Yes, there are some nutritional supplements that can help improve the appearance of your American Shorthair Cat’s coat. A healthy and shiny coat is an indication of a well-nourished cat. Some of the most common supplements used to enhance a cat’s coat are:

1. Omega-3 fatty acids: Omega-3 fatty acids are beneficial for the overall health of a cat’s skin and coat. They help reduce inflammation and improve the skin’s ability to retain moisture, leading to a softer and shinier coat. Omega-3 fatty acids can be found in certain types of fish, such as salmon, herring, and sardines.
2. Biotin: Biotin is a B-vitamin that helps the body process nutrients for healthy skin and fur. A lack of biotin can lead to hair loss and a dull coat, so supplementing with biotin can help improve the appearance of your cat’s coat.
3. Vitamin E: Vitamin E is an antioxidant that helps protect the skin and coat from damage caused by free radicals. It also helps improve circulation, which can lead to a healthier and shinier coat. Vitamin E can be found in nuts, seeds, and leafy greens.
4. Zinc: Zinc is an essential mineral that plays a role in skin and coat health. It helps the body produce new skin cells and promotes healthy hair growth. Zinc can be found in meat, poultry, seafood, and whole grains.

It’s important to note that while supplements can be helpful in improving the appearance of your cat’s coat, they are not a substitute for a balanced and nutritious diet. Before starting any new supplement regimen, it’s best to consult with your veterinarian to determine the right course of action for your pet.

It’s also important to follow the recommended dosing on the supplement label, as over-supplementing with certain nutrients can be toxic to cats. Additionally, some cats may have food allergies or sensitivities that could affect the appearance of their coat, so it’s important to identify and address any underlying health issues that may be contributing to a dull or lackluster coat.

In conclusion, a balanced and nutritious diet, along with certain nutritional supplements, can help improve the appearance of your American Shorthair Cat’s coat. However, it’s important to consult with your veterinarian and follow recommended dosing guidelines to ensure your cat is getting the right nutrients in the right amounts.