Psychotropic drugs: Why, where, when and how (Proceedings)


Drugs are not a new aspect of veterinary behavioral medicine, but coming more into the forefront.

Drugs are not a new aspect of veterinary behavioral medicine, but coming more into the forefront. Most of the drugs used in behavioral medicine are used in an extra-label fashion, under the Animal Medicinal Drug Use Clarification Act of 1994. If there is a medication that is licensed for animals for a specific purpose, theoretically the use of extra-label medications is unnecessary. However, economic reasons, side effects profile, and lack of medications licensed for the specific diagnosis are reasons to use medications in an extra-label fashion.

The veterinary extra-label use of human medications should follow these guidelines: there is a diagnosis established, with a need for pharmacological treatment; the medications are prescribed with a written or oral prescription, keeping all records; there is a specific rationale for choosing this medication, and its use accepted under prevailing medical conditions; and the medication is appropriately labeled.

It is imperative that a diagnosis is made before you start to treat any animal with a medication to treat a behavior problem. There needs to be a behavior modification plan in place that the owner is following. One should discuss with the owners that medications are not a quick fix, but usually just facilitate the overall behavioral approach. For example, treating a dog with severe separation anxiety with medication only, that is, without any behavior modification, while perhaps alleviating the worst aspects of the problem is likely to result in the animal reverting to the previous behaviors when the medication is discontinued.

We are exposed to many advertisements concerning medications, both human and animal, and pet owners are now asking for the medications they see advertised. Clients are also exposed to the Internet, and can read articles and testimonials from many sources about how a drug, such as Prozac, has helped their pets. Owners generally do not have knowledge of pharmacology and behavioral medicine, and they may come in with a diagnosis, often in human terms (obsessive-compulsive disorder), and may have preconceived notions as to what drug is appropriate for their pet. They may be personally familiar with these medications from their own use.

This topic in extensively covered in two chapters in Hart, Hart and Bain, Canine and Feline Behavior Therapy, 2nd edition, 2006, Blackwell Press.

Issues in Prescribing Medications

There are no medications licensed for the use of controlling aggression in animals. Neither is one available to treat aggressive people (otherwise imagine how empty our prisons would be!). Drug companies have no desire to undertake the liability of having a medication licensed for this purpose. Remember that most aggression is a normal response to a stimulus. It is the owner's perception of the aggression that presents the problem and the perceived need for medication.

Use of Psychotherapeutic Agents for Problem Behaviors

There are indications where behavioral approaches alone are often ineffective and drug treatment valuable. One is truly abnormal behavior, such as compulsive tail chasing, fly snapping, and flank sucking in dogs that is not a function of attention-seeking behavior. Another set of such problems are wool chewing and psychogenic alopecia in cats and acral lick dermatitis in dogs. Geriatric cognitive dysfunction in dogs also falls into this category.

There are indications where behavioral approaches are effective but medications facilitate treatment. A primary use is in urine marking in cats. Separation anxiety in dogs is an indication where the psychotropic medication may facilitate a behavior modification program.

Psychotropic Medications for Problem Behaviors

Selective serotonin reuptake inhibitors (SSRI's)

As indicated, these drugs block the reuptake of serotonin. In humans it may take 3 to 4 weeks to see the full effects; in dogs and cats, effects are often apparent in a week or two. Generally there is no evidence of dependence or side effects. Uses include, feline urine marking, anxiety and compulsive behaviors. Although gradual withdrawal of medication is recommended the value has not been demonstrated. Examples of SSRIs are fluoxetine (Prozac®), paroxetine (Paxil®) and sertraline (Zoloft®).

Tricyclic antianxiety-antidepressant medications (TCA's)

These include comipramine (Clomicalm®, licensed for dogs for separation anxiety) and amitriptyline (Elavil®). These drugs block reuptake of serotonin and norepinephrine, and dopamine to a lesser extent. Clomipramine is effective on urine marking in cats and separation anxiety in dogs.


The drug is buspirone (Buspar®) which increases serotonin in brain. A previous study from our center showed effectiveness on urine marking in cats; this use has been replaced by fluoxetine or clomipramine.

Benzodiazepine derivatives

Drugs include alprazolam (Xanax®), diazepam (Valium®) and oxazepam (Serax®). They can be effective on anxieties and feline urine marking. The advantage is relatively quick action. They are used in conjunction with SSRIs when immediate effects are needed; they are then tapered off. Prime disadvantages are dependence and tolerance, necessitating an increase of dosage.

Monoamine oxidase inhibitors (MAOI's)

The main one is l-deprenyl (Anipryl®), licensed for dogs for Canine Cognitive Dysfunction). The main effect is to counteract depletion of dopamine in aging animals which is partially responsible for the signs of behavioral senility. The drug is not effective in every case, and the disease still progresses. The dietary supplements of carnitine and lipoic acid, plus antioxidants and anti-inflammatory omega-3s, seem to work more effectively.

Phenothiazine derivatives

These are acetylpromazine (Acepromazine®), chlorpromazine (Thorazine®) and promazine (Sparine®). These are dopamine antagonists and are the oldest of psychotropic medications used in animals. They are, and were, used primarily for sedation, to decrease vocalizations and temporary sedation or restraint of animals for travel. They are not particularly effective in controlling behavior problems.

Long-acting progestins

Include medroxyprogesterone acetate (Depo-Provera®), and megestrol acetate (Ovaban®, Megace®). These have been used for reducing aggression, inappropriate elimination and urine marking. A general effect is to suppress male-like behavior. They have a calming effect as well. These are used in humans as birth control agents and treatment of reproductive disorders, but are rarely used now in animals due to potential side effects and limited effectiveness.

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