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Can Dogs Get Legionnaires' Disease?


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Legionnaires’ Disease, a mysterious illness with a rather odd name, first became widely known in 1976 when a group of Legionnaires at a hotel contracted it, resulting in multiple deaths. The disease is caused by a pneumonia-causing bacteria, Legionella pneumophila, often resident in contaminated water supplies, that infects people when aspirated. The rare, but potentially deadly bacteria, requires a unique set of circumstances to manifest. It resides in stagnant water and can infect people when exposed to high temperatures (e.g. around 100 degrees F), and when other bacteria, protozoa, rust, iron and/or scale are present. A unique set of circumstances to be sure.

A milder version of the disease, called Pontiac Fever, can aso occur under similar circumstances. Notable outbreaks have occurred when water systems in buildings became contaminated with the bacteria and were aspirated in aerosoled mist and vapor by people present, resulting in outbreaks of the disease. The bacteria Legionella pneumophila can be found in natural water bodies as well.

Can Dogs Get Legionnaires’ Disease?


Since dogs often play, drink and bathe in warm stagnant water, one would think the chance of exposure for dogs to the bacterium causing Legionnaires’ Disease to be fairly high. However, there has never been a diagnosed case of Legionnaires disease in dogs. So, while it seems unlikely that dogs can get Legionnaires’ Disease, they can get a disease known as Leptospirosis from bacteria-contaminated water sources. Fortunately, there is a vaccine for this, which you can obtain if you feel your dog is likely to be exposed to bacteria-laden water.

Does My Dog Have Leptospirosis?

As it turns out, there is no evidence of dogs ever carrying or contracting Legionnaires’ Disease from contaminated water or other animals. It is believed that dogs are resistant to the disease. However, if pneumonia-like symptoms occur in your dog after being exposed to stagnant water under the right conditions, you should check with your veterinarian. It is more likely they would have contracted leptospirosis from other animals, or from soil or water contaminated with the bacteria.

Symptoms of leptospirosis include:

  • Fever of 103-104Âş

  • Muscle spasms

  • Vomiting and diarrhea

  • Increased thirst

  • Lethargy

  • Lack of appetite

  • Symptoms relating to affected organs, such as jaundice or blood in the urine

  • Pain

  • Eye and nose discharge

Leptospirosis can be transmitted to humans and can be a very serious disease affecting multiple tissues and organ systems. The disease can be acute, manifesting quickly, or subacute, manifesting more slowly. The infection is caused by Leptospira bacteria that can be spread through contact with infected tissues, body fluids, or soil or water contaminated with body fluids such as dog urine. Wild animals can also carry the disease. 

Leptospirosis can be diagnosed based on urine, blood or tissue sample analysis by your veterinarian.

How Do I Treat My Dog’s Leptospirosis?

If your dog has leptospirosis, precautions should be taken to ensure family members and other pets are not exposed to the bacterium causing the disorder from contact with body fluids of the infected pet.

A course of antibiotics will be prescribed to treat the bacterial infection. If dehydration is present, support with intravenous fluids will be provided. Your dog may be hospitalized and provided with quarantine and rest until they recover from the illness.

How is Legionnaires’ Disease Similar in Dogs and Humans?

Although dogs are not known to contract Legionnaires’ Disease, they can catch other serious flu-like diseases from bacteria present in water contaminated with bacteria. Contamination with Legionella bacteria is theoretically possible, and if respiratory symptoms appear in a dog that look similar to Legionnaires’ disease in people after exposure to contaminated water, medical intervention should be obtained to determine the nature of the disease.

How is Legionnaires’ Disease Different in Dogs and Humans?

There has never been a case of Legionnaires’ Disease in cats or dogs. There has been one case in a calf, and some laboratory animals have been intentionally infected; however, the disease did not spread between animals. Legionnaires disease is not thought to be a danger to dogs, nor is transmission from dogs to people thought to be a risk.

Case Study

Several dogs at a dog park that contained a water feature became severely sick with various symptoms ranging from fever and vomiting to extreme lethargy and dehydration. It was later determined that the water feature at the dog park had become contaminated with Leptospira bacteria from an infected dog’s urine, and the disease had spread to other dogs at the park. All dogs infected were given supportive care and antibiotics; however, one young dog received treatment too late after organ damage had occurred and had to be euthanized. The other mature dogs made a complete recovery.

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