Laboratory findings of hyponatremia in a red fox (vulpes vulpes) with talocrural joint dislocation

       Disorder of the serum Na is an important phenomenon; it should be diagnosed as soon as possible and the patient should be treated promptly. Any delay in treatment can cause some irreversible neurological damages. In all hospitalized patients, especially those are candidate for fluid therapy, serum electrolyte, especially Na concentration should be monitored regularly. A red fox (Vulpes vulpes) with the history of vomiting, weakness and lethargy, ataxia, alopecia and a bad general condition was referred to the clinic of the faculty of veterinary medicine of Razi University. For assessing the patient’s condition and starting fluid therapy venous blood was taken and sent for hematology and biochemistry. Radiographic study of the right hind limb showed talocrural joint dislocation. It was managed by reducing and casting. The blood biochemical analysis showed severe hyponatremia, hypo-osmolality and metabolic alkalosis. Though, treatment was done based on these findings. Incorrect differentiation between false and true hyponatremia can lead to inappropriate treatment that can cause entrance of excessive Na to the interstitial tissues that can result in brain edema and convulsion. Though, careful assessment of the cause and type of hyponatremia based on physiological principles and in accordance with our suppositions is necessary for correct management of this important challenge.