When an animal is stressed, a biological action called, "the startle reflex" takes over. The breath stops, the body tightens and the eyes and ears scan for danger. If danger is close by, the animal reacts in one of four ways: Fight, Flight, Freeze or Faint. When the danger is past, the animal relaxes back into its natural state.
When a being is stressed these are the responses that prepare the body for its response :
The heart rate increases and more blood is pumped to the muscles, supplying more oxygen;the sugar percentage in the blood increases to allow rapid energy use, The metabolism accelerates for emergency actions; the blood thickens- to increase oxygen supply, enabling better defence against infections and to stop bleeding quickly. The senses sharpen, the pupils dilate allowing better vision and hearing gets better. The blood supply to digestive system and irrelevant brain regions (such as speech areas) decreases and body wastes like sweat and urine increase to leave the body lighter. Adrenaline is secreted to alert the body.Endorphins - natural painkillers- are secreted providing an defence against pain.
The problem comes when stress continues for long periods of time without the animal getting any relief. Then the chemicals in the body that have been activated to defend it start having negative effects.
In both humans and animals, stress causes the body to release adrenaline and cortisol hormones. These hormones gets into the blood and relay the news of stress triggering the "fight or flight" response. But when secreted over a long period ,these chemicals cause the heart rate and respiration to speed up, and suppress the immune system. Corticorsteriods also stimulate acidity in the stomach, causing peptic ulcers. They disrupt normal metabolism, growth, reproduction and this increases the risk for cardiovascular disease. In some cases stress leads to a decrease in heart rate, sometimes to the point of stopping completely, pooling or sludging of blood in the vessels, and loss of appetite. The animal dies "for no apparent reason." Manhandling by other species, strange sights, noises and smells, unfamiliar foods or lack of food and water, restraint, injuries, extreme temperatures and long duration of travel are some of the stressors.
Managers of an African national park trapped a giraffe using a lasso. The animal was caged and lifted up on a truck to be sent to a Zoo. As the engine started, the giraffe dropped dead. Diagnosis: death caused by stress. Even patrolling by helicopter of the giraffe herds was found harmful as the noise of the engine over their heads induced gastric ulcers. Similarly, a worker bee kept isolated from other bees, even if supplied with food, will die soon. She will move restlessly she it drops dead not of exhaustion but of stress. Fearful rats die 60 % faster than non-fearful rats .
Stressed monkeys show anxiety behavior - excessive body scratching, body shakes, excessive yawning, self-grooming, pacing. They eat food high in fat and sugar,“comfort” food as do stressed humans. Even rats, stressed out by being stuck in confining tubes for 10 minutes, preferred lard and sucrose water more than non-stressed rats.
In humans and animals gender plays a role in stress response . Exposure to stress increases brain activity in both sexes, but females have more difficulty sustaining that activity. At a certain point they overload, after which their brain shuts down and psychiatric disorders develop.
In captivity animals get stressed as they experience separation anxiety and a feeling of abandonment. An animal confined for prolonged periods may become withdrawn, or angry. Animals get stressed out if the feeding is at different times. A constant state of anxiety is created when an animal never knows when its feed is coming.
Each stressor whether occurring sequentially or simultaneously, may push it over the threshold toward illness or death. Studies of female monkeys at Wake Forest University discovered that individuals suffering from higher stress have higher levels of visceral fat in their bodies, which in turn causes hormonal and metabolic changes that bring on heart disease and other health problems.
Even your pets are exposed to stress -a new person in the home, fireworks, thunder storms, moving house, a visit to the vet. Cats get stressed when they have bad relationships with other cats in the house. Dogs get stressed by loud noises. Some are mildly anxious. Some pant, quake, drool or shiver, and are prone to fits. Some become frantic and break through windows, claw through paneling or run into traffic if left alone. Even the withdrawal of affection or verbal/physical abuse can lead to an alarming rise in cortisol in dogs which acts as a neurotoxic substance weakening the immune system .
Factors that lead to stress in birds include: physical violence, insecurity, fear of other animals, a disliked human, illness, separation anxiety; loss of mate or owner; inability to adjust to domestication; boredom, lack of physical exercise. Under stress, birds pull out their feathers, They may fly back and forth aimlessly, throw themselves at the walls of their enclosure and perform other repetitive movements.
Animals in zoos, marine parks, animal fights, polo, rodeo or racing, all face stress. Elke Riesterer, a US-based therapist is working to destress elephants in Kerala. According to her, elephants in captivity are far more stressed out than their counterparts who live in the wild. “You can see an animal is stressed when you look into their eyes, their body language, in the restlessness of their body," says Elke
Asian elephants in captivity live 18.9 years while in the wild they live 41.7 years . African elephants live 16.9 years compared to 56 years in the wild. The majority of elephants in zoos are stressed and overweight. Infant mortality rates are three times higher for those born in zoos compared to wild births. Terror, rage and stress, are commonplace. Terror afflicts baby African elephants who wake up screaming in the middle of the night after they have witnessed their families murdered - Post Traumatic Stress Disorder. Researchers suggest a species-wide trauma is taking place in wild elephant populations, with them suffering from chronic stress after sustaining decades of killings .
A wild animal is in chronic stress the entire time it is in captivity. Factors include fear, over exertion, repeated handling, lack of rest, prolonged transportation, and confinement in cages or sacks. A wild animal reacts to strange sounds, sights and odours, changes in locality and temperature. A study shows that concentrations of the stress hormone cortisol in saliva from circus animals remains abnormal up to 12 days after transport and more for new captive animals .
Feces samples from lions and rhinos in zoos always show hormones that indicate high stress levels which results in a slow breeding rate and reduced immune system. An increase in the number of visitors at the zoo led to an increase in urinary cortisol in spider monkeys.
Many zoo animals show signs of chronic stress such as head bobbing, trunk swaying in the case of elephants, rocking, repeatedly retracing their steps, sitting motionless or biting themselves. Large animals pace back and forth in an effort to soothe themselves, minks chew their own fur. Even parrots adopt repetitive movements and pacing. research has shown that higher-than-average concentrations corticosteroids in the feces—an indicator of stress—are positively correlated with the occurrence of self-injuring behaviors, as well as the frequency of pacing and hiding.
Chimpanzees subjected to laboratory experiments suffer the same levels of post-traumatic stress disorder as humans who have been tortured. The study, presented to a scientific conference in Edinburgh, called for a ban on the use of primates in medical and pharmaceutical trials. An assessment of the behaviour of 116 chimps involved in animal research found that 95% displayed the distinctive patterns of behaviour that humans show - depression, anxiety and compulsive behaviors not observed in wild populations.
Left to themselves animals try and deal with stress. Cocks interrupt their fight by beaking the ground. Male starlings put an end to the hostilities by starting to cleanse their plumage. Bonobo apes use sex as a tool for discharging stress. When the tension is high, orgies break out. When you expose a rat to stress and then bring it back to its group, the others in the cage start taking care of the suffering animal by surrounding and licking it. There are traces of valium like compounds in vegetables like potatoes and fruits that people call comfort foods and use to combat anxiety and depression. Monkeys seek out a calming herb called valerian after stressful fights. Rats in the wild develop gastric ulcers due to stress. They seek out unripe bananas which stimulate the recovery of mucosa, healing stomach wounds.
I have only talked about animals in confinement. Next time you go to a zoo or circus to “ enjoy” yourself , keep their suffering in mind.