What is leptospirosis?

Leptospirosis is a disease transmitted by a spirochete type bacteria called leptospira interrogans sensus lato .Of this species, there are eight important different serovars for dogs, which are associated to different clinical syndromes. For each serovar there exists subclinicly infected domestic and wild animal species which we characterize as reservoir hosts, and who serve as a source of exposure and disease for dogs, humans and other accidental hosts. When these accidental hosts are infected, they can show severe symptoms.


Dogs may then suffer from one or several of the following symptoms: lethargy and depression, loss of appetite, vomiting, fever, weight-loss, an increase in urine production and water consumption, abdominal or lumbar pain, stiffness caused by joint pain, diarrhea, jaundice, ocular and nasal discharge, petechiae (small red marks on the skin representing tiny hemorrhages caused by a lack of blood platelets), weakness as well as respiratory difficulty and/or cough. Renal failure has now become the main symptom affecting dogs suffering from leptospirosis.


In order to diagnose the disease, we have recourse to different tests. Blood analysis often reveals changes associated with symptoms and affected organs. We may observe a reduction in the number of blood platelets as well as a reduction or increase in the number of white blood cells. Electrolyte imbalances and increase renal enzymes are present when the kidneys have been attained. A reduction in blood PH and CO2 are signs of metabolic acidosis. An increase in hepatic enzymes and the concentration of biliruben (yellow pigment) are signs that the liver has been affected. A urine analysis may reveal a low urine density, the presence of sugar, protein, biliruben, inflammatory cells, red blood cells and renal cells reflecting kidney damage.

There exists other tests that diagnose leptospirosis more precisely, but the one that remains the most frequently used and readily available is the microscopic agglutination test (M.A.T.). It consists of detecting antibodies that are aimed against the leptospiral antigens in the patient’s blood. When the level of antibodies in a single blood sample are elevated in the animal who presents symptoms and laboratory anomalies compatible with the disease, then the diagnosis can be made, given that he did not recently receive a leptospirosis vaccine (although the post-vaccinal titers are generally quite low). In the opposite case, a diagnosis cannot be made if it is based only on the M.A.T. results. Given that the antibody titers may be negative in the first 7-10 days of the illness, it may be necessary to take a second, and sometimes even a third blood sample at 2 to 4 week intervals to observe the rise in antibody levels.


To treat the disease, we use antibiotic therapy and support treatments whose aggressiveness will depend on the clinical condition of the patient, as well as, the degree to which the organs are implicated. The earlier the treatment is administered during the course of the disease, the better the chances of success. In general, support treatment consists of the administration of fluids given intravenously, in order to correct dehydration and electrolyte imbalances. In cases where the animal is unable to urinate, we must use diuretics (medication that increases urine production). Antiemetic, as well as, stomach mucosa protectors may also be used if necessary. We’d aim to returning the animal as quickly as possible, to enteric nutrition (via the digestive tube), either orally (preferably) or by a gastric tube. For animals that do not respond well to conservative treatment, we may turn to more aggressive treatments, such as hemodialysis. The prognosis for dogs with light to moderate renal failure, and are conservatively treated, is generally good. Blood transfusions may prove necessary when there is evidence of hemorrhaging.

Generally, in-clinic recovery is complete, however, it sometimes happens that some dogs who survive the critical period suffer from permanent renal insufficiency requiring treatment for life. It is therefore important to closely monitor all dogs having suffered from leptospirosis, for at least 6 to 12 months following treatment in order to detect any development or complications associated to chronic renal failure such as, hypertension, gastrointestinal ulcers, vomiting and electrolyte imbalances.


Several steps may be taken to prevent the disease. For example, maintaining strict sanitary practices in kennels, controlling rodents and isolating infected animals are good methods for reducing the exposure and transmission of leptospirosis in endemic regions. Fortunately, since they are fragile organisms ,they are easily killed by common disinfectants such as bleach, among others . Vaccination is another good method for preventing the disease, so long as the given vaccine contains the serovars most often implicated. Generally, we administer two doses as early as 7 to 8 weeks of age, at 3 to 4 week intervals, and then annually, Anaphylactic reactions may occur in the hours following vaccination and manifests itself as facial swelling, intense itching, respiratory difficulty as well as, hypotension. When this type of reaction occurs, it is important to consult a veterinarian immediately.

Zoonotic disease

Leptopsirosis is a zoonotic disease, which means that humans can catch it from animals. However, certain groups of people are more at risk of contracting the disease. They consist of, for example, farmers, sewer workers , miners, slaughter house workers, veterinarians and other animal care-givers, people who travel to tropical regions, as well as, people who practice nautical sports in warm or tropical climates. It seems however, that the incidence of disease is also very high in the city.

Given that infectious leptospires may persist in the kidneys of chronically infected dogs, they are excreted over prolonged periods. Contaminated urine is very contagious to humans and other animals. It is therefore important that certain rules of hygiene, such as the washing of hands, be respected when manipulating dogs suspected of having leptospirosis. Gloves and a mask should be worn when cleaning up contaminated material. Gloves should be worn at all times and excretions must disposed of in the appropriate medical containers. All dogs suspected should be isolated from other animals.

Leptospirosis in humans greatly resembles a flu syndrome and is therefore, probably often misdiagnosed. In effect, we may suffer from fever, headaches, chills, muscular pain and sometimes even vomiting, jaundice and anemia. Unfortunately, there may also be a progression of the disease to the point of severe renal and hepatic failure leading to death in the worst untreated cases. In 60-70% of patients suffering from leptospirosis, another diagnosis was initially made. This is why people having potentially been exposed and suffering from symptoms of leptospiroses should alert their doctor in order to avoid any delay in treatment or the appropriate diagnostic procedures.


The transmission from one animal to another occurs by direct contact with infected urine, venereal secretions, bites or by ingestion of infected tissues. Indirect contact with water, soil and contaminated food also constitutes as a frequent mode of transmission. Stagnant water is a good environment for bacterial conservation. Consequently, human and canine epidemics have been associated with heavy rainfall and flooding. This is why the disease is most often seen at the end of the summer or at the beginning of autumn.

Following exposure to contaminated urine, water or infected tissues, the bacteria enters the body via the mucous membranes or broken skin. After prolonged contact, the leptospires may even enter through intact skin. Next, they rapidly invade the blood stream and reach different organs such as the liver, spleen, kidneys, eyes, central nervous system as well as, the urogenital track. The symptoms that will appear depend of the age and immunity of the host, the environmental factors affecting the bacteria as well as, the virulence of the implicated serovar. It seems that males are more at risk than females. Furthermore, dogs aged between 4 and 7 years of age are more at risk than dogs under 1 year. Herding dogs, working dogs and dogs of mixed breed are more at risk than pet dogs, probably due to the greater exposure to sources of water that are contaminated by leptosprises.