My male cat had just a little operation to remove a 'crystal' which blocked him from peeing. After that the vet nurse advised me to strictly cut any food apart from certain Virbac dry food brand which they sold me and by the way was 10x more expensive than usual cat food.

I asked her if it is OK to feed the cat with human grade poultry or fish, but she said no, only the 'tried and tested' brand.

I am not convinced that my cat is doomed to eat only that sort of food for the rest of his life. So I'm wondering what is the best diet for cats in this situation? Which foods are allowed and which are forbidden?


2 Answers 2


The answer is it depends. And there is not even consensus among veterinarians about what diet is best for this situation. It depends on the cause of the urethral obstruction – if it was struvite crystals or stone, or a calcium oxalate stone, or a mucus plug causing the obstruction. It depends on chemical analysis of the human grade fish you would like to feed.

Struvite crystals may be fairly easily manageable with diet. Calcium oxalate, much less so. Cats with an obstruction caused by other causes may not benefit from any particular diet formulated for "crystals".

The urinary diets are, in my opinion, the safest bet. They are restricted in magnesium and phosphorus, which are the components of struvite crystals (also known as magnesium ammonium phosphate). They are also calcium restricted to prevent calcium oxalate stones. The goal is a 'neutral' urine pH which is not prone to struvites (which form in alkaline urine) nor oxalates (which form in acidic urine).

Your location will dictate which urinary diets are available - but there are a number of brands available, and you may be able to order other brands online if they are not available at your vets. These diets are more expensive than normal cat foods, and do usually require a prescription.

The most important thing, in my opinion, is keeping the urine as dilute as possible. Crystals form because the urine is supersaturated in the components that form those crystals. If the urine is kept more dilute, then the crystals will less easily form. The best way to promote dilute urine production is with increased water intake. Dry cat food has very little water, so is much less preferable in this regard. Putting urethral obstruction cats on a predominantly or even solely wet food diet can help to promote a more dilute urine environment. Also offer plenty of water sources, perhaps a water fountain if your cat is amenable.

If you would prefer to avoid the urinary diets, then please speak to a veterinary nutritionist who can formulate a balanced home-cooked diet that is suitable for prevention of lower urinary tract disease. There are so many home-prepared diets that are not balanced for cats' nutritional needs.

At the end of the day, there is only so much we can control in urethral obstruction patients. But diet is one of the things we can easily control, and does seem to play a major role. I often see several urethral obstruction patients in a week, and in my experience it is uncommon to have an obstruction in a cat that has already for some time been on a strict urinary diet. So in that respect, these diets do seem to really help.

  • Thanks for the tips. What's your opinion on feeding such cats with raw turkey or chicken?
    – Karlom
    Commented Sep 25, 2020 at 5:36
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    @Karlom There is no evidence in support of raw diets. There are significant concerns about high bacterial loads in these raw foods, some pathogens which are zoonotic (transmissible to people). From a urethral obstruction point of view, I cannot say, I am not aware of any study that looks specifically at raw poultry and feline lower urinary tract disease.
    – Harry V.
    Commented Sep 25, 2020 at 5:55
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    @Karlom Concerning the raw poultry diet, please have a look at these question with very comprehensive answers: How to make my own BARF food (for a cat) and Is it possible to feed a cat a healthy meat diet?
    – Elmy
    Commented Sep 25, 2020 at 11:57
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    I have a cat that has been on a 50/50 diet for over a decade after surgery to remove UT crystals: urinary diet food in the morning, and ordinary cat food in the evening. It has worked well for him, and mixing has kept the food costs lower than 100% urinary diet. We also try to entice him to drink more water (including all meals being wet food).
    – Upper_Case
    Commented Sep 25, 2020 at 14:12
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    @HarryV. There is no evidence in support of raw diets perhaps because there is no money to be made for big corporations to conduct such studies. To my mind, it is silly to try to fix a problem that is caused by artificial food, by appealing to yet another artificial food.
    – Karlom
    Commented Sep 25, 2020 at 15:11

I have a cat with a similar complaint to yours and we feed him either:

  • Hill's Prescription Diet Feline c/d Urinary Stress
  • Royal Canin Urinary S/O Moderate Calorie Adult Dry Cat Food

I am not sure if it is permitted to link to sites where I purchase this but buying larger 8kg bags of the dry food work out quite affordable to most reasoanble quality cat food brands.

If we allow him to eat standard dry cat food in any significant amount or for a sustained period of time he always gets minor to sevear problems again. Recently he managed to sneak a load of the standard cat food and ended up going in for surgery for the first time in years. We were very lucky to catch him in time.

The key things in these specialised foods seem to be: lower salt and sugar levels, something to premote more frequent urination and for us especially the "anti-stress" which seems to have some calming medication.

We did find that sourcing the food online was much cheaper than purchasing it directly from a vet or buying from a local pet shop.

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