Veterinary medicine has come a long way since the days when "animals don't feel pain" was a common belief. Even when pain was acknowledged in mammals, it was often seen as a form of restraint, as in, "A little pain will keep the pet quiet."
Today, we know that the sensation of pain itself inhibits healing and raises stress levels in animals, and that by preventing and treating pain aggressively, we promote faster recoveries and avoid many post-operative complications.
Recently, the Winn Feline Health Foundation published an overview of research and data on the pain medication buprenorphine, an opioid widely used in cats.
First, the good news: Yes, it works.
The bad news is that it doesn't work in the way, or as well as is generally believed.
1. How the drug is given matters. The gold standard of administering buprenorphine is the intravenous (IV) method. However, this requires IV access, which is not always available in a shelter setting, in a foster home or in emergency situations.
The next best method of administration is by intra-muscular (IM) injection.
Giving buprenorphine by subcutaneous (sub-Q) injection does not give reliable pain control.
Buprenorphine is often given by letting it be absorbed from under the tongue, known as oral-transmucosal administration (OTM). This has the advantage of being painless and relatively non-stressful to cats. Unfortunately, the literature review did not reveal good data supporting the pain-relieving effect of this method of administration, and it is not recommended to use this as the sole form of analgesia.
The authors suggest, "Cats who are going to receive OTM buprenorphine should be given a dose of a full agonist opioid or even injectable buprenorphine beforehand as premedication."
2. Buprenorphine takes longer to take effect, and lasts less time, than veterinary textbooks indicate. Time to pain relief with the most effective route, via IV, takes around 30-45 minutes, and while the drug is frequently given only once, that's just not enough.
For example, the article authors reported, "(C)ats undergoing ovariohysterectomy may require a second dose of buprenorphine 4 hours after surgery, especially if an NSAID had not also been given."
For that reason, they said, "cats receiving buprenorphine should be routinely reassessed for rescue analgesia needs after buprenorphine administration."
3. Giving buprenorphine with other drugs works best. As has been found in many studies of pain in humans and other animals, an approach known as "multi-modal" works best. This means giving two or more drugs, with different methods of action, to get better pain control.
In the case of buprenorphine, the authors conclude, "Optimal pain relief usually is obtained when buprenorphine is combined with an NSAID, loco-regional anesthesia, or both."
To read the complete article and view its citations, visit the Winn Feline Health Foundation blog.
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