Hello and welcome from me, too. In honesty, I am highly doubtful that Cushing's has anything to do with Laci's seizures, even if she truly has Cushing's. Since she has exhibited seizure disorder her entire life, I am guessing she has epilepsy or some specific physiological trigger other than Cushing's. I really don't know why your vet even thought about Cushing's based upon seizures alone. Seizures are not a typical Cushing's symptom.

I currently have a non-Cushpup Labrador retriever who first exhibited grand mal seizures of unknown origin several years ago at age 6, and she has been treated successfully with phenobarbital since that time. However, here are some important things for you to know about phenobarbital. First, it skews the results of basic thyroid tests and can make a dog appear to have low thyroid function even if that is really not the case. So before starting thyroid supplements, it would be important for the vet to request more involved thyroid testing than just the simple T4 level that appears on a basic blood chemistry panel.

Also, phenobarbital has to be monitored very carefully with regularly spaced blood tests. There is a therapeutic range within which the dosing must be maintained. If you give too little of the drug, it won't control the seizures. If you give too much of the drug, the liver can be damaged. If Laci has been taking the phenobarbital for a couple of years now, I would hope that the drug level in her bloodstream has been carefully monitored during this time. It is true that elevated liver enzymes can be caused by Cushing's, but they can also be caused by phenobarbital. Either way, for the safety of her liver, she may need to be switched from the phenobarbital to a different seizure medication that is not so hard on the liver. I would be very worried about a dog who has those liver readings and is continuing to take phenobarbital. There is a specific blood test that helps judge the actual liver function and it is called a bile acids test. It might be very important to see how well Laci's liver is actually working right now.

So in the absence of any overt Cushing's symptoms, I would be worrying much more about clarifying Laci's liver function and also requesting more thorough thyroid testing. I would want to ask the vet whether her phenobarbital level has been within tested therapeutic range during these past couple of years. And given her abnormal liver values, I would want to talk about switching her to a seizure medication that does not carry such a strong risk for damaging the liver further.

Marianne