Short Synopsis: Puppies separated from their litter at 30-40 (4-5 weeks) days were far more likely than puppies separated from their litter at 60 (8.5 weeks) days to exhibit behaviors including destructiveness, excessive barking, fearfulness on walks, reactivity to noises, toy possessiveness, food possessiveness, and attention-seeking.
Correlations were stronger with puppies that were younger, and especially if they came from a pet store.
Authors:L. Pierantoni, M. Albertini, F. Pirrone
Publication: Veterinary Record
Publication Date: October 2011
Applies To: Pet stores, breeders
Sample Size: 70 dogs
Limitations/Drawbacks: Correlation/observation only, based on owner report