There are many signs that may show that an animal is poisoned. These signs depend on the type of poison and the extend of poisoning. In severe cases, the animal may just die suddenly without any previous sign.
At other times, the animal may how in like vomiting, diarrhea, and may foam before eventually death if left unattended to.
How to tackle it:
This depends on the nearness of your consultant. If he/she is very near, you can call on the person for an appropriate attention. However, some first aids can be administered before the arrival of your Vet. Doctor.
You should give the animal plenty of water to drink to neutralize the effect of the poison and after this then quickly call your Vet. Doctor for further treatment.