Written by Holly Pollard-Wright DVM, CCRP

An essential component of any veterinary rehabilitation program is nutritional management because it is integral to the dog and cat’s longevity and quality of life.1, 2  As such, the central consideration of a complete rehabilitation plan for canine and feline patients considers vulnerable life stages. These stages include growth, gestation, lactation, and advancing age, altering the patient’s energy and nutrient requirements.1, 2  Veterinary Kinetics Rehab Inc designs a comprehensive exercise plan for each patient that includes a thorough nutritional assessment that begins with a screening evaluation. This evaluation aims to identify risk factors by evaluating nutritional history, environment, and activity level before or during the initial exam. The initial exam includes a physical exam, body weight (BW), visualization, and palpation of the musculature. In this process, Dr. Pollard-Wright evaluates the patient’s current level of physical fitness, including desired weight loss (if needed) and muscle mass. She assesses body condition score (BCS), a physical assessment of body fat mass, along with muscle condition score (MCS), a physical assessment of the patient’s muscle mass.2  Notably, because BCS and MCS are not causally related, they are assessed and scored separately.2  For example, there can be instances where an animal may be overweight yet have muscle loss. Alternatively, an animal might be underweight with a loss of both body fat and muscle mass.The loss of lean body mass and overall weight loss can occur during senior and geriatric life stages.2 

Basics of energy requirements, age, and diet 

The daily energy needs of dogs and cats include activity level, life stage, percent lean body mass, age, and environment. Metabolizable energy (ME), that portion of the total energy of a diet retained within the body, is the most useful measure of energy for nutritional purposes. It is typically measured in calories or joules, and the caloric content of pet foods is often reported in kilocalories (kcal), which is 1,000 calories. The Association of American Feed Control Officials (AAFCO) publishes dog and cat nutrient profiles for adult maintenance and reproduction. The National Research Council (NRC) publishes nutrient profiles for dogs and cats for various life stages. Notably, although as dogs and cats age, their energy requirements can vary, there are no specific nutritional requirements set by AAFCO.3  For this reason, if an older dog or cat is doing well with a complete and balanced adult maintenance diet, it is appropriate to continue feeding that diet until a medical condition prompts otherwise.3


Dogs are a biologically diverse species, with an average body weight of 4–80 kg (2–175 lb) and where body mass varies greatly across breeds.1, 3 The dog’s body composition will vary with the breed but largely depends on the age.2, 3  The normal birth weight of pups depends on breed type (120–550 g), in which growth rates of puppies are rapid for the first 5 months.3  During this period, pups gain an average of 2–4 g/day/kg of their anticipated adult weight, and where growth rate begins to plateau after 6 months.3  Growth may be completed by 8–12 months of age in small and medium breeds and 10–16 months in large and giant breeds. Suggested is that puppies be fed a diet appropriate for growth until they reach skeletal maturity: small and medium-size dogs (provide a diet for growth until approximately 1 year).3  Regarding large- and giant-breed dogs (in which their skeletal maturity may not be achieved until closer to 15–16 mo), it is essential to support growth while maintaining a lean BCS and avoid excessive calcium intake.2  Both breed and age can influence metabolic rates, and research indicates canine resting metabolic rate declines with age. For example, dogs aged 7 to 8 years have 1/2 of the resting metabolic rate of dogs aged 1 to 2 years.1, 2, 4  Notably, high energy expenditure in dogs appears positively linked to increased life expectancy, in which metabolism affects life expectancy in different ways.


Domestic cats’ average mature body weight is 3.2 kg (7 lb) for toms and 2.8 kg (6 lb) for queens. The normal birth weight of kittens is 90–100 g, where the growth rate is rapid for the first 3–4 months, and kittens gain 50–100 g/week.The growth rate begins to plateau at 150–160 days of age, and growth is usually completed within 200–220 days.3  It is suggested that kittens should be fed diets appropriate for growth until they reach skeletal maturity, which occurs approximately 1 year. In cats, fat, protein, and energy digestibility can decrease with age. Because of this, energy intake can be higher for senior cats to compensate for this decrease in digestibility. A reduction in digestive capabilities can lead to decreased BCS and increased caloric intake, where being underweight is a common problem in senior cats.5  Although there is a lack of consensus regarding optimal dietary protein levels in mature adult cats, research has suggested that aging cats should receive diets higher in protein to avoid losing lean muscle mass.A diet with a minimum protein allowance of 30–45% dry matter is considered a moderate protein amount recommended for healthy mature adult/senior cats. In the case of cats with chronic kidney disease, they may benefit from prescription renal diets. These diets have restricted, high-quality protein and restricted phosphorus levels and other ingredients that may promote renal health.5

