Zoopharmacognosy

(How animals self-medicate)

Have you ever seen dogs eat grass and wonder why they do it, particularly as it usually makes them sick? Well, if you observe them more closely you will notice that they prefer a particular type of broadleaf grass called couch grass or, as it is also known, dog grass.

The reason why they do it is to detox themselves as couch grass has well-known liver detoxification properties and aids with digestion by helping absorb toxins and sooth the lining of the gut. Dogs, it would appear, are innately aware of this and eat it to cleanse their systems. What these dogs are doing is called zoopharmacognosy, which is the ability of animals to self-medicate by selecting and ingesting or topically applying plants and other substances with medicinal properties to prevent or treat disease.

It seems like a bizarre idea but, of course, it is perfectly logical. Animals have survived for millions of years without the need for human intervention. It would be extreme arrogance to assume that, without the use of modern veterinary medicines, animals all over the planet would be dying of multifarious illnesses. In fact, most veterinary pharmaceuticals have adverse side effects associated with them so if a natural alternative is available that a particular animal species have utilised successfully for thousands of years, who are we to say that modern treatment is best.  

Primates

One of the main animals studied with respect to self-medication are primates. For example, chimpanzees in the Mahale Mountains national Park, Tanzania, suffering from parasitic related diseases frequently eat the leaves of the vernonia amygdalina plant. Analysis of the plant found substances known as sesquiterpene lactones and stigmastane-type steroid glucosides This combination of substances have antiparasitic properties. It would appear that this is the reason why these chimpanzees consume them. 

Chimpanzees eat certain plants the rid themsleves of parasites

The chimpanzees also consume the leaves of the aspilia plant. However, they swallow these leaves whole, unlike other plant leaves which they chew. The odd feeding behaviour prompted scientists to analyse the leaf of the plant to see if there were any substances that may be of pharmacological benefit to the primates.

They were found to contain high concentrations of a natural antibiotic called thiarubrine-A. Thiarubrine-A is known to be a potent antibiotic and plants containing this substance has been used by the Okanagan-Colville Indians of British Columbia, Canada and Washington, to teat infected wounds. It is also an effective treatment against e-coli, and other bacterial infections as well as the fungus candida albicans.

Another species of aspilia - aspilia mossambicensis - has been used by the people of in East Africa for the treatment of intestinal worms. As thiarubrine-A is effective against nematode worms, it is speculated that that is another reason why the chimpanzees use it as they are susceptible to many of the same intestinal worms that humans harbour.

Capuchin monkeys in Costa Rica also use plants as an insect repellent. In this case, they use four different varieties - Citrus, Clematis, Piper, and Sloanea – the same genera of plants the Indigenous people use for similar purposes.

Other mammals

Primates, though, are not the only mammals to self-medicate. The Panamanian white-nosed coatis, for example use the resin from the bark of trattinnickia aspera plant to rub in their fur. This resin has chemicals called triterpenes which have proven antimicrobial and antiparasitic properties.

A study of lambs with a parasite burden, showed that if they were given the choice of normal grass or grass with added tannins, which have anti-parasitic properties, they would choose the grass with tannins more often whereas the lambs without the parasite problem chose the normal grass more often. In Spain, goats that were suffering from parasite infestation chose tannin-rich heather more often than goats that had been treated with antiparasitic drugs.

Porcupines, too, have been shown to self-medicate. Again, the reason is to protect themselves against parasitic infestation. Three separate groups of porcupines were studied in Italy and it was discovered that during the winter months, when they are prone to 14 different types of parasites, they ingest a higher proportion of plants with anti-parasitic properties.

For Madagascan lemurs, pregnancy would appear to be the trigger for self-medication. When pregnant lemurs are approaching their time to give birth, they start eating plants rich in tannins. Tannins are known to kill parasites and increase milk production, with vets often using them to prevent animals form miscarrying.

Pregnat lemurs eat plants rich in tannins to increse milk production.

One of the interesting aspects of the phenomenon is that frequently the plants chosen by the animals for certain ailments are the same ones used by people for the same reason.

