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Nutrition of elderly dogs and cats

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Category: Schede
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  • Disciplina: Alimentazione
  • Specie: Cane e Gatto

Given that the age at which animals are considered old differs enormously depending on breed and body mass, there are no clearly established nutritional requirements for elderly dogs and cats, in contrast to the situation for other physiological stages of their life (growth, maintenance, lactation, gestation). The population of elderly dogs and cats in industrialised countries is becoming ever more numerous. The number of dogs over 7 years old has increased by 50% from 1983 to 1995.1 Ageing is not a disease, but rather a stage of life characterized by greater morbidity and an increased predisposition to pathologies.2

Dietary management is considered one of the pillars of management of both elderly humans and companion animals because it can prevent or delay the major causes of death which, in the dog, are cancer, kidney disease and heart disease.3 The aim of alimentation in the elderly animal is to fulfil nutritional requirements without creating unnecessary surpluses which in a young animal could be used up, but in an elderly animal could be a cause of overload to the organs.

In order to understand how the nutritional needs of the elderly animal are altered, it is important to remember the major changes occurring during the geriatric period. Ageing is characterized by progressive and, often, irreversible changes that are manifested to various degrees in relation to intrinsic and extrinsic factors, with one of the most important of these latter being the diet.4 These changes also influence the use of some of the main nutrients and, for this reason, have an impact on nutritional requirements. First, age influences the digestibility of some foods. Furthermore, in humans, age alters the physiological mechanisms regulating hunger and thirst; this means that although fluid intake in controlled environments may be adequate, in particular circumstances (e.g. exertion in hot environments) dehydration can occur. It is hypothesized that the situation is similar in dogs and cats.5

Generally speaking, elderly dogs have a greater amount of adipose tissue, less lean mass and a lower lean mass/fat mass ratio compared to young animals.6 Since muscle tissue is more metabolically active than adipose tissue, these changes could explain the decreased maintenance energy requirements characteristic of elderly animals.This decrease was recorded in dogs by Speakman et al.,7 but seems not to occur in cats since some studies8 have shown that cats aged more than 11-12 years old have an increase in maintenance requirements (Fig. 1). The suggested explanation for this difference between species is based on the fact that the physical activity of cats is limited throughout their lifespan but, as digestive efficacy decreases during old age, the energy requirements during this period increase3 compared to maintenance energy requirements. Peachey et al.9 reported less efficient digestion of some main nutrients (fatty acids and energy) in elderly cats (mean age, 11.6 years) compared to in young adults (mean age, 3.0 years). In contrast, no difference was found in the pattern of food intake (number and size of meals).10 Insulin sensitivity was dependent on age.11 Taking into consideration the results of these studies, when planning the diet of an elderly, healthy animal, without specific pathologies, it must be appreciated that some nutrients are less well digested and, therefore, the ratios between the main nutrients and energy density must be calculated in order to supply the correct amount of energy without risking deficiencies of the nutrients.12   

The results of the most important studies, considering the main nutrients separately, are described below.

 

CARBOHYDRATES

There is scientific evidence that glucose tolerance decreases with age because of a decrease in the sensitivity to insulin.13,14 When comparing elderly animals (mean age, 9.6 years) with young ones (mean age, 0.7 years) given a meal of identical composition, Hayek et al.15 observed that the peak blood glucose level occurred later in the former (60 minutes versus 30 minutes, respectively), but that the glycaemia returned to basal values much more slowly in the elderly animals (at 240 minutes the basal value had still not been reached in the senior animals, while the blood glucose level had already normalised at 180 minutes in the young ones). Further data are available for the digestion of starch (the main source of carbohydrates in foodstuffs for companion animals) by pancreatic a-amylase and of maltose and sucrose by maltase and saccharase, respectively.16

 

LIPIDS

Although energy requirements do not seem to be influenced by age in the cat,17 cats frequently lose weight when they become elderly.18 This phenomenon is related to the decreased digestibility of lipids observed in geriatric cats.9,18 The situation in dogs is different; the energy requirements of elderly dogs are decreased because of the decrease in lean mass, thus predisposing the animals to problems of obesity. The data on digestibility of lipids in elderly dogs are conflicting, since some authors reported an increase in digestibility with age,19,20 while others reported that age does not have any influence on this parameter.21-23