Nutrition and physiological aspects of rehabilitation

A targeted rehabilitation with a proper conditioning program provides a good healing environment for injured tissues while considering the physiological aspects of rehabilitation. The type of conditioning determines the content of proteins, carbohydrates, and fat in the feeding program. Nutritional needs can change throughout treatment and time of rehabilitation, including where initially, there is a decrease in energy used by the patient.1  In this case, targeted rehabilitation aims to address changes in nutritional needs to prevent the patient from becoming overweight. Increased body mass occurs with excessive caloric intake and inadequate exercise expenditure. In this process, energy storage is in the form of glycogen or fat. Animal factors must also be considered to effectively prevent obesity in which energy requirements are reduced after spaying or neutering, necessitating intake reduction. The literature suggests that certain breeds (e.g., Labrador retrievers, beagles, Norwegian forest cats, Persians) are predisposed to weight gain and thus have an obesity risk.2  It has been suggested that combatting obesity with appropriate nutritional and exercise intervention can improve movement function, decrease discomfort, and help retain lean muscle mass.1, 2, 6  In dogs, it has been consistently shown that obesity decreases longevity and increases morbidity.6  Additionally, geriatric animals account for half of the pet population in the United States, with obesity, sarcopenia, and a sedentary lifestyle representing a trifecta of age-related morbidity.6 Sarcopenia, the loss of lean mass associated with aging due to multifactorial components, has been shown to increase morbidity and mortality.6  Both nutritional and exercise interventions may help reduce the morbidity associated with sarcopenia. A combination of strength training and aerobic activity may benefit both function and muscle mass.6

A targeted rehabilitation plan includes adding nutritional components to accommodate the dietary demands due to increased physical activity when reconditioning begins. Caloric balance is an essential consideration for the dog’s diet in which body mass decreases in situations where caloric expenditure exceeds caloric intake. In this process, energy comes from various deposits within the body, such as stored fat, glycogen, and muscle.1  For example, the basic nutritional needs for dogs performing strength workouts include immediate and glycolytic energy systems.1 As such, their basic nutritional needs include carbohydrates to produce adenosine triphosphate (ATP), an energy-carrying molecule found in the cells of all living things, along with a lower percentage of fat in their diets. In addition, a post-workout snack such as simple carbohydrates, or a meat protein source, may benefit conditioning by replenishing nutrients. The idea is that snacks offered immediately after the workout replenish nutrients of the energy systems lost during the exercise.1


  1. Millis, D. L., & Levine, D. (2014). Canine rehabilitation and physical therapy (2nd ed.). Saunders, Cop.
  2. Cline, M. G., Burns, K. M., Coe, J. B., Downing, R., Durzi, T., Murphy, M., & Parker, V. (2021). 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats. Journal of the American Animal Hospital Association, 57(4), 153–178. https://doi.org/10.5326/jaaha-ms-7232
  3. SANDERSON.SHERRY. (2019). Nutritional Requirements and Related Diseases of Small Animals – Management and Nutrition – Veterinary Manual. Veterinary Manual. https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-and-related-diseases-of-small-animals
  4. Speakman, J. R., Van Acker, A., & Harper, E. J. (2003). Age-related changes in the metabolism and body composition of three dog breeds and their relationship to life expectancy. Aging Cell, 2(5), 265–275. https://doi.org/10.1046/j.1474-9728.2003.00061.x
  5. Mature Adult and Senior Cats. (n.d.). Www.aaha.org. Retrieved May 1, 2022, from https://www.aaha.org/aaha-guidelines/life-stage-feline-2021/nutrition-and-weight-management/mature-adult-and-senior-cats/Frye, C., Carr, B. J., Lenfest, M., & Miller, A. (2022). 
  6. Canine Geriatric Rehabilitation: Considerations and Strategies for Assessment, Functional Scoring, and Follow Up. Frontiers in Veterinary Science, 9. https://doi.org/10.3389/fvets.2022.842458