How are drugs used for behavior modification in pets?
Several drugs are now used to help treat pet behavior problems. To determine whether drug therapy should be considered, it is essential to determine the cause of the behavior.
- Drugs may be recommended when behavior techniques alone are unlikely to improve the problem or if your pet has not responded sufficiently to behavior training.
- Drugs may be recommended for humane reasons if your pet is excessively anxious, at risk of being injured, or at risk of injuring another pet or a person.
- Drugs may be used to help achieve more normal brain function, in cases where a behavioral illness relates to abnormal activity in the brain.
Even if your veterinarian determines that medication could improve your pet’s outcome, a behavioral treatment plan usually includes steps for behavior management and modification to be most effective. Conversely, some pets may not make sufficient progress in a behavior modification program until their fear, anxiety, frustration, or arousal has been reduced with medication.
Will behavioral drugs sedate my pet?
Behavioral medications used to cause sedation, but most medications used today do not. These newer medications are designed to target problematic behaviors with fewer unwanted side effects. If your pet experiences sedation with a particular medication, an alternative may be available.
Are any tests required before using behavioral drugs?
Before drugs are considered, your pet should have a full assessment, including a physical examination and diagnostic tests, to rule out medical problems that might be contributing to the behavior problem and to ensure there are no contraindications for drug therapy. Baseline tests include a serum chemistry profile, urinalysis, and complete blood count (CBC). Additional testing, such as a thyroid profile or an electrocardiogram (ECG), may be recommended for certain medications.
What are the side effects and contraindications of behavioral drugs?
Before prescribing medication, your veterinarian will discuss common side effects as well as contraindications (reasons or conditions where it shouldn’t be used), such as those related to drug interactions. If your pet experiences an undesirable side effect while taking medication, let your veterinarian know so they can substitute an alternative drug.
Are behavioral drugs licensed for use in animals?
No, most behavioral medications were designed to be used in humans and few have undergone the extensive process needed to license them for use in animals. Dosages have been extrapolated so that these drugs can be safely used in pets.
How do antidepressants help?
Antidepressants cause changes in brain chemicals called neurotransmitters, most often serotonin and norepinephrine. Antidepressants help with many behavioral illnesses besides depression, such as anxiety, panic, impulsivity, and sleep disorders. In veterinary medicine, antidepressants have been used to treat many conditions, including urine spraying in cats, separation-related problems, thunderstorm phobia, and some forms of aggression.
There are different categories of antidepressants. Even within a category, each medication can have a slightly different effect on an individual pet. Though serious side effects are not common, they may be slightly different with each antidepressant. Your veterinarian will consider both the nature of the behavior (diagnosis) and your pet’s tolerance of possible side effects before prescribing.
Most antidepressants are needed long term, except for trazodone (see explanation below). They require several weeks to reach full effect and are not typically useful on an as-needed basis. After long-term use, they should be withdrawn slowly.
Are any antidepressants officially approved for use in animals?
There are two antidepressant drugs now authorized in the United States and Canada for the treatment of separation anxiety: fluoxetine (Reconcile®) and clomipramine (Clomicalm®). Although these drugs have been approved specifically for the treatment of separation anxiety, both are useful for the treatment of other behavioral disorders, including generalized anxiety, certain fears and phobias, panic disorders, and urine marking.
- Fluoxetine is in a class of drugs known as selective serotonin reuptake inhibitors (SSRIs). SSRIs typically have a calming effect but seldom cause sedation. Other side effects may include decreased appetite, weight loss, gastrointestinal upset, or restlessness.
- Clomipramine is in a class of drugs known as tricyclic antidepressants (TCAs). Clomipramine has a greater influence on serotonin than other TCAs, so it is often more effective for treating moderate to severe behavioral conditions in dogs and cats.
What other antidepressants are used?
Many other medications were originally designed to treat depression in humans and are therefore referred to as antidepressants. The labels can be confusing, as most of these drugs are routinely used to treat a wide range of behavioral conditions in people and are similarly very helpful for treating pets. Here are some examples:
Amitriptyline, like clomipramine, is a TCA, but it is not specifically licensed for use in pets. It is mainly effective due to its mild influence on serotonin. Because amitriptyline can also affect other chemicals in the body, it can be associated with more side effects than clomipramine and SSRIs. Sometimes, these side effects can be advantageous. For instance, amitriptyline has antihistaminic properties that can help pets with allergies and it has analgesic properties that can benefit patients with chronic pain. Some of amitriptyline’s less desirable (and less common) side effects can include a dry mouth, urine retention, sedation, or constipation, especially during the first few days of therapy. Amitriptyline should be avoided or used cautiously in patients with glaucoma, seizures, or heart disease.
