Hi C4C,
Glad to hear that your cat is doing better. What a scary incident that you sure don’t want to repeat.
I’ve come to view urinary blockages as a multi factorial problem. Sometimes blockages are composed of mucoid matrix without any crystals, so be cautious on not having tunnel vision in regards to struvite. You can find good information on OSU indoor pet site which used to be indoor cat initiative.
The old adage “the solution to pollution is dilution” applies here. Crystal formation is a factor not only of pH but concentration of components that make up the crystal. Because pH can fluctuate throughout the day I think striving for a dilute urine is as important if not more important along with watching mineral content of the diet. I’d be willing to sacrifice a bit in the pH department to get a dilute urine. Moist foods can help along with extra water mixed into the food, flavored water “treats” providing multiple water sources and knowing what your cat likes. Some cat like “staler” water and others absolutely fresh!
pH varies with dietary factors, management factors and likely individual cat factors. Evaluating what goes in is important but I think close monitoring of what comes out is even more important. Veterinary diets are formulated to hit certain pH and concentration milestones. Some of the veterinary diets rely on salt to drive thirst. But I don’t think this “guarantees” that when fed to “your” cat the appropriate pH and concentration are achieved. Investing in a pH meter and refractometer to test urine at home is a good investment.
How often the cat eats also plays a role in urine pH. After eating the urine will become basic due to what is called the “alkaline tide”. This is noted in the cat more so than in the dog. The generation of HCL in the stomach releases bicarb in the blood which alkalizes the urine. Multiple 4-6 small meals a day are preferable to 1 or 2. I can see that there could be a bit of a trade off here. With a dry diet the cat is free to and often does eat multiple small meals a day with moist diet the food can’t be left out for hours and people usually don’t feed 4-6 times a day. If this results in the cat eating a larger amount less often the alkaline tide could result in a higher urine pH for many hours during the day despite a diet that would be otherwise be acidifying.
I personally don’t think the answer to struvite and urinary blockages can be found solely in added methionine to a diet without looking at the entire picture. Methionine is metabolized in the body and the sulfur excreted as sulfuric acid hence it is acidifying to the urine. But since minerals in the diet and feeding practices also influence pH I don’t think all the eggs should be put in one basket per say. Methionine can cause GI upset, and hemolytic anemia( large doses).
If you can achieve a dilute mildly acidic urine by adding methionine to a base diet that otherwise wasn’t reaching those parameters than great but be open to finding what works in your cat.
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