Puppies and supplements: what to know before you start

Start with the food, not the supplement

Puppies grow remarkably fast. UK Pet Food points out that in the first months they have to develop muscles, bones, skin and coat, teeth and internal organs, and that in larger breeds such as Great Danes and Labrador Retrievers the growth period is longer — some large breeds take up to two years to reach full adult size. That is exactly why puppy nutrition is built around a properly formulated food rather than add-ons.^[1]

The key word on the bag is ‘complete’. UK Pet Food explains that ‘complete’ is a legal term: the product must, by law, contain all the nutrients a pet needs, and the most important factor in choosing is that the food is clearly labelled as complete for the puppy or growth stage of life. Blue Cross says the same in plainer terms — any commercial puppy food appropriate for your dog’s age and size and described as ‘complete’ will be nutritionally balanced and won’t need to be mixed with anything else.^[1],[3]

Do puppies need supplements?

Generally, no. UK Pet Food states that there is no need to supplement a complete and balanced commercial puppy diet, and warns that supplementing a complete diet can be risky and lead to growth abnormalities, especially in large and giant breeds. Its example: giving calcium supplements to growing puppies already on a balanced diet can damage their skeletal growth and development. The Royal Kennel Club similarly notes that overfeeding a puppy may cause excessive weight gain and, particularly in larger breeds, bone deformities.^[1],[2],[4]

UK Pet Food does acknowledge there are occasions when a supplement may be helpful even alongside a complete food, and that ‘supplement’ has no legal definition — the word covers everything from vitamin powders to functional ingredients and treats. That breadth is a good reason to ask your vet about any specific product rather than relying on the label alone.^[2]

The same goes for an unsettled tummy. The PDSA advises seeking advice if you have a puppy with diarrhoea, as this can be more serious than in an adult dog, and lists very young dogs among those who should be checked by a vet sooner. A supplement is never a reason to wait — see when to see a vet about your dog’s digestion.^[8]

Puppy nutrition basics

Our guide to building a daily feeding routine covers meal timings in more detail.

Large and giant breed puppies

Bigger breeds need particular care. UK Pet Food explains that larger breed puppies generally need fewer calories per unit of body weight and mature more slowly than smaller breeds, and that taking on too many calories can accelerate growth and put extra stress on a growing skeleton. Large-breed puppy foods are designed for gradual growth and are often lower in calcium and phosphorus than other puppy foods. That is one more reason not to add extra minerals or vitamins to a large-breed puppy’s complete food without your vet’s advice.^[1]

UK Pet Food suggests moving from a growth diet to an adult one once a puppy reaches around 90% of their expected adult weight — around nine to 12 months for small breeds, and up to two years for large and giant breeds. Your vet can help you judge when your puppy is ready.^[1]

Questions worth asking your vet

Introduce one new thing at a time

A new puppy’s world changes quickly — new home, new routine, often a new food. Blue Cross advises changing a puppy to a different food gradually over a week to 10 days, adding a small amount of the new food to the current food and slowly increasing it, to avoid an upset tummy. The same principle is worth applying to anything new: if you change the food, add treats and start a supplement all in the same week and your puppy’s stools change, you won’t know which one to look at. Change one thing, give it time, then consider the next — and see switching dog food gradually for a day-by-day approach.^[3]

Vaccinations and worming are vet conversations

Supplements are optional; vaccinations and parasite control are core puppy healthcare, and both are planned with your vet. The PDSA recommends registering with a vet before your puppy comes home, so they can advise on vaccine timings and support you if your puppy becomes unwell. It says puppies should ideally start vaccines at around six to eight weeks old, with your vet setting the exact schedule.^[5],[6]

For worming, the PDSA says puppies are commonly wormed from around three weeks old and then regularly in the first months, but to check the schedule with your vet because each product has its own guidelines — and to use a product suitable for your puppy’s age and weight.^[7]

Puppies grow fast — so weigh them often

The Royal Kennel Club says regularly weighing your puppy helps you check they’re growing at a healthy rate for their age, size and breed, and suggests asking your vet whether they can supply a puppy growth chart. Regular weighing also matters for anything dosed by weight: the PDSA notes that the right dose of a wormer depends on your dog’s age and weight, and the same logic applies to any weight-banded product. A puppy who was in one band last month may be in the next band now.^[4],[7]

Our step-by-step guide to weighing your dog at home covers the bathroom-scale method, which works well for puppies you can lift.

If you are considering DIGEST+ for an older puppy

DIGEST+ is a complementary feed for daily digestive support in dogs. Its label is explicit that it is not suitable for puppies under 12 weeks. For a puppy over 12 weeks, speak to your vet before starting, and keep it as an addition to a complete puppy food — never a replacement for any part of it.

DIGEST+ is fed by weight band, so a growing puppy’s daily amount can change as they grow. Weigh your puppy regularly and recheck the band with the dose calculator each time their weight changes.