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Leptospirosis 1

Pet Tales
by Barry B. Burtis D.V.M.

Leptospirosis

It was all really quite low key in the beginning, There was nothing to indicate a serious, possibly life threatening, battle had begun. Her owner, in a matter-of-fact manner, listed the signs that had led her to bring Bonna, a grey and white spayed female husky, born in 1997, to see the veterinarian. Bonna had been off her food the day before, but, that wasn't unusual, almost once a week she would have a day when she wasn't very hungry. Her stomach had been doing a great deal of rumbling the evening before but that seemed better now. She drank water and had no trouble keeping it down. She was quite quiet, as she usually was, when having an off day. However, even though quiet on such days, she could always be enticed to play a bit. This time, though, she had even refused to go for her morning walk. Her owner was certain that meant, something, was very wrong.

The veterinarian gave Bonna a thorough physical examination. Her body temperature was 39.5 Celsius, just a bit above normal. The mucus membrane colour of her gums and eyelids was perhaps a bit pale but still quite pink. Her pulse and breathing rate were normal. Her heart and lung sounds were normal when her chest was auscultated. Nothing unusual was detected when her abdomen was palpated. Her lymph nodes were normal. Bonna's weight had not changed from her last visit, 5 months earlier. From her check-over there was no apparent cause for her symptoms of mild fever, loss of appetite and lethargy.

Furthermore, a diagnosis for Bonna's problems could not be made when results from a blood sample, collected when she was examined, were received from the laboratory, a day later. Her complete blood count was normal. Her hemoglobin level was fine, no evidence of anemia. The number and types of white blood cells in her circulation all okay. Twenty-two different indicators were measured in biochemistry tests performed on the serum or fluid portion of the blood. Protein levels in the blood, enzymes that are used to assess liver, kidney and pancreas health, blood electrolytes, blood sugar level, cholesterol, all these and more are part of  that biochemical profile. Every one of those twenty-two measurements for Bonna were in normal range.

In hindsight, it is not surprising that a diagnosis of the disease that was affecting Bonna could not be made at that early stage. The clinical signs or symptoms of this disease vary greatly depending on the patient and the exact type of agent causing the illness. Sometimes the disease is almost totally inapparent, sometimes it is peracutely fatal - that is, death occurs before any symptoms are detected. This wide spectrum of clinical signs makes a definite diagnosis with routine laboratory tests and physical examination findings essentially impossible. The disease is known as leptospirosis.

Leptospirosis is a disease caused by infection with any of the more than 250 serovars (types or species) of a corkscrew-shaped bacteria, called Leptospira. It is not a new disease, it was first described in dogs in 1899. In many parts of the world it is still an important cause for sickness and death in dogs and people. Until about five years ago, this disease was thought to be of less concern in developed Western countries. In these developed countries the incidence of this disease was thought to have decreased significantly for the dog population. There were several explanations as to why this had happened. A vaccination for dogs against the disease had been available for many years. Also stray dog populations were much better controlled than in earlier times. However, retrospective analysis of data from veterinary teaching hospitals in Canada and the United States has found that the prevalence of leptospirosis increased between 1983 and 1998.

It is a disease that can be very serious and possibly fatal in dogs. It is also a zoonotic disease - a disease that has the potential to spread from animals to people. For these reasons, it is important for dog owners to know about this health problem that seems to be a reappearing disease in dogs.

How do dogs become infected? What symptoms do dogs exhibit if they are infected? How is the disease treated? Is there anything that can be done to prevent it? What happened to Bonna? These are some of the questions about leptospirosis that I will try to answer in my next column.