Reasons for discolored discharge in cats:
1. When a cat gets a sore throat or fever, it will tear up and have brown discharge. If it is not cleaned, the discharge will turn red over time and may even cause obvious tear stains on the cat.
2. If a cat's food has a high salt content, it may also cause tearing and increased eye discharge. Generally, switching to food with a lower salt content can alleviate these symptoms.
3. Conjunctivitis or eye irritation from foreign objects can also cause tearing in cats. If left untreated, brown discharge will appear around the eyes, and the condition will worsen. 
How to treat discolored discharge in cats:
1. Adjust their diet. Human food is too high in salt for cats, so don't feed it to them. Choose low-salt cat food and canned cat food. Also, keep their diet light and avoid feeding them foods that cause internal heat.
2. If inflammation causes increased eye discharge in cats, it can also worsen tear stains, and may even lead to dark brown tear stains. Check the cat's eyes. If there is redness and swelling, you can use eye drops, 1-2 drops 2-3 times a day, and you should continue to use them.
3. Clean your cat's tear stains regularly. If there are only tear stains and no other symptoms such as runny nose or sneezing, it may be due to a blocked nasolacrimal duct.
