Magnetic resonance imaging (MRI) is now widely used in equine veterinary practice. However, themandatory European legislation regarding horse identification imposes the implantation of a tran-sponder within the fatty tissue of the neck cervical ligament. While performing brain MRI for scientificpurposes in ponies, we faced artifacts produced by such transponder and reported here this problem.Indeed, pony mares were anesthetized for 2 hours and placed, bedded on their back, in a 3T MRI scanner.A four-elementflexible antenna positioned around the head was used. Three MRI sequences wereperformed on each animal: three-dimensional T1, three-dimensional T2, and two-dimensional T1. Theanesthesia allowed the acquisition of MRI for 2 hours. The images for the three MRI sequences for eachpony exhibited great quality on all the anterior parts of the brain but began to become distorted pos-teriorly to the pineal pituitary axis and completely disappeared at the level of the cerebellum. Tofind theorigin of the artifact, the transponder used for the identification of the animal was inserted in an inert geland imaged in the same conditions as the ponies. The images obtained looked similar to the observedartifact. Our study thus advocates for the further exploration of such kind of artifact when using 3T MRIin brain imaging in horses.