Cat obesity study could have implications for human gut health research

22 Jul 2024 --- A new study investigating pet cat’s gut health in relation to the process of weight loss and maintenance has put the animals forward as an optimal model to study human obesity as well, finding a striking similarity between the microbiomes of pet felines and humans.

“Animals share our beds. They share our ice cream. There are all these things that people do with their pets that highlight they are a naturally occurring disease model with similar environmental exposures as humans,” comments lead study author Jenessa Winston, assistant professor of veterinary clinical sciences at The Ohio State University (Ohio State), US, where the study was conducted.

“Being able to see changes in cats that come up in the context of obesity and type 2 diabetes in people makes them a really good model to start looking at more microbiome-directed therapeutics for obesity in humans if we’re seeing a similar shift. Microbes we saw in this study also come up again and again in human studies,” she adds.

Cat microbiome 
For the study published in Scientific Reports, the veterinary research team analyzed fecal samples from obese pet felines as they lost weight through changes in diet. These changes included a strict reduction of caloric intake.

Seven obese cats were fed a “four-phase diet” over 16 weeks. The phases included free-feeding of commercial cat food for two weeks, free-feeding of a specially formulated weight-loss diet for one week and calorie-restricted feeding of the weight-loss diet (aiming for 1–2% body weight reduction per week) for 11 weeks. The last phase was the return to the original maintenance diet.

The changes in the cat’s microbiomes were found to be notably similar to those of humans when going through the same process of weight loss.The researchers collected fecal samples during the different phases, observing changes in the short-chain fatty acids metabolites, molecules produced by bacteria during digestion. Fatty acids are known to be linked to the communication between the gut and other tissues in the body, including those related to the release of hormones related to inflammation and insulin resistance. 

As the feline study participants lost weight, the presence of propionic acid (a short-chain fatty acid shown to regulate appetite, reduce fat accumulation and protect against obesity and diabetes in other mammals) increased in their feces. 

“When the cats are on the special diet formulated for weight loss, propionic acid goes up and stays high, and then goes back down when they’re put back on the maintenance diet. So it really is a dietary change,” Winston outlines. “This paper highlights that when we calorie-restrict cats that are obese, we can alter their microbial ecosystem and those community shifts that we see likely correlate with some metabolic outcomes.”

Pet obesity 
The changes in the cat’s microbiomes were found to be notably similar to those of humans when going through the same process of weight loss. This revelation places them at the very top of the list of animals that could play a role in gut microbiome research, due to the extent of similarity in bacteria. 

Beyond implications for research into the relationship between gut health and obesity in humans, the study findings are also promising for future research into feline obesity and overweight, an issue currently affecting 60% of domesticated cats in developed countries. 

For example, Winston is in charge of two large clinical trials currently ongoing at Ohio State, looking into the potential of transplanting fecal matter from lean cats and dogs into that of animals with overweight and obesity. Recent research into dog gut health reveal that probiotics could facilitate weight loss in obese dogs.

“My lab is focused on how we can harness the therapeutic power of microbes. In order to do that, we have to understand how disease states may be different from health so that we can better try and figure out and target, mechanistically, changes that occur in the microbiome,” she explains.