Weight loss outcomes are generally worse for dogs and cats with class II obesity, defined as > 40% overweight.

Abstract

In pet dogs and cats, adiposity is most-often estimated clinically using a 9-category body condition score (BCS), with BCS 9 equating to&#x2009;~&#x2009;40% overweight. Animals that are more overweight (>&#x2009;40%) are seen in clinical practice but are not appropriately depicted by descriptions in the existing categories. To determine whether being&#x2009;>&#x2009;40% overweight has clinical relevance, this study aimed to compare the outcomes of weight management in animals that were&#x2009;>&#x2009;40% overweight with those&#x2009;<&#x2009;40% overweight. Records of dogs and cats attending a specialist obesity care clinic, where adiposity is determined using dual-energy X-ray absorptiometry (DXA), were reviewed. Animals were assigned to two classes (class I&#x2009;&#x2264;&#x2009;40% overweight: 118/398 [40%] dogs and 68/116 [59%] cats; class II,&#x2009;>&#x2009;40% overweight: 180/398 [60%] dogs and 48/116 [41%] cats) based on DXA results, and weight loss outcomes were compared. Fewer class II dogs obesity completed weight management than class I dogs (P&#x2009;<&#x2009;0.001), rate of weight loss was also slower (P&#x2009;=&#x2009;0.012) and lean tissue loss greater (P&#x2009;<&#x2009;0.001). Compared with class I, cats with class II obesity lost more weight (P&#x2009;=&#x2009;0.048) albeit over a longer period (P&#x2009;=&#x2009;0.043) leading to greater lean tissue loss (P&#x2009;=&#x2009;0.004). Approximately half the pets presenting to a specialist clinic were have class II obesity (>&#x2009;40% overweight), and some weight loss outcomes are worse for these animals.