A new study has revealed how overeating affects a cat’s digestion and gut microbiome. The greater understanding provided by the study may help to prevent pet obesity and the health problems associated with it.
Cat obesity is on the rise, which can lead to health problems just like in humans. And while cat owners want to keep their feline fur babies happy, providing an abundance of food and snacks is not the way to go, according to a new study. Researchers from the University of Illinois Urbana-Champaign examined the effects of overeating and being overweight on the digestive system and gut microbiota of cats.
“About 60% of cats in the US are overweight, which can lead to health problems such as diabetes and chronic inflammation,” said Kelly Swanson, corresponding author of the study. “While many studies have investigated feline weight loss, there has been little focus on the opposite process, which is also important. In this study, we wanted to learn more about the metabolic and gastrointestinal changes that occur as a result of overeating and weight gain in cats.”
The researchers recruited 11 adult spayed female cats. After two weeks of baseline measurements and eating standard dry cat food, they could eat as much as they wanted for 18 weeks while the researchers collected blood and fecal samples at regular intervals and monitored physical activity.
The cats immediately increased their food intake substantially and started to gain weight. At the beginning of the study, the cats’ average body condition score (BCS) was 5.41 on a nine-point scale. After 18 weeks of overfeeding, it had increased to 8.27, equating to 30% overweight. BCS is equivalent to body mass index (BMI) for humans.
The researchers analyzed changes in fecal output, gastrointestinal transit time, digestive efficiency (nutrient digestibility), and microbiota bacterial composition over the 20-week study.
“We found that as cats ate more and gained weight, gastrointestinal transit time was reduced, and so was digestive efficiency,” said Swanson. “When the body gets less food, it will be more efficient in extracting nutrients. But when the amount of food increases, it passes through the digestive system faster and fewer nutrients are extracted in the process.
Significant changes in gut microbiome composition were observed between the lean cats at baseline and after 18 weeks of weight gain. Bifidobacterium, which is antimicrobial, inhibits pathogens and stimulates the immune system, increased, while Collinsella, which degrades fiber and has been linked to pro-inflammatory diseases, decreased. These observations were opposite to what is seen in overweight humans and suggested to the researchers that cats’ association with weight gain is complex.
“The change in the gastrointestinal transit time was a novel finding and a potential reason for the change in fecal microbiota,” Swanson said. “Future studies should consider measuring transit time to better explain modifications to the microbiome of pets.”
Perhaps unsurprisingly, the more the cats ate, the more they pooped. However, their feces had a lower pH, indicating it had become more acidic.
“In humans, a low fecal pH indicates poor absorption of carbohydrates and fat,” said Swanson. “Our findings correlate with this, as reduced fecal pH aligned with higher foot intake and reduced digestibility.”
Interestingly, the researchers found that weight gain did not decrease the cats’ level of physical activity.
“We expected weight gain might lead to decreased physical activity, but we did not observe any consistent changes in activity level,” Swanson said. “However, this could vary with individual cats and their environment, and how much their owners interact with them.”
The researchers say that a greater understanding of the metabolic and gastrointestinal changes that occur with weight gain and obesity in pets may help with future prevention and treatment plans.
At the conclusion of the study, the cats were placed on a restricted-feeding diet that helped them return to normal weight.
The study was published in the Journal of Animal Science.