Idiopathic Epilepsy Update!
A recent article out of the Vet Record by Dr. Rachel Hall and colleagues outlines the prevalence of idiopathic epilepsy and structural epilepsy in dogs.* I found this a very interesting read, packed with useful information so I thought I'd pass along a bit (get it?) of it to you!
Study Design and Points Worth Noting
This is a retrospective study based out of the UK.
900 cases with MRI, a neurologic examination and medical record history were included. (wow!)
Structural epilepsy is defined as a seizure disorder secondary to an identifiable structural cause. Examples include neoplasia, meningoencephalitis, hydrocephalus, etc.
Idiopathic epilepsy is defined as the lack of identification of a structural abnormality in a pet with 2 or more discrete seizures.
Small (< 10 kg), medium (10-20 kg) and large breed (>20 kg) dogs were represented in approximately the same percentage in this study.
Results of Interest (there are a lot of interesting results in this study!)
About 50% of the dogs were between 6 months and 6 years old, and 50% were > 6 years old.
About half of the dogs had structural epilepsy based on abnormal MRI findings
The other half of dogs had no significant findings on MRI and the majority were classified as having idiopathic epilepsy. (The others had toxin and metabolic disease diagnosed).
Prevalence of idiopathic epilepsy in dogs in the UK? 50%!
Okay, fine (you might think) how does knowing the prevalence of idiopathic epilepsy in dogs in the UK help me?
I'm glad you asked...
Idiopathic epilepsy was the leading diagnosis for dogs between 7 months and 6 years old. Inflammatory brain disease was second.
Take away point? Meningoencephalitis is NOT rare! Oh, and idiopathic epilepsy is most common in the group of dogs we thought it would be most common.
Idiopathic epilepsy was also the leading single diagnosis (34%) for dogs over 6 years of age. HOWEVER when they combined all types of neoplasia together into one group they found 43% of dogs over 6 years of age had neoplasia making it the leading singe diagnosis in this group.
Take away point? Read that sentence above again! I considered making this TidBit Tuesday a one line update because it's so critical to make sure we don't forget that "old" dogs can actually have idiopathic epilepsy!
Also, dogs over 6 years of age had structural epilepsy more often than idiopathic epilepsy if all causes for structural epilepsy were combined. (Not surprising, I know.)
What do you do with this information?
Do a neuro exam on every patient with a seizure history!
If the exam is NORMAL, include idiopathic epilepsy on the differential diagnoses list, regardless of age.
If the exam is ABNORMAL, include causes for structural epilepsy on your differential diagnoses list, regardless of age.
Thanks for reading - I hope you have a great week!
Reminder! Upcoming Webinar "The Neurologic Exam for the Busy Vet" on Wednesday May 27th 12-1pm and repeated 7-8 pm.
Check out my website at www.barnesveterinaryservices.com for details and registration.
* Hall R, et al. Estimation of the prevalence of idiopathic epilepsy and structural epilepsy in a general population of 900 dogs undergoing MRI for epileptic seizures. Vet Record 2020.