Nutritional assessment focuses on evaluation of animal-specific, diet-specific, feeding management, and environmental factors. Assessment includes evaluation of a patient’s medical history, comprehensive diet history, and physical examination including body weight, body condition, and muscle condition. Diagnostic testing may identify comorbidities associated with obesity or concurrent health conditions that need to be considered when developing a nutrition plan. When obesity is diagnosed during the nutritional assessment this finding along with health implications must be clearly communicated to the pet owner. Careful consideration of animal-specific, diet-specific, owner-specific, and environmental factors allows the clinician to develop a specific nutrition plan tailored to the needs of pet and owner.