How is the puppy weight inherited?

The size or weight of puppies at birth is an important parameter, which influences neonatal mortality and morbidity. It is also a predictor of puppy survival. Puppies should be weighed daily for at least the first three weeks to control weight gain, allowing an early detection of potential problems.

Both offspring and maternal genetic and environmental factors affect birth weight. Data about genetic parameters for the birth weight in dogs is limited, however studies have already been conducted in some breeds to assess the direct heritability for this feature.

This study aimed to estimate heritability for the puppy weight on birth (PWB) in Labrador Retrievers. It included various statistical analyses considering 7827 puppies from 1013 litters (with 4 to 11 elements).

In this research, males were in average 24 g heavier than females. The season of birth did not seem to affect PWB, however an increase of the litter size by one puppy resulted in a moderate decrease of 11 g in average and longer gestation resulted in heavier cubs (around 6 g per additional day). The dam weight seems to be related to an increase in the puppy weight of 5 g per kg adult weight but the same does not apply to the sire. Parity, year of birth and inbreeding coefficients of the dam and the puppies had minor effect. Other factors, like the diet of the dam during pregnancy are known to influence the puppies birth weight but they were not included in this investigation.

Understanding what influences neonate weight can help us promote welfare and preventing the birth of extremely heavy neonates. Furthermore, individual PWB is known to influence the choice of the surgical procedure to perform in the parturition of Labrador Retriever dogs.

Schelling, C., Gaillard, C., Russenberger, J. et al. Heritabilities for the puppy weight at birth in Labrador retrievers. BMC Vet Res 15, 395 (2019). https://doi.org/10.1186/s12917-019-2146-8