Causes of dog coat turning red:

1. Growth changes. As time goes by, puppies gradually become adult dogs, and their hair changes accordingly, which is influenced by genetic factors.

2. Malnutrition. The body lacks trace elements, is malnourished, and has rough and dull hair. After a dog becomes sick, his body becomes weak, causing his coat to become discolored.

3. Postpartum phenomena. The female dog's pregnancy has ended, and her hair will become discolored and hairless.

4. Caused by food. When the dog is eating, food spilled on the body is not cleaned up in time, which can easily lead to discoloration of the dog's hair.

5. Climate change. Changes in dog coat color are related to climate. Temperature or sun exposure can cause changes in coat color.