This paper details two prospective, multicenter studies (conducted in the UK and US) evaluating the acceptance and physiological effects of a new, calorically dense, and nutritionally complete dry food specifically designed for dogs with malignancies. Over a 56-day period, adult dogs undergoing anticancer therapy demonstrated high eating enthusiasm and maintained a high quality of life while consuming the study food. The research found that dogs fed this new diet experienced significant weight gain—twice as much as a no-intervention group in the US study—along with improved muscle condition scores and increased serum 25-hydroxyvitamin D levels. Ultimately, the authors conclude that this palatable therapeutic food supports key health measures and can serve as a vital component of a multimodal treatment plan for canine cancer patients.