How to remove tear stains from cats:
1. Unblock the nasolacrimal duct. The nasolacrimal duct is a passage located from the inner corner of the eye to the nasal cavity, helping cats drain tears and reducing tearing. Owners can keep the nasolacrimal duct clear by massaging the cat's eyes, thus reducing tear stains.
2. Clean the stains with hot water or saline solution. If you find tear stains on your cat, wipe them away immediately to prevent oxidation and evaporation from worsening the stains.
3. Owners can regularly give their cats anti-inflammatory and antibacterial eye drops, such as chloramphenicol eye drops or erythromycin eye drops, which can also prevent and improve tear stains in cats.
4. If the tear stains on your cat do not improve after several days and instead show signs of worsening, you should seek veterinary care promptly and receive medication or surgery. 
Causes of tear stains in cats:
1. Dietary problems, such as feeding cats poor-quality cat food or frequently feeding them high-salt snacks, can cause cats to become overheated. When cats eat too much food that is difficult to digest and lacks nutrition, their detoxification ability will be weakened, resulting in tear stains.
2. In the process of raising cats, some pet owners easily neglect the cleaning and care of their cats' ears. This can lead to ear mites and chronic ear diseases, which can cause cats to tear up frequently and worsen tear stains.
3. Parasitic infection. For example, the sucking nematode, which can survive in the host's eye for up to a year, continuously irritates the eye within the conjunctival sac, causing tear stains.
