Dr. Pamela Reid, ASPCA
Stress in the Shelter
By Dr. Pamela Reid, ASPCA
Merlin, a beautiful brown and blue mottled Australian Cattle Dog mix, peered out at me from his hospital cage. He’d come into the clinic two days before for routine neutering; however, the owner failed to return for him and, as it turned out, left illegitimate contact information. The Animal Placement department wanted to know if Merlin would be suitable for adoption. He had recovered from his surgery so I brought him to the training room to undergo our standardized behavioural assessment. He skulked along at the end of the leash, trembling in fear and unresponsive to my attempts at reassurance. During the evaluation, he did his best to avoid me by cowering under the chairs. If I approached too close or tried to reach for him, he lunged out at me, with teeth bared, then made a hasty retreat back to his “cave.” Needless to say, I couldn’t put Merlin in the adoption room if he was going to behave like this. I decided to wait a couple more days and then re-evaluate him.
I was hoping that Merlin was behaving atypically as a result of being unduly stressed. Stress is a biological response that occurs when an animal or person perceives a threat to their well-being and Merlin was acting very much like a distressed dog. Dogs in a shelter are exposed to a variety of stressful events: the place is novel and often extremely noisy; the feeding and walking routine is likely to be quite different from what the dog is accustomed; the dog has no control over what happens to him; and moreover, the dog is probably experiencing distress over being separated from those with whom he was attached. These types of events are known to activate stress-related physiological systems in laboratory animals.
A group of researchers in Ohio, headed by David Tubor and Michael Hennessy, determined that dogs coming into a shelter normally experience high levels of stress for the first three days. Stress can be manifested in both behavioural and physiological changes. One fairly reliable indicator is the increased secretion of the adrenal glucocorticosteroid, cortisol. The Ohio researchers measured cortisol levels in shelter dogs shortly after their arrival and for several days thereafter. The levels gradually declined until stabilizing on Day 4 or 5. They also discovered that cortisol levels in the newly arrived shelter dogs were almost three times higher than those of pet dogs sampled in their homes. I wanted to give Merlin the chance to “de-stress” before checking him out again.
What exactly does “being stressed” mean?
Stress is a necessary part of life and not all stress is bad. Humans sometimes seek out stress, for the exhilarating thrills. Judging how long squirrels wait before fleeing from my dogs, I expect that animals may well do the same! However, stress can be harmful. It is believed that organisms exposed to stress go through three stages. The first stage is alarm, during which the body readies itself for action by activating the hypothalamic-pituitary-adrenocortical system and producing glucocorticoids, such as cortisol and corticosterone. If the stressful event continues, the second stage is adaptation, during which the animal takes action to resist or escape from the stressor. If the animal is unable to return to a comfortable state, it enters the third stage of exhaustion, during which a variety of pathologies can develop, including susceptibility to disease, inability to reproduce, and compromised psychological welfare.
It is impossible to measure stress levels through behavioural indices because animals vary in their behavioural responses to stress. Years ago, I witnessed an interesting illustration of this individualized responsiveness. I was competing in the Utility obedience ring with my Saluki, Shaahiin. Shaahiin appeared to understand and even enjoy the scent discrimination exercise during training but his reaction to the same task in the ring, in front of a judge and an audience, was quite shocking to me. He became almost “zombie-like,” moving very slowly, as though in a daze. I recall that he walked right through the pile of scented articles, mindlessly picking up one without sniffing at all. My friend, who was competing with her Border Collie at the same time, had quite a dissimilar experience. She also characterized her dog as “stressed” but, unlike my slow-motion dog, her dog was zipping round the ring like a whirling dervish. He was moving so quickly he blasted right through all the articles, sending them scattering! Two dogs with very different temperaments manifested two extremely different responses to a stressful event. Veterinarians are familiar with such variation. Some dogs on the examination table lash out to fend off the perceived threat, others become rigid in terror, while still others try to leave or simply go belly up and urinate. Responsiveness to stress is influenced by a host of factors, including temperament traits, such as timidity and emotionality, and early experience. In particular, exposing a young animal to mild stressors appears to equip the animal with strategies for coping with stress in later life.
