Objective—To determine whether clomipramine differs
from fluoxetine in reducing feline urine marking;
whether reduction of marking continues in cats treated
> 8 weeks; whether recurrence of marking, after
abrupt drug withdrawal, is less in cats treated > 8
weeks; and whether cats that are successfully treated
but resume marking after drug withdrawal can be successfully
treated again with the same drug regimen.
Animals—22 neutered cats (2 females, 20 males) ≥ 1
year old with objectionable urine marking.
Procedure—Cats that marked vertically ≥ 3 times/wk
were treated with fluoxetine (1 mg/kg [0.45 mg/lb],
q 24 h, PO) or clomipramine (0.5 mg/kg [0.23 mg/lb], q
24 h, PO) for 16 weeks, and efficacy was compared.
Recurrence of marking was determined after abrupt
withdrawal of fluoxetine at 16 or 32 weeks. Reduction
in marking in cats treated with fluoxetine for 8 weeks
after returning to marking following drug withdrawal
was compared with the initial 8 weeks of successful
Results—Efficacy of fluoxetine and clomipramine
was similar. Treatment > 8 weeks revealed increasing
efficacy in reduction of marking. Return of marking
after termination of fluoxetine administration occurred
in most cats. Cats successfully treated initially with
fluoxetine responded similarly to repeated treatment.
Conclusions and Clinical Relevance—Clomipramine
and fluoxetine were equivalent in treating urine marking.
Longer treatment increased efficacy. Most cats
return to marking after abrupt drug withdrawal. A second
course of treatment can be expected to be as
effective as the first. (J Am Vet Med Assoc 2005;226: