Why do cats get black chin? And what should you do if your cat has black chin?
I. Understanding Black Chin in Cats
A cat's black chin is similar to a person's acne or pimples. Black chin is usually caused by abnormal secretion of sebaceous glands, resulting in localized oil accumulation, which leads to secondary bacterial and fungal infections of the skin.
In the early, mild stages, black or white pimples may appear on the cat's chin, and the surrounding skin may become red, swollen, and lose fur.
In more severe stages, the hair roots of the black spots turn yellowish-brown, pustules appear, and there is severe redness, swelling, and pus discharge. 
II. Causes of Black Chin in Cats
1. Hormone secretion
When a cat is in heat and has not yet been spayed/neutered, its hormone levels increase, causing hormonal imbalances.
This can eventually lead to an excess of male or female hormones, resulting in a dark chin.
2. Environmental stimuli
If the house isn't kept clean, cats, which love to roam around, will easily accumulate dust and bacteria in places that are often difficult to clean, such as under tables, sofas, and beds.
This situation occurs when a cat is constantly under stress or tension.
This can affect the functioning of most of the cat's organs, such as heart rate, blood pressure, metabolism, and endocrine disorders, leading to abnormal secretion of sebaceous glands and causing the cat to develop black chin.
3. Dietary habits
Starting with the food containers cats use, most cat bowls are made of plastic because they are portable and inexpensive.
However, plastic bowls are the easiest containers to harbor bacteria. The plastic material itself has pores, and washing dishes often cannot eliminate them.
When a cat's chin, fur, and nostrils come into contact with the surface of a bowl, bacteria can transfer to its skin, and after a period of time, the cat will develop black chin.
Starting with what cats eat, cats generally eat other cat foods. Except for specific low-fat prescription foods, most cat foods are fat as the second largest component.
If a cat eats food with too high a fat content, the cat will not be able to excrete the oil in its body over a long period of time. The oil will accumulate in the hair follicles, causing excessive local sebum secretion and resulting in black chin. 
III. What to do about a cat's black chin?
1. Change cat food
If you can confirm that your cat doesn't have any obesity-related health issues, there's no need to easily switch to low-fat food.
You can try switching to other brands of cat food. Cat food with an oil-sprayed surface is not recommended.
2. Change equipment
It is generally not recommended to use plastic bowls. Instead, you can replace the cat food bowl with a ceramic or glass container.
Even if you change the equipment, you still need to wash it frequently to prevent bacteria from growing.
3. Staged treatment
In the early stages of black chin on cats, there are only a few black spots, and routine cleaning is sufficient.
You can use a warm saline solution to apply a compress to your cat's chin to clean and relieve pressure on the hair follicles.
Next, you can wash with antibacterial soapy water or disinfectant. Disinfectant such as chlorhexidine is usually suitable, as it is gentle and non-irritating and can reduce bacterial growth in hair follicles.
In severe cases of black chin, it is usually necessary to trim the fur on the cat's chin and apply antibiotic medication, such as the most common mupirocin antibiotic ointment, which can effectively inhibit and kill bacteria.
Black chin in cats usually recovers quickly with simple treatment.
However, to effectively prevent black chin in cats, owners need to maintain good hygiene for both the cat and the environment. Cleaning the cat's mouth with salt water after meals can also reduce the occurrence of black chin!
