Analgesia for Animals: My Lottery Theory of Multimodal Pain Treatment


My Lottery Theory of Multimodal Animal Pain Management:

Good lab animal welfare requires effective treatment of any pain scientists cause. It is way too easy to pick a drug from the list, pick a dose, and never really know if the drugs is actually helping the animal feel better. One variation on this is to use three drugs, or multimodal analgesia treatment — going Beyond Buprenorphine (the most common single-agent treatment) to maximize pain relief

It’s been years now that I’ve been advocating combining different classes of pain medicines to treat research animal pain. I haven’t always prevailed; most notably, I consistently failed to get the vets or the animal committee on my recent job to enforce this standard on one particularly resistant monkey-user scientist.

I think a lot about evidence-based ethical treatment of animals when the evidence just isn’t there. When it comes to fine-tuning pain treatments for animals, our evidence is so very sparse. Whether it’s monkeys, mice, fish or others, how do we evaluate the level of pain they’re experiencing? How do we evaluate if pain medicines truly make them feel better? How then can we know if combining analgesics is even better (or worse) than using single drugs? What about side-effects of pain drugs? What about how either drugs or untreated pain might affect the experiments the animals are on?

We totally lack the most important info for even our most common drugs, and that is, what if our animal patients could self-medicate or somehow tell us they need another dose, or a stronger dose, of their pain meds?

Frankly, we don’t have the info we need to pronounce on the best pain management — other than the obvious, which is to first, cause no pain. And so IACUCs end up making an ethical decision, in what I call the ethics-of-uncertainty. Do they err on the side of caution, and require more aggressive pain treatment than some scientists want to provide? Or do they privilege concerns about how drugs will affect research data?

With my recommended 3-drug multimodal regimen, we combine an opioid (usually buprenorphine; an MD would rely more on morphine or codeine) with a Non-steroidal anti-inflammatory NSAID (for animals, we use carprofen or meloxicam; an MD might rely on ibuprofen) and also, a local “block” at the surgical incision (bupivacaine or lidocaine; your dentist uses a lot of lidocaine). Our doses for these drugs are not wild guesses, but neither are they very solid science either. We don’t know exactly how much to use, we don’t know when to re-dose, we don’t give mice or monkeys their own medicine chests, and we don’t have the best skills at round-the-clock pain evaluations.

Hence, the Lottery Theory: use all three and hope you’re getting at least one of them mostly right. While I’m watching the science develop and hoping we’ll get good answers on just what pain management, my short term approach is that we should buy three tickets in the analgesics lottery, and hope at least one of them is a winner. And yes, let’s scale back on doing painful things to animals in the first place