Treating Behavior Problems in Dogs (cont.)
Medicines for the Treatment of General Anxiety
Some dogs suffer from a more generalized form of anxiety that leaves them nervous in many everyday situations. Benzodiazepines are not a good choice for everyday, ongoing treatment, so they aren't appropriate for dogs with generalized anxiety. These dogs do better with treatment that can be continued for a period of time rather than given in anticipation of frightening events. The medicines that help dogs with general anxiety problems are TCAs, MAOIs and SSRIs.
Tricyclic antidepressants (TCAs) were originally used to treat depression in people. They work primarily by increasing serotonin and norepinephrin-two neurotransmitters that are involved in regulation of emotional activity. They also affect other neurochemicals involved in emotional reactivity. The TCAs prescribed most for dogs are amitriptyline (Elavil® or Tryptanol), clomipramine (Clomicalm® or Anafranil®), doxepin (Aponal®), imipramine (Antideprin or Deprenil), desipramine (Norpramin® or Pertofrane) and nortriptyline (Sensoval). Every dog is unique behaviorally and physiologically, so one TCA might not work well in a dog whereas a different TCA in the same dog could have excellent results.
Although TCAs were originally labeled to treat depression, they also reduce anxiety, manage compulsive behavior and can help people with anger problems. In dogs they have been used successfully to help with treatment of separation anxiety, general anxiety and compulsive behavior problems like compulsive licking. For instance, amitriptyline is a good choice for treating generalized anxiety and separation anxiety. Studies have shown that clomipramine is quite beneficial when used in combination with behavior modification for treating separation anxiety. This medication is approved for dogs by the FDA. (It's sold under the name Clomicalm®.) It‘s also effective for reducing compulsive behavior.
TCAs are prescribed for daily use. If the medicine isn't taken every day, it won't work to treat the problem behavior. TCAs are not usually effective the first day-or even the first few days that they are taken. Because at least some of their effectiveness comes from the changes they make to the brain, they must be taken for at least two to three weeks before they produce results. Treatment should continue for at least two months before a decision is made regarding the success of the drug.
TCAs are metabolized in the liver and excreted through the kidneys of a dog, so if your veterinarian advises you to treat your dog's behavior problem with a TCA, she should give your dog a simple blood test to make sure that these organs are working well before beginning treatment. If your dog has had problems with his kidneys or liver, be sure to let your veterinarian know about your dog's history. Recheck blood tests are recommended every year (twice a year in older dogs) to ensure that the medicine has not damaged the liver or kidneys.
Some drugs, such as amitraz (a chemical found in some tick repellant collars), have been found to cause dangerous problems such as lethargy, weakness and increased heart rate when used on dogs who are taking imipramine. Pet parents should read the ingredients of their flea and tick treatments carefully and avoid amitraz if their dog is taking or has taken imipramine.
TCAs can increase water retention, and water retention produces dry mouth. Some dogs might foam at the mouth, and they may also be extra thirsty. Because they are thirsty, they might drink extra water and then have to be let outside more. Water retention can also lead to constipation and even diarrhea, and all of these things can show up as house soiling problems. TCAs can also cause a sudden increase in heart rate.
Monoamine Oxidase Inhibitors
Monoamine oxidase inhibitors (MAOIs) work on similar neurotransmitters as TCAs, but they work differently and with less selectivity, so they have a more general effect on the brain. Selegiline (Anipryl®) is an MAOI that affects the neurotransmitter dopamine. It's the only MAOI that is used with any regularity in dogs. It's used to treat cognitive dysfunction in elderly dogs. Studies indicate that selegiline may slow aging of the brain. (Please see our article, Behavior Problems in Older Dogs, for more information on how to preserve the quality of life of your older dog).
Some MAOIs can have dangerous side effects in dogs who have eaten cheese. Selegiline does not fall into this category, but because some humans have been known to react to cheese when on selegiline, pet parents should avoid giving their dog cheese when he's taking selegiline. MAOIs should not be used with SSRIs because the combination can increase serotonin to unhealthy levels.
Selective Serotonin Reuptake Inhibitors
SSRIs affect the brain chemical serotonin. Common SSRIs are fluoxetine (Reconcile® or Prozac®), paroxetine (Paxil®), sertraline (Zoloft®) and fluvoxamine (Luvox®).
Fluoxetine and sertraline have been used successfully to treat a number of anxiety-related behavior problems such as separation anxiety and fear of people, other animals or other things that the dog may encounter daily. SSRIs are also useful in reduction of compulsive behavior in dogs. SSRIs may be prescribed for certain aggression problems, but the effects are mixed and can, in some instances, make a dog worse. Only consider SSRIs for your dog's aggression if you have been advised to do so by a veterinary behaviorist or Certified Applied Animal Behaviorist.
SSRIs are metabolized in the liver and excreted through the kidneys. Even if your veterinarian does a pretreatment blood test to check liver and kidney health, be sure to let her know of any medical problems with your dog. It's a good idea to have your dog's liver and kidneys rechecked each year if he is kept on an SSRI.
SSRIs should not be used with MAOIs because the combination can increase serotonin to unhealthy levels.
SSRIs need to be taken every day to be effective. If the medicine is not taken every day, it won't work to treat the problem behavior. SSRIs are rarely effective the first day, and in fact can increase anxiety in some dogs before they begin to have therapeutic effects. Because SSRIs create changes in the brain, they must be taken for at least six weeks before they produce therapeutic results. Any decisions regarding the success of the treatment should be postponed until the dog has been on the medicine at least four months.
Because SSRIs require a few weeks to build up in the dog's system and take effect, some people will also use other medicines at the beginning of treatment. One choice is to use benzodiazepines when the dog may encounter a frightening thing or event. Another choice is to use a medicine known as a serotonin agonist, which can sometimes be useful at the beginning of SSRI treatment. The most common is buspirone, sold under a number of brand names, including Bespar and BuSpar®.
Serotonin (5-HT) Agonists
Buspirone (BuSpar or Bespar) is the only 5-HT agonist that's used regularly in companion animal behavior. As mentioned, it's sometimes used in conjunction with SSRIs and TCAs when treatment is begun, but it's also sometimes used by itself.
Like other medicines that act on serotonin, buspirone needs to be taken every day to be effective. If the medicine isn't taken every day, it won't work to treat the problem behavior. Buspirone usually requires about thee weeks to show an effect, although this may be shortened if it's taken in addition to SSRIs.