There have been a lot of scare stories in the media recently about the new L4 leptospirosis (lepto) vaccine. Sadly, some of these have been very misleading, and some owners are even talking about stopping using the lepto vaccine, or reverting to an older and less effective version (the L2 vaccine).

In this blog, we’ll have a look at the disease leptospirosis, and the various risks that you need to be aware of. It’s important to remember that not vaccinating doesn’t necessarily put your dog at lower risk of severe illness, just at risk of different diseases!

So, what is Leptospirosis?

Leptospirosis is a bacterial infection caused by bacteria called Leptospira. There are many different varieties of these bacteria, and protection against one variety doesn’t necessarily give protection against the others.lepto

How is it transmitted?

Primarily in urine – the main route is from the urine of infected rats, foxes and other dogs, but infected cattle and humans can also spread the disease. It is unusual in that the bacteria can infect many different species, including humans, through intact and healthy skin and gums – it doesn’t need to enter through a cut, or by being swallowed.

What does it do to dogs?

Once in the body, the bacteria spread through the bloodstream and over two to four days invade many different organ systems. In the process, they often destroy red blood cells causing anaemia, and may disrupt the normal blood clotting mechanisms causing abnormal bleeding.

The organs most commonly affected are the liver (causing hepatitis and jaundice) and the kidney (causing kidney damage and a persistent infection –  dogs may excrete the bacteria for many months even after they have apparently recovered). Occasionally they may also attack the lungs (causing pneumonia), the brain (causing seizures and meningitis), the reproductive tract (leading to abortion or weak, feeble puppies), or the eye (resulting in inflammation and blindness).

Sometimes, the infection is so severe that the dog will die from liver failure, acute kidney failure or septicaemic shock.

What are the symptoms?

As the bacteria can infect any system in the body, they can cause almost any clinical sign! However, the most common symptoms are:

  • Fever
  • Stiff or sore muscles
  • Lethargy and depression
  • Loss of appetite and vomiting
  • Diarrhoea (sometimes with blood)
  • Jaundice
  • Increased urination
  • Abnormal bleeding (e.g. bruises under the skin)
  • Sometimes, sudden death

OK, but it’s not that common is it?

Because most dogs nowadays are vaccinated, it’s difficult to know exactly how common it is. In America, where vaccination is rarer, approximately 35% of dogs are infected. In the UK, the figures we have available suggest it is more like 25% of unvaccinated dogs are infected in any one year. This means that roughly one in four dogs is exposed to the bacteria – and any of them, if they’re unlucky, could develop the full-blown clinical disease; and most of them will be spreading the bacteria to other dogs and (potentially) to their owners.

But isn’t the vaccine really dangerous?

Basically, no.

There are a lot of scare stories around about this, but it’s really important to remember the context. It has been claimed that “In the last two years, regulators have received 2,000 reports of dogs having suspected adverse or fatal reactions”, and this may well be true – but these “suspected adverse reactions” the most common is described as “lethargy” – a perfectly normal physiological reaction to vaccination. With over a million doses being given annually, the actual chance of any adverse reaction (many of which are probably unrelated to the vaccine itself) is only 1 in 1600 – making this a very safe product!

In the UK, all suspected adverse reactions are monitored by the Veterinary Medicines Directorate (part of the government ministry DEFRA); if a product is shown to be unsafe they remove it from sale. So far, they are not reporting any evidence of unusual or alarming numbers of adverse reactions being linked to the L4 vaccine.

Why not go back to the old vaccine?

The old Lepto 2 vaccine only covers 2 strains of Leptospirosis – canicola and icterohaemorrhagiae. However, it provides no protection against bratislava or gryppotyphosa, which are known to be circulating in the UK.

What should I do?

Basically, any medical treatment has risks – anyone who produces a medicine claiming to have no side effects is either lying or it doesn’t work! The trick is to choose the option with the lowest risk for your particular dog – and to do that, you need to talk to your vet for advice about your dog’s lifestyle and risk factors.

If you have any worries about your pet, please make an appointment with your vet, or try our Symptom Guide.