Q: I am a horsewoman who has a lifelong history of headaches. Because of my own background, I was wondering if horses also get headaches, and if so, how do we know when they are having one? How would it be treated? Because horses can experience other human ailments, wouldn't they have headaches, too? I would be most interested in any information you can provide on the subject.
A: We don't really know. Headaches are a subjective event, which means that when treating them in people, physicians rely on the patients to describe their experiences. There often are no objective signs a clinician can observe.
Therein lies the problem: A horse can't verbally tell us if his head hurts. However, horses can experience very serious head maladies and show little or no outward evidence of discomfort until the lesions start interfering with bodily functions. Some good examples would be rotten teeth and sinusitis, which for you or me would be devastatingly painful, but horses show few if any signs until they are no longer able to chew or until a swollen sinus blocks tear ducts or causes nasal discharge.
Encephalitis, which is inflammation of the brain, and meningitis, which is inflammation of the coverings of the brain, might be exceptions. Encephalitis and meningitis cause headaches in people, and horses with these conditions do become quiet and often stand with their head kept still and pressed against a wall. But those signs can also be behavioral changes associated with the "damaged" brain rather than a reflection of head pain.
Certainly anti-inflammatory drugs, such as bute, might relieve headache pain associated with encephalitis or meningitis in horses, just as aspirin relieves headaches in people. But those drugs also give relief to the damage in the brain cells.
The bottom line is that without being able to verbally communicate with animals, we will never know if horses suffer headaches.
I. G. Joe Mayhew, BVSc, PhD
Palmerston North, New Zealand