 

PROTEINS

The digestibility of proteins is decreased in elderly cats.18 Twenty percent of cats over 14 years old digest less than 77% of the protein in their diet (normal range: 85-90%). The lean mass of both dogs and cats decreases as the animals enter the geriatric age and protein consumption would have the purpose of counterbalancing this tendency. Laflamme8suggested that 25% of the daily calorie intake in dogs should come from proteins in order to support protein turnover. Elderly dogs require triple the amount of proteins needed by younger ones in order to maintain correct turnover of proteins.24

 

MINERALS

Few studies are available on the influence of age on the absorption and metabolism of minerals. One of the few studies that has been conducted20 (presumably ref. 25) showed that the apparent digestibility of calcium, phosphorus, magnesium, zinc, copper, iron, potassium and sodium was not influenced by age (in Beagles 10-12 years old) but that there was large individual variability.

 

Suggested readings

  1. Lund EM, Armstrong PJ, Kirk CA, et al. Health status and population characteristics of dogs and cats examined at private veterinary practices in the United States. J Am Vet Med Assoc 1999;214:1336-41.
  2. Hayflick L. Aging is not a disease. In: How and Why We Age. New York, NY: Ballantine Books 1994;43-49.
  3. MacDougall DF, Barker J. An approach to canine geriatrics. Br Vet J 1984;140:115-23.
  4. Mosier JE. How aging affects body systems in the dog. In: Proceedings. Symposium on Clinical Conditions in the Older Cat and Dog. London, UK, June 15, 1988:7-14.
  5. Fahey GC, Barry KA, Swanson KS. Age-related changes in nutrient utilization by companion animals. Annu Rev Nutr 2008;28:425-45.
  6. Harper EJ. Changing perspectives on aging and energy requirements: aging, body weight and body composition in humans, dogs, and cats. J Nutr 1998;128:2627-31S.
  7. Speakman JR, van Acker A, Harper EJ. Age-related changes in the metabolism and body composition of three dog breeds and their relationship to life expectancy. Aging Cell 2003;2:265-75.
  8. Laflamme DP. Nutrition for aging cats and dogs and the importance of body condition. Vet Clin Small Anim 2005;35:713-42.
  9. Peachey SE, Dawson JM, Harper EJ. The effect of ageing on nutrient digestibility by cats fed beef tallow-, sunflower oil-, or olive oil-enriched diets. Growth Dev Aging 1999;63:61-70.
  10. Peachey SE, Harper EJ. Aging does not influence feeding behavior in cats. J Nutr 2002;132:1735-9S.
  11. Larson BT, Lawler DF, Spitznagel EL Jr, Kealy RD. Improved glucose tolerance with lifetime diet restriction favorably affects disease and survival in dogs. J Nutr 2003;133:2887-92.
  12. Lowe JA. Lifestage nutrition of companion animals. II Congresso Latino-Americano de Nutricao Animal (II CLANA), Sao Paulo, Brazil, 2006 pp. 1–9
  13. Mosier JE. Effects of aging on body systems of the dog. Vet Clin North Am Small Anim Pract 1989;19:1-12.
  14. Strasser A, Niedermueller H, Hofecker G, Laber G. The effect of aging on laboratory value of dogs. J Vet Med 1993;A40:720-30.
  15. Hayek MG, Sunvold GD, Massimino SP, Burr JR. Influence of age on glucose metabolism in the senior companion animal: implications for long-term senior health. In: Recent Advances in Canine and Feline Nutrition Vol III. Iams Nutrition Symposium Proceedings. Orange Frazer Press, Wilmington, OH, pp. 403-14.
  16. Kienzle E. Enzymeaktivitaet in pancreas, darmwand und chymus des hundes in abhangigkeit von alter und futterart. J Anim Physiol Anim Nutr 1988;60:276-88.
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  18. Perez-Camargo G. Cat nutrition: what is new in the old? Comp Contin Educ Pract Vet 2004;26:5-10.
  19. Lloyd LE, McCay CM. The use of chromic oxide in digestibility and balance studies with dogs. J Nutr 1954;53:613-21.
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  22. Lloyd LE, McCay CM. The utilization of nutrients by dogs of different ages. J Gerontol 1955;10:182-7.
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