Serum Melatonin Values in Normal Dogs and Dogs with Seizures

ABSTRACTEpilepsy, or recurrent seizures, is reported to be the most common neurologic condition in dogs; 20–30% of epileptic dogs are considered to be pharmacoresistent to one medication. The hormone melatonin has been shown to have significant anticonvulsant effects; epileptic humans have lower serum melatonin levels than unaffected individuals. We hypothesize that serum levels of melatonin will be lower in dogs with seizures as compared with normal dogs. Sixty-two dogs were enrolled in the study: 29 normal dogs (Group 1) and 33 dogs with seizures (Group 2). Blood sampling was done at three separate time points (8:00 a.m., 12:00, and 4:00 p.m.). The majority of dogs in Groups 1 (69%) and 2 (76%) had serum melatonin levels <0.5 pg/mL as measured by radioimmunoassay. There were no significant differences in serum melatonin values between the groups or within groups when time of blood draw, length of sample freezing, time of day/year of sampling, or presence of anticonvulsant therapy were compared. There we...