Signs of feline poisoning include gastrointestinal symptoms such as vomiting, diarrhea, drooling, nausea and lack of appetite, according to the Pet Poison Hotline. The cat may also exhibit signs of internal bleeding, such as coughing up or vomiting blood, weakness, lethargy, racing heartbeat or pale gums.
In addition, poisoning may result in signs of kidney failure, including bad breath, excessive urination or thirst, or decreased or absent urination, notes the Pet Poison Hotline. Liver failure symptoms may also indicate poisoning. These include yellow discoloration of the gums, jaundice, black tarry stools and dulling of the mental processes. The cat may also collapse or become weak due to low blood sugar caused by liver failure.