Trazodone is an antidepressant in a class of drugs known as serotonin antagonist and reuptake inhibitors (SARIs). Trazodone begins to work within a few hours and is often used in the short term, until primary medication (usually an SSRI or TCA) has time to take effect. Trazodone can sometimes be helpful in the long term as an adjunctive or add-on therapy with other antidepressants. There is some risk of drug interactions, especially the potential for serotonin overdose, which is known as serotonin syndrome. It is essential that you check with your veterinarian before combining trazodone with any medication and report any unusual side effects immediately.
Since trazodone works quickly, it can also be useful on an as-needed basis when you expect an exposure to a trigger for fear or arousal. For instance, for a pet with a thunderstorm phobia, you can give trazodone before a storm.
Buspirone is an antidepressant in the azaperone family. It has few side effects and is sometimes used in the treatment of generalized anxiety. It may be useful for cats that experience distress related to interactions with other cats in the home. Increased aggression is a reported side effect in cats, so buspirone is not usually recommended if a cat is already exhibiting aggressive behavior. Buspirone may take several weeks to take effect and is not useful for temporary, situational anxieties.
Venlafaxine is in a drug category called serotonin-norepinephrine reuptake inhibitors (SNRI). This antidepressant category affects both serotonin and norepinephrine and is most often used when an SSRI has been only partially effective. Because of their greater effect on norepinephrine, SNRIs are used to reduce arousal and frustration.
What other medications are used to reduce anxiety?
Benzodiazepines are very effective at reducing anxiety and panic. Examples of benzodiazepines are alprazolam, lorazepam, and diazepam. Because of their rapid onset of action and relatively short duration, these drugs are primarily used for specific anxiety-inducing situations, such as in anticipation of a thunderstorm, fireworks, or a car trip.
Benzodiazepines may cause sedation and appetite stimulation and some pets might even become more agitated or anxious when they first start therapy. These effects usually resolve within a few days. Benzodiazepines should be tapered gradually after long-term daily use.
Caution: Diazepam should NOT be used in cats, as there have been reported cases of liver damage. If your pet has taken even a single dose of diazepam, report any unexpected behavior or medical changes to your veterinarian immediately (e.g., decreased appetite or vomiting).
Clonidine works on the sympathetic nervous system and is part of a class of drugs called alpha-2 agonists. In humans, clonidine is licensed for the treatment of hypertension (high blood pressure), but it also has anti-anxiety effects. One way it can reduce anxiety is by blocking norepinephrine. Clonidine begins to work relatively quickly, which makes it useful when an anxiety-evoking situation is expected. It is also used to reduce daily anxiety or frustration, most often in conjunction with an SSRI. Clonidine might be prescribed to help with conditions such as storm phobia, separation-related distress, or hyperarousal on walks. Clonidine must be tapered gradually after long-term, daily use.
Gabapentin is an anti-seizure medication that can also relieve anxiety and pain. Gabapentin works relatively quickly and can be used in anticipation of situations that trigger anxiety, such as a visit to the veterinary office, a car trip, or a thunderstorm. It can also be used chronically, usually in combination with an SSRI, for pets experiencing daily anxiety. Gabapentin may cause sedation in some pets, especially at higher doses or when used only occasionally.
Are there medications for other behavioral conditions?
There are many other types of medications available for the treatment of behavioral disorders. Many of these medications will only help with specific conditions, which is why it is important to have a full behavioral assessment to learn the diagnosis for your pet. Here are two examples of medications used to treat specific behavioral conditions:
Methylphenidate is a stimulant used for attention deficit disorders in people. Although rare, some dogs may have an attention deficit disorder. These dogs may have a short attention span, be difficult to train, display repetitive behaviors, or be extremely active and have difficulty settling down. Stimulants generally cause an increase in heart rate and activity level but have the opposite effect in hyperactive dogs: the heart rate slows and activity is reduced.
Selegiline (Anipryl®) is a monoamine oxidase B (MAO-B) inhibitor. It is licensed for use in dogs in both Canada and the United States for the treatment of cognitive dysfunction syndrome (CDS) and in the control of clinical signs of Cushing’s disease. Signs of CDS can include disorientation, change in social interactions, altered sleep-wake cycles, house soiling, and anxiety. Selegiline mainly affects the neurotransmitters called dopamine and norepinephrine, which may decline with age. Selegiline may also help protect brain cells.
Selegiline should not be used with any other medications that affect serotonin, including most antidepressants (SSRIs, SNRIs, TCAs, trazodone, buspirone).
Are drug interactions common with behavioral drugs?
It is important to tell your veterinarian about all your pet’s medications, as there are many contraindications with other behavioral drugs. Serious interactions can occur even with topical products such as amitraz (used to treat ticks and mites in dogs).
How do I know if a medication is helping?
Keep a journal of your pet’s response to each medication, as the dosage or combination of medications may need to be adjusted. The goal is always to improve the behavior without causing undesirable side effects.
