Leptospirosis is spread through contact with the urine of infected dogs. It can also spread to humans.
There are two types of the disease, Leptospira icterohaemorrhagiae (Weil's disease) which is normally spread by the urine of rats. This disease can be contracted through direct contact, or from swimming in water that has been urinated in by infected rats.
Symptoms for this form of the illness can range from mild lethargy to more severe symptoms such as abdominal pain and liver damage. It can cause sudden death.
The second form of the disease, Leptospira canicola, is spread through the urine of infected dogs. A dog that has recovered from the disease can still spread it via their urine.
This latter form of the disease can cause kidney failure and can be fatal.
Although the disease is treatable, treatment is not always effective and sometimes involves blood transfusions. Treatment always involves anti-biotics.
It is vitally important that your puppy is fully vaccinated against the disease before being allowed out into the world, where infected dogs and rats may have urinated.
This is just one of the horrible, life-threatening diseases from which your puppy must be vaccinated. The disease is easily contracted, so the utmost care must be taken to prevent your puppy from contact with it.