Most dogs and cats in developed countries are fed commercial dry extruded kibble pet foods. Some authors believe that the availability of nutritionally complete and balanced pet foods have contributed to the longer and healthier lifespan of pets, while others blame the increased prevalence of obesity in pets on such availability. Precision and accuracy in the amount fed are important in weight management. This study examined 6 different commercially available extruded dry kibble pet foods from 3 different manufacturers. The measuring cups supplied by the manufacturers were used. The desired amount of food was first weighed and then put in the correct cup, which was shaken to level it. An indelible pen was then used to mark the top line of food. The investigators then measured portions of food with the cup and placed it in plastic bags. After all portions had been measured, they were weighed without the plastic bag. Poor precision was noted in all studies with the intrasubject coefficient of variation ranging from 2% to 13% and the intersubject coefficient of variation ranging 2% to 28%. Accuracy included an 18% underestimate to an 80% overestimate of portion size. There are multiple causes of obesity, including individual variations in energy requirement; however, this level of imprecision has the potential to cause problems, such as weight gain, and complicates weight loss programs. Study supported by Royal Canin

Commentary: I’ve had people swear they were feeding only a cup of food to a pet only to find out that the cup was a 16-oz drink cup. It was disheartening to read that imprecision occurs even when people are using the cup provided by the manufacturer. Other options must be considered, particularly for our smaller veterinary patients. Some companies are offering portion-control packaging, which might be helpful for some patients. For other patients it might be best to encourage use of a kitchen scale to determine the appropriate amount of food to offer.—Patricia Thomblison, DVM, MS

Imprecision when using measuring cups to weigh out extruded dry kibble food. German AJ, Holden SL, Mason SL, et al. J ANIM PHYSIOL ANIM NUTR (BERL) doi: 10.1111?j.1439-0396.2010.01063.x (Epub ahead of print).