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An Urban Experience
J. Bartges1
1The University of Georgia, Athens, GA, USA 30606
Objectives of the Presentation
Following this presentation, the attendee should be able to
- define low, adequate, and high dietary protein for dogs and cats
- compare and contrast potential benefits and detriments of dietary protein restriction with CKD
- describe role of dietary protein in managing patients with CKD
For decades, dietary protein restriction has been a cornerstone of nutritional management of pet dogs and cats with chronic kidney disease (CKD). Whether dietary protein restriction is beneficial or necessary; however, has been controversial for decades as well. Chronic kidney disease is defined kidney damage present for at least three months, with or without decreased glomerular filtration rate (GFR) or greater than 50% reduction in GFR persisting for at least three months. Kidney damage is further defined as either 1) microscopic or macroscopic pathologic changes detected by histologic or direct visualization of the kidneys or 2) markers of damage detected by blood or urine tests or imaging studies. The International Renal Interest Society (IRIS; http://www. recommends that the appropriate term
is chronic kidney disease and proposes a dynamic staging system based on serum/plasma creatinine concentration, presence of proteinuria, and presence and degree of systemic arterial hypertension. Before staging is undertaken, the patient must be proven to have kidney disease that is chronic in nature. Based on staging, therapeutic interventions may be undertaken including nutritional.
Proteins are large, complex molecules composed of amino acids. Amino acids are composed of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur
and phosphorous. Although hundreds of amino acids exist, only 20 are commonly found in protein of which 10 are essential for dogs and 11 are essential for
cats. Essential amino acids must be supplied by diet as they cannot be synthesized endogenously in sufficient amounts. Proteins provide structure (e.g. collagen, muscle, keratin, hemoglobin), function (e.g. enzymes, hormones, antibodies), and are an energy source
after the amino group is removed by deamination or transamination. Proteins also provide a source of nitrogen for synthesis of nitrogen containing compounds such as nucleic acids, creatinine, and some neurotransmitters.
Dietary proteins are digested and absorbed from the gastrointestinal tract with digestion beginning in the stomach by acid hydrolysis and pepsin. Pancreatic
and brush border enzymes further metabolize protein
so that amino acids, di-peptides, and tri-peptides are absorbed primarily. Amino acids are absorbed by a sodium-dependent energy-requiring process using one of 6 transporters for neutral, basic, acidic, tricarboxylic acid, imino, and beta- amino acids. Absorbed amino acids and di- and tri-peptides are reassembled into “new” proteins by the liver and other tissues. Amino acids are used for tissue protein synthesis; synthesis of enzymes, albumin, and hormones, and other nitrogen- containing compounds; and deamination and use of carbon skeletons for energy. Amino acids and proteins not absorbed in the small intestine may be fermented in the large intestine to produce fecal odor compounds and utilized by colonic bacteria. There is no storage pool of amino acids, per se, although structural and functional proteins can be catabolized and in essence represent a storage pool; however, their utilization results in depletion of such protein. In catabolic situations, the amine group is removed and the carbon skeleton of the amino acid used for glucose and/or ketone body production. The amine group can be converted to urea via the urea cycle or used for urinary ammonia excretion (glutamine) or purine synthesis.
When discussing dietary protein, it is not only the quantity provided, but the quality of the protein. Protein quality refers to the efficiency by which amino acids from food are converted into tissue. The efficiency depends
on the protein source, concentration of essential amino acids in the food, and their availability.(1) High quality proteins provide all essential amino acids in high amounts and in proportion, whereas poor quality proteins have low amounts or lack one or more essential amino acids (limiting amino acid(s)). Poor protein quality can also result from an excess of certain amino acids that interfere with availability or usage of essential amino acids. Other factors affect protein quality as well.
Protein requirements for healthy pet dogs and cats depend on whether a high quality protein or commonly used protein sources are used. When using a high quality protein, growing dogs require approximately 18% protein (dry matter basis; DMB) and adult dogs require approximately 8% protein (DMB), while growing kittens require 18% protein (DMB) and adult cats require approximately 16% protein (DMB). The Association
of American Feed Controls Officials provides daily

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