Fortunately, 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.
According to the ASPCA Animal Poison Control Center, 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 may also be 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 need to 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.