Tuesday, August 3, 2010

To be Fit as a Fiddle, a Cat Has to ....

OK, there it is, right in the title, my homage to Fellini. Not that the oblique film reference has anything to do with today's topic, I'm just trying to show that I am a multi dimensional kind of guy. The first person to identify the reference and leave it in a comment will win ..... My undying respect for your film knowledge. I mean come on, I gave you the artist, you should be able to figure this one out.

But on to our first topic in nutritional therapy, feline lower urinary tract disease. (maybe we should have stayed with Italian films). Back in the dark ages, when I graduated from vet school, (go Penn class of '84), we used to see a lot of cats with signs of lower urinary tract disease. You know, increased frequency of urination, perhaps some blood or straining in the litter box with little urine produced. In male cats it would frequently get bad enough that they would block and be unable to urinate at all, necessitating surgical intervention of some sort. Ultra sound was not readily available, so we assumed that these cats had infections and gave them antibiotics and made some diet recommendations (at the time Hills Prescription Diet C/D was all that was really available) and lo and behold, most of these cats got better. Logic, incorrect as it might have been, dictated that there was an infection that the antibiotics cured. Current theory was that the ph of the urine (measure of acidity calculated by the inverse of the negative log in base 10 of the hydrogen ion concentration, but now I am just showing off) was too high so we added acidifiers to the diet as well.

Theories came and went over the next few years, but the antibiotics stayed. In that time we thought it was the ash content of the diet, the magnesium content of the diet, the ph of the urine, and people even thought that urinary disease in cats was related to the phase of the moon. What did change, is that we started to culture some of these cats' urine and we found, you guessed it, no infection. So what was going on? We had made the urine acid, we had given antibiotics, but then after really screwing up the urine of these felines, we started to do some imaging. First was x rays. It's hard to see in this photo, (and I don't know how to put arrows in these yet but hey, I'm an old dog learning new tricks.)

The bladder is to the left of the bones and to the right of the black gas. If you look carefully, you can see a line of small white stones. This is what we started to see on a certain percentage of our bladder x rays. Stones are made of minerals so they show up white. Most are struvite (phosphate) or calcium oxylate stones. It is hard to tell which are which on radio graphs, you need to take them out and send them off for analysis. The thing is, a lot of cats had urinary tract signs, negative cultures, and no stones on radio graphs. Enter the ultrasound machine. Now, some people can read ultrasounds with no problem. I on the other hand have difficulty. So, I have a doctor that does imaging come to our practice to do our studies. And what he finds in many cases, is simply a thickening of the bladder wall. No infection, no stones, no nothing.

These are cases of sterile interstitial cystitis. A potentially serious inflammation of the bladder that causes all of the signs that we see. Sometimes it is self limiting and usually episodic. That explains why so many cases get better after a week of antibiotics. They would have gotten better even without antibiotics. Some do not resolve so quickly and others are real bears to manage. They require constant dietary manipulation and medication just to keep the disease under control.

So what do we do to manage feline lower urinary tract disease? Well if we find an infection, antibiotics are still the answer. If we find stones, we take them out. Here are the stones from the cat in the above radiograph. Easier to see now that they aren't in the cat.
We will send these off to the lab and once we know what type of stones they are, then we will make long term management recommendations. The tough cats are the ones with the sterile cystitis (SC). These get a combination of pain medications, anti inflammatory medications and even some anti anxiety medications. But the only thing that seems to have any science behind it is dietary manipulation. Now, anicdotally, colleagues of mine in feline only practices have told me that they have significantly reduced the incidence of FLUTD (feline lower urinary tract disease) in their patients simply by having all of their clients feed canned food. It seems that the increased moisture may play a roll. Cats are notoriously poor drinkers so it does make sense that a more dilute urine brought on by increased water intake might help with irritants in the bladder. There are actually studies showing that feeding canned SO a diet made by Royal Canin actually has been demonstrated to decrease the signs of FLUTD in cats. It will also dissolve those pesky struvite stones and prevent new calcium oxylate stones from forming. It is our go to diet for most of our cats with FLUTD. There are some issues tho, it is high in salt which can be a problem if cats have marginal kidney function.

Another choice is a Diet made by Hills. Remember the C/D I mentioned earlier? Come on, pay attention. Well it has been reformulated. It is designed to dissolve struvite stones in the dry form, so it probably will in the canned form as well. The canned formulation is lower in salt than the Royal Canin diet and we are going to start using this a bit more for our cats with SC.

So we have come a long way from just popping our feline friends with antibiotics every time they strain to urinate. And, we have done far fewer urethrostomy surgeries on blocked male cats, which is a good thing. We can control and treat many cases of FLUTD in cats with diet and common sense. Talk to your veterinarian for dietary recommendations and don't forget to let me know if you figure out the reference at the beginning of this post.

I didn't forget about dogs, they are just entirely different beasts and I will post about them next time.

1 comment:

Keith Niesenbaum, VMD said...

Here is the citation from Veterinary Theraputics, 2006. It shows that cats on a high sodium diet had more kidney problems than ats on a low sodium diet.

Special thanks to jessica Wolf of Hills for getting me the article.

Effects of Sodium Chloride on
Selected Parameters in Cats*
Claudia A. Kirk, DVM, PhDa
Dennis E. Jewell, PhDb
Stephen R. Lowry, PhDb
aDepartment of Small Animal Clinical Sciences
C247 Veterinary Teaching Hospital
College of Veterinary Medicine
The University of Tennessee
Knoxville, TN 37996-4544
bScience and Technology Center
Hill’s Pet Nutrition, Inc.
PO Box 1658
Topeka, KS 66601-1658