Leptospirosis in Dogs

Leptospirosis is an infection of bacterial spirochetes, which dogs acquire when subspecies of the Leptospira interrogans penetrate the skin and spread through the body by way of the bloodstream. Two of of the most commonly seen members of this subspecies are the L. grippotyphosa and L. Pomona bacteria. Spirochetes are spiral, or corkscrew-shaped bacteria which infiltrate the system by burrowing into the skin.

Leptospires spread throughout the entire body, reproducing in the liver, kidneys, central nervous system, eyes, and reproductive system. Soon after initial infection, fever and bacterial infection of the blood develop, but these symptoms soon resolve with the reactive increase of antibodies, which clear the spirochetes from most of the system. The extent to which this bacteria affects the organs will depend on your dog’s immune system and its ability to eradicate the infection fully. Even then, Leptospira spirochetes can remain in the kidneys, reproducing there and infecting the urine. Infection of the liver or kidneys can be fatal for animals if the infection progresses, causing severe damage to these organs. Younger animals with less developed immune systems are at the highest risk for severe complications.

The Leptospira spirochete bacteria is zoonotic, meaning that it can be transmitted to humans and other animals. Children are most at risk of acquiring the bacteria from an infected pet.

Symptoms and Types

• Sudden fever and illness
• Sore muscles, reluctance to move
• Stiffness in muscles, legs, stiff gait
• Shivering
• Weakness
• Depression
• Lack of appetite
• Increased thirst and urination, may be indicative of chronic renal (kidney) failure, progressing to inability to urinate
• Rapid dehydration
• Vomiting, possibly with blood
• Diarrhea - with or without blood in stool
• Bloody vaginal discharge
• Dark red speckled gums (petechiae)
• Yellow skin and/or whites of eyes – anemic symptoms
• Spontaneous cough
• Difficulty breathing, fast breathing, irregular pulse
• Runny nose
• Swelling of the mucous membrane
• Mild swelling of the lymph nodes

Causes

The Leptospira spirochete infection mainly occurs in subtropical, tropical, and wet environments. Leptospira spirochetes are more prevalent in marshy/muddy areas which have stagnant surface water and are frequented by wildlife. Heavily irrigated pastures are also common sources of infection. The infection rate for domestic pets has been increasing in the U.S. And Canada, with infections occurring most commonly in the fall season. Dogs will typically come into contact with the leptospira bacteria in infected water, soil, or mud, while swimming, passing through, or drinking contaminated water, or from coming into contact with urine from an infected animal. This last method of contact might take place in the wild. Hunting and sporting dogs, dogs that live near wooded areas, and dogs that live on or near farms are at an increased risk of acuiring this bacteria. Also at increased risk are dogs that have spent time in a kennel.

Diagnosis

Because leptospirosis is a zoonotic disease, your veterinarian will be especially cautious when handling your pet, and will strongly advise you to do the same. Protective latex gloves must be worn at all times, and all body fluids will be treated as a biologically hazardous material. Urine, semen, post-abortion discharge, vomit, and any fluid that leaves the body will need to be handled with extreme caution.

You will need to give a thorough history of your dog's health, including a background history of symptoms, recent activities, and possible incidents that might have precipitated this condition. The history you provide may give your veterinarian clues as to what stage of infection your dog is experiencing, and which organs are being most affected.

Your veterinarian will order a chemical blood profile, a complete blood count, a urinalysis, an electrolyte panel, and a fluorescent antibody urine test. Urine and blood cultures will also be ordered for examining the prevalence of the bacteria. A microscopic agglutination test, or titer test, will also be performed to measure the body's immune response to the infection, by measuring the presence of antibodies in the bloodstream. This will help to definitively identify leptospira spirochetes and the level of systemic infection.