Spirochetes, the bacteria that cause canine leptospirosis, are slender and look like a bunch of question marks when seen under a microscope.
There are many different species (or serovars) of leptospira bacteria.
Eight of the species can infect and cause health problems to dogs, people, and livestock (e.g. pigs, cattle).
Of these, at least four species are particularly problematic for dogs. They are canicola, icterohemorrhagiae, grippotyphosa, and pomona.
Leptospira bacteria are found not only in dogs and livestock, but also in wild animals (e.g. rats, raccoons, skunks, opossums).
The bacteria are spread in the urine which may end up in water sources. They remain infective in the soil for up to six months.
Leptospirosis is mainly a disease of tropical and temperate climates, because freezing greatly reduces the survival of the bacteria in the environment.
Transmission of Leptospirosis in Dogs
Dogs get infected when the spirochetes gain entry into the dog’s body, usually through direct contact with the urine of an infected animal, or a break in the dog’s skin, or when the dog drinks water contaminated with the bacteria.
As you can imagine, dogs get infected with leptospirosis more readily than people because dogs like sniffing the urine spots of other animals.
People are at a higher risk of getting infected if they come in constant contact with animal wastes, such as kennel owners, veterinarians, and other animal care-givers.
Slow moving water or stagnant water is a perfect breeding place for the bacteria. As a result, outbreaks of leptospirosis often increase when there are floods.
In dry areas, places where there are water sources have higher chances of being contaminated.
Therefore, dogs who spend a lot of time in the water are at increased risk, as are those who have a habit of drinking out of puddles.
Symptoms of Leptospirosis in Dogs
In many cases, dogs infected with leptospirosis show little and mild symptoms. Signs of infection usually appear 4 to 12 days after exposure to the bacteria.
Early signs include:
- Fever (103°F to 104°F)
- Loss of appetite for a few days
- Vomiting
- Depression
- Lethargy
- Muscle pain
- Sometimes diarrhea or blood in urine
Leptospirosis can affect different organs, but primarily the kidneys and/or the liver.
The species canicola and gripotyphosa usually cause kidney damage, and the pomona and icterohemorrhagiae species tend to affect the liver. However, all species tend to cause liver damage in young dogs.
If the liver is involved, jaundice may develop – the whites of the dog’s eyes turn yellow.
This is an indication that the liver cells have been affected and hepatitis has occurred. This may be followed by coagulation problems – there may be blood in the stools or bleeding from the mouth.
If a dog’s liver or kidney has been involved, he may either start to show signs of improvement in the functioning of the affected organ in about 2-3 weeks, or he may develop chronic kidney failure.
Diagnosis and Treatment of Leptospirosis in Dogs
Diagnosis is based on clinical signs as well as positive blood tests. A urinalysis may detect spirochetes in the urine.
Conventional treatment includes the use of antibiotics such as penicillin, streptomycin, or doxycycline to eliminate the bacteria.
Kidney failure and liver disease are treated with fluid therapy and supportive measures are used to control other symptoms such as diarrhea, vomiting, and dehydration.
Prevention of Leptospirosis in Dogs
A vaccine is available for the four species canicola, icterohaemorrhagiae, grippotyphosa, and pomona. Vaccination is recommended at yearly intervals but may be needed more frequently in high risk areas.
However, leptospiral vaccine reactions (such as soreness and swelling of the injection site, temporary appetite loss or ill feeling) are common among dogs.
In serious cases, a dog may have difficulty breathing, or develop hives or facial swelling.
Because of the potential vaccine reactions, if you are not living in a high risk area, talk to your vet to determine if vaccination is justified.