PHOSPHATE ENEMA TOXICOSIS
"But if it's safe for kids...?"
When owners are faced with a constipated cat, they may be tempted to take the matter into their own hands and administer an
enema. Fleet enemas (Fleet Company) labeled for children ages 2 to 9 are commonly selected, but they contain sodium phosphate
and biphosphate (several Fleet enemas labeled for adults do not contain phosphates). Acute hyperphosphatemia associated with
this enema administration is not unique to cats and has been seen in people with a preexisting compromising factor.
Rapid absorption of sodium and phosphate results in hypernatremia, hyperphosphatemia, hypocalcemia, and hypomagnesia. This
rapid shift in electrolytes produces cerebral dehydration.
Within one hour of enema administration (attributed to cerebral dehydration and hypocalcemia):
- Muscle tremors
- These patients are too sick to display the facial itching associated with hypocalcemia.
- Clinical signs and history (ask "Has your cat been constipated?")
- Electrolyte abnormalities (hypernatremia, hyperphosphatemia, hypocalcemia, and hypomagnesemia)
Treatment is supportive only and must be initiated promptly.
- Low-sodium fluids, if given soon after the enema, can be given rapidly without concern for cerebral edema.
- If therapy is not initiated for several hours after the enema, isotonic fluids must be used judiciously to bring down plasma
sodium concentrations slowly to avoid cerebral edema.
- Phosphorus will decrease as other electrolytes normalize and with fluid diuresis.
- Treat any life-threatening arrhythmias by monitoring ECG while giving 10% calcium gluconate intravenously at a rate of 50
to 150 mg/kg (0.5 to 1.5 ml/kg) over 20 to 30 minutes. If bradycardia develops, halt infusion.