If you are trying to control rats and mice, you need to do so with a little thought. Naturally you will want to ensure the safety of your children, pets and wildlife in your area. In addition, you would want to dispatch the rats as quickly and humanely as possible.

Why control rats?

Rats are tenacious, wise and cunning critters. They have been plaguing people for thousands of years and over that time have really learnt how to be ‘as cunning as a rat’.

Their claim to fame started at least three thousand years ago with The Plague. The plague is a disease spread to humans by rats and their fleas. Epidemics of the plague have been recorded in China since 224 BC. The disease occurred in huge pandemics that destroyed the entire populations of cities throughout the Middle Ages. Nasty critters, rats.

It is no wonder that for years mankind has been attempting to control rats and often not very successfully.

Rat baits pose a danger to pets and wildlife

Rodenticides are dangerous. In America, 14% of deaths relating to toxins were due to rat poisons.

The danger to pets and wildlife with rodenticides comes from either primary poisoning or from secondary poisoning.

Primary poisoning is caused when a pet eats the rat bait directly. The commonest way this occurs is when a pet gets into a container of bait that has been incorrectly stored. None of us are infallible and sometimes we can forget that we have a container of rat bait on the shelf in a shed. If the packet is accidentally knocked to the ground, spilling its contents, a pet will readily eat it.

Secondary poisoning is different. It occurs when an animal eats a poisoned rat. The residue of bait in the rat’s stomach is the cause of the toxicity. Often this occurs when an affected rat, perhaps slower and more lethargic than a normal one and thereby less able to defend itself, falls victim to a dog or cat or to a bird of prey such as an owl, a hawk or a falcon.

There are many rat poisons on the market, and some are safer for pets and wildlife than others. No matter which rat poison you use, be especially aware that all of them pose some danger to pets. This danger can be minimised by the careful choice of baits, by using effective baiting procedures and by ensuring you store baits safely.

Multi-feed versus single feed rodenticides

Most rat baits that you can get from the supermarket are based on anticoagulants. These baits are of two basic types. The first are those generally termed multi-feed rodenticides and the second are those that are single-feed rodenticides.

The oldest anticoagulant bait is based on the chemical warfarin. Ratsak is the most commonly recognised. Another readily available rodenticide is based on the chemical coumatetralyl available as the Bayer product Racumin. Both warfarin and coumatetralyl are multi-feed rodenticides. This means that the rat must eat these types of baits over several days to become affected by them. This means that pets and wildlife are less at risk because they either have to consume a large quantity of bait in one sitting or consume small quantities of bait over a long period.

Single feed rodenticides act more quickly. These rat baits are more toxic to rats and pets and a single dose is more likely to cause poisoning. Single feed rodenticides are those containing brodifacoum (e.g.Talon) and bromadialone (e.g.Bromakil). They are commonly available from local supermarkets.

Brodifacoum is at least 40 times more potent that warfarin and is much more likely to cause the death of a rat, a pet or a wild animal with a single feed. Secondary poisoning is also more likely to occur because a rat can have enough bait in its stomach to poison a dog and certainly a bird. Large dogs are less at risk because they are less likely to hunt and because they are less likely to ingest enough bait to affect them.

What are the signs of anticoagulant poisoning?

If a pet is affected by an anticoagulant poison, the signs of the toxicity may not be evident for several days. The main signs of such toxicity relate to anaemia from blood loss. The blood can be lost from many areas of the body but commonly it is seen in bloodstained faeces, blood appearing in the saliva or appearing from the nose. Breathlessness, from blood pooling in the chest cavity, is a common sign also. Weakness is very common and the gums and tongue are usually very pale due to blood loss and the resultant anaemia.

Your veterinarian will treat you pet with Vitamin K and other medications and if the condition is caught early enough, treatment is usually effective, particularly so with the multi-feed rodenticides.

Store rat baits carefully

To minimise the risk of accidental poisoning of pets, wildlife and children, the baits should be placed in areas that are accessible only to the rodents. Safe places are in the roof cavity, between walls, and along known rat runs. Rat baits should be stored in their own container which itself is placed inside another sealed container out of reach of pets and children.

Poisons and pets don’t mix. No matter what rat poison you use, it is dangerous and needs to be used with utmost caution. If you think your pet has eaten some rat bait, see your veterinarian urgently.

Dr Julia Adams BVSc

Article reprinted with permission from Petalia A world of Petcare  www.petalia.com.au. Petalia makes no representations about, and accepts no responsibility or liability for, the accuracy or currency of the information provided.