Feeding a large-breed puppy: growth rate, calcium and when to switch

Is your puppy a large breed?

The cut-off is the expected adult weight, not the breed name. AAHA’s 2021 nutrition guidelines say that if a puppy is predicted to weigh 70 lb (31.8 kg) or more as an adult, it should eat a diet formulated for large-breed growth. Merck says the same thing through the food label: large- and giant-breed puppies should get a complete and balanced growth food carrying AAFCO’s statement for large puppies, which Merck quotes as “including growth of large size dogs [32 kg or more as an adult].”

If you don’t know your puppy’s adult size, estimate it. The puppy weight calculator predicts adult weight from today’s weight and age, with a range, using growth data derived from the Salt et al. 2017 data (CC BY 4.0). For example, a male Labrador Retriever weighing 25 lb (11.3 kg) at 16 weeks is predicted to reach about 61 lb (27.9 kg), with the middle half of the range at 55–69 lb. That is under AAHA’s 70-lb line even though Labradors are often thought of as large dogs, so a puppy near the line is a good question for your vet.

Small- and medium-breed puppies, Merck notes, can eat a growth or all-life-stage food that doesn’t meet the large-size criteria.

How many calories: 3.0 × RER, then 2.0

The calorie rule is the same for every puppy; what changes for big puppies is how closely you follow it. AAHA and Merck both start from resting energy, RER = 70 × body weight in kg^0.75, and multiply it by 3.0 before 4 months of age and 2.0 from 4 months to adulthood.

Two examples, computed with our engines:

For the 26-week puppy eating a dry growth food with 380 kcal per cup and 3,600 kcal per kg, keeping 10% for treats, that is 3.18 cups (about 3⅛ cups) or 336 g a day. Had the puppy stayed on the under-4-months factor, the number would be 2,017 kcal — half as much again.

You may also see the National Research Council’s 2006 puppy growth equation, which uses the expected adult weight. For these two puppies it gives 1,547 and 1,799 kcal. A study in Norfolk terriers, a small breed, found that it overestimated those puppies’ energy needs throughout their first year, so our calculator shows it only as an upper reference line. The full method is in how much to feed a puppy.

Grow slowly and stay lean

This is the part that matters most for big puppies. Merck states plainly that overfeeding during growth speeds up the growth rate, which is not compatible with proper skeletal development and also sets the puppy up for obesity later. It adds that a slow growth rate is preferable to a fast one, even though breed-specific growth curves are limited.

How lean is lean? WSAVA’s nutrition FAQ says large-breed growing puppies should be fed measured portions — not left with a full bowl all day — to keep weight gain slow and a body condition score of 4 out of 9, to avoid the joint and skeletal problems linked to fast growth. On the 9-point scale, 4 means ribs that are easy to feel under a thin layer of fat, a waist you can see from above and a belly that tucks up. AAHA likewise advises keeping large-breed puppies at an ideal body condition to lower the risk of orthopedic disease.

A lean puppy is not a stunted one. Merck describes large-breed puppies fed 50–70% of what their littermates ate when given free access to food: adult height, length and bone and muscle mass were not reduced; only body fat differed.

Calcium and supplements: let the food do it

A complete and balanced growth food already contains calcium, phosphorus and vitamin D. Merck says adding more of any of them beyond what such a diet provides is rarely necessary and may be contraindicated — that is, it may do harm. That is why this guide gives no calcium target or ratio to aim for at home: the target is built into a food that carries the large-size growth statement.

If you are thinking about any supplement, or about a home-made diet for a growing puppy, talk to your vet first; for home-made growth diets, a veterinary nutritionist can formulate one.

When to switch to adult food

Big puppies stay on growth food longer than small ones, and the two main sources use different yardsticks:

• Merck: after a dog reaches about 90% of its expected adult weight, a less nutrient-dense diet than the growth food is generally recommended. Merck also notes that growth and skeletal maturity may not be complete until 10–16 months in large and giant breeds, and that a puppy should stay on a growth diet until skeletal maturity, not just until obvious growth stops.
• AAHA: switch to an adult formula once the puppy reaches 80% or more of skeletal maturity; switching too early may cut nutrients the puppy still needs, and some dogs can stay on an all-life-stages food.

To put the 90% point on a calendar, here is when the median puppy in each size class of our growth data reaches 90% and 95% of its adult weight:

These are medians — half of the puppies got there later. The figures for dogs over 40 kg are the least predictable: the original study says its standards don’t apply to dogs with an adult weight above 40 kg, so that row comes from our own summary of the same data. Your vet can tell you when your puppy has reached the point to switch. When you do, WSAVA suggests changing gradually over at least 3 days, mixing more of the new food in each day.

Spaying or neutering also changes the numbers. AAHA notes that energy needs fall after the surgery, and because it is often done while a puppy is still growing, feeding enough for growth without excess takes frequent body condition checks.

Meals and weigh-ins

Merck’s general recommendation is three meals a day from weaning to 6 months and two meals a day from 6 to 12 months; your vet may suggest a different schedule for your puppy. Divide the day’s amount between meals rather than adding to it.

Merck advises watching weight gain closely — weekly — and adjusting the food so the puppy gains a small amount each week. Weigh on the same scale, and write the numbers down; a puppy growth chart shows whether the curve is steady. If your puppy’s body condition creeps above 4 or the weight jumps, ask your vet before cutting food sharply.

Next step

Enter your puppy’s age, weight and expected adult weight in the puppy feeding calculator. It applies the 3.0 or 2.0 factor, shows the range and the reference equation, converts the result to cups and grams for your food, and gives the size class’s age at 90% of adult weight.