Leptospirosis is a bacterial disease of great importance as it can affect both humans and animals, and can readily be spread from one species to another (i.e., from our dogs to us). For many years the occurrence in pets was rare, however, in the past few years, the disease has become diagnosed more frequently-I myself have treated four dogs suspected of having Leptospirosis just this past year. The disease is caused by a bacteria that is spread through the urine of infected animals into the soil and water where it can survive for up to 180 days, given the right conditions. Then, as other animals come in contact with this contaminated area, the bacteria can then be taken up through their skin and mucus membranes (gums, nose, eyes) or through drinking the contaminated water (another reason to stay clear of puddles!).
There are several environmental factors conducive to letting this bacteria flourish and increase risk of exposure. Warm, moist environments favor this bacteria, and they especially love stagnant water. With that being said, Leptospira do need water or damp soils to survive, and they will rapidly die on dry surfaces. The density of animal population, such as kennels and urban settings, also increases urine contamination and thus exposure. Also, areas that are heavy populated with rodents or wildlife also increases risk; they serve as “innocent hosts” meaning they are not affected by disease, but they continue to spread it to the environment through urination.
The clinical signs of disease can be vague and mimic many other disease processes. Signs can include fever, lethargy, loss of appetite, muscle stiffness or soreness, or vomiting and diarrhea to name a few. If the liver is involved, a yellowish discoloration of the gums or whites of the eyes can also be observed. Because Leptospirosis can look like any other disease, confirming the infection is generally not an “ah ha!” diagnosis when your pet walks into the exam room. This is something I tend to diagnosis by a “second round of tests” when the initial blood work and urinalysis look suspicious for disease. What can raise a suspicion of a Leptospira infection is an elevation in both kidney and liver values and sometimes the white blood cell count. If this is observed, your veterinarian will then recommend a special blood and urine test be sent to an outside laboratory. These results can take several days, and so antibiotic treatment is often started prophylactically pending the confirming results.
Most infections are subclinical, which means no signs of disease will ever develop and your pet will never experience illness. However, if your pet does develop sudden signs of disease, and those signs appear severe, we generally give a guarded prognosis (50/50 chance of survival). If your pet becomes ill, the extent of care needed depends on the severity of disease, but in my personal experience, the treatment generally requires a hospital stay with extensive supportive therapy. Without treatment, Leptospirosis can lead to kidney failure, liver failure, and even death. Blood or plasma transfusions are sometimes needed if the body losses its ability to clot due to liver compromise. Yes: this can be one bad bug.
So, how can you keep you and your pets safe? In addition to good sanitation practices and limiting your pets access to areas with standing water, there is a vaccine available. Vaccines contain what are known as “serovars,” which are “components” of the bacteria used to stimulate protection from disease. However, there is a catch. There are at least nine serovars, or strains, that can cause disease, yet the vaccine contains only a fraction of these, offering incomplete protection. Often people think their dog is safe from disease because it has been vaccinated, but sadly, this is not the case. Additionally, immunity may only last 6-8 months, and some veterinarians recommended that you should vaccinate high-risk dogs (such as dogs who hunt, show dogs, dogs with access to lakes and ponds, and endemic areas) every 4-6 months. Vaccines do not come without risk, and the use of this vaccine with regards to risk vs. benefit is definitely a conversation to have with your veterinarian. Your veterinarian can assess your dog's risk of exposure, discuss the most common “local” serovars found in your specific area and can recommend a vaccine protocol that makes sense for your pet.