Do hot dogs need less food?

Investigation of pet dog diets in Bengaluru, India suggests canine energy requirements in the sub- tropics may be lower than previous studies

Nutrition

Dog ownership in India is skyrocketing. Reliable figures are hard to come by, but there are thought to be over 10 million pedigree dogs on the sub-continent. The market research website Euromonitor International has predicted that India will soon be the fastest growing global pet market, with rising ownership rates driving demand for food, health products, and other accessories. The local industry is already worth over $800 million annually, and is expected to register strong double-digit retail value growth in the coming years.

However, fast growth presents new challenges. In Europe and North America, pet food manufacturers invest heavily in nutrition research. This has created a huge repository of knowledge on pet dietary requirements for a healthy life. But there is almost no research about what constitutes an ideal pet diet in emerging markets - neither how much food nor what kind. In many circumstances this may not matter; results obtained in more temperate climates may well be universally applicable. However there is scant evidence that this is necessarily the case. The effects of, say, sub-tropical heat and humidity on pet energy requirements are simply unknown.

So a team from the Veterinary College, Hassan and the Veterinary College, Bangalore, India, supported by WALTHAM, decided to find out more. The results have just been published in the Journal of Animal Physiology and Animal Nutrition.

The researchers selected 37 adult domestic dogs through a local vet practice in Bengaluru (Bangalore): 17 German shepherds and 20 Labrador retrievers. The dogs were all fed the same dry pet food for 10 weeks and body weight, food intake, body condition score and physical activity were monitored. Then, for each breed, the minimum energy requirements (MER) were calculated using basic formulae developed in cooler climes.

Body weights remained stable over the study period, with an average daily gain of just over 9g. Mean (SD) MER was 103.4 (16.3) kcal/kg BW0.75, which was some 20% lower than that currently suggested for moderately active young adult dogs. There were no significant differences in MER between the two breeds, or between males and females within and between the two breeds, although there were some marked differences between the MER of individuals.

“This is, to the best of our knowledge, the first report of MER in free-living domestic dogs on the Indian subcontinent,” says H. S. Madhusudhan, who led the research. “It highlights important variations in MER among young adult moderately active pet dogs. However, at this point we do not know what causes the disparity. The lower MER of dogs in this study, relative to previous observations, may reflect climatic and environmental differences to some degree, but other factors may also be at work.”

It is worth noting that the energy requirements of the dogs in this study are fact only slightly higher than the US/Europe derived figures. The MER of typical inactive pets in US/European studies, as defined by the US National Research Council, is 95 kcal BW0.75 – a figure that many petfood manufacturers use as a basis for their feeding guidelines. Given the extremes of temperature and often markedly different pet lifestyles, it might be expected that the differences with the Indian dogs would be more extreme. In the Labradors, for instance, the observed value of 105.9 kcal/kg BW0.75 is in fact comparable with mean values previously reported for older dogs of 7 years of age upwards.

This suggests multiple factors at work. The lower calculated MER in the present study is not readily explained by disparity in breed or age of dogs. Differences in methodology, gender, lean body mass or activity of the dogs, or environmental temperature may be responsible.

However the influence of lifestyle remains unclear in this case. The dogs were all reasonably active, with mean daily physical activity totalling between 45 min and over 6 hours, so the relatively low MER cannot be simply explained by relatively lack of exercise. The two groups of dogs were also well balanced with respect to males and females, making it unlikely that a predominance of one or another gender may have unduly influenced the MER calculations.

This strongly suggests that it is environmental and climatic factors that are influencing the MERs to some degree. Annual mean maximum and minimum temperatures in Bangalore are 39°C and 8°C, respectively, with humidity ranging between 57% and 91%. These conditions are a stark contrast with those of northern Europe and the United States where much of the previous work on canine MER has been undertaken.

“Substantial over or underestimations of energy requirements can result in under or overfeeding with consequent loss of body weight or risk of obesity,” says Madhusudhan. “This study has highlighted the fact there can be substantial variation between individuals, as well as between geographic regions. These factors should definitely be considered in the formulation of pet foods and feeding guides.”

Madhusudhan HS, Chandrapal Singh K, Krishnamoorthy U, Umesh KG, Butterwick R, Wrigglesworth D. Estimation of maintenance energy requirements in German shepherd and Labrador retriever dogs in Bangalore, India. J Anim Physiol Anim Nutr. 2017;00:1–5.
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