We’ll start by saying that no poison is working on a very long run. The best rat poison is in fact a combination of different poisons and presenting techniques, which leads to an efficient mass kill.
Sooner or later if you don’t choose and plan your actions accordingly, the rats will become immune to the poison bait they’re been offered, or they will just simply refuse to eat it due to their taste aversions (bait shyness).
Rats tend to eat small amounts of a new presented foods, especially because they can’t vomit in case of toxic bait.
So logically you have to either gain their trust with nontoxic food and then add the poison, or start with a slow-rate poison which affects them on a longer period of time. At the moment they realize the food is making them sick, it is too late.
Choose the best rat poison to save time and money
Anticoagulants like D-Con Rat & Mouse Bait Pellets, JT Eaton A-C Formula 90 Rodenticide, Tomcat All Weather Bait Chunx, Havoc Rat Poison and many others, will kill the rats in a few days after ingestion by internal bleeding. Some of best rat poisons are faster killers, but you need to be extremely precise when using them because rats can learn to avoid these kind of poisons. Toxic doses of 4-hydroxycoumarin, 4-thiochromenone and indandione anticoagulants are often used in combination with the main anticoagulant poison to increase the damage to blood cells, raising their permeability levels, leading to internal bleeding and anemia, and calmly bringing the rat down. Due to it’s calm death, without major pain, this is questioned to be a humane method of rat extermination. When having this factor in mind, this could be the best rat poison.
Metal phosphides like Motomco Eraze AG and Kaput Combo Bait Pellets 32 Place Packs KAP008 are fast killers, mostly used in single dose.
The main ingredient, zinc phosphide, reacts with the rat’s digestive acids releasing the toxic phosphine gas and killing the rat in a couple of days. This might be the best rat poison when anticoagulants don’t work.
This method is especially helpful when anticoagulants doesn’t seem to work, or when a large infested area is needed to be cleared. Most of the times the zinc phosphide bait is used to significantly reduce the initial rat population, while after the effect passes and the rats became resistant, an anticoagulant is used to get rid of the remaining individuals. Inversely, if the anticoagulant is used first, and the rats tend to overcome the poison and become resistant, a nontoxic bait will be used for a couple a weeks to give the rats the time to overcome the bait shyness, and get used to the new food and feeding location. Applying the same bait but with poison added after this period of time, until the feeding ceases (usually 2 to 4 days) will eradicate often the entire population. This method of alternating baits or modes of action, could turn a non-working poison into the best rat poison.
Hypercalcemic agents, are also used in human medicine, but for rats a higher doze is fatal. The main ingredient which may be calciferol, cholecalciferol or elgocalciferol will increase the absorption rate of calcium in rodents organism. It deposits on rats internal organs, especially on stomach walls, kidney and lungs, mineralizing and calcificating them, leading to ruptures in tiny blood vessels and capillaries , and heart and kidney failure. This type of poison is best used in combination with anticoagulants because it synergize with it, making each other more efficient. Using a calciferol poison with a low dosage of anticoagulant, and vice versa will have a much better effect than using only one type of poison in a greater dosage.
This type of poison, especially in combination with an anticoagulant, is toxic for pets or even for humans. Careful control is advised when using it. The best antidote for this poison is calcitonin, a hormone that lowers the blood levels of calcium.