Can Dogs Get STDs?

Thanks to effective public awareness campaigns, many of us are very savvy when it comes to common human sexually transmitted infections, and pet parents may be wondering if the same is true for their dogs. The good news is that sexually transmitted disease is not as common in pet dogs, especially those that are spayed and neutered and have limited interactions with unfamiliar dogs.

The not-so-good news is that diseases spread through sexual transmission can also be spread through non-sexual modes of transmission as well. This means that dogs do not have to get busy in order to acquire these infections. Read on to learn all about STDs in dogs and how to protect your pup.

Can dogs get sexually transmitted diseases?

Yes, sexually transmitted diseases do exist in dogs. Oftentimes they are not labeled specifically as STDs since they are also transmitted in many other ways. Many responsible dog breeders also screen their dogs for these conditions and take aggressive measures to prevent infections.

Pet parents may not know what to look out for if they intend to breed their dog for the first time, or sometimes accidental matings occur, which can unintentionally put dogs at risk for infections. Therefore, it is important to see a vet if a dog is showing signs of illness and to make sure to mention any recent breeding or mating attempts that may be relevant.

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Common STDs found in dogs

Brucellosis

This bacteria can infect dogs who come into contact with infected urine, semen, vaginal secretions, saliva, blood, and/or milk. While this means that Brucella may be transmitted sexually, it is also contagious in other ways. Dogs that are in close contact with an infected dog are likely to get sick. This is a very challenging infection to treat and due to the fact that it is also contagious to humans, it requires very intensive monitoring and treatment. Brucella is a reportable disease in most states due to the public health risks associated with it, meaning that the health department must be notified of all positive cases. 

Canine herpesvirus

This virus is in the same family as the human herpesvirus but tends to impact dogs differently. Canine herpesvirus is most dangerous to unborn puppies and newborn puppies who often die suddenly after infection. In most of these cases, a pregnant dog is infected in late pregnancy, leading to high rates of fatalities in her puppies.

Adult dogs do not usually show any signs of herpesvirus, but occasionally they may develop cold-like signs, genital sores, or injuries to their eyes. While this virus can technically be spread through sexual transmission from infected semen, it is also spread through contact with secretions from the nose or eyes.  

Canine transmissible venereal tumor (CTVT)

This is a contagious form of cancer that can spread from one dog to another through intimate contact. It is often acquired during mating, because it requires the tumor cells to come into contact with small scrapes on the surface of the skin. It can also spread when dogs sniff or lick each other’s hind ends and genital regions.

As a result, dogs can develop tumors on their faces, eyes, and noses, as well as their genital areas. These tumors are more common in some countries outside of the United States and in stray dogs. The good news is that these tumors tend to be curable with proper treatment and are unlikely to spread to other body parts. 

Toxoplasmosis

This is an infection caused by a parasite called a protozoa. While cats are the main host for this parasite, all mammals including dogs and humans can also become infected. Most of the time, dogs are infected by eating prey animals like rodents that are already carrying the parasite, or from ingesting contaminated food, water, or soil.

There are also cases of female dogs becoming infected from contaminated semen. For most healthy adult dogs, the infection does not cause serious disease but can put them at risk for spreading the disease to humans and other animals. Toxoplasmosis infection can be more serious when pregnant dogs become infected because it can cause death of the fetuses.  

Symptoms of STDs in dogs

The signs of sexually transmitted diseases are highly variable because they cause such different kinds of infections. Some dogs with diseases like brucellosis, canine herpes, or toxoplasmosis may be asymptomatic, meaning they show no signs of illness at all. This makes it difficult to know they are infected without screening tests. Other times, these diseases may cause respiratory signs like a cold, visible changes to the genitals, injuries to the eyes, fever, lethargy, a wobbly walk, vomiting, diarrhea, or more serious damage to internal organs. These diseases also are likely to cause fetal deaths as well as serious illness and/or death to newborn puppies.

Canine Transmissible Venereal Tumor is unique in that it causes easy-to-see tumors on the genitals and/or face of dogs. These tumors tend to have a bumpy appearance and may bleed easily. It is important to note that none of these diseases can be diagnosed based on the symptoms or visual appearance of a sick dog alone.

There are also many other types of infections and tumors that look similar but are caused by completely different disease processes. Any dog showing these signs or any signs of illness should be examined by a veterinarian to determine the underlying cause.  

How dogs contract STDs

Dogs can contract these diseases through both sexual and non-sexual activity. Many can spread through close contact and do not require mating specifically. It is possible that dogs that are housed together or play together could transmit many of these diseases to one another even if there is no sexual contact.