So how did Merlin do on re-test?
Sure enough, two days later, Merlin was transformed into a friendly and playful pup. He showed none of the fearful and aggressive behaviour of before. We discovered he was particularly fond of children. A few days later an African American family with two young boys came in looking for a great pet and it was love at first sight. Merlin joined a busy household with two cats and another dog. He never looked back! Now, lest I mislead you, Merlin still showed that undesirable fear and aggression toward strangers when he was stressed. A minor injury a few months later required a stay at the veterinary clinic and Merlin reverted back to that frightened dog, fending off the caring medical staff. Fortunately, his family was able to help him through his treatment and recovery and he continues to build confidence and trust in people.
While Merlin’s story is a happy one, it illustrates a significant problem for those of us working in shelters. No-kill shelters have to be very selective about the dogs they take into their care, so they are not faced with the dilemma of placing a potentially dangerous dog into the community. Often, though, decisions have to be made on the spot. They don’t have the luxury of waiting for the dog to adjust to the shelter first. How common is it for dogs like Merlin to be passed over, because they are under severe stress at the time of their behavioural assessment? It’s impossible to know. Stress can impact dogs in many ways but, clearly, reacting aggressively while severely stressed does not mean the dog will behave aggressively under normal conditions. Unfortunately, at this time, we do not know how to compensate for the possibility of stress-induced undesirable behaviour.
Can stress in shelter dogs be reduced?
Those innovative researchers in Ohio were motivated to find ways to minimize the aversive impact of the shelter environment. One of the interventions they tried was to establish a simulated “living room” in the shelter. Each dog was brought into this room daily to escape the chaos and noise of the shelter and to receive one-on-one attention from a person. At the same time, the dog was provided with manners training, emphasizing the sit response for all attention, in a home-like environment. They compared the behaviour of dogs that received this training with dogs that spent time in the “living room” without the sit training. The trained dogs were more likely to approach familiar people and were more likely to interact quietly with a person than the untrained dogs. The untrained dogs were more likely to spend their time playing with toys.
Shelter dogs at the Ohio shelter that participated in a blood donor program invariably experienced an increase in cortisol levels following the venipuncture procedure. If the dog received 20 minutes of stroking from an unfamiliar person following the procedure, rather than being returned directly to his cage, cortisol levels remained close to what they were before venipuncture. This short period of interaction with a person virtually eradicated the stress response.
Dogs adopted from shelters are exceptionally prone to developing separation anxiety. Many assume that separation anxiety was the reason why the dog was in the shelter in the first place. However, there is another explanation. We know that psychologically traumatic events cause long-term changes in the activity of certain neurochemicals, such as norepinephrine, making people more susceptible to developing anxiety disorders in the future. One hypothesis is that the trauma associated with being separated from the people with whom the dog is attached sensitizes his neurochemical systems, so that following adoption even short separations from the new owner evoke an extreme response from the dog. At the Ohio shelter, some dogs were trained to accept being in an airline crate or wire pen during their living room time. These dogs were eventually adopted to owners who were encouraged to crate their dogs when left alone. The crate-trained dogs were significantly less likely to be returned for developing separation anxiety than were untrained dogs.
Finally, it is well established that providing opportunities for zoo animals to perform species-typical behaviour patterns can reduce stress. Enriching captivity by increasing the complexity of the environment provides such benefits as reducing aggression, increasing activity, improving reproduction, and enhancing health and survival. Adding vegetation, barriers, climbing structures, and other forms of landscaping enriches enclosures. Offering mental challenges, such as television viewing, puzzle devices, and training allows animals to exercise their cognitive abilities. Presenting daily food rations more naturally, such as offering lions complete carcasses or presenting polar bears with fish frozen inside lumps of ice, stimulate normal foraging activities. More and more shelters are establishing enrichment programs, presumably with similar results, although the benefits of enrichment have yet to be documented in shelter animals.
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