I believe this is what's going on with Topaz...not sure if this is related to the twitches/tremors though...I need to ask the vet.
What is ataxia?
Simply said, ataxia occurs when the body is out of balance. Symptoms of ataxia include: wobbliness, buckling leg joints, a drunken, staggering gait, lack of coordination, a tilted head carriage, tripping, falling, or collapsing.
This inability to coordinate voluntary muscular movements is often a side effect of anti-seizure medications which can cause weakness or loss of control of the hind legs, especially when the anti-seizure medication is first introduced, or when the current dosage has been increased. There are many other reasons that ataxia may be present in your pet, including ear infection and other health problems, but, if you noticed the ataxia soon after introducing anti-seizure medication, chances are, the anti-seizure medication is the source.
Another cause of ataxia is seizures. For a few days after a seizure your dog may not be able to jump up on the bed or couch and may have trouble going up and down stairs. Tremendous isometric stress is put on the muscles during a seizure. Immediately afterwards the back legs may not be strong enough for normal "romping" and it may take a few days to a week for that strength to return.
Both Phenobarbital (Pb) and Potassium Bromide (KBr) can cause ataxia, and the combination of the two drugs can often cause increased ataxia. Often, as the dog becomes used to the medication, the ataxia diminishes. If your dog is in this initial stage of getting used to the medication, it's prudent to go slowly with your dog on slippery surfaces and stairs. In time, your dog will gain more control of his/her hind end, so try to be patient.
It can be depressing to see your pal with ataxia. If medication was only recently introduced or increased, try to be patient and encourage your dog to go on short walks.
Problems can occur with older dogs who may be weak in the hind end already, or for dogs whose flooring is slick, as with hard wood or tiled floors. If you find your dog is unable to move safely on your wood or tiled floor due to ataxia, try putting down throw rugs to provide extra traction.
If you find that your pup's ataxia is pronounced, and shows no sign of lessening, please talk with your vet. Sometimes the anti-seizure medication can be reduced slightly and the ataxia will be greatly reduced. Of course, having ataxia is better than having a seizure, so we have to consider the balance there. If the blood levels of the medication are in question, the best way to know how much medication is being absorbed is with a simple blood test. Often the drug to reduce if you dog takes both Pb and KBr is Pb. Please do not try to reduce Pb without your vet's supervision and also you do not want to reduce it more than 10% every two weeks.
If your dog is only on KBr you might ask your vet if you can drop the KBr for just one day and see if that lessens the ataxia. If it does, you could ask you vet if a slightly lower dose could be achieved while keeping it in the therapeutic range.
Moderate and sensible exercise is recommended for dogs with ataxia. It is important to keep muscles strong and flexible. If your dog seems tired, take a break and continue on your walk when the dog is ready again.
http://www.canine-epilepsy-guardian-angels.com/ataxia.htm
