Recreational use of drugs by humans has been occurring for centuries, ever since farmers discovered the intoxicating properties of mead and the hallucinogenic properties of poppy seeds. Continuing into the 20th century, with the introduction of psychedelics, our ancestors have engaged in alcohol or drug use for pleasure for a very long time.
While the availability of intoxicating substances was unlimited, knowledge of the long-term impact of their use was not. Because of this, consumption went largely unchecked and was actually condoned, resulting in rampant addiction.
Substance abuse has generally been thought to be a uniquely human affliction, but, in recent years, research has revealed that it also occurs among animals.
Addiction in Animals
Studies have shown that animals can develop a dependence on substances. It is for this reason they are used in research into the effects of drugs and alcohol on people, raising many ethical concerns. Animals become addicted to substances even more easily than humans do, and demonstrate all of the negative consequences.
They suffer withdrawal symptoms, and will engage in any behaviour in order to obtain more of the substance that has been removed, including self-harm or starvation.
The parallels between addiction in animals and people are striking, but this understanding is still evolving.
Animal Addiction in Nature
Just like people in the middle ages enjoying a cup of mead to relax without truly knowing why they were compelled again and again to do so, animals also consume items found in nature that produce a pleasurable effect.
Many pet owners recognize catnip, and know the lengths to which a cat will go to obtain more after the first taste. This fragrant herb contains a hormone that alters behaviour. Catnip sensitivity is genetic, and only about a third of cats will not respond.
This effect is not only seen with house pets, but big cats such as lions and tigers display it as well. Another favourite, particularly of jaguars, is yage, a plant containing DMT. This causes hallucinations, and physiological changes in the animal.
Monkeys may actually become intoxicated on purpose. Sugar cane crops ferment prior to harvest, producing alcohol. The animals will repeatedly choose the liquid containing the alcohol over that without intoxicating properties. Younger monkeys are more likely to drink, even to the point of unconsciousness.
Other Animals Displaying Addictive Behaviour
Herds of goats and sheep will travel great distances, and over very rough terrain, in pursuit of hallucinogenic lichen. Specific breeds of moose and caribou can be found grazing on psychedelic mushrooms.
In Australia, where a large percentage of legal opium is grown, ranchers must protect their crops from wallabies, who return again and again to enjoy the highly addictive seed.
Many species of birds, rodents and other mammals eat intoxicating insects and plant life, which results in altered states of consciousness. They repeat the behaviour again and again, and overcome obstacles in order to get more of the substance, suggesting that they are addicted.
The pattern of substance abuse in nature is strikingly similar to that of human addiction, making them a logical choice for research studies. Addiction also occurs in captivity.
Animal Addiction in Domestic Animals
Vets see many cases each year of animals who have accidentally ingested drugs like marijuana, nicotine, and prescription medications. This often causes long term health issues, or death.
Drug abuse by animals is also frequently caused by pet owners. People report giving alcohol or drugs to their pets because they think that the animal will like it, or they enjoy watching the effects (e.g., the pet stumbling).
Deliberately giving drugs to animals is cruelty, and against the law. There is also an expectation to keep pets safe, and not allow accidental ingestion of substances.
People choose to consume drugs and alcohol. Animals cannot choose for themselves – they are reliant on their owners.
Researchers understand addiction, and animals are routinely trained in labs using that knowledge. Offering treats, affection and/or praise stimulates the pleasure centre in the brain. Once this happens, the brain will make associations with what was happening at the time of the pleasant feeling.
Neurons then create a neurological pathway, and the animal will be compelled to repeat the action that resulted in the appearance of the reward again and again. This is particularly the case when the reward is a drug that is highly addictive.
Studies into alcohol or drug addiction using animals have been instrumental in providing insight into substance abuse, and other mental illnesses, in people. Animal use in research makes it possible to test the efficacy of medications, and the effects of alcohol or drugs like heroin, cocaine, opioids, or methamphetamines without putting human lives in danger.
Is Animal Testing Ethical?
In spite of the benefits, testing using rabbits, mice, monkeys, birds, and other mammals is very controversial.
Images of animals spending their entire lives in cages, not always having enough water, or palatable food, and suffering the effects of the testing to which they have been subjected against their will, make a strong argument against their use.
Another argument is whether or not animal studies have true value. The results are often called into question because of problems with procedure, and the reliability of using animals instead of people.
When animal studies are discounted, at the cost of their lives and/or suffering, organizations that advocate for animal rights hold researchers and governments accountable, challenging their use as unethical.
Addiction is a terrible disease that causes great suffering in its victims, and animal testing has resulted in great advancement in its treatment. The debate about using animals in substance use disorder research will not end anytime soon.
Bethany N. Kuhn, et al., Frontiers in Behavioral Neuroscience, Article Date: November 29, 2019
CDN.intechopen.com, Copyright 2018
BBC, March 27, 2017
Animal Studies of Addictive Behaviour
NCBI, Louk J.M.J. Vanderschuren, et al., Article Date: April 3, 2016
Animal Models of Substance Abuse Addiction: Implications for Science, Animal Welfare and Society
NCBI, Wendy J. Lynch, et al., Article Date: June, 2015