Cat grass is oat or wheat seedlings supplying plant fibre, which helps cats bring up hairballs or pass them in stool. Hairball paste is built on oils and fibre to lubricate the gut, delivered in a concentrated, easier-to-dose form.

Grass suits cats that like chewing plants and need daily fibre, though growing it takes light and water, and some cats ignore it. Paste suits short use in shedding season, easy to administer, with dose set by weight and label.

The trade-off is natural versus controlled: grass fibre is hard to quantify, and indoor trays can grow mould or harbour soil contamination, while paste is calorie- and fat-dense, so frequent long-term use may affect weight and digestion.

Build on grooming, with grass and paste as supplements and more brushing in shedding season. Frequent retching, vomited hairballs or difficult stools may point to hairball disease or another problem, so confirm with a veterinarian.