A recent study from Brazil (www.veterinaryworld.org/Vol.17/February-2024/13.pdf) evaluated 10 dogs diagnosed with Tier I level idiopathic epilepsy to determine if changes to the EKG were present. The rationale for doing this study was initiated by the human epileptic syndrome of "sudden death in epilepsy, or SUDEP". SUDEP is a devastating syndrome wherein human patients are found dead after recovery from a recent seizure. This is most traumatic for the parents of pediatric epileptics who may help their child through a seizure, see that they are recovered and then find them deceased a short while later without any signs of additional seizures. The cause of SUDEP is debated however a cardiovascular cause appears most likely. This syndrome is rarely identified and poorly published in veterinary medicine.
During a seizure, a tremendous release of catecholamines occurs which may stimulate hypertension, as well as intoxicate the cardiac muscle causing poor relaxation and cardiomyopathy. The study reported findings in 10 dogs with epilepsy and compared them to 11 dogs without epilepsy who were apparently healthy on laboratory testing, physical and neurologic examination and without a seizure history.
Results
The QRS complex was significantly longer in dogs with epilepsy compared to the control group suggesting left ventricular enlargement or left bundle branch block. Additionally, the QT interval was prolonged, and this was attributed to the below reference range ionized calcium concentrations in the epileptic dogs. Interestingly, the control dogs also had lower ionized calcium concentrations so one might question the validity of this test. What do these cardiac changes mean for us? It means that even "well controlled, healthy" epileptic dogs may have occult cardiac damage. Use caution when providing anesthesia to this group and perhaps reach for a preoperative EKG for this population even if their breed or age wouldn't otherwise spur you to do so. Lastly, I found it interesting that the serum glucose concentration was significantly higher in dogs with idiopathic epilepsy compared to the control group. This likely harkens back to the high sympathetic response and catecholamine release mentioned above but another idea crosses my mind as well. Many internet sites still recommend giving glucose or honey to a pet after a seizure, even without evidence of hypoglycemia. Ice cream, popsicles, and honey are frequent additions to post-ictal care in many of our patients. If given prior to the laboratory samples, it could falsely increase the serum glucose concentration. What's the take away here? Don't rule out hypoglycemia as a seizure etiology on a single blood sample. Consider a second one 4-6 hours later, during hospitalization, and note if the glucose drops below the therapeutic range. (Oh, and make sure your clients are advised against giving sugar products postictal. No one needs a sugar rush when you're on a catecholamine rush!)
Thanks for reading! This little article crossed my radar this week and I thought it was good enough to share with all of you! I hope you have a great first full week of Spring (anyone else looking at snow on their forecast??) and I look forward to working with you soon.