Leptospirosis is an emerging threat to Australian dogs, with cases rising sharply in urban and coastal areas since 2017. Here is what every dog owner needs to know about recognising symptoms, acting fast, and protecting your pet in high risk seasons.
Key Takeaways
- Leptospirosis is an emerging disease in Australian dogs, with cases increasing significantly since the first urban outbreak in Sydney in 2017.
- The predominant serovar in NSW has shifted from Copenhageni to Australis, which is carried by native wildlife including bandicoots and native rodents.
- Seasonal risk peaks after heavy rain and flooding, particularly during the warmer months in southern states and the wet season (November to April) in tropical northern Australia.
- Vaccination is not yet routine across Australia but is strongly recommended by the Australian Veterinary Association (AVA) for dogs in identified risk areas.
- Leptospirosis is zoonotic: infected dogs can pass the bacteria to humans. Wear gloves when handling a potentially infected dog's urine.
- If exposure is suspected, contact an emergency veterinarian immediately. Early antibiotic treatment dramatically improves survival.
Why Leptospirosis Is a Growing Concern in Australia
Historically, leptospirosis in dogs was considered uncommon across much of Australia. That changed in 2017 when cases of highly fatal canine leptospirosis emerged in urban Sydney. Since then, the disease has been diagnosed with increasing frequency in New South Wales, and cases have also been reported in Victoria, Queensland, and the ACT.
Research published in the Australian Veterinary Journal has documented the changing epidemiology. Initially, serovar Copenhageni (carried primarily by rats) was the dominant strain in Sydney's urban outbreak. More recently, serovar Australis has become the most commonly identified cause of canine leptospirosis in NSW. Importantly, reservoir hosts for Australis include native Australian animals such as bandicoots and native rodents, meaning dogs in suburban and peri-urban areas with wildlife corridors are at risk, not just those near obvious rat populations.
The Australian Centre for Disease Control notes that between 1991 and 2025, the majority of human leptospirosis notifications in Australia came from Queensland (57%), followed by NSW (20%) and Victoria (15%). While human and canine cases do not map exactly, these figures highlight the geographic spread of the disease.
Seasonal Timing: When Risk Is Highest
Unlike the Northern Hemisphere where spring snowmelt drives risk, Australia's leptospirosis season is shaped by rainfall, flooding, and warm temperatures. Leptospira bacteria thrive in warm, moist environments, typically above 10°C.
- Southern states (NSW, VIC, ACT, SA, TAS): Risk is highest from late spring through autumn (October to May), particularly after periods of heavy rain or flooding. The 2022 east coast floods were followed by a significant cluster of canine leptospirosis cases near affected waterways in NSW.
- Tropical north (QLD, NT, northern WA): The wet season from November to April brings sustained high risk. Flooding, standing water, and high wildlife activity create ideal conditions for bacterial transmission year round in some areas.
Any significant rainfall event can elevate risk at any time of year. Dog owners should be especially vigilant in the days and weeks following storms, floods, or king tides that push water into parks and urban areas.
How Australian Dogs Contract Leptospirosis
Standing Water and Contaminated Soil
The primary route of infection is contact with water or mud contaminated by the urine of infected animals. Leptospira spirochetes penetrate mucous membranes (eyes, nose, mouth) and can enter through cuts or abrasions on the skin. Dogs that drink from puddles, wade through flooded parks, or dig in saturated soil are at significant risk.
Native Wildlife and Rodent Exposure
In Australia, the reservoir host picture is unique. While introduced rats (particularly the brown rat, Rattus norvegicus) carry serovar Copenhageni, native animals including bandicoots, bush rats, and other native rodents are carriers of serovar Australis. Dogs in areas where native wildlife visits backyards, particularly in peri-urban and coastal regions, face exposure even without obvious rat problems.
Dogs used for pig hunting in North Queensland face an especially high risk. Research from James Cook University has identified pig hunting as a significant risk factor for leptospirosis in both dogs and humans in tropical Australia.
Dog to Dog and Zoonotic Transmission
Infected dogs shed Leptospira in their urine, sometimes for weeks after clinical recovery. Shared water bowls in dog parks, boarding kennels, and communal exercise areas can become transmission points. Humans can also contract leptospirosis from infected dogs, making this a genuine public health concern.
Vaccination: What Australian Dog Owners Need to Know
Leptospirosis vaccination has not traditionally been part of the standard C3 or C5 vaccination protocol in Australia. However, the AVA now recommends vaccination for dogs considered at risk, and many veterinary practices in Greater Sydney, the Hunter region, Wollongong, the South Coast of NSW, and parts of South East Queensland now actively advise it.
