Leptospirosis: Fact or fiction?

Leptospirosis can make dogs very ill, cause long-term damage, and even be fatal. Incidence rates vary depending on where you live, your lifestyle and the area where you walk your dog, but most dogs are at some level of risk. The disease is seen in veterinary clinics all over the country and has been labelled ‘re-emerging’ as it seems to be on the increase. It’s also zoonotic, meaning it can spread from animals to humans. The human form (Weil’s disease) is thought to be the most widespread zoonotic disease in the world. There were 87 cases confirmed in people in 2017 in the UK alone, an increase from the previous year. Although usually treatable, fatalities can occur. British olympic rower Andy Holmes died of organ failure after contracting Weil’s disease in 2010, days after competing in a marathon rowing event.

What causes it?

Leptospirosis is a bacterial disease caused by a complex group of closely related bacteria of the genus Leptospira. Only some strains cause disease, some affect certain species more than others (cats are rarely affected), and are more prevalent in certain areas. The bacteria survive well in warm, humid areas, and are often found in stagnant water like ponds.

How is it caught?

Wild animals can carry the bacteria for years without signs, spreading it via their infected urine. Once in moist soil or stagnant water, the bacteria can remain infectious for several months. Any pet of any age, going out in any area, can be infected, but dogs that spend lots of time outside, especially in areas prone to flooding and high rainfall, are at higher risk.

As well as being inadvertently swallowed, contaminated water can more rarely pass on the infection through broken skin, such as cuts or scrapes.

Although infected pet dogs’ urine can be a source for humans, more often it comes from contact with infected water, often during watersports.

What signs should I look for?

The signs are not unique to this disease and can be vague. There is often a fever. The bacteria most commonly affects the kidneys, causing tiredness, lack of appetite, vomiting, abdominal pain, and changes in urination. Dogs with a poor immune system may not survive this phase or may go on to have long term kidney damage. Some will have less severe signs. The bacteria often affects the liver instead of or as well as the kidneys, causing similar signs but accompanied by yellowing of the gums or skin. Some dogs have respiratory signs such as a cough, snotty nose or eyes, and less commonly, their muscles are affected causing trembling. The bacteria can attack blood vessels, causing nosebleeds or blood in their faeces or vomiting due to clotting issues, but this is rare.

How do you diagnose leptospirosis?

If a dog presents signs of kidney and liver disease, a fever, and is either unvaccinated or at high risk, leptospirosis will be high on the list of potential diagnoses. Blood and urine tests can confirm if there is any liver and/or kidney damage and changes to red and white blood cell counts and blood clotting tests may be helpful.

There are specific blood and urine tests looking for antibodies to the bacteria itself, but if treatment has already started these can be hard to interpret. Furthermore, if vaccinated, then the immune system will often have produced antibodies in response, so results are again hard to interpret. The most reliable test may be a repeated antibody test, 2 weeks after the first (in an infection, the antibody levels will be rising) – but obviously this does not help with initial management of the patient.

What treatment options are there?

An initial course of antibiotics is given, followed by a longer course of antibiotics to reduce bacterial shedding. Importantly, damaged organs must be supported, often via intravenous fluid therapy, and medications to address any pain and respiratory or gut signs.

In all but the mildest cases, infected dogs are usually hospitalised in an isolation ward. Whether in the hospital or at home, care is needed when handling infected dogs and their blood and urine to reduce the chance of infection. We can advise you on how to disinfect your home, and how to reduce spread as dogs may shed the bacteria for some time.Washing your hands after contact, ideally wearing gloves, disinfecting frequently, and disposing of any soiled bedding are important. Pregnant women, immunosuppressed people, children and other dogs should avoid contact with the dog until at lower risk. Anyone who feels unwell while looking after a dog suspected of having leptospirosis, must seek medical advice.

The outlook is very variable. Some dogs seem to have minimal signs, while in others it is fatal, or causes lasting damage.

What’s the best way to prevent it?

Fortunately, vaccines are available – we include them in the regular primary course in dogs. Unfortunately the immunity does not seem to last as long as with many other vaccines. The manufacturers recommend yearly boosters to keep immunity at a protective level. In the past, two main strains were responsible for most disease in the UK, but recently additional strains have been implicated. Vaccines are now available covering the four most disease causing strains in Europe (L4), compared to the previous two (L2).Vaccination may reduce bacterial shedding in dogs carrying the bacteria without signs, so are of value to public health protection.

If your pet goes outside, it’s hard to eliminate the risk. Avoid stagnant, shady water, especially after flooding, as the bacteria is rapidly destroyed by light and temperatures above 20C.

Is the vaccine safe?

There have been reports in the media questioning the safety of the L4 vaccines, however, there is a risk of adverse effect with any medication or vaccine. The incidence of L2 vaccine reaction is 0.015%, and is 0.069% for the L4 vaccine. Both are statistically low when you consider the risk of actual disease. Our team are always available to discuss the pros and cons of any decision regarding the health and welfare of your pet, so if you have any further questions, please do get in touch and we’ll be happy to help you.