Heart failure associated with minoxidil intoxication in a cat

A 13-month-old female spayed Russian blue cat was presented for acute respiratory distress. Thoracic radiographs revealed signs of left-sided congestive heart failure with pulmonary oedema, and the echocardiogram showed left ventricular myocardial thickening and concurrent left atrial dilation. In the first hours following admission, in addition to the classic management of congestive heart failure, dobutamine was used because of hypotension. The cat was discharged five days after admission with a prescription of furosemide 1.11 mg/kg PO q 12 h and pimobendan 0.15 mg/kg PO q 12 h. An echocardiographic follow-up, one month later, showed normalisation of the left ventricular walls and atrial size, justifying a gradual withdrawal of drugs. Eight months later, the cat experienced recurrence of clinical signs. Thoracic radiographs suggested a relapsing pulmonary oedema. The echocardiogram showed again a hypertrophic phenotype with moderate left atrial dilation. The cat was hospitalised, and the case was treated similarly to the first episode. Cardiac troponin I was increased to 9.89 ng/mL [<0.2 ng/mL]. Infectious disease tests were negative. Two weeks later, echocardiography showed again normalisation of left ventricular walls and atrial diameter. Treatments were gradually stopped, and subsequent echocardiographic checks showed no abnormalities. After the resolution of the second episode, it was noted that both respiratory distress events appeared after contact with a family member who was using minoxidil to treat androgenic alopecia and whose hair the cat had insistently licked. Minoxidil intoxication was retrospectively considered a likely contributor to these episodes of transient myocardial thickening associated with congestive heart failure.