Canine Leptospirosis: Diagnosis and Treatment

While not everyone has heard of Leptospirosis, it can make dogs very unwell. We advise every dog to be vaccinated against a bacterial infection once a year. Notably, dogs can pass the condition to humans, meaning it is even more vital to prevent it whenever possible.

This article discusses how dogs contract Leptospirosis, their symptoms, treatment options, and how this disease can be prevented. It also touches on the potential for chronic carriers and the long-term outlook for infected canines.

What is Canine Leptospirosis?

This bacterial infection caused by Leptospira bacteria can potentially damage the liver, kidneys, and lungs and can be fatal.

Since leptospirosis is mainly preventable, a better understanding of the disease and the importance of vaccination can help keep your furry friend safe and healthy.

Causes and Risk Factors

Not every dog is highly susceptible to Leptospirosis, and certain conditions must be met before an infection is contracted.

Bacterial Origin (Leptospira spp.)

We typically see the Interrogans Species, and some of the most common serovars here in the UK include L. Australis, L. Icterohaemorrhagiae, and L.Canicola. Knowing the most prevalent serovar(s) is key to a successful vaccination programme.

Environmental Exposure

Rodents and other wildlife are the reservoirs for these bacteria, and dogs can be infected by contact with them or their excretions. Though sometimes seen as a ‘rural’ disease, given the prevalence of rats in the urban UK, it is evident that Leptospirosis is a countrywide problem.

Still, leptospirosis is more commonly seen in rural places and on farms, particularly in humid environments and where there are standing bodies of water such as ponds and lakes.

High-Risk Dogs

Dogs frequently exposed to stagnant water during work or swimming for leisure are at the highest risk. This is especially true if they like to drink from these bodies of water.

Dogs are also at risk if they’re bitten by wildlife, so hunting dogs have a greater chance of becoming infected.

If a dog has an open sore or wound, it could become infected if it comes into contact with bacteria. For this reason, it is wise to keep sores covered when outside and to avoid swimming until they’ve healed.

Puppies are especially susceptible due to their lack of antibodies. This is one of the main reasons why walking a new puppy outside before its vaccination course has finished is so risky.

Recognising the Symptoms of Canine Leptospirosis

It is not uncommon for the initial signs of Leptospirosis to be overlooked, as they can mimic many other diseases, including simple stomach upsets or toxicities.

Though signs usually begin within a week after exposure, sometimes they take longer to become apparent.

Early Warning Signs

The first symptoms include lethargy, food refusal, and fever. Those with a fever may shake and feel warm to the touch. Some dogs will also have conjunctivitis and runny eyes.

As the disease progresses, many develop vomiting, diarrhoea, and abdominal pain.

Advanced Symptoms

Dogs can then develop more serious symptoms, including yellowing of the skin and mucous membranes (jaundice due to liver damage), excessive thirst and urination (due to kidney damage), joint pain, bleeding disorders, and a cough or trouble breathing (if there is lung involvement).

You should contact an emergency vet immediately if these more serious signs develop. If you suspect Leptospirosis, especially if your dog is unvaccinated, inform your vet of this.

Subclinical Infections (dogs showing mild or no symptoms)

It is important to note that not every dog will be affected to the same degree. Some dogs will have subclinical infections and may contract Leptospirosis but remain well or develop mild signs. This is most common in healthy adults. These carriers can then infect other dogs via their urine.

Diagnosis for Canine Leptospirosis

This is a zoonotic disease (meaning it can be transmitted to humans), so it must be diagnosed early on. This allows the people in contact with the dog to take special precautions, preventing them from becoming unwell.

At the same time, we want to identify the infection promptly, as starting the right therapy quickly improves the dog’s prognosis.

Physical Examination

Your vet will check your dog from nose to tail, assessing the colour of its eyes, gums, and skin, taking its temperature, listening to its chest, and feeling for any joint stiffness.

They may already be suspicious of Leptospirosis if there have been local outbreaks and if your dog has not been vaccinated within the last year.

Laboratory Tests

Initially, your vet will likely run some basic blood and urine tests to assess your dog’s liver and kidney function and rule out other causes of its symptoms. They can then run more specific tests, such as a PCR or Antibody MAT (Microscopic Agglutination Test).

A PCR test can be run on the urine, but false negatives can occur with low antigen levels. It provides rapid results, but it must be run before any antibiotics are given to be accurate.

The MAT test can detect antibodies in the blood, but they won’t be present in the early stages of the disease. For this reason, comparing two samples taken a week or two apart is advised.

