Leptospirosis in Dogs - An Infection by Leptospira Bacteria
What is Leptospirosis?
Leptospirosis is a disease that affects dogs, other animals and humans. In dogs, the symptoms of the disease range from nonexistent to life-threatening. The problem is caused by an infection with a bacterium known as Leptospira. This bacterium is found around the world and is absent only in polar regions and extreme environments such as Saharan Africa.
Dogs may develop leptospirosis when they come into contact with the urine of infected animals. This encounter is most likely to happen in the stagnant water found in puddles, ponds, bogs and waterlogged soil. If urine is present in the water, Leptospira may enter a dog’s body when the pet drinks or moves through the water. The bacterium is able to penetrate the mucous membranes in the body. It can also enter the body through skin wounds.
A mucous membrane lines the passages and cavities in the body and has important functions. Unfortunately, Leptospira is able to move through the membrane.
The Leptospira Bacterium
The biological classification of the genus Leptospira is complex and changes as new analysis is done. There are multiple species in the genus, which all look the same when viewed under a microscope. The pathogenic (disease-causing) members of the genus are often grouped together as Leptospira interrogans.
Leptospira interrogans is a one-celled bacterium with a long, spiral body. Like its relatives, it belongs to a group of corkscrew-shaped bacteria known as spirochaetes. One or both ends of Leptospira interrogans are hooked and resemble a question mark. This feature gives the bacterium its species name. The bacterium can move, which it does at high speed, rotating and flexing as it travels. It's an interesting creature, despite the problems that it can cause.
Leptospira interrogans contains multiple serovars. A serovar has slightly different molecules on its surface compared to the other serovars in its species. The goal of a leptospirosis vaccine is to protect dogs from the serovars that are most likely to infect them. It can be very effective in doing this. It doesn't give protection against every serovar that could make a dog sick, however. If the serovars in an area change, a different vaccine may be needed.
Causes of Canine Leptospirosis
Leptospira interrogans can infect most mammals, including humans, some domestic animals and many wild ones. Not all of the animals get sick from the infection, however. Some carry the bacteria in their body but don't develop symptoms. Rodents are considered to be the most common transmitter of the disease.
Still water is most likely to contain Leptospira. The water in muddy areas, puddles, drainage ditches, ponds and shallow lakes is potentially dangerous. Wild or domestic animals may deposit urine containing bacteria into the water, or the urine may drain into the water from the surrounding area. In urban areas, garbage soaked with rat urine can transmit the bacteria. Even a damp patch of garden or soil can contain Leptospira if an infected animal urinates there.
The Leptospira bacterium enters a dog's body when water containing infected urine contacts the mucous membranes lining the mouth, the nose, the eyes or the anus. Contaminated soil and food can also transmit the bacterium. The bacteria may also enter a dog through a skin wound, even if this is only an abrasion.
The bacteria that cause leptospirosis can live for a long time at the surface of fresh water. Once they get into a dog's body they enter the bloodstream and travel through the body. Their main targets are the kidneys and the liver, but they affect other parts of the body as well.
Symptoms of Infection
Some dogs with leptospirosis exhibit no symptoms and are said to have a subclinical infection. Some develop a chronic infection. Other dogs exhibit mild symptoms that disappear on their own. Still others experience major problems that require immediate medical attention. If symptoms develop, they generally appear after an incubation period of around four to twelve days.
The symptoms listed below can be caused by other diseases besides leptospirosis. As always, a pet owner should pay attention to their dog's physical condition and behaviour. A vet should be consulted if the pet has serious symptoms of illness, multiple symptoms or mild ones that don't go away.
A Veterinarian Discusses Leptospirosis in Dogs
Possible Symptoms of Canine Leptospirosis
Possible problems in dogs who become sick from a Leptospira infection are listed below. A particular dog is unlikely to have all of the symptoms. The problems that do develop and their severity depend on the serovar of the bacterium, the way in which the dog's immune system reacts to the bacterium and the prior health of the dog.
Possible symptoms of the infection include the following.
- a fever
- loss of appetite
- Increased urination
- muscle tenderness
- joint pain
- reluctance to move (due to muscle, joint or kidney pain)
- depression and lethargy
In some cases, a dog may exhibit other symptoms, such as the following.
- blood in the urine, stool, saliva and vomit
- tiny red spots on the gums or skin
- a yellow tinge to the whites of the eyes and the skin (jaundice)
- fluid accumulation in the legs, abdomen or chest
- difficulty in breathing
Some Common Treatments
A diagnosis of leptospirosis is generally confirmed by a variety of blood tests. Sometimes a urine test is performed as well. Treatment often includes the administration of antibiotics and, if necessary, intravenous or subcutaneous fluids. Intravenous fluids are inserted into a vein; subcutaneous fluids are inserted under the skin. Additional medications may be given to the sick dog, such as one that controls vomiting.
