“Penny” is a 7 year-old Golden Retriever. She has been healthy until recently. She has had three seizure episodes in the last month. The seizures appear to be grand mal type with tonic and clonic muscle movements and brief loss of consciousness. Patient appears normal in between the episodes.
Magnetic resonance examination was carried out with a high field, superconducting unit. Sequences included T2 sagittal, T2 transverse, a Fluid Attenuation Inversion Recovery sequence (FLAIR) in the transverse plane, and T1 before contrast in the transverse plane. Gadolinium contrast agent was administered and T1 post-contrast images were obtained in all three planes. Each sequence has approximately 20-25 images and Figs 1-7 illustrate one image per sequence.
All sequences revealed normal anatomy and bilateral symmetry. The mild asymmetric changes within the lateral ventricles are commonly seen as a normal finding in this species. Magnetic resonance imaging has the ability to see macroscopic structural lesions larger than a grain of rice. Therefore, macroscopic structural lesions have been ruled out in this case. The seizures could be due to microscopic or physiologic/metabolic etiologies.
Magnetic resonance imaging is an expensive diagnostic test. The value of the test is also high. Dogs that are 7 years of age, when they have their first seizure, could have numerous diseases. The most common etiologies would include infectious conditions, cerebral infarction (strokes), brain tumors, or delayed onset of epilepsy.
An accurate diagnosis is needed for the proper therapeutic options. Early diagnosis can lead to improved treatment outcomes. Placing animals on anti-seizure medication without a proper diagnosis exposes the animal to medications that have significant serious side-effects. In this case, in the absence of a macroscopic finding, anti-seizure medication appears warranted. Proper therapy requires diligence in administering the medication and having blood levels checked for therapeutic levels. The veterinarian and owner can be confident that macroscopic structural lesions, including infarctions, infections, and tumors have been ruled out.
A proper study requires numerous sequences, as illustrated in this case. In addition, the interpretation needs to be done by a skilled professional with experience and the ability to distinguish pathologic change from similar appearing lesions that could be artifactual.