STDs and Other Mammals

You’d be surprised to hear this, but even animals get STDs!

Cases of sexually transmitted diseases grow within the minute, with over 19 million new infected patients yearly in the US. However, what many people do not know is that STDs actually occur in animals, too.

Still not interested? Then you should know that scientists are exploring a Chlamydia vaccine for koalas, which can rapidly turn into a breakthrough in vaccinating humans.

The Relationship of STDs in Humans and Animals

STDs in humans and animals are closely related and have a strong historical relationship. The vice president at Wildlife Trust, Alonso Aguirre says: ”Two or three of the major STDs have come from animals. We know, for example, that gonorrhea came from cattle to humans. Syphilis also came to humans from cattle or sheep many centuries ago, possibly sexually”.

According to this veterinarian, the deadliest sexually transmitted disease to migrate from animals to humans is HIV. This disease originated in chimpanzees, where hunters acquired the infection from their blood.

Later on, this disease got transmitted from one person to another and became one of the biggest threats to the health of the human population. This disease is transmissible through bodily fluids, such as semen and blood.

STDs in Animals


Nowadays, the most common STD among animals is the undulant fever or brucellosis. This disease is mostly found in domestic livestock and some mammals such as goats, deer, dogs and rat.

This disease can be transmitted sexually, but also in other ways. For example, the cattle often consume the placenta of their spontaneously aborted fetuses, which leads to them infected by the disease.

Symptoms of brucellosis include:

  • Inflammation of the testes
  • Miscarriage
  • Uterine infection

People can contract this infection through direct contact with the animal or drinking milk that is contaminated.

Fortunately, the brucellosis can be treated with antibiotics.


Animals and humans share Chlamydia, too. This is a bacterial infection found in people, birds, reptiles and many mammals.

Even though we share the disease, this STD cannot be spread between animals and humans.


Because animal and human STDs are spread by different Chlamydia species – C.psittaci and C.trachomatis.

Unlike the case with humans, animals can transmit Chlamydia through the mucous membranes in the urogenital tract and the eyes, which means that they become infected through fighting and mothers can transmit this disease to newborns.

With humans, Chlamydia can do serious damage to the reproductive system, cause abortion and infertility, inflammation of testicles, high fevers, respiratory problems, as well as sterility.

Chlamydia in Koalas

Australian koalas of both genders often suffer from Chlamydia. In addition, this disease can be transmitted to the joeys – the baby koalas through the process of suckling.

When infected, the koala develops urinary infections, conjunctivitis, incontinence, blindness and infertility. Knowing this, scientists think that this is the main reason why the number of koalas has declined greatly in the past decade.

However, there is hope. Last year, some researchers announced that a test vaccine showed promising results and none of the tested koalas developed the infection.


Dourine is a disease that can affect donkeys, horses and mules. The stallions who have the parasite Trypanosoma equiperdum in their bodies have urethral discharges and swelling in their scrotum and penis. The mares also have skin problems, while some horses may experience loss of coordination, facial paralysis and in very few cases, even death.

The US eradicated this problem back in the 1950s, after several unsuccessful attempts. In 1906, Canada slaughtered over 400 horses with the goal of squashing the outbreak of the dourine.

At this point, Dourine still continues to infect animals, mostly in Africa, Asia and South America.


One of the most confusing viruses in animals, IIV-6, manifests in making Texas crickets infertile and yet, horny. The field crickets that have been infected with this virus become horny and have more sex than the uninfected crickets.

Still, this cannot result in baby crickets. The virus actually makes the animals infertile.

Infected males produce slower sperm and cannot reproduce, while females develop a bluish body cavity tint and swollen fat cells in their eggs.

Coccipolipus Hippodamie

This parasitic mite infects the ladybugs or as UK calls them – ladybirds. The mite larvae accumulates at the wing tip when the beetles mate and hops onto the beetle that is yet not infected. According to experts, the mites simply sit on the ladybug to suck their blood.

As a result of this STD, female ladybugs become infertile and suffer damage to their wing case. This damage is easy to notice even with a naked eye, but female ladybugs remain acting as if nothing is happening.

Is There any Hope?

You probably think that there is no hope for the animals. After all, you cannot teach them to practice safe sex or use condoms. They are not humans.

However, even though this sounds counterintuitive, many think that animals can actually benefit from the STDs. Even though some of these are very dangerous and bad for the animal, there are also STDs who help the animals.

Take for example the Anopheles mosquito larvae. When infected with the Asasia bacteria, they actually grow and develop more rapidly. The Asasia bacteria is transmitted sexually or passed down to the offspring.

In addition to this, some animals found their own way to avoid becoming infected. When they mate with various partners, they are less likely to get an STD.

Masturbation is an act that is considered to be ‘genital grooming’. For example, the male African ground squirrel masturbates after the copulation, which reduces the chances of getting a sexually transmitted disease. In fact, this can increase the number of males a female squirrel will accept, which reduces the chances of STD transmission significantly.

Now that you know animals also suffer from STDs, you can take some steps to prevent becoming infected from their products or direct contact with them. Furthermore, testing of animals can improve the chances of vaccinating people against STD greatly, which gives us a great deal of hope in fighting even the life-threatening sexually transmitted diseases.

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