chihuahuas mental health

Question
Hi!

I found my chihuahua on the side of the road near a freeway onramp seven months ago.  He was terribly frightened, extremely underweight, and filthy.  I took him to the vet who wouldn't even vaccinate him at that time because of his being so underweight.  Other than that, she estimated his age at approximately six years and pointed out things that indicated some past abuse or other traumas.  He had a deep scar across his nose and a couple of his toes were bent up as if they'd been broken.

Putting weight on  him has been difficult.  I don't know if he's picky or if it's indicative of a larger problem but sometimes he won't eat at all for a day or more and other times, normally. I've tried to love him as much as possible and while I'm home, he stays in the house with me. Occasionally he ventures out into the backyard with my three lab mixes, whom, by the way, he never seemed that afraid of and the four of them get along great. When he has one of his "episodes" however, he acts deathly afraid of me and I have to go pick him up to put him on the couch beside me where, normally, he wants to be.

That's the background, but my real concern and reason for writing is regarding his "episodes".  For no apparent reason, his behavior and personality radically changes for a period of time. I can't identify any antecedent to these changes (i.e., loud noises, my leaving the house, etc.)but the following are the traits that appear:
l.  Constant whimpering/crying even when I'm petting and trying to console him.
2.  Wants nothing at all to do with me.
3.  Wants nothing to  do with the other dogs
4.  Goes off in another room
5.  Has a weird little "tic" where he keeps turning his head every second or so
6.  Won't eat, even "people food" like steak and chicken.
6.  Generally just looks terribly frightened

Then, as quickly as it comes, it goes and he's his self again.  These episodes last anywhere from a couple of hours to a couple of days.  Normally, he's happy, acts silly sometimes being playful and excited, etc.  He's always scared around other people but as long as I'm holding him, he's ok. From the beginning, because I didn't want to leave him alone while I was at work, I've taken him to my mom's house every morning and pick him up at the end of the day.  She has two little dogs and he does well with her and them.  She has reported witnessing the bizarre changes in him behavior too, where he wants nothing to do with her or the other dogs, won't eat and will just sit in the middle of the backyard or even hide under a bush or something and "pout" as he puts it.

My question is this: Is it possible for a dog to be schizophrenic or bi-polar, etc.? And if so, is there some way I can help him? Medicine to help him? The vet says he's healthy in every other way, especially now that he's gained some weight. I know he should neutered for his own well-being, but I'm a little reluctant because of his obvious psychological problems.

Any advice you can give me to help my beloved little Poochie would be greatly, greatly appreciated.  It's frustrating because I don't know what to do and I know he must be suffering when he goes into these changes. He's obviously had a rough time in the past. I want to give him the security, love, health and happiness he deserves for the remainder of his life and hope perhaps you can help both of us.

Thanks again,
Julie and Poochie

Answer
What a wonderful woman you are to have given this dog such a marvelous new start in life!! You have no idea how refreshing it is for me to read stories from people like yourself.

Your dog appears to be suffering from a seizure disorder or some neurologically driven problem (perhaps the result of physical abuse.)  Temporal lobe seizures produce visual and auditory hallucinations (as reported in humans) and can produce (in dogs) extremely bizarre behaviors, both for short term and long term (after effects).  Your veterinarian sounds as terrific as you do, for not having vaccinated the dog while he was so underweight (which might have resulted in his death.)  Discuss this with your veterinarian and investigate finding a veterinary neurologist.  This sort of problem is quite difficult to diagnose, strictly because the dog can't TELL us what's happening, and without grand mal seizure (where it's obvious) it's quite difficult to determine cause.  Phenobarbital is one drug of choice to control seizure disorders and also has a calming effect; this is a benign substance if used correctly and, in short term trial, can't harm the dog (although it may somewhat affect personality.)  I suggest you also google canine epilepsy, starting with http://neuro.vetmed.ufl.edu/neuro/seizures/seizures.html

Even MRI or CT scan, both of which are extremely expensive (not to  mention frightening, requiring total sedation) may not give a definitive answer unless there is a glaring structural problem.  Spinal tap can be attempted to rule out disease.  Much luck with your dog, keep up the good work.  When he appears to be so affected and so long as he doesn't respond with aggression (out of fear), continue to offer him comfort by placing him nearby but don't make too big a deal out of this or you may be inadvertently rewarding his fear and anxiety.  Please repost with followup.