Better Living Through Chemistry

February 18, 2013

Maeby with a blanketThere’s been a lot going on at the Dr. D household over the past few weeks. We sold our house, bought a new house nearby and, sadly, had to say goodbye to our dog Kona. With all this turmoil, our other dog Maeby has been quite out of sorts. Maeby was very attached to Kona, and we knew his passing would be as difficult for her as it has been for us. As is true for many dogs, Maeby has always suffered from some minor anxiety since she was a puppy and this behavior has worsened as of late.

For Maeby, her anxiety primarily manifests as trembling and panting when she is in a new or unfamiliar environment. For instance, she becomes particularly agitated when I take her to work and leave her alone in a cage. At home, fortunately, she does not display symptoms of separation anxiety. Maeby is also what I would describe as a “needy” dog, in the sense that she follows us everywhere in the house; we refer to her fondly as “The Barnacle” since she seems to require being in constant physical contact with us.

With all the changes in our home, I decided it was time to try a course of anti-anxiety medication for Maeby. This was something I debated for a while, but after a particularly long day at my hospital, where Maeby whined, panted and hypersalivated for the greater portion of the day, I decided it was time to prescribe something to ease her stress.

During an average week, we see a good number of patients for concerns about anxiety-related behaviors. Separation anxiety, barking at strangers, inappropriate urination in a multi-cat household, submissive urination…all of these undesirable behaviors are often rooted in fear or anxiety. Behavioral modification techniques can be very effective in resolving some of these problems; often, pharmacologic intervention is also needed to achieve the best result.

Over the past decade or so, the anxiolytic of choice in veterinary medicine has been Prozac (fluoxetine). Fluoxetine is a selective serotonin re-uptake inhibitor (SSRI) that has been used for decades for the treatment of anxiety disorders in people. Humans are our best test subjects! Once a medical therapy has been used successfully in humans, it’s only a matter of time before the same therapy is tried on cats and dogs. The majority of human meds can be used safely in animals, but there are some very notable exceptions, such as Tylenol and Advil, among many others. Never give Fluffy or Fido one of your own medications without checking with your veterinarian first!

SSRI’s block the reabsorption of the neurotransmitter serotonin; high levels of serotonin have been found to improve mood, ease depression and lessen anxiety in humans. These drugs have a very high index of safety, and rarely cause changes to the liver or kidneys in our patients. Fluoxetine is in a generic form, which makes it exceedingly cost effective for most of our patients. There is also a version of fluoxetine called Reconcile that has been FDA-approved for use in dogs; Reconcile comes in smaller doses than the generic fluoxetine, so it is great for small dogs and cats. (Use of human generic fluoxetine is considered off-label, a common occurrence in veterinary medicine, where few drugs have been studied, tested and FDA-approved for cats and dogs. Use of Reconcile in cats is still considered off-label, as it has only been approved for dogs.)

The main side effects of fluoxetine are typically only seen in the first few weeks of therapy. This drug can cause a decreased appetite, and lethargy; in my experience, if these side effects are seen at all, they almost always resolve within the first two weeks as the animal acclimates to the drug. Fluoxetine can take up to four weeks to reach therapeutic levels in the bloodstream, so it is not a quick fix or a medication to be used for isolated “panic attacks” such as thunderstorm phobias. I typically recommend that my clients commit to a minimum of three months of fluoxetine therapy (ideally six months) before we decide if it’s definitively working or not. Our hospital also requires blood monitoring every six months for our patients receiving fluoxetine; this is to ensure Fluffy or Fido isn’t one of the rare patients to have elevated liver values while on this drug.

One circumstance in which I’m uncomfortable prescribing fluoxetine is in cases of aggression. While the majority of aggression in dogs is fear-based, fluoxetine can paradoxically make aggression worse. SSRI’s can cause a “disinhibition” of aggression; by increasing serotonin levels, this can remove the remaining “censor” that a dog has, thereby making them more aggressive. The simple fact is that there is no medication for aggression. I refer the majority of aggression cases to a board-certified veterinary behaviorist, and allow them to create a behavioral modification plan and determine which, if any, medications may be appropriate for the aggressive patient.

Fluoxetine has really been a godsend for veterinarians and anxious pets; I know many inappropriately urinating cats and destructive, separation-anxious dogs who were spared from being returned to the shelter after a dramatic improvement on fluoxetine. Let’s hope Maeby responds just as well! I will certainly keep you posted on her progress.