1. Genetics: Some chihuahuas have less hair around their ears due to genetics and they may never have a full coat in that area. It's called Spot Baldness and is more prevalent in Chihuahuas with long hair but can also be seen in short-haired Chihuahuas.
2. Ringworm: This fungal skin infection starts with small red round patches that are itchy and can cause hair loss. It can spread quickly to other parts of the dog's body and even to humans and other pets.
3. Allergies: Chihuahuas can have allergies to various substances in their food or environment, including dust mites, pollen and grasses. Allergies can cause itching, scratching, which can lead to hair loss.
4. Hormonal imbalances: Certain hormonal imbalances, such as hypothyroidism, can cause widespread hair loss, affecting areas like ear regions.
5. Nutritional deficiencies: A lack of essential nutrients in a Chihuahua's diet, including vitamins, minerals, and proteins, can contribute to hair loss.
6. Parasites: Sometimes, parasites, like fleas, mites, or lice can cause hair loss in Chihuahuas.
7. Autoimmune disorders: In rare cases, hair loss around ears can be due to autoimmune disorders.
If you notice your Chihuahua is balding around the ears, it's best to consult with a veterinarian to determine the underlying cause and recommend appropriate treatment, if needed.