text: The birth of a litter of puppies is often eagerly anticipated. Unfortunately, this happy event is sometimes marred by tragedy. Puppy deaths occur, and sometimes the dam is the apparent cause of these deaths. On rare occasions, mother dogs will even eat her puppies. Although it is easy to be angry at the mother dog or to be disturbed or disgusted by her actions, there are many reasons that she might harm or kill her puppies.
  When an animal eats another animal of the same species, it is called cannibalism. Cannibalism is rare in dogs, especially if the litter is birthed (whelped) in a home environment as opposed to a loud or crowded kennel. Puppy cannibalism can occur at birth or even after a few days of life. Female dogs of any breed or mix of breeds can cannibalize their puppies. Cannibalism may or may not be an inherited trait and it may or may not recur from one litter to the next.
  Lack of Recognition
  An inexperienced mother dog (dam) may not recognize her puppies as being her own offspring. In addition, dogs who have had cesarean sections may also fail to recognize their offspring because of the lack of hormones produced during a natural birth. Newborn puppies move erratically and make high-pitched sounds. These behaviors mimic the actions of prey animals, such as mice. Some dogs, especially terriers and terrier mixes, have a rodent-killing heritage. Although any dam can cannibalize her pups, these dogs may instinctively be compelled to eat their puppies if they fail to recognize them as their own.
  Mastitis is the inflammation of the dam’s teats. The infected teats may be red, swollen and hard or hot to the touch. Although very serious, mastitis can be easily treated. When puppies clamp down to suckle, the dam may feel enough pain to cause her to reject the puppies. On some occasions, the pain is sufficient to cause the dam to become aggressive to her puppies and to kill and cannibalize them.
  Stress or Fear
  If a mother is stressed or fearful for her litter, these negative emotions may trigger aggression. This aggression may be directed toward the puppies and result in cannibalism.
  Stillborn or Unhealthy Pups
  In nature, when one or more members of a litter are unhealthy or stillborn, they put the rest of the litter at risk. A dam’s instinct will tell her that she must remove the unhealthy and stillborn puppies from the den. Most of the time, domestic dogs will simply reject unhealthy puppies, pushing them away from the nest. They may carry stillborn puppies away from the nest or “bury” them someplace in the house. However, if instinct takes over and the puppies are young enough, the dam might kill and eat unhealthy puppies, as well.