Study: Cats in little crocheted hats shed light on feline chronic pain

For the fashion-forward cat —

The custom-made caps hold electrodes in place and reduce motion artifacts during EEGs.

Our feline overlords aren't particularly known for obeying commands from mere humans, which can make it difficult to study their behaviors in controlled laboratory settings. So a certain degree of ingenuity is required to get usable results—like crocheting adorable little hats for kitties taking part in electroencephalogram (EEG) experiments. That's what researchers at the University of Montreal in Quebec, Canada, did to learn more about assessing chronic pain in cats—and they succeeded. According to their recent paper published in the Journal of Neuroscience Methods, it's the first time scientists have recorded the electrical activity in the brains of conscious cats.

According to the authors, one-quarter of adult cats suffer from osteoarthritis and chronic pain that worsens with age. There are currently limited treatment options, namely, non-steroidal anti-inflammatory drugs, which can have significant side effects for the cats. An injectable monoclonal antibody tailored for cats has recently been developed to neutralize excessive nerve growth factor, but other alternative treatment options like supplements and regenerative medicine have yet to be tested. Nor has the effectiveness of certain smells or lighting in altering pain perception in felines been tested.

That was the Montreal team's primary objective for their experiments. Initially, they tried to place electrodes on the heads of 11 awake adult cats with osteoarthritis, but the cats kept shaking off the electrodes.

“When you spend more time putting electrodes back on than you do actually recording the EEGs, you get creative,” co-author Aliénor Delsart of the University of Montreal told New Scientist. So he and his co-authors tapped a graduate student with crocheting skills to make the little hats. Not only did the hats hold the electrodes in place, but the cats also stopped trying to chew the wires.

With that problem solved, the real experiments could begin, designed to record brain activity of cats in response to smelling certain substances or seeing different wavelengths of colored light. The kitty subjects were housed as a group in an environment with lighting, temperature, and humidity controls, along with perches, beds, scratching posts, and cat toys.

Electrodes were attached with no need to shave the cats' hair, thanks to a conductive paste to improve electrode/skin contact. First they recorded the basal activity before moving to exposure to sensory stimuli: a grapefruit smell for olfactory stimulation, and red, blue, and green lighting in a darkened room for visual stimulation.

Granted, there were still a few motion artifacts in that data; two cats were excluded from the data analysis for that reason. And the authors acknowledged the small sample size and largely descriptive nature of their analysis, which they deemed appropriate for what is essentially a test of the feasibility of their approach. The study met the group's primary objectives: to assess whether the EEG method was feasible with conscious cats and whether the resulting analytical methods were an efficient means to characterize how the cats responded to specific sensory stimuli. "This opens new avenues for investigating chronic pain mechanisms and developing novel therapeutic strategies," the authors concluded.

Journal of Neuroscience Methods, 2024. DOI: 10.1016/j.jneumeth.2024.110254  (About DOIs).