Leptospirosis in Dogs Prognosis

Leptospirosis in dogs can be caused by any one of the eight strains that can infect dogs, cats or even humans. There are other strains that affect other animals. Vaccination against one strain does not protect against the others. It is advised to consult a veterinarian as to which is the prevalent strain in your geographical location before vaccinating your dog.

Transmission Can Be Direct Or Indirect

Leptospirosis can be transmitted both directly and indirectly. Direct contact with infected urine, bite wounds, venereal and placental transfer, or the ingested of infected tissue, can infect other dogs, cats and even humans. Crowding increases the spread, so kennels are likely places for infection to take place. Indirect transmission occurs with contact of contaminated food, water sources and bedding. Slow moving and/or stagnant water is an ideal breeding ground for the disease. Freezing temperatures kill the organism so infections are more common in summer and fall and in areas with temperate temperatures.

The Leptospira bacteria multiply rapidly upon entering the bloodstream through a cut in the skin or through mucous membranes. From there it spreads to other tissues and organs, including:

  • eyes
  • spleen
  • nervous system
  • genital tract
  • liver and kidneys

The organism clears from most other organs as the body fights the infection; however, it can remain in the kidneys and be shed for weeks or months thereafter in the urine. Depending upon the strain of the disease, the amount of damage done to internal organs is variable. Recovery begins 7 to 8 days after the infection if damage to the liver and kidneys is not too severe. Depending upon the strain, either kidney or liver disease can develop. Dogs younger than 6 months usually develop liver disease no matter what the strain involved.

Symptoms Vary In Severity

Muscle tenderness, shivering and a fever of 103 to 104 degrees are usually the first signs of acute infection, followed by vomiting and rapid dehydration. Some severely infected dogs develop hypothermia and depression and may die before kidney or liver disease can develop.

Subacute symptoms include:

  • anorexia
  • fever
  • dehydration
  • muscle pain
  • kidney pain
  • vomiting 
  • increased thirst

Dogs with kidney or liver involvement may show improvement in organ function after 2 to 3 weeks or they may develop chronic renal failure. The majority of cases of leptospiral infections are usually chronic or subclinical. Unfortunately, a dog with a chronic infection can show no outward signs but can shed the bacteria in his urine for months or even years, thereby infecting other animals.

Diagnosis and Treatment of Leptospirosis in Dogs

A blood test is the best diagnostic tool even though a false negative can occur after the first 10 days of infection. A urine test is not accurate since the bacteria are constantly being shed through the urine.

The first part of treatment consists of antibiotics, such as penicillin and then doxycycline to cure and prevent a long-term carrier state. Fluid replacement and controlling vomiting along with treating liver and kidney problems is the secondary part. Prevention involves keeping away from infected water sources and animals. Vaccines also work for about 6 to 8 months, but cannot prevent every strain. It is important to determine the strain prevalent in your area and act accordingly.