|The medical records of 223 cats with urethral obstruction were reviewed for signalment, previous medical history, indoor/outdoor status, body weight, clinical signs, physical examination findings, renal function tests (blood urea nitrogen and creatinine), and blood gas and electrolyte analysis.
The majority of cats were relatively stable without serious metabolic derangements. Only 12% (24/199) of cats had severe hyperkalemia (>8.0 mmol/L). Hyperkalemia did not occur in isolation; the majority of these cats had concurrent acidemia and low ionized calcium concentrations. Potassium was significantly inversely correlated with pH, bicarbonate, pCO2, sodium, chloride, and ionized calcium, but positively correlated with blood urea nitrogen and creatinine.
Ionized calcium was positively correlated with pH and bicarbonate. Of the animals with a potassium concentration greater than 8.0 mmol/L, 75% (18/24) had an ionized calcium concentration of less than 1.0 mmol/L.
Seventy-nine percent (19/24) of cats with a potassium concentration greater than 8.0 mmol/L had a blood pH<7.20. Similarly, 74% (23/31) of cats with a pH<7.20 had an ionized calcium concentration <1.00 mmol/L.
The majority of cats with urethral obstruction presented with mild electrolyte and blood gas changes and were relatively stable, although 12% of cats had multiple, life-threatening metabolic derangements.
Of 219 cats in this study, 205 (93.6%), where it could be determined, survived to discharge from the hospital, supporting the fact that most cats with urethral obstruction survive the acute episode with emergency treatment.
Source: Lee, Justine A. & Drobatz, Kenneth J. (2003): Characterization of the clinical characteristics, electrolytes, acid-base, and renal parameters in male cats with urethral obstruction. In: Journal of Veterinary Emergency and Critical Care 13 (4), 227-233.
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