Most livestock out on pasture come in contact with Leptospira bacteria through contaminated standing water that an infected animal has urinated in. The spiral-shaped bacteria burrows its way into the body through exposed mucous membranes such as gums or around the eyes.

Most livestock out on pasture come in contact with Leptospira bacteria through contaminated standing water that an infected animal has urinated in. The spiral-shaped bacteria burrows its way into the body through exposed mucous membranes such as gums or around the eyes.

1. How much risk does leptospirosis pose for livestock and pets within the Northeast?

Leptospirosis seems to be more common the farther west you go, and is less common in the Northeast. Studies done in the early 2000s showed a 59% overall national presence of leptospirosis on dairies, and a 42% prevalence in beef herds.

While not a very common disease in humans, those who spend a lot of time working with animals like farmers, veterinarians or persons working outside, particularly mine and sewer workers, and those who have come into contact with floodwaters or contaminated water like lakes, ponds and streams, are most at risk for contracting leptospirosis.

2. How can livestock come in contact with leptospirosis? How do dogs come in contact?

Leptospira bacteria are spiral-shaped, mobile bacteria that burrow their way into the body through exposed mucous membranes such as gums, conjunctiva around the eye and vaginal tissue. It lives and persists within the kidneys of its maintenance host — the species in which that particular Leptospira serovar persists and is most often spread via urine or sexual transmission, and can also be spread via milk or placental fluids.

Most animals, particularly dogs or livestock out on pasture, encounter Leptospira bacteria in contaminated standing water that an infected animal has urinated in.

3. Can cats become infected with leptospirosis? If yes, how?

Yes, cats can become infected with Leptospira bacteria. In fact, nearly every mammal including humans is susceptible to infection. It was thought for a long time that cats somehow were not susceptible because they don’t seem to show the same common clinical signs of other animals with leptospirosis. However, it turns out that recent studies have suggested there may actually be a link between leptospirosis and chronic kidney disease in cats, and there is currently more research being done to investigate this.

It is thought that their exposure is mainly through hunting infected rodents or by cohabiting with infected dogs, which would inevitably result in them coming into contact with Leptospira-infected urine.

4. Why does the bacterium, Leptospira, like late summer-fall conditions?

Leptospira is a sensitive bacteria that prefers moderate temperatures and moist environments. So it doesn’t tend to thrive in harsh winters or dry mid-summers and prefers the wet, warm late summer and fall conditions.

5. What are the earliest clinical signs of an infection in livestock animals and pets?

Depending on whether an animal is infected by a “host-adapted” or “nonhost-adapted” strain of Leptospira, clinical signs can vary. Severe, acute clinical signs such as fever, anemia, neurologic symptoms, and death are typically but not always due to a “nonhost-adapted” infection.

6. What are the common clinical signs that cattle display when they have a Leptospirosis infection?

Again, depending on whether an animal is infected by a “host-adapted” or “nonhost-adapted” strain of Leptospira, clinical signs can vary. In cattle specifically, infections with “host-adapted” Leptospira or L. hardjo-bovis often will not result in noticeable early clinical signs and are considered a subclinical infection.

But cattle may experience chronic kidney disease, or more commonly infertility, due to the Leptospira bacteria that has colonized the reproductive tract — specifically the uterus and the oviducts. You may also see sporadic late-term abortions or stillbirths.

If infected by a “nonhost-adapted” strain, clinical signs may include a high fever, anemia due to the breakdown of red blood cells, jaundice, meningitis and death. Groups of multiple late-term abortions or stillbirths are generally associated with L. Pomona infections as well. Occasionally, cases of severe reduction in milk production and blood-tinged milk have also been associated with Leptospirosis.

7. Can nutritional deficiencies in vitamins or minerals play a role in a livestock animal and a pet’s susceptibility?

While I am not aware of any specific nutritional deficiencies that can lead to an animal’s increased susceptibility of contracting Leptospirosis, any significant nutritional deficiency has the potential to lead to a compromised immune system and therefore an increased risk of developing any disease.

8. What treatment is available for Leptospirosis?

The good news is that several different antibiotics are very effective against Leptospirosis. Most commonly penicillin, tetracycline and oxytetracycline, ceftiofur, tilmicosin, or tulathromycin are used to treat Leptospirosis and eliminate the bacteria that are persisting in the kidneys of reservoir hosts.

Several other types of antibiotics can also be used to treat more acute disease caused by “nonhost-adapted” Leptospira, but are less effective at treating the carrier state within the kidneys.

9. What methods can livestock and pet owners do to prevent the disease in their animals?

While there are several different effective treatments for Leptospirosis in the form of antibiotic therapy, prevention is always the best medicine. There are Leptospirosis vaccines commercially available for cattle, dogs and horses. It is important to follow all label instructions when administering these vaccines and to follow the advice of your veterinarian. Often multi-way vaccines for cattle will include Leptospirosis coverage and will generally require a 4-week booster after initial administration, followed by an annual booster.

Separating your animals from natural water sources, particularly standing water, may prevent exposure as well. And always practice good rodent and pest control because rats, mice, and raccoons (among other wildlife) are known to carry and spread Leptospirosis.

10. How does Leptospirosis transfer to humans?

It is most often contracted due to exposure to urine or water sources containing the Leptospira bacteria. Exposure and subsequent infection can occur after contact with pets or livestock that are infected, after recreational swimming in natural water sources, and even after floods and exposure to floodwater.

The infected water or urine then comes into contact with the mucous membranes, allowing the Leptospira bacteria to penetrate susceptible areas like eyes, the mouth, or broken skin.

11. What are some steps owners can take to reduce the spread between themselves and an infected animal?

Good hygiene and personal protective equipment are most important, in addition to vaccinating your dogs and livestock. Wash your hands regularly, and wear gloves when working with livestock or animal urine. And if there is a risk of urine splashing like in a milking parlor, safety glasses can be important as well.

12. Is there a checklist of items farmers and pet owners should conduct every summer to reduce the spread of Leptospirosis or any other common blood infections?

Be sure any animals that can be vaccinated are vaccinated. Keeping a closed herd is always a good idea if you want to reduce introducing and spreading disease, and diligent hand-washing and personal protective equipment wearing is a must.

Editor’s note: Tara Gaab is a resident in the Field Service Department of Clinical Studies — New Bolton Center for University of Pennsylvania’s School of Veterinary Medicine.

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