The health of adult dogs and cats is affected positively or negatively by their development in utero and throughout postnatal growth. Preventive veterinary care is particularly important when animals are physiologically immature and sensitive to modifiable environmental factors. Veterinary nurses/technicians are often at the forefront of promoting healthy development, reinforcing the work of veterinarians and using their knowledge, experience, and passion to lead initiatives with breeders and pet guardians. This opinion article considers the role of qualified veterinary nurses/technicians in the care of puppies and kittens throughout their developmental life stages—gestation, the suckling period, growth post-weaning to puberty or neutering, and late growth to adulthood. Much of their influence is through the education of pet carers; they provide trustworthy information relevant to the individual pet and focused on the practicalities of best husbandry practices. These include practical advice on recognizing dystocia, neonatal care, weaning, introduction to the new home, the prevention and management of infectious diseases, socialization with conspecifics and humans, habituation to potential environmental stresses, nutrition, oral hygiene, and grooming. The veterinary nurse’s goal is not only to see young pets develop into healthy, well-adjusted adults but also to see pet guardians developing sustainable human–animal bonds.