The Relation Between Plasma Protein Content, Plasma Specific Gravity and Edema in Dogs Maintained on a Protein Inadequate Diet and in Dogs Rendered Edematous by Plasmapheresis

Abstract

Clinical edema of several types and its relation to low serum proteins have been adequately discussed in recent publications (1,2,3,4,5). Experimental edema in animals has resulted from two methods which have in common the lowering of serum protein, that is, plasmapheresis in dogs (6,7,8,9,10,11), and low protein diets in rats (12) and in the dog (8). The experiments to be discussed in this paper were performed by utilizing both methods of experimental approach. Dogs were maintained on a diet deficient in protein. Edema was produced sometimes acutely by plasmapheresis, sometimes more slowly as the result of dietary deficiency alone, and in several instances after recovery from the edema of plasmapheresis the edema of protein starvation was allowed to supervene in the same animal. Nine dogs have been followed over periods varying from 59 to 107 days and averaging 84 days. It has seemed worthwhile at this time to present together the results of both methods of study and to compare the events attending the onset of edema in both groups of animals and the relationships found for plasma protein concentrations and plasma specific gravity. METHODSThe animals were kept in metabolism cages throughout the periods of observation, the daily urine collections being measured and aliquots saved for analysis. The importance of washing the cages to insure complete urine collection was not appreciated at first. Later observations indicated an average loss of 1.9 per cent through neglect of this precaution and accordingly records of total urine have been increased by this amount. Stools were not saved regularly but only over short periods often enough to determine approximately the necessary balance corrections. Since the substances studied (sodium, chloride and nitrogen) are excreted chiefly in the urine, these corrections were not large. The diets were offered in weighed amounts and corrected for refusals National Research Council Fellow. 193

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