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In the Literature

Gilbert-Gregory SE, Stull JW, Rice MR, Herron ME. Effects of trazodone on behavioral signs of stress in hospitalized dogs. J Am Vet Med Assoc. 2016;249(11):1281-1291.

From the Page …

Stress related to hospitalization can negatively impact the physical and emotional well-being of patients and make patient monitoring and management difficult. Unlike the tranquilizer acepromazine maleate, trazodone, a serotonin antagonist and reuptake inhibitor, provides anxiolysis with mild sedation and is well tolerated at a wide dose range via oral administration.

In a blinded, prospective study, the behaviors of 60 hospitalized dogs receiving oral trazodone (mean dose, 4.65 mg/kg ± 0.97 mg/ kg; range, 2.83-6.75 mg/kg) were compared with behaviors of 60 environmentally matched dogs that did not receive trazodone. A trained observer scored the presence or absence of 17 stress-related behaviors, including lip licking, pacing, panting, whining, whale eye sign (ie, eyelids widened such that sclerae are easily seen), growling, and snapping at 2 time points: ≤45 minutes after trazodone administration (time 1) and 90 minutes later (time 2). Stress-related behaviors were grouped into 3 summation categories: frenetic, freeze, and fractious. 

After trazodone treatment, observation of stress-related behaviors, including lip licking, panting, whining, and whale eye, was significantly reduced. Except for whale eye, the same reduction was not observed in environmentally matched controls. Comparing time 2 with time 1, there was a significant reduction in median total stress scores and median frenetic and freeze scores for trazodone-treated dogs but not environmentally matched controls. Neither group exhibited a statistically significant decrease in fractious behavior scores, but fractious behavior was uncommon overall. Except for one patient that exhibited an increase in aggression, no adverse events could be attributed to trazodone treatment alone or concomitant treatment with other medications including, but not limited to, NSAIDs, tramadol, opioids, gastroprotectants, and antibiotics.

… To Your Patients 

Key pearls to put into practice:


A checklist should be used to identify signs of stress in hospitalized dogs throughout their stay.



Trazodone may be administered PO at 4-6 mg/kg with reduction in stress-related signs and behaviors occurring within ≈90 minutes.



Although adverse events are rare, clinicians should consider the potential for behavioral disinhibition, including aggression, and drug interactions resulting in serotonin syndrome.


Author information Show

Karen Lynn C. Sueda

DVM, DACVB VCA West Los Angeles Animal Hospital

Karen Lynn C. Sueda, DVM, DACVB, is a veterinary behaviorist at VCA West Los Angeles Animal Hospital in Los Angeles, California. In addition to in-office appointments, Dr. Sueda handles house call appointments throughout southern California. Her special interests include feline behavior, canine anxiety disorders, and the human–animal bond. She also is a frequent lecturer and past president of the American Veterinary Society of Animal Behavior. Dr. Sueda earned her DVM from University of California, Davis, where she also completed a residency in clinical animal behavior. 

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