Once a dog has puppies its personality can change, at least for a time. The stress of a new litter and the instinct to protect further influence dog behavior in ways otherwise unexpected.
After giving birth your dog's No. 1 instinct will be to protect her litter. This means protecting it from danger, intruders and even you. Hormones will increase this instinct further and can make for an edgy demeanor. If you get close to the babies or if she perceives there is danger due to sudden noises or movements, she may even become snippy. New faces are another irritant to be avoided. Keep your dog as comfortable and as far away from outside interference as possible to reduce the impact of her temporary personality change.
Your dog immediately will become devoted to her offspring. She will spend day and night cleaning and caring for the new puppies for a period of 10 days-to-several weeks. During this time, your dog will show little or no interest in things other than her babies and may rarely leave the nest. While the personality change you see may be dramatic, it is an instinct programmed into canines when they once lived in the wild. Mother dogs will begin the process by eating the placenta from each puppy, then licking them clean both after birth and in the weeks that follow.
Certain strange postpartum behavior can be attributed to an illness called eclampsia, which is the result of a calcium deficiency. The mineral may come into short supply as more of it is used to supply puppies with milk. Symptoms of eclampsia include tremors and stiffness, a nervous disposition, elevated heart rate and fever. Your dog also will neglect her maternal duties as she struggles to regain her own composure. Sometimes the symptoms of eclampsia are far more subtle and include laziness and a lack of normal personality. If this happens to your dog, take her to the vet who will use a blood test to determine the cause.
Return to Normal
After 60 days or so, puppies tend to reach a point of self-sufficiency that allows them to roam on their own. They can find and eat food and fend for themselves in many ways. While guidance and assistance are still necessary in many situations, the independent puppies allow their mother to return more or less to her normal state. Expect your dog to begin to exhibit her true personality again soon and watch all the changes you've witnessed slowly fade.