Understanding the Risk of Leptospirosis

Leptospirosis is an infectious disease that causes serious illness in dogs, other animals, and people throughout the United States and the world. This disease is caused by a spiral-shaped bacteria called leptospires that live in water or warm, wet soil. It is a zoonotic disease, which means it can be spread from animals to people. In the United States, most cases of human leptospirosis comes from recreational activities involving water. Infection resulting from an infected pet is much less common, but it is possible. Leptospirosis causes a variety of flu-like symptoms, but it can develop into a more severe, life-threatening illness that affects the kidneys, liver, brain, lungs, and heart.

Dogs are most commonly affected. Leptospirosis in cats is very rare. The most common way dogs become infected with this disease is by coming into contact with the urine of infected animals such as raccoons, skunks, squirrels, opossums, or deer. Dogs can become infected by swimming or drinking contaminated water or by playing in areas where infected urine is present.

The bacteria enter the body through the dog’s eyes, nose, or mouth, or through a break in the skin caused by a cut or scratch. Once a dog has become infected, the leptospires reproduce, multiply, and begin to spread throughout the body. If the infection reaches the kidneys and bladder, the dog may become a carrier of leptospirosis, spreading the bacteria each time it urinates.

The signs of leptospirosis in dogs vary. Some infected dogs do not show any signs of illness, while some have a mild illness and recover spontaneously. Others may develop severe illness that could result in death.
Signs of leptospirosis may include fever, shivering, muscle tenderness, reluctance to move, increased thirst, changes in the frequency or amount of urination, dehydration, vomiting, diarrhea, loss of appetite, lethargy, jaundice (yellowing of the skin and mucous membranes), or painful inflammation within the eyes. The disease can cause kidney failure with or without liver failure. Dogs may occasionally develop severe lung disease and have difficulty breathing. Leptospirosis can cause bleeding disorders, which can lead to blood-tinged vomit, urine, stool or saliva; nosebleeds; and pinpoint red spots (which may be visible on the gums and other mucous membranes or on light-colored skin). Affected dogs can also develop swollen legs (from fluid accumulation) or accumulate excess fluid in their chest or abdomen.
If any of these symptoms are noticed, you should contact your veterinarian. More than 80% of dogs with leptospirosis develop serious, short-term kidney problems. While most dogs do get better with prompt treatment, dogs that suffer severe liver or kidney damage can die within days. Even dogs that do recover may still be at risk for chronic kidney failure or become carriers of the disease.
Leptospirosis can be difficult to recognize by its clinical signs because the infection affects many different areas of the body and causes a variety of symptoms. Many of these signs can also be seen in other diseases. Leptospirosis may be suspected based on the exposure history and signs shown by the dog. In addition to a physical examination, your veterinarian may recommend a number of other tests such as blood tests, urine tests, radiographs (x-rays), and an ultrasound examination.
Leptospirosis was once thought of as a warm-weather disease that occurred in the rural south, but cases have been reported in regions all over the United States. Because of an increase of building and development in areas that were once rural, pets are being exposed to more wildlife which puts them at risk. Dogs at a higher risk for leptospirosis include working, hunting, and herding dogs that live in rural areas, dogs in suburban areas that live near water or wildlife, and dogs in urban areas that live in crowded shelters or are exposed to rodents.
You can lower your dog’s risk of leptospirosis by limiting exposure to sources of contamination such as stagnant water, rodents, and unmaintained canine facilities; however, the best way to protect your dog is with an annual vaccination that protects against the leading causes of leptospirosis. Talk to your veterinarian today to see if this should be included as part of your pet’s vaccine protocol.

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Information for this article taken from Merck Animal Health, the Center for Disease Control and Prevention, and American Veterinary Medical Association