A registered monovalent vaccine targeting serovar Copenhageni is available in Australia. However, with serovar Australis now the most commonly identified strain in NSW, the current vaccine may not provide full cross protection against all circulating serovars. Despite this limitation, vaccination remains a valuable tool as part of a broader prevention strategy.
Recommended Protocol
- Puppies: An initial dose from approximately 12 weeks of age, followed by a booster 2 to 4 weeks later.
- Adult dogs (first time): Two doses administered 2 to 4 weeks apart.
- Annual boosters: Leptospirosis vaccines require yearly boosters because immunity wanes more quickly than with core vaccines. The final dose should be given at least two weeks before anticipated exposure.
Discuss vaccination with your veterinarian, particularly if your dog lives in or visits identified risk areas, has access to waterways, or encounters wildlife regularly.
Recognising a Leptospirosis Emergency
Early Symptoms That Mimic Other Conditions
One of the most dangerous aspects of leptospirosis is that early signs closely resemble less serious illnesses. Owners commonly report that their dog "just seemed a bit off" for a day or two before rapidly deteriorating. Early signs include:
- Mild lethargy or reluctance to move
- Decreased appetite or refusal to eat
- Low grade fever (normal canine temperature is approximately 38.3°C to 39.2°C; temperatures above 39.5°C warrant concern)
- Vomiting or loose stool
- Muscle stiffness or reluctance to be touched along the back or abdomen
These signs overlap with gastroenteritis, tick borne diseases (including those caused by paralysis ticks in eastern Australia), dietary indiscretion, and early kidney disease.
Red Flag Progression Signs
As the disease advances, often within 2 to 5 days, more alarming signs develop:
- Jaundice: Yellowing of the gums, whites of the eyes, or inner ear flaps indicates liver involvement. Dogs infected with serovar Copenhageni are more likely to show hepatic signs.
- Dark or orange coloured urine: Suggests kidney or liver damage. Dogs with serovar Australis may show glucosuria (glucose in the urine).
- Marked dehydration: Skin tenting, dry or tacky gums, capillary refill time (CRT) exceeding 2 seconds.
- Reduced or absent urine output: Signals acute kidney injury.
- Petechiae: Small red or purple spots on the gums or skin indicating coagulation disturbance.
- Rapid or laboured breathing: May indicate pulmonary haemorrhage, a severe and life threatening complication.
- Collapse or profound weakness
Immediate First Aid Steps
Leptospirosis does not respond to home treatment. However, what owners do in the first minutes after recognising warning signs can meaningfully impact outcomes.
- Check your dog's gums. Lift the lip and assess colour. Healthy gums are pink and moist. Pale, white, yellow, or brick red gums are emergencies. Press the gum with a finger and release: colour should return within 1 to 2 seconds (CRT).
- Take a rectal temperature if possible. A reading above 39.5°C or below 37.5°C is abnormal and urgent.
- Note urine colour. If your dog urinates, observe the colour. Dark, concentrated, orange, or blood tinged urine is a critical finding. Photograph it for the veterinarian.
- Limit movement. Keep the dog calm and resting. Do not encourage exercise.
- Protect yourself. Wear disposable gloves, especially around urine. Wash hands thoroughly. Avoid letting the dog lick open wounds or your face.
- Phone the emergency vet clinic. Call ahead so the team can prepare isolation protocols.
Call the Animal Emergency Service or find your nearest 24-hour emergency vet clinic.
AES operates in QLD, NSW, and VIC. For other states, search for your nearest after-hours veterinary hospital.
What NOT to Do
- Do not "wait and see." Owners frequently delay because early symptoms look mild. By the time jaundice or kidney failure is obvious, organ damage may be severe.
- Do not give human medications. Ibuprofen, paracetamol, and aspirin are dangerous to dogs and can worsen kidney or liver injury.
- Do not withhold water. If the dog is willing to drink, allow small amounts. Dehydration accelerates kidney damage.
- Do not attempt to induce vomiting unless specifically instructed by a veterinarian.
- Do not ignore potential human exposure. If you have contacted the dog's urine without gloves, inform your GP, especially if you develop flu like symptoms.
Getting to the Emergency Vet
Transport the dog in a secure, easily cleaned carrier or on towels that can be laundered or disposed of. Handle soiled materials with gloves and clean surfaces with a dilute bleach solution (1 part household bleach to 10 parts water), which effectively kills Leptospira.