One example of this is elephants choosing the plant, boraginaceae, to induce labour which Kenyan women use for the same reason. The plant is related to borage which is used in other parts of the world for the same purpose.

Elephants are also known to eat soil. It is believed they do this to detoxify themselves of any poisonous substances they may encounter in the forest. The act of eating soil or clay is called geophagy. Again, this makes perfect sense as humans have been eating soil for millennia. Indigenous people have mainly used it during pregnancy. One of the main reasons is that it is thought that the bacteria in the soil can alter the gut bacteria in the microbiome and strengthen immunity against pathogens. Clay, in the form of kaolin, is used as a medicine today to treat digestive complaints.

Another case of humans and animals using the same plant for medicinal purposes is that of osha, (ligusticum porteri) otherwise known as the bear root. In this case, though, humans have copied the animal’s and used it after watching them. It is called the bear root because brown bears use it to smear over their fur to prevent infection from parasites. Native American tribes who witnessed this, then began using it as a medicine themselves. It has anti-fungal, anti-viral and anti-inflammatory properties as well as being a natural antibiotic. It is used to treat respiratory illnesses, tonsilitis, digestive complaints, as a painkiller and is even a potent venom antidote.

Brown bears smear Osha on their fur to prevent parasitic infestation.

Birds

However, it is not just mammals, that have learned the art of zoopharmacognosy. Birds indulge in it too.

Great Bustards have been shown to prefer two species of weed that are known to have nematocidal properties that have been used in traditional medicine. They also consume beetles during the mating season that contain a poison that not only kills parasites but also bacteria that cause sexually transmitted diseases. The toxin, Cantharidin, is also an aphrodisiac.

Norfolk Island green parrots strip pieces of bark from pepper trees, chew them and them rub them into their feathers. Piperine, one of the phytochemicals from the pepper tree, is known to have antimicrobial and insect-repelling qualities.

One the main traits of birds that use plants for medicinal purposes is to incorporate them into their nests.

Starlings use their sense of smell to choose aromatic herbs for nest building. Fledglings raised in the herb nests have less parasites, better immune systems and are heavier than chicks in non-herb nests.

Blue tits also incorporate aromatic herbs such as yarrow, lavender and apple mint into their nests. These plants are antimicrobial and reduced the bacteria on the chicks leading to healthier birds.

Bonelli’s eagles also use choose aromatic plants over other species, in this case pine, as it has insect repellent properties and has proven to reduce the number of parasites in the nest.

Bonelli’s eagles are one of many species of birds that use aromatic herbs in their nests to ensure their chicks stay healthy

In China, sparrows use wormwood to ward off parasites. Artemisia Verlotiorum is well known for its anti-parasitic properties and is used by herbalists for that reason. A study proved that sparrows that incorporated more wormwood into their nest had heavier chicks.

Reptiles

Reptiles, too, know how to self-medicate. The International Journal of Fauna and Biological studies reported how an injured Oriental Indian garden lizard, with weeping wounds and showing signs of lethargy, was observed going from plant to plant in a garden until it came across the herb known as holy basil (osmium sanctum) which to proceeded to eat.

The lizard was subjected to various stimuli but refused to move and appeared semi-conscious. However, after a twelve- hour period, the wounds had begun to heal and the lizard appeared to be fully active again.

An Oriental garden lizard was observed eating holy basil to heal itself

Holy basil is one of the best know herbs used in Ayurvedic medicine and is used for colds, headaches, stomach disorders, inflammation, heart disease and various forms of poisoning. Scientific studies have proved its anti-inflammatory, analgesic, antipyretic, antiseptic, anticonvulsant, and anti-spasmodic properties.

In Brazil, it is believed that certain species of lizard ingest the roots of the Jatropha elliptica plant in order to recover from snake bites. It is also used by people as an anti-venom antidote amongst other medicinal uses.

The plant Microglossa pyrifolia has been used as an antidote for snake bites after observing snake’s behaviour.  A herbalist in Uganda saw two snakes fighting and one of them getting injured but, after ingesting the leaves of the plant, it made a full recovery.

