Cat on Elavil for frequent urination

Question
One morning 2 months ago, my 9-year old male mixed-breed cat presented with frequent urination and straining (producing a dime-sized amount of urine), and urinated outside of his litter box. We immediately took him to the vet, where x-ray and urinalysis confirmed a bladder stone (calcium oxalate) and urinary tract infection. One month later, following 17 days of baytril and a change in his food to Hill's prescription diet (c/d), both the stone and the UTI had disappeared.  However, because the cat was still urinating frequently (4-5 times in a 2-3 hr period), our vet put the cat on Elavil (amitriptyline). He said that there were still inflammatory cells present in the urine (confirmed by urine cytology), and that this anti-anxiety med would help.

My cat was taking 5mg/day of Elavil daily for a week and a half. Things were fine for the first week. The frequent urination stopped, and the cat urinated once per a 6-8 hr period. A repeat urine cytology test showed no inflammatory cells. The vet told us to continue giving him the Elavil for another week, but across the next several days, the cat went from peeing once every 8 hrs to once every 12 hrs (with a HUGE amount of urine coming out), to once every 17hrs (even more urine), and he even lasted for a 21-hr stretch without urinating (I was shocked his bladder did not explode!). I called the vet again and asked if we could stop the medicine, and the vet said no -- to continue giving him 5mg but *every other day* for 1 week, and see what that would do. During this period, the cat urinated once per 5-6 hours on NON-pill days, and once per 11-12 hrs on pill days. The vet said to continue this dosing schedule for 2 more weeks. Across those 2 weeks (and this finally brings us to present day), my cat was urinating every 6-9 hrs on NON-pill days, and every 12-15 hours on pill days. I think this shows some improvement from previously, and think that urinating every 6-9 hrs is not so bad for a cat that consumes canned food and drinks a couple of times a day...  But after talking to the vet today, he said that the cat is still urinating too frequently (I did not think 3-4 times per 24-hr period is too frequent at all?), and the vet suggested that we move him back to the 5mg per day DAILY regimen of dosing.....

This makes absolutely no sense to me, because on the daily 5mg/day regimen, the cat was retaining urine for up to 21 hrs -- and it occurs to me that this is the opposite of what you would want in a cat that had a UTI not so long ago....  But the vet insisted that the cat should be kept on Elavil daily for probably the next few months, and perhaps for the rest of his life...! He insisted that there are no side-effects to the long-term use of this drug, but I have read that liver damage can be one long-term effect of Elavil use. My question is what to do at this point. I don't agree with the vet, but I also don't know whether to keep the same dosing schedule we've been using (5mg/day every other day), or if I should to try to decrease it to 2.5 mg/day or 2.5mg every other day and re-evaluate his frequency of urination... I definitely don't want to go backwards, and I want to do what's best for my cat. Thanks for any advice that you can give.

Answer
I am as confused as you are Janet. I am not a vet, but I do have a dog on this drug since she has some anxiety when I am not home (she is 11).
I know it works sometimes for cats that like to urinate on everything, but I have never heard of it being used for a cat that has had an UTI.

This flies in the face of all the research which is to make them go, go, go as much as possible to keep the bladder cleaned out of bacteria and any sediments that can form.
You want your cat to urinate often and as much as he has to go. Wet food is given or added to help encourage this. I understand the worry of inflammation, but if the tests show that the inflammatory cells are gone, then the maintenance program is to keep the urination often during the day.

Now of course you don't want him urinating 3-4 times in 2-3 hour period. That would indicate some burning still and that isn't good. I would try to give a half pill every other day at this point and see how he does. He should never have to hold his urine more than 5 hours or so. I have read that any more than that is what causes this buildup and can start the whole infection over again.

Now I am not a vet, so you might want to re-post to a vet on here or you might want to ask the vet Peter Knapp, that runs the e-vet group on yahoo.com.
I would copy and paste your whole question to him.

Just remember that all vets are not always correct all of the time. I would definitely seek another opinion. Mine is just advice as I cannot diagnose.
I think you are correct and on the right mode of thinking by dividing the pill for a daily or every other day dose, but I really would like you to re-post this.

I am very interested in what the other vets have to say, so please let me know what you find out. I will do some research myself and let you know what I find out.