Publication history: Accepted - 27 October 2021; Published - 29 October 2021.The dams of gregarious animals must develop a close bond with their newborns to provide
them with maternal care, including protection against predators, immunological transference, and
nutrition. Even though lactation demands high energy expenditures, behaviors known as allonursing
(the nursing of non-descendant infants) and allosuckling (suckling from any female other than the
mother) have been reported in various species of wild or domestic, and terrestrial or aquatic animals.
These behaviors seem to be elements of a multifactorial strategy, since reports suggest that they
depend on the following: species, living conditions, social stability, and kinship relations, among
other group factors. Despite their potential benefits, allonursing and allosuckling can place the health
and welfare of both non-filial dams and alien offspring at risk, as it augments the probability of
pathogen transmission. This review aims to analyze the biological and physiological foundations
and bioenergetic costs of these behaviors, analyzing the individual and collective advantages and
disadvantages for the dams’ own offspring(s) and alien neonate(s). We also include information on
the animal species in which these behaviors occur and their implications on animal welfare