Use of products (eg, nutraceuticals, pheromones, commercial diets) and medications to decrease fear, anxiety, stress, and overall arousal is the second step in a comprehensive treatment plan for aggression. It is important to reduce stress and anxiety because aggression is a behavioral strategy a cat may employ when scared. There are no FDA-approved medications for treatment of behavior problems in cats. Commonly used products and anxiolytics include pheromones, which have been shown to decrease intercat conflict in multicat households over 28 days13; these products should be placed where the cat spends most of its resting time.
Studies on nutraceuticals and prescription diets used to reduce fear, anxiety, and stress in cats have been conducted, but their clinical significance for fear-induced aggression may be limited due to lack of placebo controls and limited number of enrolled patients in each study. L-theanine, an amino acid found in green tea, has been shown to decrease signs of fear and anxiety in cats.14,15 α-casozepine,16 a naturally occurring protein in cow’s milk, and prescription diets17 containing α-casozepine and tryptophan, a precursor for serotonin, have also been shown to help decrease fear, anxiety, and stress in cats.
Medications, such as selective serotonin reuptake inhibitors (SSRIs; eg, fluoxetine, paroxetine), tricyclic antidepressants (TCA; eg, clomipramine, amitriptyline), serotonin antagonist and reuptake inhibitors (eg, trazodone18), and α2δ ligands (eg, gabapentin19,20) can also be used. SSRIs increase the amount of serotonin available in the synaptic cleft by blocking its reuptake into the presynaptic neuron. TCAs also block reuptake of serotonin but additionally block norepinephrine reuptake. TCAs have anticholinergic effects and, thus, have a higher number of adverse effects than SSRIs. Because TCAs have shown similar efficacy as SSRIs in the treatment of certain anxiety disorders in cats,21 TCAs are no longer as commonly used. Unfortunately, there are no studies on the use of psychotropic medications to specifically treat aggression in cats; therefore, all use is anecdotal and extrapolated from studies on use for other anxiety disorders,22 including inappropriate elimination23 and urine spraying.24,25
Patients should be individually evaluated to determine the suitability of these products in reducing both daily and event-associated anxiety. If the aggression is either unpredictable or frequent in nature, a daily medication (eg, SSRI, TCA) should be chosen. If the aggression is predictable and infrequent, an event medication (eg, trazodone, gabapentin) alone may be suitable. Some patients with multiple diagnoses may need a daily medication plus an event medication for higher stress events (eg, veterinary clinic visits). Consultation with a board-certified veterinary behaviorist or resident in clinical behavior medicine may be needed.