Thursday, September 19, 2013

Electroencephalography Veterinarian Style: EEG Recordings on Dogs and Cats

One of the abstract presentations at the ASET 2013 Annual Conference in Reno last month was particularly of interest to me as a dog lover and owner of two Labrador retrievers.  The title of the presentation was  “Electroencephalographic and Clinical Findings in 37 dogs and 4 cats.”  The author of the abstract was Dr. William Bush, V.MD, DACVIM, and his presentation was fascinating!
He showed videos of some of his canine and feline patients having clinical spells that could very well be seizures.  The confirmation of seizure activity has been a challenge in veterinary medicine, and for the most part, is done by clinical observation and pathology affecting the brain may be detected with MRI, and lab studies of the cerebral spinal fluid.  Dr. Bush explained that when these tests are positive, there is a greater chance that the EEG recording will be abnormal as well.  But in cases where there is no structural or infectious process to cause seizures, an EEG recording can be done and is very helpful.  His study included three patients who were diagnosed with non-convulsive status epilepticus based upon their EEG findings.
It is also interesting to contemplate exactly how an EEG can be done on cats and dogs.  Dr. Bush discussed the use of sedation and a small number of needle electrodes.
I actually have some experience with recording an ambulatory EEG on a dog.  In the past, when I was working at Children’s Hospital in Boston, I was contacted by a veterinary behavioral specialist from Florida, who was a consultant for a show dog: a standard poodle, living in New Hampshire, who had frequent spells which may represent seizures.  Since the animal was a show dog, the owner did not want to start prescription anticonvulsants unless the seizures could be documented.  She was seeking a neurodiagnostic technologist who would be willing to work with the dog to record an ambulatory EEG at the nearby state-of-the-art facility, “Angell Memorial Animal Center”.  That person would be me!
We coordinated a dedicated exam room at the veterinary hospital, a flight to Boston for the specialist, and the use of the ambulatory EEG equipment donated for the session by Digitrace.  We knew that the dog would need to wear a backpack with the ambulatory recorder so for a few weeks prior to the recording session, the owner placed a harness and backpack on the dog for several hours per day, to acclimate the dog to the device he would be wearing.
A team of helpers met the dog, Flair, the owner and the behavioral specialist on the appointed day.  Our team included a clinical applications specialist from Digitrace, a veterinary neurologist from Angell and myself and another tech from Children’s.  We were prepared to administer a sedative for lead placement.  I had brought disk electrodes, collodion, and an air compressor with me.  We decided to try applying electrodes without sedation first.  The owner held the dog’s muzzle still, made eye contact with the dog, and calmed him verbally, while I placed leads.  No problem!  Frankly, the dog was easier to work with than most 2 year olds!

The dog wore the equipment for 48 hours and stayed with the owner in a pet-friendly hotel nearby.  Once a day, she brought the dog to a Digitrace office to have the leads checked and regelled.  It took a while but eventually typical clinical events were recorded which correlated to EEG activity that could be electrographic seizures.
We videotaped the patient set-up and the owner videotaped the clinical events.  I presented this case study as an abstract at the ASET annual conference in New Orleans in 2002.
A picture of me with my poodle patient:

It is interesting to speculate that in the future, there will be more utilization of clinical EEG in veterinary practice.  My thanks to Dr. Bush for sharing this fascinating topic with us.  Many of the techs in the audience agreed with me and would like to hear more from him in the future.