Measurements of serum osmolality and plasma colloid oncotic pressure are becoming increasingly valuable in veterinary medicine. These measurements can be used to assess patient hydration status, electrolyte balance, response to fluid therapy, and evaluation of patient status in states of renal disease, hepatic disease, shock, vasculitis, and toxicity. Although elephant species are under public focus, much still remains to be understood of their physiology. Both African and Asian species are often compared physiologically to equids, however, recent research has elucidated several differences that indicate elephants are even less similar to equids than previously recognized. In this research study, the serum of twenty Asiatic elephants was evaluated by vapor pressure osmometry, freezing point osmometry, calculated osmometry, and colloid membrane oncometer. Serum osmolality was determined to be a measurable value with a consistent reference range in the Asian elephant (Elephas maximus) when measured by freezing point osmometer. The normal serum osmolality value for the elephant was found to be significantly lower than in other species. Colloid oncotic pressure was determined to be a measurable value with a consistent reference range in the Asian elephant. This information is valuable to the practicing veterinarian in properly assessing elephant health and preventing erroneous diagnosis of a hypo-osmolar disorder in this species.
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