Cats commonly consume grass, a behavior observed in a large majority of domestic felines, though the precise reasons and effects remain topics of investigation among veterinarians and researchers. David Grant, a veterinarian with over half a century of experience, addressed common questions about this behavior, highlighting both potential explanations and associated risks.

Many cats appear to eat grass regularly, often soon after being let outside. While some assume this may be due to taste preference, expert views extend beyond this simple explanation. One widely suggested reason is that grass consumption aids digestion. It may stimulate intestinal motility, also known as peristalsis, which helps move indigestible material such as hair through the digestive tract. This process potentially reduces the formation of hairballs, a common concern for cat owners. Additionally, grass may provoke vomiting, thereby assisting cats in expelling indigestible substances from the stomach. This vomiting behavior is thought to be inherited from wild ancestors as a natural cleansing mechanism.

However, grass consumption is not without hazards. Fertilizers and chemical treatments used on lawns can be toxic to cats, and pet owners are advised to ensure that any grass their animals encounter is free from such substances. Physical injuries can also occur; large grass blades occasionally become lodged in sensitive areas like a cat’s nose or throat, which may lead to sneezing or choking episodes.

Scientific studies have contributed empirical data to these observations. A 2021 study conducted by the University of California found that approximately 89% of cats engage in grass-eating behavior, most of which are otherwise healthy. The study also reported that between 27% and 37% of cats vomited after consuming grass, with older cats exhibiting vomiting more frequently. More recent research from December 2025 employed scanning electron microscopy to analyze regurgitated grass alongside hairballs collected from cats. The findings suggested that microstructures on grass blades might physically entangle hair, facilitating its removal during vomiting.

While grass eating appears to be a common and generally normal behavior among cats, vigilance is necessary regarding potential environmental hazards and physical risks. Most cats seem to benefit from this habit as a natural digestive aid, though pet owners should monitor any unusual symptoms and consult veterinarians if concerns arise.