Leptospirosis, ‘Rat Disease/Sydney Dog Disease’ ‘Lepto’ Information Update.

As Leptospirosis is location specific with regards to risk and vaccine protection, the information in this post relates only to our clients in the Illawarra, not to other parts of Australia or overseas.

The behaviour of the vaccines in this disease also cannot be used to understand how Parvo, Distemper, Canine Cough vaccines work, they are two very different topics.

To make for easier reading for non-medical owners, we have taken the liberty to use some general terms such as strain/strains to describe serovars and multivalents etc.

This week we are having a run of worried clients wanting the Leptospirosis/Rat Disease vaccines for their pet.

These owners have seen reports about the fatal Lepto case from Figtree in February. There has only been this ONE case in Wollongong. The Previous recorded case was in 1970s…

  • What none of the clients have realised is that there is No vaccine available in NSW for the ‘strain’ (L. Australis) of Leptospirosis that killed the local Figtree dog…
  • There is a vaccine against Lepto for use in NSW called C2i (BI L.Copenhageni strain). However, as protection is serogroup specific (strain), whilst this C2i will offer significant protection against L. Copenhageni, it will NOT protect against L. Australis…(Figtree strain).
  • Vaccinating with this BI C2i single ‘strain’ vaccine will provide some protection for pets in contact with rats in the Surrey Hills-Newton-Paddington-Crow’s Nest areas of Sydney but will do nothing against our strain seen locally. Owners or visitors to those high risk Sydney Suburbs have been given their own location specific advice and they should follow that.
  • Overseas where Lepto is at constant high levels, different vaccines are available that cover for several ‘strains of Lepto and so do provide good coverage in high risk areas.
  • Historically, Lepto vaccine was the one vaccine most likely to be reported for inducing a vaccine reaction. Over time the vaccines have been improved and the reports of severe pain and of malaise afterwards are less common. The vaccine is a ‘killed’ vaccine that may induce a vaccination reaction as a side-effect of injecting it. One older study found that the Lepto vaccine was highly immunosuppressive, and recommended that the vaccine should not be given in conjunction with other vaccines, but only ever by itself. The BI 2ci vaccine is a combination killed virus vaccine, not a standalone Lepto vaccine, so we never rushed to use it routinely.

Where the vaccine is currently used in our area, the concern then becomes that owners could be lulled into a false sense of security thinking that their Lepto vaccinated pet is protected, when it is not.

If this false sense of security means owners delay presenting their ‘vaccinated’ dog to a vet, then the risk of death increases.

When we treated Lepto overseas in Europe, we didn’t see the level of fatalities seen in the NSW cases in recent years. Maybe, part of the reason for that is that Lepto is on the radar of all vets and owners overseas, but it is not something that reasonably comes to mind early on by owners or vets for Australia cases. It could also be the ‘strains’ here are more aggressive etc.

Our personal experience, and that of overseas vets we have checked in with recently, is that early aggressive antibiotic therapy is one of the most important factors to treatment and recovery. Fluid therapy is also super-important, but for many overseas dogs, the main determinant of survival was early use of (often dual) antibiotic therapy. As soon as dog showed early signs of being off-colour with a history of exposure to rats or rat nests or of swimming in stagnant waters etc, then affordable antibiotic therapy commences, even before laboratory results came back.

  • The Illawarra is not currently a high risk area with just One case since the 1970s and that case in a dog who returned from the ACT in the previous 14 days. As the incubation period can be 2-30 days, average 5-15, then the dog in that instance could possibly have contracted the disease from outside our area.
  • Whilst Lepto is an infectious bacterial agent, it is only contagious via secretions like urine, blood etc. Lepto is not airborne like Corona virus, therefore you need really close up contact with infected dogs and their urine etc.


A)In areas of high risk, where an effective vaccine exists to protect against more common ‘strains’, vaccination is of benefit.

B) Anywhere else, you need to know your Risk; Benefit analysis of the Vaccine V Disease risk. Currently, our area is low risk and doesn’t have a vaccine to protect against the current ‘strain’.

If different strains appear and vaccines are available against those strains, then our advice would change,

C) Yes. the disease can be transmitted to humans from dogs. However, by way of context, the most common risk factor for human Lepto in some countries is nothing to do with pet ownership, but rather water sports-particularly freshwater (canoeing) with cuts or wounds on your skin or living near swamps or cane sugar fields.

D) Owners must remain to be alert for any changes in their dog-vaccinated or otherwise-that has been to high risk areas or doing high risk actives like rat hunting etc. Prompt presentation to your vet and the early use of cheap affordable antibiotics could be a game-changing, life-saver for those pets.