* Allergies: Flea allergies, food allergies, or environmental allergies can cause excessive scratching and licking, leading to hair loss in areas like the armpits.
* Skin infections: Bacterial or fungal infections can also cause hair loss and irritation.
* Hormonal imbalances: Certain hormonal imbalances can lead to alopecia (hair loss) in dogs.
* Parasites: Mites or ringworm can cause hair loss and skin problems.
* Stress or anxiety: Excessive licking or chewing due to stress can cause hair loss.
* Underlying medical conditions: Certain medical conditions, like hypothyroidism, can also cause hair loss.
If you notice bald patches under your dog's arms, it's important to consult a veterinarian. They can help you determine the underlying cause and recommend appropriate treatment.