In some cases, mating increases the risk of infection as it causes small traumatic injuries to the delicate tissues of the reproductive tract, which may allow infections to enter the body. Male dogs who are not neutered may also spread certain infections through their semen. 

Diagnosis of STDs in dogs

To be diagnosed with one of these diseases, a dog will need to have a thorough exam by a veterinarian, as well as a carefully reported history including any recent contact with other animals and/or recent mating. Depending on the veterinarian’s physical exam findings and pertinent history, they may recommend additional tests to make a diagnosis.

This often includes blood tests, X-rays, bacterial cultures, and/or measuring antibody levels to determine if a dog has an infection. To diagnose specific types of tumors such as a transmissible venereal tumor, samples of the tumor cells must be taken for analysis, either using a technique known as a fine needle aspiration and cytology, or a biopsy. If a pregnant dog has stillborn puppies or newborn puppies who die suddenly, a necropsy, which is the veterinary version of an autopsy, may be performed. This allows a veterinarian to examine the deceased puppies and analyze tissue samples to determine their cause of death.     

How to treat STDs in dogs

Each of these diseases is unique in terms of its underlying cause and how best to treat it. For adult dogs with mild symptoms, supportive care like fluids, pain medications, anti-nausea medications, and good nutrition are often part of their care plan. T

reatment of infections like brucellosis and toxoplasmosis are challenging as there is no single protocol that works consistently on all cases and many dogs do not completely clear the infections. This is complicated by the fact that these infections are also zoonotic, or contagious to humans, making them public health concerns to the general population.

It may require long courses of treatment and trial and error to find a protocol that works for each case, but a complete cure is not always possible. In contrast, transmissible venereal tumors are usually treated with chemotherapy or radiation and most cases are completely curable. 

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How to prevent STDs in dogs

Preventing STDs in dogs is all about avoiding high-risk situations. One of the most effective ways to prevent STDs is to have female dogs spayed and male dogs neutered. This will prevent the spread of diseases that may be transmitted in semen. It also reduces the urge dogs have to attempt to mate, which will reduce the likelihood that they come into contact with an infected dog.

All of these diseases can also spread from one dog to another without sexual activity. This means that it is important to protect your dog from other potentially risky behaviors, such as eating wild prey animals and interacting with stray dogs, sick dogs, or dogs that may have an unknown medical history. Pregnant dogs and newborn puppies should also be kept away from other dogs, especially in the second half of pregnancy and the first three weeks after birth to prevent exposure to infections that could seriously harm the puppies.   

Bottom line

Dogs can acquire STDs, but the types of diseases and symptoms they cause are different from STDs in humans. All of the diseases that can be spread sexually are also spread in other ways as well, meaning that even dogs that have not recently mated with another dog could still be at risk for infection.

It is important to protect your dog from high risk situations that could expose them to these infections. See a vet right away if your dog has any concerning signs of illness. 

FAQs

Can dogs transmit STDs to humans?

Some STDs, like brucellosis and toxoplasma, are transmissible to humans through non-sexual modes of transmission. 

How do I know if my dog has an STD?

Each disease causes unique symptoms; any dog with signs of illness should be examined by a vet to determine if they have an STD or other illness. Dogs without symptoms can be screened for some STDs prior to planned breeding attempts. 

What types of STDs can dogs get exposed to?

Dogs can be at risk for STDs that include bacterial, viral, parasitic, and cancerous infections. 

How are STDs in dogs different from in humans?

In dogs, all of the infections that can be spread sexually are also spread through non-sexual routes as well. Many of them do not cause symptoms in healthy adult dogs but can be serious in pregnant dogs and newborn puppies.  

References

• Arantes, T, et al. “Toxoplasma gondii: Evidence for the transmission by semen in dogs,” Experimental Parasitology, October 2009, vol. 123, no. 2, pp. 190-192. 

• Chu, RM, et al. “Proliferation characteristics of canine transmissible venereal tumor,” Anticancer Research, vol. 21, no. 6A, November-December 2001, pp. 401- 4024. 

• Cosford KL, “Brucella canis: An update on research and clinical management,” Canadian Veterinary Journal, 2018, vol. 59, no. 1, pp. 74-81.  

• Creevy, K. “Canine Herpesvirus Infection,” Merck Manual, March 2025. 

• Ganguly, B. “Canine Transmissible Venereal Tumor,” Merck Manual, March 2024.