Emergency veterinary treatment for leptospirosis in Australia typically involves several days of intensive hospitalisation. Costs can range from $1,500 to $5,000 AUD or more depending on the severity and duration of treatment. Understanding your pet insurance policy and any applicable waiting periods before an emergency arises can reduce financial stress. For owners concerned about costs, discussing payment plans with the treating hospital is worthwhile.
What Happens at the Emergency Clinic
Veterinary teams typically pursue rapid diagnostics including blood chemistry panels to evaluate kidney (BUN, creatinine) and liver (ALT, ALP, bilirubin) function, a complete blood count, urinalysis, and specific Leptospira testing such as PCR or microscopic agglutination testing (MAT). MAT remains the reference standard but requires paired titres 2 to 4 weeks apart for confirmation.
Treatment generally involves:
- Intravenous fluid therapy to support kidney perfusion and correct dehydration.
- Antibiotic therapy: Doxycycline is the antibiotic of choice, effective in clearing the acute infection and reducing the carrier shedding state.
- Supportive care: Anti nausea medications, gastroprotectants, and nutritional support.
- Monitoring: Serial blood work to track organ function, urine output measurement, and assessment for complications.
Survival rates for dogs receiving prompt, aggressive treatment are generally favourable (often reported around 80% or higher), but outcomes worsen significantly with delayed treatment or when pulmonary haemorrhage develops.
Recovery and Home Care
- Complete the full antibiotic course: Doxycycline is typically prescribed for a minimum of 2 weeks to eliminate the carrier state.
- Recheck blood work: Kidney and liver values should be monitored at intervals recommended by the treating veterinarian.
- Hygiene precautions: The recovering dog may shed Leptospira in urine for several weeks. Clean urination areas with dilute bleach. Prevent other pets and children from contacting the dog's urine. Use gloves during cleanup.
- Gradual return to activity: Dogs recovering from organ injury should not resume vigorous exercise until the veterinarian confirms adequate function. Our Rebuild Your Dog's Stamina This Spring Safely offers useful principles.
- Vaccination reassessment: Prior infection does not guarantee lasting immunity against other serovars. Discuss future vaccination with your vet.
Preventing Leptospirosis Exposure
- Avoid letting dogs drink from puddles, ponds, creeks, or communal water bowls in parks.
- Carry fresh water and a portable bowl on walks.
- Be especially cautious after heavy rain, floods, or storm events.
- Rinse your dog's paws and underbelly after walks through wet or flooded areas.
- Manage rodent attractants around the home: secure bins, remove fallen fruit, and seal entry points.
- In areas with bandicoot or native rodent activity, supervise dogs outdoors, especially at dusk and dawn.
- In multi dog households, isolate any dog showing early illness signs until veterinary assessment is complete.
Spring and summer also increase exposure to paralysis ticks along the east coast, which can cause life threatening illness. A comprehensive parasite prevention plan, covered in our Flea and Tick Prevention for Dogs in Australia (2026), complements leptospirosis protection.
When to Seek Emergency Care: Quick Reference
Contact an emergency veterinarian immediately if your dog shows any of the following after potential exposure to standing water, flooded areas, or wildlife:
- Fever above 39.5°C
- Jaundice (yellow gums, eyes, or skin)
- Dark, orange, or bloody urine
- Refusal to eat for more than 24 hours combined with lethargy
- Vomiting that does not resolve within a few hours
- Rapid or laboured breathing
- Collapse, severe weakness, or inability to stand
- CRT greater than 2 seconds or pale, tacky gums
Leptospirosis is always a veterinary emergency. Early treatment saves lives. When in doubt, call your nearest emergency vet.
Animal Emergency Service (AES)
Call the Animal Emergency Service or find your nearest 24-hour emergency vet clinic.
AES operates in QLD, NSW, and VIC. For other states, search for your nearest after-hours veterinary hospital.
Frequently Asked Questions
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Is the leptospirosis vaccine part of the standard dog vaccination in Australia? ↓
Which animals carry leptospirosis in Australia? ↓
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Dr. Ana Reyes
Emergency & Critical Care Veterinarian
Emergency and critical care veterinarian — life-saving first-aid guidance and emergency recognition for pet owners.
Content Disclosure
This article was created using state-of-the-art AI models with human editorial oversight. It is intended for informational and entertainment purposes only and does not constitute veterinary medical advice. Always consult a licensed veterinarian for your pet's specific health needs. Learn more about our process.
