what is the difference between specialty cat foods at the grocery store or prescription

My cat is on  Purina Pro Plan Veterinary Diets UR St/Ox Urinary Formula Dry Cat Food and also wet food due to a crystal blockage that he experienced. The problem is the prescription food is extremely expensive and I have 3 cats so they all eat it  - Since they have always been free fed I just don't want to change that as it is convenient and they have been raised that way.  MY QUESTION  - Can I mix the store bought Purina Urinary Tract food with the Prescription Urinary Tract?   What is the difference?  They are both designed to do the same thing but the prescription food is 3 times the price -  I was wondering if mixing them would be o.k.?

Check the ingredients list to see if there's any differences. From what I've been told prescription foods tend to be exactly the same as their cheaper counterparts, but definitely look at what's in them to make sure.

Do you measure the PH in your cat's urine that had the crystals?  I would say if you DO, then try it and see if things stay in balance.  If they do, then you might even gradually decrease the amount of prescription food and keep checking the PH and eventually you might be able to go strictly to the non prescription food.  Wouldn't THAT be nice

Of course, you DO know that putting him on WET Purina Urinary Tract (or Dave's brand  has one too that I'm told is very affordable) is better than the dry, because cats prone to crystals need LOTS of water?  I converted 3 of my cats who'd been free fed kibble all their lives to scheduled wet meals.  It's not that hard.  We have articles than can help you if you'd like.

Not quite your question, but with allergy cats there can a difference between prescription and non-prescription limited ingredient diet foods. The prescription foods are more highly regulated, and you're more guaranteed to only be getting the proteins listed on the label. The non-prescription foods are often processed using the same equipment as other flavors, and there can be some residues from the last flavor made causing small amounts of other proteins to be in the food, so you could think you're doing an elimination diet when you're actually not.

The most important thing is to learn to read labels, pay attention to what's in the food, and know what an appropriate diet for a cat should be.  If you are working with a cat because of crystals, you should definitely get pH test sticks (super cheap on eBay) and monitor the urine pH.  In this case, the special food is about  CRYSTALS AND ALLERGIES, both. 

Here are the ingredients in your dry food (which costs $62.99 for a 16-lb bag through Chewy.com, usually the lowest prices available)

Purina Pro Plan Veterinary Diets UR St/Ox Urinary Formula Dry Cat Food:

Corn gluten meal, chicken, poultry by-product meal, brewers rice, oat fiber, wheat gluten, whole grain corn, animal fat preserved with mixed-tocopherols (form of Vitamin E), salt, animal liver flavor, phosphoric acid, dried egg product, calcium carbonate, potassium chloride, fish oil, choline chloride, taurine, zinc sulfate, Vitamin E supplement, ferrous sulfate, manganese sulfate, niacin, Vitamin A supplement, calcium pantothenate, thiamine mononitrate, copper sulfate, riboflavin supplement, Vitamin B-12 supplement, pyridoxine hydrochloride, folic acid, Vitamin D-3 supplement, calcium iodate, biotin, menadione sodium bisulfite complex (source of Vitamin K activity), sodium selenite

Consider the things a cat might be allergic to:  corn gluten, whole grain corn, wheat gluten.  Instead of the more natural DL-methionine, it uses phosphoric acid as a urinary acidifier.  I know of one person's cat already that got diarrhea on this food (I was cat sitting) and he recovered when put on plain Iams for his dry food (see below).  He also gets wet food, Fancy Feast, 2 cans a day, with water mixed in. 

