Why all puppy and kitten foods are not created equal

by Dr Jessica Mills BVSc (Hons I), Hill’s Technical Services Veterinarian

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We know that all pet owners want to give their new furry friends the best start in life. Feeding a good quality puppy or kitten diet is a great step to achieving this goal, but how do we advise them which diet to reach for?

A good starting point is to look at the key nutritional factors for growth.

  • Energy – Required for both growth and maintenance. Daily energy requirements can be as much as 3 times resting energy requirements (RER) in puppies and 2.5 x RER in kittens at weaning. This decreases over time as they get closer to their adult body weight. Given their relatively small stomach size, the energy density of a diet is important and should be at least 4kcal/g DM (dry matter basis).
  • Digestibility – As alluded to above, the relatively small stomach sizes of puppies and kittens limits their food intake. The more digestible the food, the more they are able to utilise the ingested nutrients and the smaller the amount of food required to meet their needs. From a pet owner’s perspective, the decrease in volume and odour of stools can be a distinct advantage as well.
  • Protein – Compared to adults, growing animals need increased levels of high quality, highly digestible protein to support lean body mass development as well as to aid with development of the immune system by providing the building blocks for antibodies. Utilising both animal and plant sources of protein can help provide the optimal balance of amino acids in the diet.
  • Calcium – A good quality complete and balanced diet for growth can help ensure puppies and kittens receive the optimal amount of calcium to support skeletal development. Kittens fed on all meat diets are prone to calcium deficiency whilst puppies can be prone to calcium excess through supplementation of the diet either directly or indirectly through foods such as cheese, milk and bones. Dietary intake of phosphorus is another important factor in bone development, however as long as the minimum dietary requirements are met, the calcium to phosphorus ratio is more important than the actual level of phosphorus.
  • Antioxidants – A published paper showed that puppies consuming antioxidant enhanced foods had significantly higher antibody responses following vaccination to distemper and parvovirus, and had increased numbers of memory immune cells (memory CD4+ lymphocytes) which may help provide longer lived protection.1
  • Fatty Acids – Omega 3 fatty acids, particularly docosahexaenoic acid (DHA) are important in healthy brain and vision development. Published studies have demonstrated how feeding diets enhanced with DHA can optimise the development of rods and hence enhance the development of visual acuity in both puppies and kittens.2,3

If puppy and kitten formulas are complete and balanced for growth, why do we need specific diets for large breed puppies? Large breed puppies (any dog that will have an adult size >25kg) have an inherently fast growth rate –  just compare the size of a 4 month old Labrador to a 4 month old Jack Russel Terrier. This is one of the factors that predisposes them to developmental orthopaedic diseases (DODs) such as hip dysplasia and osteochrondritis dissecans. By modulating their nutrition, we can control their growth rate to allow them to achieve their genetic potential at a slower rate, thereby minimising the risk of DODs. As a leader in the area of small animal nutrition, Hill’s realised this and brought the first diet specifically designed for the growth of large breed puppies to market in 1996. Energy and calcium are the drivers of bone growth, so you’ll find that these nutritional factors are relatively lower in super premium large breed puppy foods. Large breed puppy formulas should also be enriched with L-carnitine to help optimise metabolism of fat and maintain lean body mass.

Hill’s Science Diet has a range of foods in different formulations specifically designed to meet the needs of kittens and puppies.

For more information on optimal nutrition for puppies and kittens, and also information on feeding dogs and cats during pregnancy and lactation, check out the webinar at this link.



Debraekeleer J, Gross KL and Zicker SC. Feeding growing puppies: postweaning to adulthood In: Hand MS, Thatcher CD, Remillard RL et al. Small Animal Clinical Nutrition 5th Edition. Mark Morris Institute, Kansas, 2010: 311-319

Gross KL, Becvarova I and Debraekeleer J. Feeding growing kittens: postweaning to adulthood In: Hand MS, Thatcher CD, Remillard RL et al. Small Animal Clinical Nutrition 5th Edition. Mark Morris Institute, Kansas, 2010: 429-436


  1. Khoo C, Friesen J, Wedekind K et al. The role of supplementary dietary antioxidants on immune response in puppies. Vet Ther 2005; 6(1):43-56.
  2. Pawlosky RJ, Denkins Y, Ward G et al. Retinal and brain accretion of long-chain polyunsaturated fatty acids in developing felines: the effects of corn oil-based maternal diets. Am J Clin Nutr 1997; 65:465-472.
  3. Heinemann KM, Waldron MK, Bigley KE et al. Long-chain (n-3) polyunsaturated fatty acids are more efficient than α-linolenic acid in improving electroretinogram responses of puppies exposed during gestation, lactation, and weaning. J Nutr 2005; 135:1960-1966  HIMA-JM-1731557D




Dr. Jessica Mills graduated as a veterinarian from the University of Sydney with honours in 1999. After graduation she spent 10 years working first in mixed, and then small animal practice at a number of clinics both in Australia and the UK. She moved into industry in 2009, initially immersed in the world of fleas and ticks at Merial Australia and more recently enjoying utilising her skills in the field of nutrition as the Technical Services Veterinarian for NSW/ACT for Hill’s Pet Nutrition Australia