Plus-Hex CLINICAL excess weight , a weight-reduction programme should be instigated ( Corbee , 2018 ). Although many middleaged and older pets are overweight , a large percentage of senior dogs , and cats in particular , have a low body condition ( Laflamme , 2005 ). Any unintentional weight loss after the age of 7 years old , particularly of 10 % or more , could be significant and should be investigated and addressed as a priority issue . BCS and MCS are not directly related – animals , especially those that are sick , may be losing lean muscle mass despite an abundance of body fat ( Laflamme , 2012 ), so body and muscle condition must be independently assessed in all animals , regardless of life stage .
Muscle mass results from the balance between anabolic and catabolic pathways involved in protein synthesis or breakdown . A suboptimal MCS with any degree of muscle wastage , however mild , requires prompt identification . A primary driver of basal metabolic rate , accounting for approximately 96 % of basal energy expenditure , is lean body mass ( LBM ), which includes skeletal muscle , skin and organs . Sarcopenia and cachexia are two important multifactorial syndromes associated with skeletal muscle wasting and loss of LBM that occur with ageing ( independent of illness ) and in the presence of disease , respectively ( Freeman , 2017 ;
Peterson & Little , 2018 ; Ray et al ., 2021 ). The underlying mechanisms involved in each syndrome overlap considerably and can occur concurrently ( Freeman , 2017 ), with important clinical implications . Deleterious effects include physical disability and poor quality of life , with a pronounced loss of LBM being associated with increased morbidity and mortality . Addressing sarcopenia and any potential cachectic conditions early is therefore crucial to the rapid instigation of nutritional support and an appropriate treatment plan .
While old age is not a disease , the ageing process is associated with a decline in organ function and immune response , in addition to the development of physiological changes and an increased likelihood of comorbidities ( Chandler et al ., 2018 ). The design of optimal nutritional programmes for aged animals must be underpinned by knowledge of these alterations ( Day , 2010 ) together with consideration for the potential presence of pain . Despite a lack of specific regulatory guidelines for senior diets , most focus on the general characteristics of ageing cats and dogs ( Corbee , 2018 ), so dietary recommendations reflect some of the biological effects associated with ageing and are tailored to optimise longevity , performance and health ( Table 3 , below and continues overleaf ).
Table 3 . Dietary factors requiring consideration in healthy senior cats and all breeds of senior dogs . ( This table spreads across pages 29 and 30 .)
Dietary factor Cats Dogs
Water
Water is a key nutrient and essential for life . Ageing impairs thirst sensitivity , which , combined with osmoregulatory disturbances , effects of medications ( such as diuretic drug therapy ), and disease , pose a greater risk of dehydration . Inadequately hydrated animals may be at risk of certain medical conditions including urolithiasis , constipation , diabetes mellitus and obesity . Fresh water should be supplied to cats and dogs on an ad-libitum basis , with routine monitoring of intake . If food intake is good but water intake is questionable , providing a moist diet can help to ensure adequate intake and hydration .
Energy Lean body mass ( LBM ) is the main driver of energy requirements in healthy dogs and cats , accounting for 96 % of basal energy expenditure . In both species , LBM tends to decline with age , with a pronounced loss being associated with morbidity and mortality . Not all older animals are overweight or less active , and disease can also influence energy requirements . Not all animals will benefit from restriction , so energy requirements and food intake should be adjusted accordingly to maintain a healthy weight and lean body condition .
The energy requirements of cats often decrease from 7 – 10 years old , and then increase from 11 years , with the greatest increase occurring after 13 years of age ( Cupp et al ., 2004 ). This rise is thought to be due , in part , to a reduced digestive function ( Laflamme , 2018 ). Diminished gastrointestinal tract function in senior cats may also lead to consumption of smaller volumes of food at each feeding , requiring calorie-dense diets offered in smaller , more frequent meals ( Ray et al ., 2021 ).
The energy requirements and LBM of dogs tend to decrease with age and a reduction in activity , with the greatest decline occurring in dogs over 7 years of age ( Churchill , 2018 ).
Volume 37 ( 4 ) • September 2022
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