Why Leptospirosis is an Increasing Threat

Dogs across the United States are at risk.

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Originally published in the August 2015 issue of Veterinary Practice News.

Leptospirosis is being seen in dogs in more and more places across the U.S.

The bacterial disease presents with non-specific symptoms such as lethargy, lack of appetite, changes in urination frequency and vomiting.

“We see leptospirosis every week,” said Richard Goldstein, DVM, chief of medicine at the Animal Medical Center in New York City. The hospital is a referral center for dogs from the New York, New Jersey and Connecticut area, including “dogs who never leave Manhattan.”

The disease is caused by a corkscrew-shaped bacterium called Leptospira interrogans.

Signs of leptospirosis in dogs vary depending on the infecting strain, the geographic area in which it was transmitted and the host immune response. Some dogs never exhibit symptoms, while others show mild illness and still others develop severe illness, which can result in liver or kidney disease.

“Since 2013 in Florida, we have seen a 10-fold increase,” explains Carsten Bandt, DVM, Dipl. ACVECC, assistant professor of Emergency Medicine and Critical Care at the University of Florida College of Veterinary Medicine.  

“Leptospirosis is made up of four serovars. The most common in central Florida is grippospirosis,” Dr. Bandt says. There was an initial spike in the summer of 2012, a wet summer.

Although it was once most prevalent in regions with high annual rainfall and warm climates, current indications are that dogs with leptospirosis are found throughout the U.S.

“We are a tertiary center that sees two to three cases of leptospirosis a month in the warmer months,” said Julia Veir, DVM, Ph.D., of Colorado State University in Ft. Collins. “Our patients come from southern Wyoming and across the front range, the area from Denver north to Ft. Collins.”

Leptospirosis is a zoonotic disease. In humans, the symptoms are similar to those exhibited by dogs. Cats, however, are rarely affected.

Bodies of water can be contaminated with lepto from the urine from infected animals.

“Most of the people who get leptospirosis get it from swimming in a pond. Dogs and people can get it from the same pond,” Dr. Goldstein says. “Though it can be transferred directly from dog to owner, that is rarely the case.”

Animals that are outside a lot, even in urban areas, are at risk for contracting the disease.

“It is a bacterium that is spread from the urine of mammalian species like raccoons, mice and rats,” Goldstein said. “If a dog licks a puddle on a sidewalk, or walks in wet grass or in parks where wildlife would urinate, they can ingest the bacteria.”

Caregivers must also be careful. In efforts to prevent the disease, “The staff should protect themselves by wearing gloves and a mask and protect their eyes to avoid contracting it,” explains Terra Martin, DVM, a veterinarian in New Berlin, N.Y., located in the central part of the state.

Until recently, confirming the disease was time consuming and costly and because of that, many veterinarians agree that it has been under diagnosed.

“We test for leptospirosis with the MAT (macroscopic agglutination) test, a blood test,” Dr. Veir says. Because she works at a lab, “We can get the results back in one business day.”

There is good news, though, for those in general practice.

Goldstein worked on the development of a new diagnostic test that became available in late May. It can be performed in an office with an easy-to-apply single-use kit.

“It is the Snap Lepto Test by Idexx Laboratories. It enables an answer in 10 minutes; previously, we had to wait a week.”

“This test can provide an advantage for a general practitioner,” Veir said.

First-line treatment is with antibiotics.

“When treating a dog with leptospirosis, the outcome is dependent on which treatments are initiated,” said Kenneth Harkin, DVM, professor and section head of Small Animal Internal Medicine at Kansas State University’s Veterinary Health Center.

“For instance, a patient with acute renal failure that just randomly gets an appropriate antibiotic under the presumption of pyelonephritis would probably get better. The same patient not treated with antibiotics may die. The outcomes are variable depending on the disease manifestation.

“In addition to supportive care, antibiotics are the primary therapy. We usually start with IV ampicillin or ampicillin-sulbactam and then continue with doxycycline or minocycline once they can take oral medications. Clarithromycin, enrofloxacin, marbofloxacin and ciprofloxacin are also effective at that stage.”

Dogs that are not treated may develop kidney failure, for which dialysis is sometimes recommended.

The treatment is effective.

“We see 83 to 90 percent survival with intensive care medicine, which includes dialysis, on a dog with severe kidney disease,” Bandt says.

Dog owners who fear that their animal is at risk for leptospirosis should consider purchasing pet insurance. “The dialysis and treatment could easily top $3,000 to $5,000,” Veir notes.

The Best Treatment: Leptospirosis Vaccine

Veterinarians agree that the best treatment is for a dog is to stay well and not become sick from lepospirosis. To ensure that, most specialists and generalists recommend the vaccine — for all dogs. When a vaccine was first developed it worked against only one serovar. Today’s vaccine is effective against all of them.

“Where I work, we vaccinate against lepto annually just because of all the wildlife and dairy farms,” Dr. Martin says.

“It is very rare to see a dog who was vaccinated get the disease,” Goldstein says. The first dose is two shots followed by one shot each year.

“The vaccination is effective against the four serovars of leptospirosis and may provide some cross protection against other serovars,” Dr. Harkin said.

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