The placebo effect is a curious one. By all standards of medical science, it shouldn’t work. We are sick, we take a pill which we are told will cure us, and we get better. But then the twist – there was no actual medicine in that pill! Somehow, you were cured without doing anything except believing that you are being treated.

It sounds like something that belongs in the realm of quackery and discredited folk remedies, but numerous studies have shown that the placebo effect really does work. The most logical reason is that the belief in the treatment tricks the body into feeling better, and the ailment is then healed through natural progression. A more controversial suggestion is that focusing the mind on curing a certain illness actually can directly help recovery. But either way, one thing that must be the case is the awareness of the treatment is crucial to the efficacy.

So, surely, the placebo effect would never work in veterinary medicine. If animals don’t know they’re being treated, they can’t think they’re feeling better. Can they?

The evidence for it

Well, the answer is less clear than you may expect. Not much research has been done into the placebo effect on animals, but the studies which have been conducted have produced surprising results. For example, animals receiving insulin injections will continue to experience blood-sugar changes for some time if they are instead injected with saline solution. It’s a fascinating circumstance that is probably caused by classical conditioning – the body responds to the injection and changes the blood sugar levels even though it was a placebo.

More bizarrely, the placebo effect has been observed in medical trials – dogs on placebo drugs for epilepsy have been shown to have reduced seizures. This cannot be due to classical conditioning. So how can this be the case? How does the placebo effect work on animals?

The real problem

Well, the most likely answer is that it’s not – it’s working on us. Yes, the placebo effect may also work by proxy, when the symptoms are reported through owners. In the epilepsy study, many owners said their dogs were getting better, but the gait analysis suggested this wasn’t happening. The placebo effect is often a form of denial – human asthma sufferers routinely report feeling better with placebo inhalers, yet there is no measurable improvement in lung function. If a person can convince themselves that they feel better, it is completely plausible that they might believe a separate entity is getting better, when they’re not. Pet owners can be so desperate to believe their beloved animal is getting better that they retreat into self-delusion. Many vets have seen owners who blithely dismiss the obvious signs that their pet is in serious pain, not through callousness, but through a mental block that stops them from being upset by their pet’s illness.

Of course, vets and nurses are human too, and not above this unconscious bias. When you really want to believe an animal is getting better, it can be easy to convince yourself they are. When you do that, you are unknowingly experiencing the placebo effect by proxy. This is why it’s crucial to always use scientific parameters, and not fall back on your own willingness to believe your own brain, because your brain may be deceiving you.