Introduction

Medication is one of the 3 Ms used to treat behaviour problems. However, medication should not be viewed as a quick fix or a silver bullet. The decision to use medication (or not) depends on the diagnosis, and this should include a thorough physical workup, blood work and a behavioural assessment. Medications are not generally indicated for problem behaviours, only for behaviour problems, so it is important that veterinarians understand the rationale for prescribing psychotropic medication.

Psychotropic medications are useful for reducing the signs associated with phobic, panic or chronic anxiety states and to improve animal's ability to learn calm and relaxed responses. Medication helps to reduce the anxiety, arousal or reactivity that might be contributing to the problem. There may also be some pathologic disorders affecting behaviour, such as compulsive disorders where medication might be necessary.

Medications do not change the relationship with the stimulus, so concurrent behaviour modification as well as environment management (the other two Ms) will also be needed to attain desirable responses.

Many of the medications commonly used are not registered for behavioural use in companion animals. As more medications are registered for use in animals, it is important that veterinarians are familiar with these medications and the research that supports their use. This allows veterinarians to make an informed decision about which medication to use, why and when.

Much information regarding psychotropic medication and their effects is derived or extrapolated from research in humans. However, drug metabolism and receptor effects vary between species. This can lead to inaccurate assumptions with respect to dose, duration of effect, contraindications and side effects. It is the veterinarian's responsibility to be familiar with these factors before prescribing medication.

Ideally, medications that are licensed for use in pets (e.g., clomipramine, fluoxetine) should be considered first, as there is data with respect to safety, efficacy, side effects, contraindications, toxicity and pharmacokinetics. In addition, the technical support available from the manufacturer provides additional expertise, especially in the event of adverse events. However, in many cases, off-label use of medication leads to the best results for the pet.

The final choice of medication is up to the veterinarian, and medication should be selected using the evidence available combined with the veterinarian's expertise and experience as well as information about the patient, client, the environment, as well as the presenting problem(s).

Behaviour problems take considerable time to manage. Clients need to understand that behaviour modification as well as environmental management is also necessary and part of the success of any treatment regime.

Additionally, medication may be needed for the life of the patient and the owner should be aware of this when prescribing medication. This is not dissimilar to cases involving metabolic diseases, such as diabetes. Once the behaviour is managed to the owner's satisfaction, the lifelong commitment from the owner and continued support from the veterinarian and their staff is required.

Why is a diagnosis important?

Before prescribing medication for any condition, it is important to have a diagnosis to support the decision to medicate. Behavioural medicine issues should not be approached any differently from the way that veterinarians approach internal medicine or dermatological problems.

A behavioural diagnosis should be based on a thorough physical examination and behavioural history. This should always include diagnosis and treatment of any concurrent physiological problems.

Why Use Medication?

The rationale for using psychotropic medication is based on their purported neurochemical actions in the brain. Many types of medications are now used to modify behaviour in companion animals and include the benzodiazepines, tricyclic antidepressants (TCAs), antihistamines, azapirones, selective serotonin reuptake inhibitors (SSRIs), serotonin antagonist reuptake inhibitors (SARIs) and beta blockers.

Medications may influence neurotransmitters in three main ways. They may act

 Presynaptically and affect the presynaptic action potential, synthesis, storage, metabolism, release, or reuptake

 On the enzymes that deactivate the neurotransmitter

 Postsynaptically and affect binding to receptors by acting as agonists or antagonists or actually modify receptors

Pretreatment Screening: Blood Tests, Urine Tests, Other Medications, Etc.

Blood tests prior to prescribing medication are always recommended, especially in very old or young animals or those with a previous history of medical problems. A minimum database should include complete blood count (CBC), biochemistry panel and urine test. As most of the medications are metabolised through the liver and then excreted via the renal system, liver and kidney enzyme level monitoring is important prior to and during medication.

These tests may need to be repeated, after starting medication, depending on the animal, the medication and effects seen. All animals on long-term medication should be reassessed and blood work re-evaluated at least every 6–12 months depending on age and medical history.

It is also important to question owners about what other medications they may be administering to their pet. This includes the use of natural remedies or homeopathic medications, as many owners do not appreciate that these may also have significant effects on their pet as well as interact with the medications prescribed by the veterinarian.

When to Use Psychotropic Medication?

There are several categories of behaviour problems where psychotropic medications have proven to be useful. These include anxiety-related problems (including fears and phobias), obsessive-compulsive behaviours, some types of aggression and geriatric behaviour problems.

The treatment of nonspecific signs (such as excessive vocalisation, aggression or inappropriate elimination) by using medication is not acceptable, and this approach will ultimately lead to treatment failures.

What if the Medication Does Not Work?

Owners often feel that the medication has been ineffective. This may happen for many reasons, including

 No diagnosis was made.

 Incorrect diagnosis was made.

 Incorrect medication was selected.

 An inadequate length of time was allowed for the treatment program to take effect.

 Medication has been used as "stand alone" therapy when it should have been combined with a behaviour modification program and environmental management.

 The owner was unable to medicate the pet.

In some cases, the effects of medication can only be seen when the medication has been stopped.

What do owners need to know about medication?

 Medication may take 6–8 weeks to reach therapeutic blood levels. Owners need to appreciate that the effects will not be immediate.

 The medication or the dose may need to be changed as the management/treatment progresses.

 The minimum time required for an animal to receive medication is usually at least 6 months.

 Medication may be needed lifelong. This needs to be discussed with owners in advance.

 Medication should never be suddenly stopped. It should always be weaned off gradually under veterinary supervision to avoid a rebound affect. Owners should be warned of this whenever prescribing medication.

 Medication should only be stopped, have a change in dose or medication changed on veterinary advice and under veterinary supervision.

Common Psychotropic Medications

Medications that have been used to treat behaviour problems include the benzodiazepines, tricyclic antidepressants (TCAs), antihistamines, azapirones, selective serotonin reuptake inhibitors (SSRIs), serotonin antagonist reuptake inhibitors (SARIs) and beta blockers.

References

1.  Landsberg G, Hunthausen W, Ackerman L. Handbook of Behaviour Problems of the Dog and Cat. Oxford, UK: Butterworth-Heinemann; 2013.

2.  Overall KL. Clinical Behavioral Medicine for Small Animals. St Louis, MO: Mosby; 2014.

3.  Perrin C, Seksel K, Landsberg G. Drug dosage chart. In: Lansberg G, Tynes V, eds. Behavior: A Guide for Practitioners. Veterinary Clinics of North America: Small Animal Practice; May 2014:629–632.

4.  Rang HP, Dale MM, Ritter JM, Gardner P. Pharmacology. New York, NY: Churchill Livingstone; 1995.

5.  Seksel K. In: Maddison J, Page S, Church D, eds. Small Animal Clinical Pharmacology. 2nd ed. London, UK: WB Saunders; 2008.