, Summer 2000


Beaver Psychology 101

By Dr. Darlene DeGhetto

Imagine yourself in a new place, amongst strange beings, noises and smells. You have been injured quite badly and you are in pain and afraid. Gradually you begin to feel better, your wounds are healing, you are given good food to eat and the strange beings have not been too unpleasant. How would you act during your internment? Would you continue to exhibit normal fearful behavior when approached by humans (ie. strange beings)? Would you recognize the cement swimming pool as a safe haven? Would you be “depressed” due to lack of interaction with your family group? These are just a few of the challenging questions the Wildlife Center staff must consider regarding the rehabilitation of Beaver 00-0265.

This juvenile, male beaver was admitted to the Wildlife Center on March 27, 2000. He had apparently been run over by a motorboat and sustained several deep lacerations to his back, sides and tail base. The wounds were necrotic, infected and full of maggots, indicating that the incident had occurred several days ago. Radiographs taken at a later date, when the beaver’s condition was more stable, revealed fractures of the right fibula and one caudal vertebra.

One of the more unpleasant tasks required of veterinarians and wildlife rehabbers is removing live, wriggling maggots from infected wounds. Ridding the beaver of these offensive parasites challenged the stomachs of even the most stalwart staff members. Once the maggots were gone, wound treatment consisted of surgical debridement (cleaning), placement of rubber drains to prevent abscess formation, and suturing the wounds closed. Antibiotics and cimetidine (an anti-ulcer drug) were then given for several weeks. Beavers are particularly susceptible to GI ulcers due to stress, and all beavers brought to the Wildlife Center are given cimetidine for the duration of their stay with us. Another unique medical consideration is the sensitivity of the beaver digestive tract to most antibiotics. Like other rodents, when given inappropriate antibiotics, beavers can develop an acute, fatal diarrhea due to disruption of their normal GI bacteria. In addition, a beaver’s cecum also harbors a unique microorganism which digests cellulose, enabling the beaver to thrive on a wood-based diet. If the population of these microorganisms are killed by antibiotics, they would need to be replaced by transfaunation, a euphemism for feeding feces from a healthy beaver to a sick one.

Fortunately, our beaver didn’t encounter any serious GI problems due to the antibiotics he was given. He did, however, develop several large, deep abscesses at the wound sites. Daily wound cleaning and flushing for over 2 weeks was necessary before the infection was gone and the wounds finally began to heal. The fractures appeared to be heal well without any treatment other than cage rest. Time and Mother Nature took care of those injuries.

During the several weeks of wound management, the beaver had not been given access to a swimming pool. His enclosure contained several shallow pools for drinking and defecating. (A strange but true fact: beavers need to defecate in water. If water is not provided for this purpose the beaver will become constipated. I don’t know the physiology behind this mechanism, but if anyone reading this has an explanation, please let me know.) Imagine our surprise and chagrin when, wounds healed, the beaver refused to go into the large swimming pool provided for him. Did he recognize the cement pool as a place to swim? Other beavers at the center have used it readily. Was the water too cold? He was still missing quite a bit of fur on his back. He was given a warm water pool and appeared to tolerate it better but still was not as enthusiastic as expected. Was he still in pain? Possibly, but there was no adequate way of assessing mild pain in this animal. His coordination and strength didn’t appear up to par. Was that also due to ongoing pain? We decided to wait until most of his fur grew back and then reassess the beaver’s willingness and prowess in the cold water pool. Time and patience paid off when the beaver was finally seen swimming vigorously and diving in his pool.

We must now try to assess his fear of humans, for without that, he would not be able to survive as a normal, wild animal. Because he was handled quite frequently during the period of wound management, it is likely that he has lost some of his natural fear of people. Different caging and aversion techniques can be effective tools in providing stimulation and restoring wild behavior, respectively, to mildly habituated animals. These are the next steps that will be taken to move the beaver closer to release status.

I recently watched the old version of the movie, Dr. Doolittle, with my children and, quite frankly, I wasn’t nearly as enchanted with the film as I had been as a child.

I just kept thinking to myself, “I wish it was that simple.”

This case is a good example of how important it is to know the normal behavior of the animal being rehabilitated, and also how behavior is affected by the stress of captivity and handling, injury/disease, and lack of natural habitat.

Dr Darlene DeGhetto is one of two wildlife veterinarians who care for wildlife at our two centers.

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