Treating Behavior Problems in Dogs
Medicines for the Treatment of General Anxiety continued...
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
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
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.