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Keeping Up with Canine Leptospirosis

Leptospirosis is found worldwide in both wild and domestic animals, but in small animal practice we are most concerned with this disease in our canine patients. The number of cases has been increasing worldwide, and this may be due to the increased urbanization and contact with wildlife hosts, such as raccoons, skunks, opossums and rodents. As a result, small-animal practitioners across the world are learning to be on the lookout for this infection more and more.


A threat to all dogs, large and small

For small-animal practitioners, leptospirosis has long been considered a disease of large dogs and, in particular, of the hunting breeds, which are most active swimming and running in wild outdoor settings. Because of the perception that these dogs are at increased risk of exposure, they are more commonly vaccinated against the disease.

Over the past 5–10 years, however, we have seen an increase in leptospirosis cases in small-breed dogs, often in urban settings. Historically, this subset of the canine population was less likely to be vaccinated both because they are perceived to be at lower risk of exposure—after all, pugs and pomeraneans are not typically romping around woodland swamps—as well as because there is some evidence small breeds may be more predisposed to reactions to this particular vaccine. But the infection is appearing more frequently in these unvaccinated small dogs, and it is well known that the rat population in cities can also be a common source of exposure to these smaller dogs. Veterinarians should remember to consider leptospirosis in these smaller patients that present with symptoms that may suggest the infection.

Symptoms can be vague and common

The suggestion of a  Leptospira spp. infection may be all that a given set of symptoms has to offer. A particular challenge with diagnosing leptospirosis is that the symptoms are nonspecific and may resemble many other conditions. It is important to keep leptospirosis on your differential diagnosis with dogs presenting with any of a wide range of symptoms, including fever, lethargy, anorexia, dehydration, vomiting, diarrhea, abdominal pain and muscle pain and stiffness. Occasionally, uveitis, coagulopathies and respiratory symptoms, such as coughing and dyspnea may be evident. In many cases, the minimum database will reveal azotemia with unconcentrated urine and may show increased liver enzymes indicating an acute renal injury and possibly liver involvement. Less commonly, however, dogs may appear outwardly healthy and the only abnormality noted is moderate-to-severe polyuria and polydipsia (PU/PD) and normal chemistry findings with or without concurrent glucosuria.

New diagnostic options

Historically, the most common testing method for diagnosing leptospirosis has been with serology, using the microscopic agglutination test (MAT). Due to the complexity of performing this test, it can have an extended turnaround time and higher cost than other serologic tests. The IDEXX Reference Laboratories’ offering, the Canine Leptospira spp. Antibody by ELISA, provides fast results at a lower cost to assist veterinarians in diagnosing this potentially life-threatening disease. In early 2015, IDEXX will offer an in-clinic SNAP test to further increase the speed with which practitioners can move toward diagnosing or ruling out leptospirosis. In the acute stages of the infection, practitioners should also consider theLeptospira spp. RealPCR Test, which may detect the presence of antigen in the blood and/or urine. Often, the exact time of exposure is difficult to determine in dogs, and therefore for the most complete diagnostic workup, it is important to consider both serology and PCR testing when a patient presents with clinical signs consistent with leptospirosis.

Find information for your clients about canine leptospirosis at Pet Health Network.

Sarah Tasse, DVM

Sarah Tasse, DVM

Dr. Tasse received her DVM from Colorado State University in 1997. After graduation she worked in a variety of small-animal private practices in both Colorado and New England. She joined IDEXX in August 2011 as a medical affairs marketing manager for Companion Animal Group, Rapid Assay.

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