IAMS[emoji]174[/emoji] ProActive Health[emoji]8482[/emoji] Adult Original with Chicken ($21.99 for a 22 lb. bag at Walmart; Grocery stores charge $19.99 for a 10.8 lb. bag)

Chicken, Chicken By-Product Meal, Corn Meal, Brewers Rice, Dried Beet Pulp, Natural Flavor, Poultry By-Product Meal, Dried Egg Product, Brewers Dried Yeast, Sodium Bisulfate, Potassium Chloride, Choline Chloride, Fish Oil (preserved with mixed Tocopherols, a source of Vitamin E), DL-Methionine, Calcium Carbonate, Fructooligosaccharides Vitamins (Vitamin E Supplement, Niacin, Ascorbic Acid, Vitamin A Acetate, Calcium Pantothenate, Biotin, Thiamine Mononitrate (source of vitamin B1), Pyridoxine Hydrochloride (source of vitamin B6), Vitamin B12 Supplement, Riboflavin Supplement (source of vitamin B2), Inositol, Vitamin D3 Supplement, Folic Acid), Taurine, Minerals (Zinc Oxide, Manganese Sulfate, Copper Sulfate, Potassium Iodide, Cobalt Carbonate), Chicken Fat (preserved with mixed Tocopherols, a source of Vitamin E), L-Carnitine, Rosemary Extract.

Still has corn meal and rice but no gluten and no wheat, and uses the DL-methionine (methionine is an essential amino acid found in meat) instead of the phosphoric acid, which is a mineral (nonorganic) acid. 

In MY opinion. the IAMS is a much better dry food, and in that cat's digestive system, it agreed and started producing normal tootsie rolls in the litter box.

How would you monitor urine pH if you're using clay clumping litter? Is it possible? Or do you have to use the little nonabsorbent beads and get a non-clumped urine sample?

http://www.ebay.com/itm/Laboratory-...998788?hash=item2a461e0484:g:pDoAAOSwirZTxOdv

You can get strips for $5 for about 360 of them.  If your cat is like mine, he will gladly pee in a number of non=box places given the chance -- a puppy pad left in a litterbox for instance, or a litter box with just neutral white playbox sand in it (it doesn't soak up the urine even when it gets wet), or the one I had with problems was more than willing to pee in the bathtub whenever I let her in the bathroom.  When she was sick, she would pee just anywhere and everywhere, but as she got better, she was also willing to pee in empty litter boxes, so I would always leave one box with sand, one box with a pee pad, and one empty box and she would use one or the other. My friend has a male and it's even easier, she just waits for him to pee and then picks him up and taps the pH stick against him before he has a chance to wash.  It only takes a drop.

When my cat was sick, he would always pee on the floor right in front of me to let me know there was a problem.  She got over that, but she will still go beside the box if she considers it too dirty (i.e. if it has not been dug since the last cat pooped in it) so I had plenty of opportunity to monitor her pH as she was recovering.  She has had NO recurrences in the nine months since then, and I'm sure she would let me know if there was any problem at all by just squatting wherever she was and peeing. 

Also, I have not used it but I see there is also a litter now that monitors urine pH, so if you had just one cat, or wanted to put your cat in a room wit this litter until he peed once daily, that would be a ossibility too.  You can get it at Chewy.com

https://www.chewy.com/simple-soluti...5jiNZjD3m7bGOaSdtBCjlg3dZCal8Y0DO7RoCjqnw_wcB

Here is another brand on the market as well:

http://www.entirelypets.com/perfect...S0CsmZKOT4BaVcUuj2LgJbOLjqS5vFw8VYxoCr6rw_wcB

samus said:

How would you monitor urine pH if you're using clay clumping litter? Is it possible? Or do you have to use the little nonabsorbent beads and get a non-clumped urine sample?

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If the cat will let you, stick a long handled soup ladel or other similar kitchen utensil or a small plastic cup under the cat's tail to catch the pee. If your cat always pees in the same spot in the litter box, try semi-burying a plastic cup in that spot to catch the pee. This won't work if your cat likes to dig to the end of the Earth after peeing unless you remove the cup right away.

Clean fish / aqiarum tank gravel / pebbles will also work. Use a brand new litter box (litter residue from the existintg box will contaminte the urine and affect the test reading) and put in a layer of the gravel / pebbles. After the cat pees, tip the box to pool the urine into a corner and stick the test strip into that.