Puppy growth rate during early periods of labrador retriever development: role of litter size and photoperiod of birth

Abstract

Several studies have recently investigated the birth weight of puppies from different pure-bred dogs. In general, birth weight decreased with litter size but there has been limited investigation into factors influencing growth during early development. The first month of life includes three stages of puppy development: neonatal (0–13 days), transitional (14–20 days), and first week of socialisation period (21–28 days). The aim of this study was to evaluate bodyweight and growth rate of 120 Labrador Retriever (LR) puppies during early development. Puppies from 19 show-line bitches under standardised composition of diet during pregnancy and lactation were involved in this study. Puppies were weighed weekly from birth to 28 days using an electronic digital balance. Relative weight gain (ΔW) was calculated for the neonatal period [ΔW1 = (Wday14-Wday0)/Wday0], transition period [ΔW2 = (Wday21-Wday14)/Wday14] and first week of socialisation period [ΔW2 = (Wday28-Wday21)/Wday21]. The effects of covariates on ΔW were assessed using generalised linear mixed models. Sex and photoperiod had no impact on relative weight gain, whereas litter size had a significant effect at ΔW1 (p < .01) but not at ΔW2 and at ΔW3. Relative weight gain was slightly lower in puppies from larger litter born during short photoperiod on ΔW1. A deeper knowledge of the factors that significantly influence weight gain during the first four weeks of life could be useful for physiological and behavioural science as well as for canine breeding management. Highlights 120 Labrador Retriever puppies were weighed weekly from birth to 28 days using an electronic digital balance. Relative weight gain (ΔW) was calculated for the neonatal period (ΔW1), transition period (ΔW2) and first week of socialisation period (ΔW3). Litter size had a significant effect on relative weight gain at ΔW1 but not at ΔW2 and ΔW3. Relative weight gain was slightly lower in puppies from larger litter born during short photoperiod on ΔW1.