Acute water intoxication is not common, and it generally happens during the warmer months when a pet has been at the beach or a pool. Make sure you know what to look for and the best next steps to take if a patient presents with this tricky problem.
The ASPCA Animal Poison Control Center explains that initially—and in milder cases—clinical signs may include nausea, vomiting, lethargy and abdominal distention. In more severe cases ataxia, weakness, coma, seizures, hypothermia and bradycardia may occur.
Hyponatremia will be noted on laboratory tests; however hypochloremia, hypokalemia and hyposthenuria are also seen.
The primary goal with treating acute water intoxication is to raise the plasma sodium concentration; typically this is done no faster than 0.5-1 mEq/L per hour, however if patients are showing severe symptoms in an acute situation, this rate may be faster.
For more mildly affected patients this may mean a mild water restriction with serial electrolyte monitoring and close observation for any neurological signs. In more symptomatic cases fluids containing a sodium concentration that is higher than what the patient shows are generally recommended.
In critically affected cases hypertonic saline, furosemide or mannitol may be considered.
Caution is advised in treating as there is potential risk for osmotic demyelination or brain dehydration from the rapid and large increase in serum sodium concentration. Unfortunately clinical signs that osmotic demyelination occurred do not become evident until 3-4 days after the correction of hyponatremia. Clinical signs may include lethargy, weakness, and ataxia that can progress to hypermetria and quadriparesis.