I recently received a call from the owner of Boudreaux, a four year old male bloodhound who lives in Texas. About 6 weeks after attending a SAR seminar in Virginia, Boudreaux came down with a temperature of 105.5 and began limping on his front leg. After a trip to the Emergency clinic (at 10:30 PM of course), he was prescribed on a course of Baytril since his white blood count was low. He continued to run a fever for over a week. His antibiotics were changed to a combination of Clavamox and Doxycycline. Boudreaux was not eating well, and his owner cooked him chicken breast and rice to add to his dog food. A Lyme titer had been negative, so additional bloodwork was run and came back positive for both L. pomona and L. grippotyphosa. Boudreaux had Lepto!
For over 30 years there has been a vaccine for Leptospirosis that has been a part of the annual vaccination for most dogs. Until fairly recently, people had almost forgotten about Lepto, thinking it was a disease of the past, but this is far from true. There have been hundreds of cases of Lepto in the past few years, and often the dogs do not survive.
There are many serovars of Lepto (i.e. many different 'types') icterohemorrhagia ('I'), canicola ('C'), groppotyphosa ('G'), pomona ('P'), bratislava ('B'), ballum ('b'), australis ('A'), hardjo ('H'), and bataviae ('bb'). The current lepto vaccine contains antigens from 'I' and 'C' and provides immunity to these two serovars. Since the vaccines do not have antigens for the other serovars (G, P, B, b, A, H, bb), these strains of Lepto can cause disease and death in dogs since they do not have immunity provided by vaccination.
Most serovars of Lepto replicate in the kidneys and are shed in the urine. Sources for infections for dogs in urban and suburban areas is related to carrier animals such as raccoons, opossums, skunks, squirrels, mice and rats. Outbreaks have followed periods of heavy rainfall or flooding, since the organism can survive for months in urine saturated, moist soil.
Lepto infects the dog by penetrating mucous membranes or entering through skin abrasions after the dog has been exposed to contaminated water, urine, or an infected animal. The viremic phase can persist for several days to a week after exposure and may be associated with fever, depression and muscle pain. Classic 'I' infection is characterized sudden hemorrhagic disease or severe liver failure. Dogs are jaundiced, depressed, run a fever and show signs of muscle pain. Dogs infected with 'C' show signs of sudden kidney disease and less liver involvement. The "B" serovar can cause depression, jaundice, fever and loss of appetite. Dogs infected with 'P' or 'G' often show signs of depression, vomiting, and lack of appetite as a result of sudden kidney failure.
Diagnosis of Lepto is often made by general bloodwork and also by a titer (serology), to determine which serovar is involved. In general, a high titer (>1:800) is enough to make a diagnosis of Lepto. Some titers can be elevated in response to vaccination or exposure and do not mean infection, so the interpretation of the titer is important, not just a number. Treatment of Lepto involves antibiotics (Penicillin and Doxycycline) as well as supportive care (fluids primarily, as well as other measures). Lepto can also infect people, primarily through urine, therefore care must be taken in handling a dog with Lepto. Even after recovery from a Lepto infection, a dog can still shed Lepto in the urine for months.
Just as in human medicine, diseases that were long thought to not be a problem are still out there and can still cause illness and even death. Be aware of Lepto, and if your dog shows any of the signs and is not responding to therapy, a Lepto titer may be in order. Lepto is still a disease to be concerned about.
P.S. Boudreaux was one of the lucky ones and has survived the leptospirosis infection.