Question:
I know that antidepressants can be used to successfully treat depression, anxiety and post-traumatic stress disorder (PTSD) in people. And I have heard of them being used in dogs to treat things like anxiety. Are they ever prescribed for horses? Are there any studies that looked at treating horses with antidepressants?
Answer:
Many of the brain regions and neurotransmitter systems in the equine brain are similar to those in the human brain, so it is reasonable to envisage that human psychoactive drugs would have a similar effect. That said, antidepressant-type drugs are not routinely given to horses.
Serotonin reuptake inhibitors like fluoxetine (brand name Prozac) and serotonin modulators like trazodone (original brand name Desyrel, now discontinued) have been administered to horses to facilitate stall rest after orthopedic surgery or during musculoskeletal rehabilitation. These medications have also been used to reduce abnormal (stereotypies), aggressive and anxious behaviors in the stable environment.
Changes or improvements in behavior have not been empirically reported. But more than 70 percent of horse owners have reported an improvement across many of behavioral issues after their horses received one of these medications. Other antidepressant drugs, such as tricyclic anti-depressants, including amitriptyline (brand name Elavil) and imipramine brand name Tofranil), may be prescribed for dogs and cats. But these types of drugs are less commonly administered to horses for a number of reasons such as rate of metabolism and physiological side effects.
Oftentimes behavioral issues associated with stress, depression and anxiety in horses can be resolved by changing the animal’s management, including environment, diet, turnout and training regimen. Increasing a horse’s turnout time, for example, may reduce its anxiety and related undesirable behaviors. Pharmacological intervention is best used as a last resort when management changes don’t work or when the animal’s care or environment cannot be changed due to, for example, box rest due to injury.
Aberystwyth University
Aberystwyth, Wales