Disease alert: Leptospirosis, a potentially fatal dog disease found in areas of NSW17 Jun 2022
A very serious infection of dogs, Leptospirosis, has been detected across NSW with detections on the Central Coast, Central and Northern beaches areas of Sydney and more recently NSW South Coast. The Australian Veterinary Association (AVA) wishes to alert its members to the outbreak of leptospirosis for dogs living or visiting these areas.
Seven dogs are reported to have been affected in this latest cluster, with four affected in the Newcastle area and three from the South Coast region. This is a wider area than the previous outbreak which occurred predominantly in metropolitan Sydney.1
The current outbreak has a case mortality rate of 71% (C. Griebsch, pers comm); previously, the mortality rate of affected dogs in Sydney between 2017 – 2020 was reported to be 89%.1 The disease is characterised by severe hepatorenal involvement, indicated by one or more of the following: azotemia, hyperbilirubinemia, elevated liver enzymes, glucosuria, icterus, electrolyte derangements, +/-evidence of coagulopathy. Non-specific signs such as lethargy, vomiting, and diarrhoea often occur before onset of clinicopathologic evidence of liver or kidney compromise. Pulmonary involvement, abortion and acute pyrexia can occur, but are less common.1,2
Leptospirosis is a spirochete bacterium belonging to the genus Leptospira. The disease is zoonotic and affects a number of animal species including cattle, sheep, goats, pigs, dogs and horses. Rodents, which shed leptospires in their urine, are considered to be the reservoir host. Dogs can be exposed via contact with infected urine and/or stagnant water. Risk of disease increases following periods of high rainfall.2
Risk factors for leptospirosis in dogs include a history of hunting or exposure to rodents, access to a stagnant water source, and living in or travelling to an affected area (especially within the preceding 30 days).
Areas which have had reported cases of canine leptospirosis include Annandale, Ashfield, Balmain, Cheltenham, Cooks Hill, Crows Nest, Darlinghurst, Elanora Heights, Erskineville, Figtree, Firefly, Glebe, Horsley Park, Ingleside, Lurnea, Marrickville, Medowie, Newcastle, Newtown, Old Erowal Bay, Paddington, Redfern, Sanctuary Point, Speers Point, South Coast, St Georges Basin, Surry Hills, Trunkey Creek and Waterloo.
Any unwell dog with newly discovered azotaemia, no matter how mild or severe, should be tested for Leptospirosis (using EDTA blood and urine samples for PCR) before antibiotic administration. Clinicians seeing cases with a high index of suspicion for leptospirosis should:
- Apply appropriate biosecurity measures, including PPE and isolation of affected animals for at least 72 hours after commencing antibiotics.
- Collect urine and EDTA blood samples for PCR testing before commencing antibiotics. Cystocentesis urinalysis and culture is also strongly recommended because concurrent pyelonephritis is possible.
- Collect serum for antibody testing and identification of the infecting serovar. Cases with a high index of suspicion for leptospirosis that are antibody negative but PCR positive should have repeat serum antibody titres performed two weeks later, as there may be delayed seroconversion.
- Commence treatment with IV fluids and antibiotics. It is worth noting that leptospirosis patients require very intricate fluid management plans. Iatrogenic overhydration (for example, when a patient is put on a set rate of IV fluids for more than 12 hours) is a common cause for patients becoming haemodialysis dependent. Conversely, under-hydration may slow down recovery.
- Ideally place a urinary catheter to monitor urine output and reduce environmental contamination and potential cross-infection
- Counsel the owner to seek medical advice, as it is considered zoonotic.
- Consider referring strongly suspected or confirmed cases to a specialist centre with the ability to perform haemodialysis, as highly specialised intensive care can increase the chance of recovery and survival. If haemodialysis is a therapeutic consideration for a patient, please do not use the right jugular for venepuncture prior to referral.
A monovalent vaccine containing Leptospira interrogans serovar Copenhagi is available in Australia. Current reports suggest that 75% of vaccinated dogs recover, whereas only 24% of unvaccinated dogs recover (C. Griebsch, pers comm). Therefore, vaccination is suggested for dogs with the following risk factors:
- Living in, or travelling to, the known areas affected in Sydney, Newcastle, South Coast, and the surrounding areas
- Dogs that have contact with rats or other rodents
Vaccination offers good protection against Leptospirosis. Two doses of the vaccine, given two to four weeks apart are required, followed by annual boosters. The final vaccination is to be given at least two weeks prior before traveling to areas with outbreaks.
The utility of vaccinating dogs living in, or travelling to, other areas with confirmed cases should be assessed by individual veterinarians and discussed with clients on a case-by-case basis. This vaccine can be combined with a dog’s routine annual health check and vaccination.
Researchers at the University of Sydney are compiling cases for ongoing research into serovar profiles and immunology of the outbreak. They request diagnosing clinicians report suspicious cases and store serum, EDTA and urine samples from affected, in-contact, and vaccinated dogs. Clinicians seeking further information as to how to collect and store samples can contact Dr Christine Griebsch at Christine.firstname.lastname@example.org.
AVA members have full, year-round access to the Australian Veterinary Journal, which recently featured a research article centred around the 2017-2020 leptospirosis outbreak in Sydney. For further reading, members can access this paper here.
Client based information on leptospirosis can be found on the AVA’s VetVoice site here.
- Griebsch C., Kirkwood N., Ward M.P., et al. Emerging leptospirosis in urban Sydney dogs: a case series (2017-2020). Australian Veterinary Journal
- Sykes J.E., Hartmann K., Lunn K.F., et al. 2010 ACVIM small animal consensus statement on leptospirosis: diagnosis, epidemiology, treatment, and prevention. Journal of Veterinary Internal Medicine 25.1. (2011) 1-13