Insects

Even insects appear to possess the innate knowledge of how to treat themselves medicinally. The woolly bear caterpillar, for example, will ingest plant material containing toxic pyrrolizidine alkaloids. They do this to confer resistance to tachinid flies. It is possible that the poisons in the plant kill the larvae of the tachinid flies which are implanted in the body of the caterpillar. Studies showed that caterpillars infested with flies ate more toxic plants and their survival rate improved by 20%.

Wood ants choose conifer resin for their nests more often that other material. It is thought they do this as it inhibits the growth of bacteria and fungi in their nests. Honeybees, also use resin for the same purpose as it decreases the number of bacteria in their hives and even downregulates immune genes, meaning not so much energy has to be expended on their immune system.

Honeybees and wood ants use resin in their nests as an antibacterial agent.

Fruit flies have evolved resistance to ethanol due to their larvae feeding on fermentation products produced by rotten fruit. Using this to their advantage, if they are infected by parasitic wasps, they increase their ethanol intake, causing the death of the wasp larvae. Even the fruit fly larvae increase their ingestion of alcohol- containing sources as an anti-wasp deterrent.

Sometimes, though, it is not case of using natural medicine to treat oneself but to protect one’s offspring. Such is the case with monarch butterflies who, as adults,  cannot rid themselves of protozoan parasites. By laying their eggs on plants with toxic chemical in them, they can, however, protect their offspring from parasitic infestation.

Marine animals

It is not just land animals that practice zoopharmacognosy. There is evidence that marine species also do it. A report in the Science magazine, has noted that bottle nose dolphins in the Red Sea frequently choose three types of surfaces to rub themselves on – 2 types of coral and a variety of sponge. After chemical analysis it was found that together the corals and sponge had 17 biologically active compounds with antioxidant, antibacterial and hormonal properties, suggesting the dolphins deliberately choose these surfaces to treat themselves medically.

Humpback whales are also believed to self-medicate when they are observed ‘kelping’. This is when they toy with seaweed on the surface of the ocean, rubbing it over their fins and mouth. Whales can suffer from numerous parasitic and bacterial infections and certain seaweed species are known to be antioxidant and antibacterial.

A humpback whale ‘kelping,’ to fight off paraistes.

Zoopharmcognosy has a long history

Today’s scientists may just have started noticing how animals have the ability to self-medicate, but it has been known for a very long time.

As far back as the 4^th Century BC, Aristotle, noticed how dogs ate grass to cleanse their digestive systems and Pliny the elder explained how wild oregano was first used to treat arrow wounds after observing wounded stags grazing on it. Aelian, the Roman naturalist, also noted storks, partridges and turtle doves using crushed oregano leaves to treat wounds. Oregano is known to have antimicrobial, anti-inflammatory and antioxidant properties.

Pliny noted how certain birds such as pigeons, jays and blackbirds ate bay leaves for digestive issues and commentators in the 12^th century noted how bears covered sores with mullein. Today, mullein is known to have anti-inflammatory properties as well as other medicinal uses.

It would have been great if today’s medical professionals were to appreciate animal’s innate knowledge of how to self-medicate using natural products as much as the ancient Greeks and Romans and encourage the use of more natural medicine. However, considering they ignore their ancient Greek predecessor, Hippocrates, and his oath of, ’First, do no harm,’ it is hardly surprising they ignore natural treatments.

Hippocrates, whose oath the medical profession now totally ignore.

Big Pharma do, of course, know the truth. They use plants as the source of a lot of their medicines. However, rather than using the entire plant with its hundreds of different phytochemicals they extract one substance and then synthesise it. So, instead of using the plant the way nature intended, they make an artificial version of just part of it. They do this because they cannot patent nature and they are so arrogant they think they can do better than nature.

Just as Big Pharma ignore natural remedies, we can choose to ignore Big Pharma. Instead of ingesting all the toxic, synthetic drugs they produce that have very little benefit but a vast array of side effects, isn’t it time we simply used the much more effective and safer products available in nature’s own pharmacy? Surely us humans are at least as intelligent as fruit flies and lizards, are we not?