Mouse bait is proving lethal not only for the biblical number of rodents sweeping through northern New South Wales and southern Queensland but also other animals, including domestic pets, in the affected area.
Jason Salier, a cattle farmer from the north-west slopes and plains region of NSW, said his golden retriever, Poppet, “was on death row” after eating a mouse that had been baited.
Salier drove two hours to Greencross Vets in South Tamworth where Dr Peter Best told him Poppet would need a blood transfusion to survive.
Best rang another client whose dog had a compatible blood type and asked if it could be a blood donor.
“God bless them, they brought their dog straight up and that’s what saved her,” Salier said.
The dog donor’s owners were asked if they would like to see the dog that was about to be saved. “It brought tears to their eyes,” Salier said.
Best said his veterinary practice has been treating animals – “the whole lot, household pets, working dogs” – poisoned by bait for the past four months of the mouse plague. He estimated one in 15 admissions were due to bait poisoning.
“Some days it’s 10 or 15 cases,” Best said. “Because it’s so prevalent we’re routinely testing surgery cases to make sure they might not also have been exposed to poisoned mice and one in 10 is turning up positive.”
The most common type of mouse bait is an anti-coagulate which Best said interfered with the liver’s ability to make normal blood-clotting factors. “As a result within 1.5 to two days of ingestion they can start to show signs of bleeding which can be both internal and external,” the vet said.
Best said the animals presented in haemorrhagic shock, with symptoms including pale gums and rapid heartbeats. Some dogs bled externally with blood coming out of their eyes or in diarrhoea.
“Early in the course of an animal being poisoned, often we can treat them with plasma and vitamin K – but after it’s been in their system a few days that’s not enough … they need fresh whole blood.”
In these cases, as with Poppet, Best relies on calling clients who have dogs with matching blood types and said the response was usually “fantastic”.
Best said all vets in the plague-affected area have been talking about the secondary poisonings they’ve seen. “It’s just been enormous.”
Goonoo Goonoo Road Vet hospital’s Dr Brett Chittick said the cases at his practice, also in South Tamworth, had been particularly acute during the past six weeks.
Chittick said all of the dogs had survived but the worst cases had to have blood transfusions – including one dog whose lungs filled up with blood.
“The big problem is that cats and dogs don’t have to eat the poison, they just have to eat the poisoned mouse,” Best said.
Salier said he had used the bait in sheds that were closed and which Poppet and her sister Peggy couldn’t access. But the mice had burrowed their way in and out.
Salier has lost $40,000 worth of hay to ravenous mice but he said after nearly losing Poppet they’ve “completely got rid of the poisonous baits altogether and are putting peanut butter in spring-loaded traps only in the houses”.
Best does not believe anti-coagulate bait should be banned. “It’s got to be used, you’ve got no choice, unfortunately. In these plague proportions, we’ve got to use every method available.”
Steve Henry, a CSIRO research officer specialising in the impact of mice on the grain industry, said anti-coagulate was the best bait to use in towns and around houses – as opposed to zinc phosphate bait used in fields and paddocks.
Zinc phosphate has a much lower chance of causing secondary poisoning if another animal eats a baited mouse, however it can’t be used in towns and around homes because it converts to a gas when wet which can be dangerous for humans.
Henry said: “The issue with these second generation anti-coagulates is they are perfectly acceptable humane products for the job, but people need to be conscious it takes a while to kill the animal, and while the animal is succumbing to the toxin they become a bit slow … and that sets up them up to be eaten by cats and dogs.”
The CSIRO research officer advised people using anti-coagulate bait to “keep an eye out around your gardens”. Anything that is poisoned should be disposed of in an appropriate way, following council guidance, so they aren’t available for other animals to eat.
