Harper, L. V. 1976. Behavior. In: The Biology of the Guinea Pig. Wagner, J. E. , Manning, P. J. (eds), 31-51. Academic Press, New York, NY.

Possibly related to, or derived from grooming and perhaps also involving an element of aggression is one animal grasping the hair of another in its teeth and pulling it out; the mouthful is often ingested. Hair pulling is a common pattern in pups; it is directed toward the mother and usually occurs during or shortly after the end of lactation. Occasionally hair pulling will persist into adulthood and it is the writer's impression that it may be contagious. Hair pulling was observed when animals attempted to displace one another at water spouts and feeding dishes. Especially under conditions of crowding or stress, hair pulling and ear nibbling may become so exaggerated that they become a mild form of cannibalism resulting in markedly cropped pinnae and sparse pelage.