Nutritional Assessment in Small Animals Dr Martin de Scally BVSc, Hons MMedVet (Med) Hilton Veterinary Hospital

Optimal health in dogs and cats is highly dependent on optimal nutrition. It is impossible to know what optimal is for each patient due to variation in age, breed, illness and current nutritional status; without a nutritional assessment on each individual patient.

A nutritional assessment should include a dietary history, a full clinical exam, a body condition score and a muscle condition score. After a nutritional assessment is completed the animal’s nutrition is altered accordingly to address any medical problems identified in the assessment. At this point goals are set for the nutritional intervention and a reassessment is scheduled. The length of time to rescheduling the assessment is based on the type and the severity of the condition being treated.

The assessment is repeated at the scheduled time and the nutritional intervention is evaluated for success or failure and altered again if indicated. Some nutritional interventions may take months before their full effect can be appreciated. In these cases it is helpful to explain this to clients before starting the intervention. It is important that the clinician takes time to make sure that the recommended diet is nutritionally complete as prescribed and to explain to pet owners that they should not feed anything else, as this may interfere with the dietary intervention. The goals of nutritional therapy are usually to help resolve any clinical disease and improve the animal’s quality of life.

A dietary history is simply a complete account of all that the animal eats. Figure 1 is an example of a dietary history form. The WSAVA website has both a short and long dietary history form available.

A full clinical exam is just that and therefore should be thorough enough to allow for a full assessment of the animals health and should lead to further diagnostic recommendations, should there be any abnormalities.

A body condition score assesses the animal’s body fat composition. Figure 2 and 3 are examples of body condition scores for cats and dogs. Put simply it assesses whether an animals’ energy nutritional needs are being met, are deficient or are in excess.

Muscle condition scoring may be a new concept to some clinicians. Figure 4 and 5 are examples of muscle condition scoring. It is assessed by visualization and palpation of the spine, scapulae, skull, and wings of the ilia. Muscle loss is typically first noted in the epaxial muscles on both sides of the spine; muscle loss at other sites can be more variable.

Muscle Condition Score is graded as normal, mild loss, moderate loss, or severe loss. Animals can have significant muscle loss if they are overweight (body condition score > 5 on a nine point scale). Conversely, animals can have a low body condition score (< 4 on a nine point scale) but have minimal muscle loss. Therefore, assessing both body condition score and muscle condition score on every animal at every visit is important. Palpation is especially important when muscle loss is mild and in animals that are overweight.

Veterinarians and pet owners accept poor muscle condition as a normal consequence of aging and often do nothing to counteract this condition. There are no completed studies that have investigated sarcopenia in dogs or cats to date. In human medicine increasing daily protein above the recommended daily allowance has been shown to retard aging sarcopenia 3,5. This may be an intervention target to prevent and/ or mitigate aging sarcopenia. The type of protein used in order to increase the levels of essential amino acids may also be important. The branched chain essential amino acid leucine, in particular, has been extensively studied due to its anti-catabolic properties in humans and its roles in protein metabolism, glucose homeostasis, insulin action, and recovery from exercise 6. Interventions in humans that provide targeted amino acid/protein composition to enhance musculogenesis, hold potential for even greater gains 4.

Whilst protein restriction may be appropriate for treatment of existing kidney disease in human medicine, the myth of high protein intake as a cause of renal failure has also been dispelled. No significant evidence for a detrimental effect of high protein intake on kidney function in healthy persons has emerged after centuries of humans eating high protein diets. 2. Similarly no evidence is available in the veterinary literature linking veterinary diets with significantly increased protein of high biologically value as a cause of renal failure in dogs and cats.

A word of caution is that the diet must be balanced and registered as a complete meal. This would mean that all the micro and macronutrients meet this requirement, including phosphorus. Pet foods made with high quantities of bone meal, for example, as their protein source should only be able to be registered as a supplement and not as a complete diet. These foods may be imbalanced in the phosphorus content and may indeed cause health issues if overfed. A simple way to check the bone meal content in a diet is to look at the analysis to see the ash levels of the diet. Animals with early renal failure should only be fed higher protein diets with extreme caution and serial testing.

If muscle condition is found to be low, it is reasonable to increase the animal’s high biological value protein intake to try and retard aging sarcopenia. If we are to follow the human recommendations, an increase in exercise will also be beneficial in healthy animals 1. Arthritis, which has a high prevalence in older animals, should be addressed before an increase in exercise is advocated for that animal. Addressing pain in animals is the 4th vital assessment recommended by the WSAVA.

After the nutritional assessment and diagnostic work up, all nutritional related risks are identified and addressed. Nutritional related risks include age (growing or old), suboptimal body condition score (overweight or thin), muscle loss, atypical or homemade diet, medical conditions and changes in appetite.

The nutritional tools referred to in the text can be downloaded from the WSAVA website and used by practitioners unchanged. The link to the nutritional tools is: www.wsava.org/sites/default/files/WSAVA%20 Global%20Nutrition%20Toolkit_0.pdf

References

  1. Evans WJ. Skeletal muscle loss: cachexia, sarcopenia, and inactivity. Am J Clin Nutr. 2010; 91:1123S–1127S
  2. Martin WF, Armstrong LE, Rodriguez NR. Dietary protein intake and renal function. Nutr Metab (Lond). 2005 Sep 20;2:25
  3. Morley JE, Argiles JM, Evans WJ, et al. Nutritional recommendations for the management of sarcopenia. Journal of the American Medical Directors Association. 2010;11:391–396
  4. Paddon-Jones D. Interplay of stress and physical inactivity on muscle loss: Nutritional countermeasures. The Journal of nutrition. 2006;136:2123–2126
  5. Volpi E, Campbell WW, Dwyer JT, et al. Is the optimal level of protein intake for older adults greater than the recommended dietary allowance? J Gerontol A Biol Sci Med Sci. 2013;68:677–681
  6. Wilson GJ, Wilson JM, Manninen AH. Effects of beta-hydroxy-beta-methylbutyrate (HMB) on exercise performaznce and body composition across varying levels of age, sex, and training experience: A review. Nutr Metab. 2008;5:1.

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