Preventing leptospirosis in your dog

To Lepto vaccinate or not?

The case of a sick sheepdog and the conundrum of Leptospirosis (Lepto) vaccinations that may help you make up your mind!

Gus (not his real name) was working in the sun for only ten minutes when he collapsed. Fearing heatstroke his owner cooled him in the dam and he seemed to recover. However over the next few days he became more and more lethargic, and stopped eating.

On examination at the clinic Gus was jaundiced (both his gums and the whites of his eyes were markedly yellow) and dehydrated, and bloodwork showed he was suffering from both liver and kidney failure. He also had several areas of petechiae (small bruises caused by damage to blood vessels) and developed vomiting and bloody diarrhoea.

The question was, was this a result of heatstroke? Or was he already incubating something and working in the sun precipitated a crisis? His owner was sure there was no access to any poisons, and Gus himself was not a scavenger. All his vaccinations were up-to-date.

One of the possible causes for clinical signs and blood results like this is Lepto. The trouble with Lepto is that the only vaccine available for dogs in New Zealand (NZ) contains Leptospirosis icterohaemorragiae, which gives cross-protection against Leptospirosis copenhageni. This is the main strain of Lepto we see affecting dogs in NZ, which is spread in the urine of brown rats. Recent research however has found that many rural dogs have antibodies (indicating exposure, though not necessarily becoming sick) to other strains of Lepto, mainly Leptospirosis pomona and Leptospirosis hardjo, which are not covered with the available vaccine. Lepto can be transmitted through the urine of infected dogs during the shedding phase, and contaminated water bowls are among the most common sources of infection for other dogs. Although there is no record of it happening in NZ, people overseas have contracted Lepto from their infected dog.

The most reliable test for Lepto is the rising antibody test. This involves taking two blood samples, two to four weeks apart, to see if antibodies are being produced in response to infection. Unfortunately, in the majority of cases, the animals are too sick to wait for the results. We started treating Gus on the presumption that he did have Lepto. He was in the hospital for two weeks, but has since gone home and is improving day by day. The Lepto tests have since came back negative, though the lab suggested that anti-freeze poisoning might cause similar signs, there was no clear reason as to why Gus was so sick. Luckily it meant all the other dogs (and humans) on the farm were likely safe.

So what does this mean? Even though Pomona and Hardjo aren't covered by the vaccine we have available (and Massey is working on it!) we still strongly recommend including Lepto vaccination for farm dogs as Copenhageni is endemic in the rat population, especially north of Taupo, but exposure has been found in dogs in Wairarapa and in the South Island. Please do NOT be tempted to give your dogs a dose of cattle Lepto vaccine - it hasn't yet been proved that it is either safe, or that it works!

Many thanks to the owners of Gus for permission to write up his case, and if any of your dogs show signs of weakness, jaundice, excessive drinking or dehydration (sunken eyes, slow skin tent) then assume the worst and contact the clinic ASAP! Additionally, if you have time, make sure none of your other dogs water bowls are contaminated with urine, and make sure any cuts you might have are washed thoroughly - just in case!