Matting of fur can be a problem in American Shorthairs, as well as in other breeds of cats, due to a variety of reasons including age, genetics, health, and grooming habits. To prevent matting, you can follow these steps:

1. Regular grooming: Regular grooming is crucial in preventing matting. Brush your cat’s fur at least once a week to remove any tangles and knots. Make sure to use a brush specifically designed for short-haired cats.
2. Bathing: Bathing your cat periodically can help prevent matting. However, be careful not to over-bathe your cat as it can strip their skin of natural oils. If necessary, use a gentle cat shampoo and make sure to rinse thoroughly.
3. Diet: A healthy diet is essential in maintaining the health of your cat’s skin and fur. Make sure your cat is receiving sufficient amounts of essential fatty acids, which are important for skin and fur health.
4. Hydration: Dehydration can lead to dry skin and make it more prone to matting. Make sure your cat has access to fresh water at all times and encourage them to drink more by providing multiple water sources.
5. Regular check-ups: Regular visits to the vet can help identify any underlying health issues that may contribute to matting. This can include skin conditions, infections, or allergies that need to be treated.
6. Trimming: If your cat’s fur is severely matted, it may need to be trimmed. This should be done by a professional groomer or a veterinarian to avoid injuring the cat.
7. Avoiding rough play: Cats love to play, but rough play can cause matting. Avoid playing with your cat using toys that can tangle or knot their fur, such as string or ribbon.
8. Avoiding moisture: Moisture can cause matting. Avoid bathing your cat too often and try to dry their fur thoroughly after each bath. Also, avoid exposing your cat to damp or humid environments.

In conclusion, preventing matting in an American Shorthair’s fur requires a combination of regular grooming, a healthy diet, hydration, and avoiding moisture and rough play. Regular visits to the vet can help identify any underlying health issues that may contribute to matting. If your cat’s fur is severely matted, it may need to be trimmed by a professional.