Researchers studied how cats’ intestines change as they get older. They tested 36 healthy cats—some young and some senior—by giving them a special drink with different types of sugar and checking their blood afterward. They found that older cats had leakier intestines than younger cats, which might explain why senior cats sometimes lose weight and have trouble absorbing nutrients. The study also discovered that male and female cats absorb food differently. These findings could help veterinarians develop better ways to keep older cats healthy and well-nourished.

The Quick Take

  • What they studied: How the intestines of young cats compare to senior cats in terms of how much they leak and how well they absorb nutrients from food.
  • Who participated: 36 healthy domestic cats: 21 young cats (average age 2.4 years) and 15 senior cats (average age 11.2 years). The group included both males and females.
  • Key finding: Senior cats had significantly leakier intestines than young cats. Additionally, male cats absorbed nutrients better than female cats, regardless of age.
  • What it means for you: If you have an older cat, this research suggests their digestive system may work differently than when they were young. This could explain weight loss or poor nutrition in senior cats, and it might help vets develop better diets or treatments for aging cats.

The Research Details

Scientists recruited 36 healthy domestic cats and divided them into two age groups: young cats (around 2-3 years old) and senior cats (around 11 years old). They gave each cat a special drink containing four different types of sugar molecules of varying sizes. These sugars work like tiny tracers that show how well the intestines are working. The researchers took blood samples before the cats drank the solution and again 3 hours later, then used advanced laboratory equipment to measure how much sugar appeared in the blood.

This method is called a sugar absorption test, and it’s a clever way to measure intestinal health without needing surgery or invasive procedures. The different sugar sizes help scientists understand both how “leaky” the intestines are (larger molecules shouldn’t normally get through) and how well the intestines absorb nutrients (smaller molecules should be absorbed efficiently).

The researchers carefully recorded information about each cat’s age, sex, body weight, and the date of testing to make sure these factors didn’t accidentally affect the results.

This research approach is important because it directly measures how well a cat’s intestines are functioning in a living animal. Previous studies in cats hadn’t looked at how aging affects intestinal health, so this fills an important gap. Understanding intestinal changes with age could explain why some senior cats struggle to maintain their weight and muscle mass, even when eating adequate food.

This study used a scientifically validated method (sugar absorption test) and advanced laboratory analysis (liquid chromatography mass-spectrometry) to measure intestinal function accurately. The researchers tested a reasonable number of cats and carefully controlled for factors like body weight and sex that could affect results. However, the study only included healthy cats, so results may not apply to sick cats. The study was published in a peer-reviewed scientific journal, meaning other experts reviewed the work before publication.

What the Results Show

The main finding was clear: senior cats had significantly higher intestinal permeability (leakiness) compared to young cats. This means the intestinal barrier in older cats allows more substances to pass through than it should. The difference was statistically significant, meaning it’s unlikely to be due to chance.

The second major finding was that male cats had better absorptive capacity than female cats, meaning they absorbed nutrients more efficiently. This difference was also statistically significant and appeared in both age groups.

Interestingly, factors like the cat’s body weight, the date of testing, and the cat’s sex did not affect intestinal permeability. This suggests that age is the primary driver of changes in intestinal leakiness, independent of other variables.

The study found that intestinal permeability (how leaky the intestines are) was not affected by body weight or sex, suggesting these factors don’t play a role in age-related intestinal changes. The absorptive capacity (how well nutrients are absorbed) was not affected by age, which was somewhat surprising—it suggests that while older cats have leakier intestines, their ability to absorb nutrients when they do get through may remain relatively stable.

This is the first study to directly measure intestinal permeability changes with age in domestic cats. Previous research in other animals and humans has shown similar patterns of increased intestinal leakiness with aging, so these findings align with what scientists have observed in other species. The sex-based differences in nutrient absorption are also consistent with findings in other mammals.

The study only included healthy cats, so the results may not apply to cats with digestive diseases or other health problems. The sample size, while reasonable, was relatively small (36 cats total), so results should be confirmed in larger studies. The study measured intestinal function at only one point in time for each cat, so it doesn’t show how intestinal health changes over a cat’s lifetime. Additionally, the study didn’t measure actual nutrient absorption in the cats’ bodies or track their health outcomes, so we can’t yet confirm that the increased intestinal leakiness actually causes the weight loss and nutritional problems seen in some senior cats.

The Bottom Line

Based on this research, veterinarians may want to consider intestinal health when addressing weight loss or poor nutrition in senior cats. This could involve recommending specialized diets, digestive supplements, or other interventions designed to support intestinal function. However, these recommendations should be discussed with your veterinarian, as individual cats may have different needs. The evidence is moderate—this study provides good evidence that intestinal changes occur with age, but more research is needed to determine the best ways to address these changes.

Cat owners with senior cats (typically 10+ years old) should be aware of these findings, especially if their older cat is experiencing weight loss, poor appetite, or digestive issues. Veterinarians who treat aging cats should consider intestinal health as a factor in senior cat nutrition. This research is less relevant for owners of young, healthy cats. People with cats that have existing digestive diseases should discuss these findings with their veterinarian.

Changes in intestinal function happen gradually over years, so you won’t see immediate changes. If your veterinarian recommends interventions based on this research, it may take several weeks to months to see improvements in your cat’s weight, energy level, or coat condition. Consistent monitoring over time will be important to assess whether any interventions are working.

Want to Apply This Research?

  • For senior cats, track monthly body weight and body condition score (how thin or plump the cat feels). Also note any changes in appetite, stool quality, or energy level. This helps identify early signs of digestive problems that might be related to intestinal changes.
  • If you have a senior cat, work with your veterinarian to ensure their diet is optimized for aging cats. This might include higher-quality proteins, digestive enzymes, or specialized senior cat formulas. Keep detailed notes about your cat’s response to any dietary changes.
  • Establish a baseline assessment of your senior cat’s weight and body condition, then monitor monthly. Track any digestive symptoms or changes in eating habits. Share this information with your veterinarian at regular check-ups to catch potential nutrition problems early.

This research describes changes in intestinal function that occur with age in cats, but does not diagnose or treat any specific condition. If your cat is experiencing weight loss, poor appetite, digestive issues, or other health concerns, please consult with your veterinarian. This study was conducted in healthy cats and may not apply to cats with existing health conditions. Any dietary changes or supplements should be discussed with your veterinarian before implementation. This summary is for informational purposes only and should not replace professional veterinary advice.