Mammary glands in horses are considered to be which type of gland?

Mammary glands in horses are classified as apocrine glands. This classification is based on their mode of secretion. In apocrine glands, the secretory products are released along with a portion of the cell's cytoplasm, which pinches off from the cell to form the secretion. In the case of mammary glands, milk is produced and secreted through this mechanism, which is essential for the nourishment of the foal.

It's important to recognize that while there are other types of glands such as merocrine, where secretions are released without any loss of cell material, and holocrine, where entire cells disintegrate to release their contents, the defining characteristic of apocrine glands aligns perfectly with how mammary glands function. Thus, identifying mammary glands as apocrine is rooted in their specific physiological process of secretion.