Epilepsy means repeated seizures due to abnormal activity in the brain. It is caused by an abnormality in the brain itself. If seizures occur because of a health problem elsewhere in the body, for example a heart problem, which stops oxygen reaching the brain, this is not epilepsy nor are issues such has Hypoglycaemia (low blood sugar) to be confused with it. Your vet can do tests to try to find the reason for the epilepsy but in many cases if all the tests come back negative it is simply a conclusion of it must be epilepsy because it isn't anything else that can be tested for. Epilepsy affects around 4 in every hundred dogs and In Dachshunds it is currently thought to be hereditary. To that end if a dog is found to be suffering from epilepsy and or suspected epilepsy it would be highly recommended to no longer use that dog for breeding and possibly it's offspring.

Links
Epilepsy is far too big a subject to be covered in just one page so we encourage you to explore the following links for more detailed information.