Cornell University College of Veterinary Medicine Baker Institute of Animal Health

An Overview of Leptospirosis

Leptospirosis is a disease caused by spiral-shaped bacteria known as leptospires. Infections occur worldwide and may infect humans in addition to a multitude of domestic and wild animals. The highest incidences of leptospirosis occur in warm, semitropical areas, but during warmer months nearly every climate is affected. Fatalities are not overwhelmingly common, but there is always the potential for a leptospirosis infection to become extremely serious. Vaccines are widely available and, especially if your dog spends time in slow-moving or stagnant water, highly recommended.

Why and how might my dog become infected?

Leptospirosis may be transmitted from animal to animal in a number of different ways. Direct contact, venereal or placental transfer, bite wounds, and ingestion of infected meat have all been proven as methods of infection. Perhaps the most common method however is via exposure to infected urine. Animals suffering from leptospirosis shed bacteria in their urine in large quantities, and thus anything that touches infected urine will be contaminated. In this way vegetation, food, soil, water, and bedding may be infected. Warm, stagnant or slow-moving water is a particularly welcoming habitat for leptospires, and most infections probably occur when a dog (or human or other animal) goes swimming in or drinks water harboring these bacteria.

The leptospires enter the body through mucous membranes or abraded skin. Once inside the bacteria enter the bloodstream and multiply rapidly. The incubation period between initial infection and manifestation of clinical symptoms ranges between 2 and 26 days. After reproducing in the bloodstream the bacteria invade their target organs, including the kidneys and liver.

How will my vet reach a diagnosis of leptospirosis?

A diagnosis of leptospirosis is based upon a combination of clinical observations and laboratory tests. Many subclinical infections will be asymptomatic and therefore may never be diagnosed. Symptoms that do appear vary widely in type and severity, and dogs with no apparent symptoms may in fact be severely ill and die spontaneously. The majority of cases do however exhibit some outward signs of infection, including loss of appetite, fever of 39 to 40°C (103 to 104°F), severe muscle pain, stiffness or reluctance to move, shivering, progressive weakness, and depression. Dehydration often occurs as a result of vomiting and diarrhea. Conjunctivitis is often present accompanied by difficulty breathing and a dry, hacking cough. If the disease is left untreated and allowed to progress, dogs may have markedly cold extremities, gray-colored stools, and yellow skin and eyes.

Beyond examining physical condition, your veterinarian may perform laboratory tests on urine and blood. These procedures can help detect abnormalities in blood components, liver enzymes, electrolytes, and urine chemistry. Serologic tests can be carried out to detect the presence of antibodies specific to leptospirosis.

The final diagnosis will thus be the result of any and all laboratory tests combined with clinical observations and the individual dog’s history of exposure.

What are the treatment options for dogs with leptospirosis?

The goal of treatment for leptospirosis is to control the bacterial infection before serious and irreparable damage is done to the internal organs. If the disease is caught at an early stage, antibiotics are the best treatment option. Administration of any number of common antibiotics will serve to shorten the duration of the disease, limit the amount of time the dog will be a carrier of the bacteria, and decrease the severity of liver and kidney damage.

More advanced and serious cases of leptospirosis will require various forms of supportive therapy in addition to antibiotics. The administration of lots of fluids will help to compensate for abnormal liver and kidney function. Kidney therapy may be undertaken with the goal of restoring proper urine production, kidney filtration, and blood flow. Such measures are extremely important to reverse kidney failure. Severe liver disease may necessitate blood transfusions and other types of supportive therapy.

Treatment procedures for leptospirosis are highly individualized and your veterinarian will be able to provide you with information as to what is best for your pet.

Can I vaccinate my pet against leptospirosis?

Vaccines are complex substances and often raise many questions. For information about vaccines in general, please goto An Introduction to the World of Vaccines.

There are a multitude of options available for vaccination against leptospirosis. Any vaccination schedule should be discussed thoroughly with your veterinarian.

How else can I help prevent the disease?

All dogs should avoid stagnant, muddy water as much as possible. Rodent problems should be kept under control, as these animals often harbor leptospires – not to mention a host of other pathogens.

Owners should be aware if their dog is at an increased risk. Increased risk activities include hunting, showing at large dog shows, swimming in stagnant ponds, and living in areas with especially high incidences of leptospirosis. All at risk animals should be properly vaccinated.

Any place that has housed an infected animal must be thoroughly cleaned and disinfected before another dog is introduced.

Additional resources on the web:

Centers for Disease Control
Answers common questions of pet owners, including the human health risk posed by infected animals.

VeterinaryPartner.com
A brief but thorough reference for pet owners.

University of Wisconsin-Madison School of Veterinary Medicine
Tutorial covering leptospirosis in humans and animals, with complete references.

International Veterinary Information Service
Provides a detailed article for veterinarians.

For information on specific vaccines, visit the manufacturers' websites:

Pfizer Animal Health (the Vanguard® PLUS 5/L Vaccine)
Intervet (the Progard-8® with CPV Strain 154® Vaccine)
Intervet (the Progard-7® with CPV Strain 154® Vaccine)
Schering-Plough Animal Health (the Galaxy® DA2PPvL Vaccine)
Schering-Plough Animal Health (the Galaxy ® Da2PPvL+Cv Vaccine).
Schering-Plough Animal Health (the Tissuvax® 6 Vaccine).
Fort Dodge (Duramune®)