It's important to begin treatment for leptospirosis as soon as possible in order to increase the chance of a happy outcome. Antibiotic treatment is often effective and dogs frequently recover from the illness. Serious damage to the kidneys or liver makes successful treatment more challenging, however. Unfortunately, fatalities do occur, despite medical treatment. The disease always needs to be taken seriously.
In North America, leptospirosis is most common in summer and fall. These are the times of year when it is especially important to be vigilant with respect to dog safety.
Preventing Leptospirosis in Dogs
Leptospira lives in moist areas and is most abundant in the warmer times of the year. Preventative measures can reduce the chance of a dog becoming infected by the bacterium.
- Don't allow dogs to drink stagnant water such as the water in puddles and ponds. Stop them from entering these areas as well.
- Stop dogs from entering drainage ditches.
- If there are notices by lakes advising people of bacterial contamination, don't let dogs enter the lake. If one type of bacterium can survive and multiply there, it's possible that others can too.
- Clear gardens of items that may attract wild animals, such as fallen fruit and garbage.
- Remove or enclose piles of wood and thin out dense shrubbery that may attract rats and mice.
- Improve the drainage in areas of a garden that are continually damp.
- Don't leave water sitting in children's wading or paddling pools for long periods of time.
- Try to keep your dog's immune system strong by giving him or her good food and adequate exercise.
- Investigate the use of a vaccine as a preventative measure.
Vaccines and Vaccination
The leptospirosis vaccine isn't considered to be a "core" vaccine - that is, one that is routinely given to all dogs. However, many vets recommend that dogs in high risk situations receive a vaccination against leptospirosis. These dogs include those who live on farms or in rural areas, those who are taken on hunting or camping trips, those who swim in lakes or have access to ponds and drainage ditches and those who live in areas frequented by wildlife. Some vets say that even dogs who stay in cities should be vaccinated due to the possibilty of infection by urban wildlife.
Early versions of the leptospirosis vaccine caused many unpleasant reactions in dogs, but the latest versions produce fewer side effects. The vaccine needs to be given on an annual basis or even more frequently in order to provide continuous protection.
Vaccination is sometimes a controversial topic. Anyone wondering whether a leptospirosis vaccination is advisable for their dog should talk to their vet. It would be good to know which serovars of Leptospira are common in the area, what serovar protection is provided by the vaccine and what the potential side effects of the vaccination are.
The Leptospirosis Vaccination
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A Zoonotic Disease
Preventing and treating leptospirosis in dogs is important, not only for a dog's sake but also for the sake of humans. Leptospirosis is a zoonotic disease - one that can be transmitted from animals to humans.
In North America, It's possible for a person to catch leptospirosis from a dog or another animal, but this is more likely to happen to people exposed to many infected animals than to a pet owner. Some examples of people at higher risk of developing leptospirosis are veterinarians, farmers and sewage workers. The chance of a pet owner catching the infection from their dog is low, although it isn't zero. The risk is serious enough that people should take precautions (described below) as they care for their dog.
In September 2015, a report about human leptospirosis was published. (The report is referenced at the end of this article.) It confirmed the fact that in North America the disease is a relatively minor problem for the population as a whole, although maybe not for a person who develops the disease. The estimated annual incidence of death from leptospirosis ranges from an extremely low number in the colder latitudes of North America to a low number in the warmer latitudes.
Unfortunately, this low death rate is not the case for people living in tropical areas. In fact, researchers believe that leptospirosis in some tropical countries is often misdiagnosed as other diseases and is actually becoming a serious problem. In these countries, the disease is most common in urban areas with inadequate sanitation and becomes more abundant after heavy rainfall and flooding.
How Can I Prevent my Dog From Transmitting Leptospirosis to Humans?
While you are treating your dog for leptospirosis there are things that you can do to reduce the chance that you, your family or other people will catch the disease. These are good techniques to use at any time. Dogs may not show any sign that they are infected by Leptospira, yet they may release bacteria in their urine for many months after the initial infection.
- Clean up your dog's urine with an antibacterial solution, such as a disinfectant or a mixture of bleach and water. A mixture of one part bleach to ten parts water is often suggested.
- Wear gloves if you're working in an area that may be contaminated by animal urine.
- Don't let your dog urinate in or near still or slow-moving water.
- Don't allow your dog to investigate or urinate in vegetable gardens.
- Stop your dog from entering children's play areas, including playgrounds, sandboxes and wading pools.
- Wash your hands frequently.
With the proper precautions and treatment, people can be protected from a Leptospira infection and a sick pet can very often recover and enjoy life again.
References and Further Reading
© 2013 Linda Crampton
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