Dog having seizure and losing weight

Question
Hello I have  a mixed breed he's a chow german shepard mix he's 5 years old great shape till recently about 53 pounds lives indoors also have another mix breed. Both dogs are spayed and neurted.  I have had him in the vet the last 3 weeks with no answers he was having about 2 seizures a day they just came from no where so they did blood test said everything came back negative. 2 days later I woke up he couldn't walk or move so i took him back in. They took more blood and put him on Rimadyl and Doxycycline his seizures went away few days later.He started geting fluid in his joints took him in they tapped his joints haven't gotten test back from that and they also took xrays still no answer she took him off the Rimadyl and put him on prednisone he seemed to be doing better but lost some weight in his hind end can see like back bone a little and looks as if muscle tone gone. He just had another seizure tonight and I still have no answer from the vet they were going down the line of lymes or dick disease but now she wants to look elsewhere. Have you ever seen anything like this? Oh ya he eats regularly and drinks lots cuz of the predinsone. Could the predinsone make him lose weight in his back end?

Answer
The weight loss in his back end is probably from muscle atrophy if he hasn't been very active for the past 3 weeks.  When he gets to feeling better, and is able to exercise again, the muscle tone should improve.  Generally if a dog has one seizure its not something we worry about, but if they continue to get them it is something to worry about.  There are many things that can cause seizures including low blood sugar and brain tumors.  Most times the seizures can be controlled with medication.  Since he is having other symptoms along with the seizures, I can understand why your vet wants to rule out tick born diseases.  Even if the tests come back negative your vet may still want to put him on the medication for it since often once symptoms appear, it can be hard to test for it (some tests test for certain proteins or antibodies, which may or may not be present).  It sounds like you and your vet are on the right track to finding the problem; I hope they find it soon and he gets better.

Amanda