Diseases Associated With Decreased Sodium:Potassium Ratio in Dogs & Cats

Anne M. Barger, DVM, MS, DACVP, University of Illinois

ArticleOctober 20262 min read
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In the Literature

Oriel J, Hopper K, Epstein SE. Prevalence, associated disease mechanisms, and outcome of dogs and cats with low blood sodium-to-potassium ratio. J Vet Emerg Crit Care. 2026;36(2):261-267. doi:10.1111/vec.70106

The Research…

The sodium:potassium (Na:K) ratio calculation is commonly included in serum chemistry evaluation in dogs and cats and specifically screens for hyponatremic, hyperkalemic hypoadrenocorticism in dogs; however, a low Na:K ratio has also been associated with other disease processes (eg, kidney, cardiorespiratory, GI; body cavity effusions).1-5

This retrospective study reviewed medical records for a 2-year period from a veterinary teaching hospital with the goal of describing the pathophysiology, prevalence, and outcome for dogs and cats with a decreased Na:K ratio. Included patient records (dogs, 711; cats, 159) showed a serum or plasma Na:K ratio <27; of these, underlying urinary tract disease was identified in 68% of cats and 36% of dogs, and 2% of dogs and no cats were diagnosed with hypoadrenocorticism. Other primary diseases diagnosed included hepatobiliary disease, GI disease, and neoplasia.

The cause of the decreased Na:K ratio was unidentified in 40% of dogs and 9% of cats, possibly due to missed diagnosis or clinicopathologic misclassification. The authors concluded that a decreased Na:K ratio can be caused by a wide range of pathophysiologic mechanisms not limited to hypoadrenocorticism.

…The Takeaways

Key pearls to put into practice:

  • A decreased Na:K ratio can be seen in dogs with hypoadrenocorticismbut is not specific for this disease. Other diseases (eg, urogenital, cardiorespiratory, GI) should also be considered.1 Clinical findings in combination with laboratory findings are critical for diagnosis.

  • Dogs with hypoadrenocorticism may have decreased sodium and increased potassium levels. Identifying the underlying cause of electrolyte imbalances is more useful than diagnostic reliance on a decreased Na:K ratio, particularly in dogs >10 years of age.6

  • Information on the diagnostic utility of decreased Na:K ratios in cats is limited. Urinary, cardiac, and GI diseases should be considered.2