What is it?

Leptospirosis is caused by infection with Leptospira bacteria, transmitted to dogs in rat or livestock urine. Dogs become infected when their mucous membranes (e.g. gums or genitals) come into contact with stagnant water that has collected animal urine, allowing the bacteria to survive and replicate.

Importantly, leptospirosis can be transmitted from dogs to humans, however this is uncommon.

What is the risk?

In 2022, there were 17 cases reported in the South Coast region of NSW, 5 in the Newcastle region, 2 in the Wollongong region and 6 in other regions of NSW, with 2 being from the inner city of Sydney. Almost half these dogs sadly did not survive. This is likely an underestimate, as not all cases are diagnosed and reported.

Since then, leptospirosis has continued to be reported in NSW and parts of Queensland through 2025 and into 2026, including sporadic cases in the Sydney region. Periods of heavy rainfall and flooding appear to increase risk, likely due to increased environmental contamination and rodent activity.

Risk remains higher in rainy, humid conditions, and in environments where dogs may encounter rodents, livestock, or contaminated water.

Vaccination

The current recommendation from Sydney University has been for dogs living in higher-risk regions (such as the South Coast and Newcastle), or those with exposure to rats or livestock, to be vaccinated.

More recently, updated vaccination options are available in Australia, including multivalent leptospirosis vaccines (e.g. Nobivac® Lepto formulations) that provide broader serovar coverage beyond Copenhageni alone.

This is important, as multiple Leptospira serovars are now recognised in Australia, and broader coverage may improve protection in higher-risk environments.

Vaccination is not 100% preventative, and effectiveness depends on the serovar involved. However, available data (including University of Sydney work) suggests that vaccinated dogs have a significantly improved chance of survival if infected.

Other methods of prevention

Avoidance remains the most important preventative measure.

Limiting contact with stagnant water (including wading, swimming, or drinking) is strongly recommended. Keep food and water bowls indoors where possible.

Avoid exposure to host animals including rodents and livestock, and minimise contact with potentially infected dogs. During known outbreaks, reducing close dog-to-dog contact (e.g. boarding facilities, dog parks) is advisable.

Lepto watch

We ask guardians to be aware of the clinical signs of leptospirosis. Presentation can vary, however early signs may include lethargy, vomiting and diarrhoea. This may progress to excessive thirst and urination, jaundice (yellowing of the eyes or skin), and muscle pain.

At All Natural Vet Care, our goal is to tailor preventative medicine to the individual patient. We will discuss the risks and benefits of vaccination with you during your consultation to determine the most appropriate approach for your dog.