Rats and mice can be a problem all year round but are often discovered in the winter months as they seek shelter. In an effort to evict the creatures, many people head straight to the shops to purchase rat bait without a second thought.

Though the bait is placed for rodents, it can be incredibly toxic for an unsuspecting pet dog, like Cosmo.

Christina Cornioley's pet dog and best friend, one-year-old cocker spaniel Cosmo, has eaten rat bait while out walking in Daylesford twice this year. The first sign something was wrong was that he had passed a bright green motion so she rushed him to the vet, where she was informed he had ingested rat bait.

It happened again shortly afterwards and so Cosmo is only walked on the lead now. Ms Cornioley said it was a frightening thing to happen and so she wants people to be aware that by putting out rat bait, other animals, including dogs, can come into contact with it.

She wants to raise awareness of how sick it can make dogs so other owners don't have to go through what she has.

Ballarat Veterinary Practice's Dr Melissa Hutchison said it was fairly common for dogs to present at the vet after eating rat bait.

She said there were a number of different rat bait products on the market which had all been created to be as tasty as possible to attract rats, and as a result, were also commonly sniffed out by dogs looking for a tasty treat.

Dr Hutchison said it could take from a couple of days to a week after ingesting bait for a dog to begin to show symptoms.

The most commonly used rat baits affect the way a dog's blood clots so Dr Hutchison urged dog owners to take their dog to the vet as soon as possible if they suspected their dog may have ingested bait. Initial treatment involves making a dog vomit to bring up the rat bait and possibly a blood test to check how much bait is in the dog's system.

Once the toxicity takes hold, the dog will start to bleed from its gums or into its lungs or intestines as the bait acts like a blood thinner, meaning that a dog's blood will stop clotting.

"So from an owner's point of view, they might see a dog that is lethargic or that has pale gums or that might have signs of bleeding where there is no wound," she said.

The antidote to this is giving a dog Vitamin K, usually in tablet form, so the blood starts clotting again.

Dr Hutchison said given that rat bait was designed to be highly toxic, it could stay in a dog's system for up to six weeks, so treatment for dog owners could be costly if a dog needed to be treated with Vitamin K for that period of time.

The earlier the symptoms are caught the better, because a dog can become severely anaemic and may need a blood transfusion if they have been bleeding internally for a significant period of time.

Dr Hutchison said it was not safe to use rat bait around dogs due to the toxicity.

"The most foolproof way to control rats and mice is to trap them, so not putting out any bait that a dog can eat. Obviously it's not nearly as quick or effective in terms of getting rid of them quickly, but it's safe for dogs."

She said many dogs ate rat bait while out for walks so it was important for owners to be mindful and keep an eye on what their dogs were doing.

"There's not a lot of safe ways to have rat bait and dogs together. We see lots of dogs that have eaten it after they have roamed somewhere they weren't supposed to or the bait has fallen from the roof, where a dog owner didn't think their pet would come into contact with it," she said.

"It's better to keep dogs and bait strictly separate."

She said it was also possible for a dog to be poisoned by eating a baited rodent, but it depended on the size of the dog and how much bait the rat had ingested.

Rat bait can also affect other animals such as rabbits, and less commonly, cats, as they are pickier eaters.