To know if a cat has worms, watch for these common signs:

• Visible worms or worm segments resembling rice grains or spaghetti in the cat's feces, fur around the anus, bedding, or vomit.
• Changes in appetite: an increase or decrease—sometimes the cat eats more but loses weight because worms consume nutrients.
• Scooting behavior, where the cat drags its bottom along the ground due to anal itching.
• A pot-bellied or bloated abdomen, especially in kittens.
• Poor coat condition such as dull, dry, or rough fur.
• Diarrhea, sometimes with blood or black granules resembling coffee grounds.
• Vomiting, which may sometimes include visible worms.
• Lethargy or decreased energy.
• Pale gums indicating possible anemia.
• Coughing or difficulty breathing, which can occur if worms affect the lungs.

If any of these signs are observed, particularly visible worms or changes in coat and behavior, having the cat examined by a veterinarian is important. A vet can confirm worms through fecal testing and recommend appropriate treatment.