Which serotonin reuptake inhibitor is used to treat separation anxiety in dogs and phobias?

• A. Sertraline
• B. Paroxetine
• C. Fluoxetine
• D. Citalopram

Answer: (C)

Serotonin reuptake inhibitors help dogs with separation anxiety and phobias by increasing serotonin signaling in brain circuits that regulate fear and stress. Fluoxetine stands out because it has the strongest and most consistent veterinary evidence for these conditions, making it the preferred starting option in many guidelines. It’s typically given once daily, with gradual dose increases, and many dogs begin to show meaningful improvement after several weeks—often as behavior modification and environmental management are reinforced alongside the medication. The goal is to reduce baseline anxiety so that training and conditioning strategies—desensitization, counterconditioning, and a predictable routine—are more effective. Side effects are usually mild, such as occasional gastrointestinal upset, reduced appetite, or lethargy, and dogs generally tolerate fluoxetine well. While other SSRIs like sertraline, paroxetine, and citalopram can be used in some cases, fluoxetine has the best-supported track record for separation anxiety and phobias in dogs, which is why it’s the best choice in this context.