I had left a hay bale in my old coop for most of a spring and when I moved it, mice sort of 'fountained' out of it, like something you'd see in a cartoon. The girls went CRAZY!!! They ate a feast of mice that day, though I think there was a lot more chasing than eating. They sure had fun! More fun than me because it was really creepy to be standing there having lifted that thing and have so many mice rushing out of it... I'm not afraid of mice, but it was not a good feeling.
I understand why people are reluctant to use rat poison, I share that reluctance but it IS possible to use poisons responsibly even if you have pets and children and chickens.
If you have actual RATS that have established a colony in or around your coop/barn/yard, you have a real problem. If you see a few, you probably have a few hundred. They spread disease, parasites, bugs and can kill or injure chickens, young or old, and theyll raid eggs and steal huge amounts of feed from you and your chickens.
Theyre smart and tenacious and traps are not always very effective after a time because they do learn very well.
First clean your barn, eliminate all feed sources you can, clean up all stray edible things and make sure your feed is stored in rat-proof containers and even stop feeding free-choice for a time while you work to get things under control.
Get your coop as rat proof as possible, but its not always possible, so just do your best. Rats can squeeze in through the most amazingly small holes so its very difficult, darn near impossible.
Then, go shopping for enclosed bait stations that animals other than rats cannot get into, ask at TSC or other feed and hardware stores around you or if you can find a protected area where pets or chickens cannot get to the bait thats fine. We had some bad problems at one time, and we built a box that locked on top, and had a hole too small any of our pets to get in, and then fastened some solid block type poison in there.
Then, get the right type of poison, there are two types, Multi-feed and Single-feed poisons.
First the multi-feed type, the main chemical in that is either warfarin or coumatetralyl. A 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 quite a long period of time.
This means that even if your dog or cat does get a dead or dying rat and eat it, there is little in the stomach to hurt them, and since its not terribly potent and its only the poison in the rats stomach that hurts your pet, not what's already been metabolized.
Single feed poisons are MUCH stronger and 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 poisons are those containing brodifacoum (e.g.Talon) and bromadialone (e.g.Bromakil).
BOTH the single and multiple feed types are commonly available from local supermarkets and hardware stores etc. so check the ingredients. Brodifacoum is at least 40 times more potent than 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 could possibly have enough bait in its stomach to poison at least a small dog or a cat, sicken a large one.
This is why the single-feed poison which is so much stronger and kills in one shot is more dangerous. The rat or mouse usually dies with more un-digested in their stomach, and so it's available for a pet or wildlife to ingest if they eat a dead rat.
Either way, you need to be aware of your pets and control them if/when you do set out poison. Control them more carefully than usual when trying to get rid of a rat infestation, and certainly toddlers etc, but if you really have a bad enough rat infestation, poisons may be a tool to consider, just make sure you think it through. You need to put it either well down into the actual tunnels/holes or in bait stations and/or protected areas that your chickens and pets cannot get to.
Also, watch carefully for dead or dying rats and mice etc that dogs, cats or chickens can get to. Only set out poison when you are going to be home and able to keep track of things for that whole period of time, not when you are planning to be gone a lot or going away for a long weekend etc.