Blocks aren’t blocks when tackling rats and mice


Choosing the most effective block rodenticide can be crucial to eradicate rats and mice. Finding the most effective one for your needs can be difficult, so let’s unpack what block rodenticides involve:

Most domestic rats and mice block baits use some form of anticoagulant poison. These poisons inhibit the enzyme Vitamin K affecting the rodents’ blood, reducing the animal’s ability to clot, and rodents that digest the poison bleed internally and die.

What are anticoagulant rodenticides?

First-generation bait blocks have anticoagulants in them like warfarin, coumafuryl, or coumachlor require multiple feedings to bring about a result. The “second-generation” bait blocks use anticoagulants (brodifacoum, bromadiolone, difethiolone) that are highly toxic after a single feeding. Rodents that digest second-generation bait blocks usually die within 4-6 days.

Anticoagulants found in ‘second generation’ bait blocks are very effective in eradicating rats and mice due to the delay in poisoning after eating. Rodents, especially rats are very suspicious of new food sources. They often will test food and eat small amounts initially to see if they are poisonous. If they see other rodents eat this source of food and die immediately, they will avoid these foods and they will also communicate this back to their colony and the pack will avoid the food altogether. They will, however, voraciously consume food or baits they think are ‘safe’. This is where anticoagulant baits come into their own in regards to efficacy. Due to the way anticoagulants work, a rat can consume a little of the bait and it won’t kill them immediately, so even after the initial ‘taste test’ they will still die a number of days later. This prevents the rodents from connecting the food source to the poison making anticoagulant block rodenticides extremely effective.

Are anticoagulant block rodenticides safe?

Is secondary poisoning possible either via ingestion of the livers of dead rodents or via secondary ingestion of rodent block baits? Well, theoretically it is possible, but realistically, it is highly unlikely. Let’s examine why.

First, most of the anticoagulant block baits used for rodent control are formulated with low dosages of active ingredients ranging from 25 to 50 parts per million. We also strongly recommend all block baits be used with a bait station, to avoid exposure to other non-target animals. Even with primary poisoning or secondary ingestion of bait, a 9 kg dog, for example, would need to consume anywhere from a minimum of 50g to 3kg of popular bait actives (brodifacoum and bromadiolone) to obtain the value needed for a single-dose poisoning. The range does depend on the particular active ingredient, the dog species, and several other factors.

Multiple feedings of these block baits over a prolonged period would require significantly fewer dosages. Still, consider the chances of the average person’s cat, dog, or other pet encountering and entirely consuming enough rats on a periodic basis to accumulate enough poison to cause true secondary poisoning — not to mention enough rats dying above ground in areas accessible to non-target animals. Most companion animals that receive food daily are simply not that hungry.

All this is not to say, however, that secondary poisoning is not possible. The most likely scenario conducive to secondary poisoning would be in those cases of severe or chronic rodent infestations where many rodents (particularly rats) would be poisoned over the course of days or weeks. This would need to be coupled with hungry dogs, cats, or other free-ranging animals foraging and consuming baited rodents daily.

However, there are always exceptions, in circumstances on-farm where the farmer allows “farm cats and dogs” to roam the farm, and feeds them only intermittently, this could pose a problem for those animals. Or for dogs that are non-stop eaters, their behaviour needs to be monitored.  Certainly, if these dogs and cats take full advantage of feeding on any dead rodents which happen to die in areas accessible to them, secondary poisoning can occur. In these circumstances, special precautions must always be considered. 

To prevent poisoning, do not allow your baits to be accessible to any companion or non-target animals. To prevent secondary poisonings, ensure that poisoned rodents are collected daily and either buried or incinerated. In cases of accidental ingestion of bait, or even when a homeowner observes a pet eating a dead rodent, there are likely to be concerns, so if in doubt speak with your vet just to be sure. Having Vitamin K1 on hand to be administered to your animals is an option but this also is something you need to discuss with your vet. So at the end of the day, 100% avoidance of secondary poisoning cannot be guaranteed and it always pays to play it safe. However, when dealing with a rodent plague or problem the anticoagulant block baits are an effective solution to eradicating rats and mice. 

What block bait do we recommend using?

This is a very individual question. However, if you are looking to limit secondary poisoning these bait block products are highly recommended.

Rodenticide blocks like Racumin and Surefire Couma All-Weather Blocks are made from the active ingredient Coumatetralyl.  Coumatetralyl is metabolised quickly so dead rodents carry very low residues.  This decreases the risk of secondary poisoning to pets or wildlife who may scavenge on the dead rodents. 

Using the multi-feed approach, Racumin and the Surefire Couma Blocks will kill in a similar timeframe as a single feed bait (3-8 days) without the risk of bait shyness. These blocks are formulated as wax blocks for better weather resistance. Racumin and Surefire Couma blocks are useful in damp locations such as sewers or gutters, or outdoor locations where loose grain baits spoil quickly. Rats and mice like to gnaw their teeth on hard surfaces so the wax blocks are ideal.

Racumin blocks and Surefire Couma Blocks can be used around the farm, in industrial buildings, and in crop situations as part of a rodent control strategy.

Another good block bait product we recommend is the Tomcat II All-Weather Blocks or  Surefire All Weather Rodenticide Blocks (Red). These blocks are for the Control of Rats and Mice including those resistant to other anticoagulants, in and around domestic, commercial, public services, and industrial buildings.

Tomcat II All-Weather Blocks and Surefire All Weather Rodenticide Blocks provide you with the power of a single feed, high palatability, Brodifacoum-based rodent bait and are recommended are professional rodent control.

Both the Tomcat and Surefire All Weather Rodenticide Blocks are used to clean out persistent mouse infestations where control is difficult or resistance to other baits is suspected. A hole in the centre allows you to place it on securing rods in bait stations or nail or wire it in place.

The Tomcat II and Surefire All Weather Rodenticide Blocks are a brodifacoum-based formulation featuring an enhanced blend of food-grade materials which have been demonstrated as providing superior palatability and attractiveness to rodents.  They also contain a powerful bittering agent to reduce the likelihood of accidental consumption.

Surefire Difenate Blocks ready to use bait for the control of brown or Norway rats and mice, including those resistant to other anticoagulants including Warfarin.

Surefire Difenate Blocks are for use in both damp & dry situations, in and around buildings, including industrial, commercial, agricultural, public services, and domestic structures. These blocks contain the active ingredient difenacoum which works well on rats that are resistant to anticoagulants. This formulation is attractive to rats and the purple block colour gives positive identification to the active. It contains Bitrex which helps prevent accidental human ingestion. 

Surefire Broma Blocks are excellent for controlling rats and mice, including those resistant to other anticoagulants, especially in damp areas.

Surefire Broma Blocks Rodenticide is a bromadiolone based formulation featuring an enhanced blend of locally sourced food-grade materials which have been demonstrated as providing superior palatability and attractiveness to rodents. They also contain a powerful bittering agent to reduce the likelihood of accidental human consumption. These blocks can be used indoors or outside.

We recommend bait stations when using blocks

Whenever using blocks we recommend the use of bait stations. Bait stations come with high-quality, tamper-resistant bait station that protects children, pets, livestock and wildlife from accidental bait and traps exposure.

Our Bait Stations comes with bait securing rods that hold baits including the Racumin, Talon Pellets, Surefire Allweather Blocks, Couma Blocks, Racumin, and Tomcat II Blocks etc, securely in the station. The station is suitable for use with wax block, grain bait or pellets.

Specialist Sales have a comprehensive range of block rodenticides and we encourage you to look at our product range to find the best product for you and your needs. 

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