Not All Seizures Can Be Linked to Tumors in Dogs
When I was eight we took in what was to be the sickliest, most decrepit puppy of all times; my Lhasa Apso mix, Taffy. I suppose her regular visits to the vet were what inspired me on my career path. Among her many problems, such as flea allergies, glaucoma, and recurrent ear infections, she also had epilepsy.
Though her seizures were terrifying, they were also blessedly rare. She fit the mold when it came to epilepsy. They started when she was three years old. It’s a very challenging diagnosis because there’s not really a good definitive test for it. You need to rule out other neurologic problems like infections and tumors with fairly invasive and/or expensive tests, and many owners elect to assume it’s primary epilepsy till proven otherwise when the seizures start in a young dog.
When a dog is over five years of age when the seizures begin, it’s a different story. An otherwise healthy 10-year-old Corgi who suddenly develops recurrent seizures? Conventional wisdom in veterinary medicine leads us to start putting cancer at the top of the list. The epilepsy in this case is secondary to the cancer. For some owners, that means finding a neurologist or oncologist to begin the process of MRIs, spinal taps, and intensive management, while others decide to go with the veterinarian’s best judgment and treat what is assumed to be secondary seizures as best as possible.
Being told your suddenly seizing older dog probably has a brain tumor is, understandably, very traumatic for people. The fact that the dog's behavior is so hard to predict leads to a good deal of anxiety for owners waiting to see what the next day will bring. More seizures? Sudden aggressive behavior? Or nothing?
In this month’s Journal of the American Veterinary Medical Association, a retrospective study of 99 dogs over the age of five with epilepsy shows that we have more cause for hope than we thought. While the majority of these dogs did have epilepsy secondary to another neurologic problem like cancer, infection, or stroke, a substantial number — between 23% to 45% depending on age — actually did have primary epilepsy.
Why does this matter? Because the prognosis for primary epilepsy is better than that for a brain lesion. While most brain cancers lead to progressive worsening of symptoms and eventual euthanasia, a good number of dogs with primary epilepsy can be controlled with daily medication. Some dogs, Taffy included, had seizures rarely enough where she didn’t even require that.
I love this study because it’s nice to see a journal article that gives people hope where maybe there was little before. The authors are quick to remind readers that an MRI and analysis of spinal fluid is still very much recommended in older dogs with seizures, but if it’s completely out of the question, not all hope is lost.
Seizure disorders are frustrating for both owners and veterinarians by the very nature of the nervous system. All those bones and tough sheaths that do such a great job protecting the nervous system also make it difficult to analyze. Nonetheless, your veterinarian can offer you a good bit of guidance to help you decide on a plan if your dog develops seizures later in life. Seizures don’t automatically mean death.
And Taffy? She died at the ripe old age of 15. Not from epilepsy, but heart failure.
Dr. Jessica Vogelsang
Epilepsy in dogs five years of age and older: 99 cases (2006–2011). Ghormley TM, Feldman DG, Cook Jr JR. J Am Vet Med Assoc. 2015 Feb 15;246(4):447-50