Final answer:
Acetaminophen, NSAIDs such as ibuprofen and naproxen, and opioids like fentanyl and morphine are extremely toxic and deadly to cats, as they cannot effectively metabolize these substances. Only veterinarians can determine safe pain management for cats.
Step-by-step explanation:
Acetaminophen, commonly known as Tylenol, is extremely toxic to cats and can be deadly. Cats lack certain enzymes that are necessary for metabolizing acetaminophen effectively, which can lead to severe liver damage, methemoglobinemia (which impedes the blood's ability to carry oxygen), and even death.
Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen are also highly toxic to cats and even small doses can cause serious harm. These medications can induce gastrointestinal ulcers, and kidney damage, and should never be given to cats. While medications like opium, heroin, fentanyl, morphine, oxycodone, Vicodin, and methadone are opioids that can be used as pain relievers in humans, they are generally not safe for cats. Cats are much more sensitive to opioids and these substances can cause serious harm if not dosed correctly and prescribed by a veterinarian specifically for the cat.