Animal Depression: Does it exist?

Image Credit: Unsplash: Mauricio Livio

Andrea Beyer explores the recent phenomenon of animal depression – the signs and symptoms of depression in captive wild animals and domestic pets.

Depression can be difficult to understand in animals as they cannot self-report or express how they feel with words. Hence, it is vital to examine possible signs that an animal may be unhappy with its stimulus. In an interview with a UCD lecturer from the school of veterinary medicine, Dr Sandra Nicholson highlighted that: “experts and researchers do think that depression in animals exists but it tends to be described using different terminology. We tend to use something called learned helplessness to describe it rather than depression.” 

What is learned helplessness? Learned helplessness is an abnormal passivity displayed by humans and animals after experiencing events out of their control. Signs of learned helplessness may manifest as anhedonia, a loss of pleasure from usually enjoyable activities or as stereotypies, which are recurring obsessive behaviour patterns with no apparent goal or function. Animal caregivers may notice a loss of interest in food or a lack of motivation to engage in sexual activity when an animal is feeling ‘depressed’. 

Stereotypic behaviour has been repeatedly observed in captive wildlife animals but is not commonly present in animals in the wild. Zoochosis is the term used to describe stereotypic behaviour in captive wild animals. According to National Geographic, an estimate of 80 per cent of zoo animals experience zoochosis. There are many stereotypies that an animal in captivity may display as a bi-factor of its ‘depression’. For example, pacing and circling in a trans-like manner, over-grooming, unnatural neck twisting, rocking back and forth, eating and playing with their faeces and vomit. 

if certain animals are shown by future research to be statistically more likely to self-destruct in certain environments we have a moral duty to change these environments or relocate these animals

Upon my visit to Dublin Zoo, it was evident that some of the larger mammals were expressing signs of obsessive behaviour. Two lionesses were extremely concentrated when pacing rapidly up and down in a singular line and there was an isolated gorilla vigorously licking himself without stopping. Although unable to communicate with these animals verbally, I did not doubt that they were unhappy in their environment.  It must be noted that there are visible enrichment items and enrichment feeding activities present in the enclosures of the animals, demonstrating the efforts made by Dublin Zoo to aid animals that may be experiencing learned helplessness or zoochosis. The study of zoochosis draws attention to a vital question: do we want animals in captivity suffering from zoochosis to be capable of coping or do we want them to live a happy life? Dr David M. Peña Guzmán has underlined the need to reconsider the captive environments of wildlife animals.  

“if certain animals are shown by future research to be statistically more likely to self-destruct in certain environments we have a moral duty to change these environments or relocate these animals”.

Is it possible for an animal to be driven to a state of suicidal despair? Although, as humans, we cannot determine if an animal is having suicidal thoughts we can, however, analyse signs and symptoms of depression in animals that may result in suicide. 

Neuroscientist Lori Marino has concluded in her studies on dolphin intelligence that dolphins have the cognitive ability to plan and carry out a suicide. Dolphins, unlike humans, take voluntary breaths and they make a deliberate effort with every breath they take. There are numerous examples of Dolphins in captivity that have committed suicide by stopping themselves from breathing. Ric O’Barry has previously discussed the suicide of one of the dolphins he trained. The dolphin was called Kathy and she was featured on the television show ‘Flipper’ in the 1960s in America. Kathy was retired from her career on TV and was confined to a small tank. Ultimately, in 1968 the dolphin in the arms of O’Barry took her last and final breath intentionally taking her own life. 

In 2011 in China, there was an incident exposing the suicide of a sow on a bile farm. The bear escaped from her cage after her cub was harmed and strangled the cub to death to save it from a life of torture. The bear then took her own life by running into a wall with full force.

If the animal is in that situation for a long time the problem is that those behaviours continue even when the environment is made stature for them

Although we cannot yet determine whether animals can experience suicidal thoughts it would be ignorant to believe that nonhuman mammals are unable to deliberately self-destruct and take their own lives.

Is your pet suffering from depression? Learned helplessness is not exclusive to wild animals in captivity as domestic pets are also subject to ‘depression’. Dr Sandra Nicholson explained in our interview that: “Dogs have compulsive disorders as well, they manifest as obsessive licking of certain areas of their body, they can also compulsively chase their tail and press their head against the door or perform repetitive movements such as repetitive circling of the garden and light and shadow chasing.” Dr Nicholson brought to light that an animal may persevere to express symptoms of learned helplessness after its environment is changed. 

“If the animal is in that situation for a long time the problem is that those behaviours continue even when the environment is made stature for them.”

For example, a rehomed dog may have developed a compulsive disorder over a long period as a means to cope with its conditions,  this compulsive disorder may carry on although the environment of the dog has been changed when it is rehomed. 

Dr Nicholson highlighted that it is often difficult for cat owners to identify that their pets are unhappy as cats tend to be more reserved and less social in the home. Symptoms to watch out for cats dealing with ‘depression’ may be poor grooming, loss of excitement in activities they normally enjoy and not eating. 

Dr Nicholson stated that there is animal behaviour counselling for dogs, cats, birds, small furries and rabbits. Animal behaviour counselling is not regulated at the moment in Ireland, however, it is an ongoing development. 

There are pharmacological drugs used to reduce fear and anxiety in dogs and these can only be prescribed by veterinarian surgeons. Dr Nicholson affirmed that “these pharmacological drugs are not recommended to be used on their own they are advised to be used alongside animal behaviour modification such as animal training, changes in the environment and working with the owner to understand their animal better.” 

So do animals experience depression? Emotions in animals have only recently been accepted and acknowledged, therefore it is an ongoing field of research. Recent studies have proven that animals are not automotive machines and can experience strong emotions. Whether an animal can become depressed is a complex theory as we are unable to verbally communicate and ask these animals what they may be going through emotionally. However, learned helplessness, stereotypic behaviour and the events of animal suicides incentivise our awareness of the animal mental illness and give us the moral duty to try to help them.