Differential Diagnosis

Not every dog with the symptoms listed above will have Leptospirosis. Other considerations for these signs include hepatitis, Parvovirus, canine colitis, a recent toxin ingestion, or Immunomediated Haemolytic Anemia.

For this reason, performing diagnostic tests is very important in these patients.

Treatment Options for Canine Leptospirosis

Leptospirosis requires early and aggressive therapy, and many patients will be hospitalised.

Antibiotics

Antibiotics are the mainstay of therapy, and the sooner they can be started, the better. In addition to treating the infection, antibiotics should prevent the spread of the disease and remove low-grade infections so your dog does not remain a carrier.

The treatment of choice is either IV penicillin-derived antibiotics or oral Doxycycline. If the dog vomits, it will initially be given IV medication to prevent it from coming back up.

Supportive Care

The level of support needed will depend on the severity of the clinical signs and how the patient copes. Some will require intravenous fluid therapy, anti-nausea medications, assisted feeding, and pain relief. However, not every individual will need this level of support.

Home Care and Follow-Up

Dogs will take at least a few weeks to recover if they’ve been unwell with Leptospirosis, and this period of recuperation should include plenty of rest, fluids, and a palatable and nutritious diet.

Dogs will need to be seen for regular check-ups, and owners should monitor their progress, ensuring they’re improving and responding appropriately to the antibiotics.

Complications and Prognosis

Sadly, Leptospirosis carries a mortality rate of about 25%, and patient recovery is not always predictable. The prognosis is best for those seen earlier and started on therapy immediately.

Organ Damage

Some patients will develop chronic renal or liver disease that cannot be cured and will need ongoing management for this. This can include prescribed diets, nutritional supplements, and routine monitoring tests.

Chronic Carriers

Dogs with Leptospirosis but not showing any symptoms are called carriers of the disease.

These seemingly healthy dogs excrete the bacteria into the environment when urinating, and other dogs can then become infected when they come into contact with wet soil or contaminated water. The hardy bacteria can survive for several months outside of the body.

Long-Term Outlook

Ongoing liver or kidney disease is common, and dogs can potentially spread the bacteria in their urine for months after diagnosis. For this reason, routine follow-ups are essential.

Prevention of Canine Leptospirosis

Thankfully, most cases of canine Leptospirosis are preventable.

Vaccination

The best way to protect your dog against this bacterial infection is to vaccinate it and ensure its booster vaccines do not lapse. Remember that dogs should start their core vaccination course at about 8 weeks and that the Leptospirosis vaccine only lasts 12 months.

In the UK, there are several different options regarding the vaccine and the number of strains included. Talk to your veterinary clinic about the one most appropriate for your pet, depending on your location, any travel you may have planned, and your dog’s lifestyle.

Environmental Management

Limit your dog’s exposure to wildlife and rodents as much as possible so it has less chance of coming into contact with the Leptospires.

You also want to discourage them from drinking water outside the home unless you’ve brought it along. Bringing along a collapsible bowl and bottle of water is sensible when going on longer walks.

Don’t leave rubbish or food in the garden. If you detect a rodent problem in your home or garden, try to get on top quickly.

Is Leptospirosis Contagious to Humans?

This disease can potentially spread from dogs (and other animals) to humans. When humans contract it, it is known as Weil’s disease.

We can become infected from contact with an infected dog’s blood or urine. When a diagnosis is confirmed, your dog may be kept in isolation, and staff will wear protective equipment when handling it.

The risk of disease spread lessens with treatment and is thought to decrease significantly after three days of antibiotics.

Learn More About Canine Leptospirosis

Contact us if you’re concerned your dog is showing signs of Leptospirosis or has potentially been exposed.

We’re also happy to explain our vaccinations and advise you on whether your dog is up to date with its protection.

FAQs

How do dogs contract leptospirosis?

Urine from carriers (such as rats and mice) contaminate soil and water, which dogs may ingest. They can also become infected if a cut they have comes into contact with infected urine or if they are bitten or scratched by an infected animal.

What are the early signs of leptospirosis I should watch for?

Early signs can include a fever, lethargy, and upset stomach. However, remember that signs such as fever, vomiting, and diarrhoea in dogs can have a wide range of causes, and most dogs presenting with these symptoms will not be infected.

Can leptospirosis be cured?

Yes, dogs can be completely cured of this infection. This is achieved by giving several weeks of antibiotics. The cure rate is about 75 to 80%.