Types of rat and mouse poison (rodenticides)

Rat and mouse poisons can contain various ingredients, but in the UK are broadly made up of three types:

·       anticoagulant baits that cause bleeding by preventing the blood from clotting

·       ‘natural’ cereal based baits that are not poisonous to dogs

·       alphachloralose mouse baits that can cause seizures


Anticoagulant rat and mouse poisons

The anticoagulant baits are the most commonly used. There are several different brands on the market for amateur use, the most common that we come across being Rentokil, The Big Cheese, Wilko, Raco and Tomcat.  They come in many forms including blocks, grain, pastes and gels.  They may come already packaged in pre-laid bait stations or be bought in boxes or tubs of various sizes, each containing a number of blocks, pellets or sachets.  They can be various colours; green, blue, red and black are common but unfortunately there is no standard colour for these products.  They are largely made from cereals and contain small quantities of the active ingredients which is the poison.

The active ingredients, known as anticoagulants, vary but for amateur products they are most commonly difenacoum and bromadiolone, although there are several others.  The strengths of the anticoagulants are usually 0.005% or 0.05mg/g and is can be found on the packet of the rat poison when you buy it.  An animal’s response to the different types of anticoagulant is variable, for example bromadiolone causes bleeding after a smaller amount is eaten compared to difenacoum and therefore difenacoum could be considered ‘safer’.

Many products also include the ingredient ‘denatonium benzoate’, however, this is not poisonous. It contains a bitter substance added to make these products foul-tasting to human beings.  It does not appear to be effective in deterring dogs from eating them however!

What signs will my dog show if they have eaten rat poison?

Eating too much of these anticoagulants can cause delays in blood clotting, meaning that bleeding occurs.  This can happen either externally or internally. Obvious signs to look out for are bruising, blood in the urine or stools, bleeding from the nose or gums, coughing or vomiting blood.  However, internal bleeding may cause lethargy, weakness or paleness, or breathing difficulties (including coughing) if bleeding occurs in the lungs, or lameness if bleeding occurs in the joints.  It takes a few days for the delay in blood clotting to take place due to the way that anticoagulants work, therefore these signs are often not seen not until several days after the rat poison has been eaten.

How much rat poison does a dog have to eat before he/she starts bleeding?

It is impossible to give a specific dose above which bleeding will occur given the many different types and strengths of anticoagulants, but in some cases pets will not have eaten enough to cause poisoning especially if it is only eaten once. However, there is an increased risk if rat or mouse poison is eaten repeatedly in a short space of time because the anticoagulants persist in the body for some time and small doses can ‘add up’ and cause bleeding.  This is particularly common in rural areas and on farms where there is often a larger quantity of rat or mouse poison in the environment and dogs and cats have access to it on a regular basis.

Does my dog require treatment after eating rat or mouse poison?

This depends on several factors: which product has been eaten, what strength it was (it may be stronger than 0.005% if put down by a professional), how much was eaten and whether it was eaten once or over several days.

This means that, although owners are often very worried when their pet has eaten rat and mouse poison, it is worth checking whether treatment is definitely necessary.  Here at Animal PoisonLine we can assess the risk and advise you whether you need to go to the vet. We know about all the rat and mouse poisons on the market and how much a pet needs to have eaten before being at risk of poisoning.

What do you need to tell us when you call Animal PoisonLine?

When you call us please have as many of the following details to hand as possible:

·       the product name

·       the active ingredient and strength – this information should be part of the product information available on the packet or on the internet

·       roughly how much of the bait approximately your pet has eaten in grams

·       whether the exposure was a ‘one-off’ or has been repeated

·       your pet’s weight

Top tips from Animal PoisonLine  to prevent rat poison exposure:

  1. Keep all rat and mouse poison in places inaccessible to your pets, including house rabbits who can access smaller spaces than cats and dogs
  2. If your pet has eaten rat or mouse poison, call Animal PoisonLine to find out if treatment from your vet is needed or whether you can stay at home and not worry
  3. If a professional has put down rat or mouse poison in your house make sure that they tell you what it was and what strength, as well as how much they put down. That way if your pet has eaten some you will have all the information you need
  4. If you notice ANY signs of bleeding you need to go to your vet immediately, taking the details of the rat or mouse poison with you, if possible