Vets commonly get cases of known or suspected exposure to various toxins and poisons. A couple of months ago I saw a case where a dog ate rat poison. Today I saw a dog who at the cap off some weed killer. Thankfully neither case was serious and we were able to quickly and successfully treat the pets. However, the owner unknowingly made the proper treatment more difficult. How? They didn't bring the poison in with the pet.
This is actually a very important point, and one that most pet owners don't realize. There is not one type of rodenticide, herbicide, or pesticide, and different chemicals can cause significantly different symptoms. For example, let's look at common rat poisons. Historically most rodenticides have been based off anticoagulants. The rat/mouse/etc. eats the poison which interferes with the blood's ability to clot, and the animal hemorrhages to death from simple movement and bruises. In recent years the rodenticides have changed to where they cause death from brain swelling and other problems unrelated to blood clotting. Anymore we can't assume that a rat killer is an anticoagulant, and the treatment for the various poisons is very different. If we don't know which kind it is and make the wrong guess on treatment, the pet could easily die.
Weed killers are similar. Some of them have a very low potential for toxicity, some cause gastrointestinal problems, and some will cause fluid to accumulate in the lungs. There is no single treatment for "poison", as it all depends on what chemicals the pet was exposed to.
And this is why it is very important that we can identify the specific toxin. Without knowing exactly what the pet swallowed we won't know what symptoms to look for and what treatment to give. Thankfully, active ingredients must be clearly printed on the package and are easy to identify. The names are often long and difficult to remember, so if you are in a situation like this in the future, be sure to bring the package or label to your vet when you take your pet in for an exam and treatment. If we can read the active ingredients we can tell what treatment we need to do.
This is also a good time to plug the ASPCA Poison Control Center (here in the US); 1-888-426-4435. They are staffed 24/7/365 and will take calls of suspected or known toxin exposure. There is normally a charge for the call, but they should be able to tell you how serious the problem might be, how quickly you need to see a vet, and what you might be able to do before going to the vet. However, they will need to know the specific chemical or ingredient, so have that handy before you call.