The pathogenesis of a number of common diseases of production animals, although largely related to production or management factors, is primarily related to alterations in metabolism. In most cases, the basis of disease is not a congenital or inherited error in metabolism, but rather an increased demand for a specific nutrient that has become deficient under certain conditions.
Diseases such as hypocalcemia Hypocalcemia in Dogs and Cats Hypocalcemia causes the major clinical manifestations of hypoparathyroidism by increasing the excitability of both the central and peripheral nervous systems. Peripheral neuromuscular signs... read more , hypomagnesemia, and hypoglycemia are augmented by management practices directed toward improving and increasing production. They are therefore correctly considered production-related diseases. However, they are also metabolic diseases because management of the animal is directed at production, which at its peak is beyond the capacity of that animal’s metabolic reserves to sustain a particular nutrient at physiologic concentrations. For example, ketosis Ketosis in Cattle Ketosis is an elevated concentration of ketone bodies (acetone, acetoacetate, beta-hydroxybutyrate) in all body fluids. Key clinical signs of ketosis are vague but include anorexia, decreased... read more occurs when cows are in negative energy balance, and parturient paresis of cows Parturient Paresis in Cows Parturient paresis (milk fever, hypocalcemia, paresis puerperalis, parturient apoplexy) is a disease of adult dairy cows in which acute hypocalcemia causes acute to peracute, afebrile, flaccid... read more (milk fever) occurs when the mass of calcium in the mammary secretion is greater than the cow’s diet or its skeletal reserves can supply. Comparable situations occur with magnesium and glucose metabolism, and with phosphorus in relation to postparturient hemoglobinuria Postparturient Hemoglobinuria in Dairy Cows Postparturient hemoglobinuria most often affects high-yielding dairy cows at the onset of lactation. Clinical signs can include a drop in milk production, anorexia, lethargy, and pale, icteric... read more . Other factors that contribute to hypocalcemia in dairy cattle include age, breed, and endocrinologic factors (eg, estrogen concentration).
Most production-induced metabolic diseases result from a negative balance of a particular nutrient. In some cases, dietary intake of the nutrient is rapidly reduced while the animal is experiencing an ongoing high metabolic requirement for that nutrient. Examples include pregnancy toxemia in ewes Pregnancy Toxemia in Sheep and Goats Pregnancy toxemia, the most common metabolic disorder of pregnant small ruminants, occurs during the final stage of gestation as the result of inappropriate metabolism of carbohydrates and fats... read more , protein-energy malnutrition Nutritional Requirements of Beef Cattle Beef cattle production, whether on range, improved pasture, or in the feedlot, is most economic when feedstuffs are used effectively. Young growing grass or other high-quality pasture crops... read more in beef cattle, fat cow syndrome Fatty Liver Disease of Cattle Fatty liver disease is a disorder of highly productive dairy cows resulting from an excessive negative energy balance at the onset of lactation. Mobilization of large amounts of body fat reserves... read more in dairy cattle, and hyperlipemia Hyperlipemia and Hepatic Lipidosis in Large Animals Poor feed quality or decrease in feed intake, particularly during a period of high-energy requirement (eg, pregnancy, systemic disease), may result in hyperlipemia syndrome. Hyperlipemia is... read more in ponies. Furthermore, some diseases may be precipitated when producers, primarily because of economic concerns, are compelled to not supplement the diet of animals that already have a substandard nutritional plane.
Exertional rhabdomyolysis Exertional Myopathies in Horses Exertional myopathy in horses is a syndrome of muscle fatigue, pain, or cramping associated with exercise. Less common exertional myopathies that cause exercise intolerance without muscle necrosis... read more of horses is another production-induced metabolic disease. In this case, the production activity (draft or racing) is maintained by and matched to a level of caloric intake. Management decisions not to work or race these horses without a concomitant decrease in caloric intake may result in accumulation of muscle glycogen to dangerous levels. Disease results when work is resumed and the production of lactate exceeds its metabolism.
The difference between production-related metabolic diseases and nutritional deficiencies is often subtle. Typically, nutritional deficiencies are long-term, steady-state conditions that can be corrected via dietary supplementation. Metabolic diseases are generally acute states that dramatically respond to the systemic administration of the deficient nutrient or metabolite, although affected animals may require subsequent dietary supplementation to avoid recurrence. An important aspect of dealing with production-induced metabolic diseases is accurate and rapid diagnosis. Ideally, diagnostic tests can be used to predict the occurrence of disease before its clinical onset.
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Also see pet health content regarding metabolic disorders in dogs Introduction to Metabolic Disorders of Dogs Metabolism refers to all processes in the body that break down and convert ingested substances to provide the energy and nutrients needed to sustain life. Foods, liquids, and drugs all generally... read more , cats Introduction to Metabolic Disorders of Cats Metabolism refers to all processes in the body that break down and convert ingested substances to provide the energy and nutrients needed to sustain life. Foods, liquids, and drugs all generally... read more , and horses Introduction to Metabolic Disorders of Horses Metabolism refers to all processes in the body that break down and convert ingested substances into the energy and nutrients needed to sustain life. Foods, liquids, and drugs all undergo metabolic... read more .