Leptospirosis in Dogs

Leptospirosis in dogs is a disease that is caused by a bacterial organism known as Leptospira interrogans sensu lato. This is a disease that has the potential to be fatal, although death usually only occurs in dogs under six months of age. Because leptospirosis infects the blood stream, it can cause liver and kidney disease. Leptospirosis has many strains of infection, but there are only eight that remain dangerous to dogs.

What Causes Leptospirosis?

In dogs with leptospirosis, the toxins of the bacteria attack the internal organs, causing their eventual shutdown. Leptospirosis can be caused by any one of eight different strains of bacterium. The various strains of infection use wild or domesticated animals as their hosts, such as rats, raccoons, skunks, cows, horses and dogs. These are the eight strains of infection that are most common and highly dangerous to dogs:

  • Bratislava
  • Autumnalis
  • Ictero-haemorrhagiae
  • Pomona
  • Canicola
  • Bataviae
  • Hardjo
  • Grippotyphosa

These strains of infections are passed to dogs through the transmission of urine, wounds, in-utero or through infected tissue. Water sources are also a great place of transmission for the Leptospira organism. The organism is equipped to survive in stagnant water and can be a means of transmission from an infected dog, simply by drinking from the same water dish.

Signs of Leptospirosis

Leptospirosis may or may not show signs of presentation in your dog. The severity and development of leptospirosis in your dog will determine whether or not he shows any outward signs of infection. Some signs of infection include:

  • Vomiting
  • Jaundice
  • Loss of weight
  • Fever
  • Blood in the urine
  • General appearance of pain

Some dogs experience leptospirosis chronically. In chronic cases, a dog is not likely to show any outward signs of infection, but will still be able to transmit it to other dogs.


The diagnosis of leptospirosis can be accurately made through blood and urine samples. Both samples can be looked at under a microscope, and the organism can be seen. Microscopic view will also determine which strain of leptospirosis is present.


After the diagnosis is made, treatment can begin based upon which strain has infected your dog. Certain strains are known for more commonly affecting the blood, liver or kidneys, and treatment can very differently in each situation.

Regardless of which strain is present, treatment will begin by the administration of antibiotics. Penicillin is a very good medication for treating an infection of the blood. However, other antibiotics, such as tetracyclines, are effective at treating infection of the kidneys.

In addition to antibiotics, other medications might be required to help your dog feel more comfortable. If he is vomiting and feeling nauseous, a motion sickness medication can be given. However, the main cause of treatment is to rid the bacterium from your dog’s body so that he does not become a life-time carrier.

Prevent Leptospirosis in Dogs

There are vaccinations available to stop the development of leptospirosis. However, the vaccinations are only effective against four strains.

Because you cannot protect your dog from all strains of leptospirosis through vaccination, it's important to keep him away from stagnant or shared water, as well as wild animals that may be infected.