Animals can experience pain in many situations including trauma, post-surgery and arthritis. Luckily we have quite a few options nowadays for pain control in pets.
Opioids are a class of painkillers that include drugs like morphine and buprenorphine. They are strong narcotics and generally result in sedation. They may cause constipation, nausea or vomiting but in general, they are very good for controlling pain associated with surgeries or traumas.
Anti-inflammatories (like Rimadyl, Deramaxx, Zubrin, Metacam and Previcox) decrease inflammation and thereby control pain in pets. They are great for control of inflammation after surgeries or traumas. Long-term, they control pain associated with arthritis. They do not cause sedation but like any other drug, your pet may experience an adverse reaction while taking them. Close monitoring is important for any pet on anti-inflammatories. Bloodwork is done to look at liver and kidney function. If everything looks good, the drug of choice is started. Bloodwork is then repeated in one month. If liver or kidney values have risen, the drug is stopped and another one can be tried in a week. This is similar to people who cannot tolerate Advil but are ok taking aspirin or Tylenol. If vomiting or anorexia ever occurs, anti-inflammatory medications should be stopped.
Tramadol is a new opioid-like drug that can be combined with anti-inflammatories or other opioids. It acts on the brain, basically telling it not to feel pain. It usually does not cause vomiting or constipation like true opioids but may result in decreased appetite and depression. In any case, it is a wonderful drug for a second-line of treatment for severe arthritis cases.
Animals (especially cats) are very good at hiding pain. If you'd like more information on signs of pain in pets, visit: http://ijustasked.com/facts.html