Before 4 months
10 guides · You're caring for a very young animal — possibly unexpectedly.
This is the age range our calculators deliberately leave out, because energy needs move too fast there for a single formula to be honest. It is also the age range where waiting to see if something resolves is the most dangerous instinct, so every page here leads with the thresholds for getting help.
Development timeline
Birth – 16 weeksEyes, ears, teeth, weaning, and growth rates for puppies and kittens — as reference windows, not deadlines every animal must hit.
Temperature & warming
Birth – 5 weeksNewborn body temperature runs lower than an adult's, and a chilled newborn must not be fed until it is warm again. Reference ranges, safe rewarming, and when to call.
Hand-rearing & milk replacer
Birth – weaningWhy the milk you choose matters, how aspiration happens, and why this is the one topic where you need a veterinarian to show you in person.
Elimination stimulation
Birth – 6 weeksNewborns cannot go on their own at first. What assistance involves, when they start managing alone, and what straining without output means.
Stool changes
Birth – 16 weeksWhat stool consistency can and can't tell you, which changes need a call, and why a nursing newborn is not judged by the same timeline as an adult.
Weaning & growth food
3 weeks – 16 weeksWhen solids start, how to read a nutritional adequacy statement, and why large-breed puppies need a different label check than everyone else.
Vaccines & parasites
2 weeks – 16 weeksWhy one injection never completes the series, what the core schedules actually say, and why no flea product has a single universal starting age.
Socialisation
2 weeks – 12 weeksKittens start and finish earlier than puppies. What to expose them to, how to handle the vaccination conflict, and what fear looks like.
Emergency signs
Birth – 16 weeksWhich signs mean go now, which mean call now, and which mean call today — plus why daily weight is the earliest warning you get.
Dangerous myths
Birth – 16 weeksXylitol, paracetamol in cats, dog flea products on cats — the mistakes that kill, plus the neutering-timing debate handled honestly.