Leptospirosis is a bacterial infection that’s been described as a re-emerging problem in dogs in North America. (It’s been described as that for many years now so maybe we should drop the "re-emerging" and just say it’s a problem). The causative agent, Leptospira interogans, is a widespread bug that’s carried by a variety of wildlife species, and it can cause disease in many different animals, including dogs and people.
In dogs, lepto is an important cause of kidney disease in some regions, and infected dogs pose some degree of risk to people who come in contact with their urine. While it used to be mainly associated with rural dogs here in Ontario, it’s increasingly being found in urban dogs because of the proliferation of raccoons (that can shed the bacterium in their urine) in cities.
A recent study from the University of California Davis (Hennebelle et al, Risk factors associated with leptospirosis in dogs from northern California: 2001-2010, Vector Borne and Zoonotic Diseases, 2014) looked at 67 dogs with lepto and 271 non-lepto controls. You can’t extrapolate all the results to other regions, because there are different animal reservoirs and other factors to consider, but the study provides some good information.
Here are the highlights:
- Vomiting, lethargy, increased white blood cell count and increased kidney values (azotemia) were the most common presenting problems. That’s not surprising but it’s a constant problem. Dogs don’t come in screaming “I have lepto!!!” They often have vague signs and it may be a little while (and a lot of handling) before lepto is considered or diagnosed. That in-between period poses a risk to handlers if good practices to avoid urine contact aren’t used, so practicing good general infection control and keeping lepto under consideration in any of these cases are important to reduce human risks.
- Dogs with lepto can be pretty sick and treatment can be pretty expensive. On average, affected dogs were hospitalized for 11 days at a cost of $5459 (USD). This doesn’t mean it’s always this expensive. This is a referral hospital that probably sees a caseload that’s sicker than average, but regardless, it’s a serious and often very expensive disease.
- 13% of affected dogs died. Again, that’s based on a biased caseload, but still shows it’s not to be taken lightly.
- The main serovar was Pomona. That’s different than we see here in Ontario, where Grippotyphosa (mainly from raccoons) predominates.
- There were regional differences even in California, with more cases from the central or south coast, Sierra Nevada foothills, San Francisco bay area or north coast compared to the distribution of control dogs.
- Owners of dogs with lepto were more likely to report that their dog had contact with water or wildlife, or visited a ranch. These are risk factors for lepto that have been found in other studies as well, and make sense biologically.
- Other risk factors included being 5-10 years of age or over 10 years of age, or being hound breeds.
Lepto’s a big problem in many regions, including around here. That’s why my dog Merlin’s vaccinated against the disease. Lepto vaccines have gotten a bad rap because the older ones were relatively ineffective and associated with increased risk of adverse reactions. However, today’s vaccines protect against the important strains (for most regions) and are quite safe. Discussing the risk of lepto and whether vaccination is indicated is something every dog owner should do with their veterinarian. Knowing regional trends in lepto help make that determination.
Some information about lepto distribution in dogs is available at http://www.wormsandgermsmap.com We don’t have a lot of cases entered yet, so more data would help. If you are a veterinarian or veterinary technician and would like to know how you can help contribute data, click here.