There is a lot of mixed reviews on certain pet food brands, one of the reasons being the level of salt, and by-products, fillers etc.
So I learnt today from someone on Petschannel.com that Royal Canin is high in salt level, whereas Science Diet is low in salt level. Hence Science Diet > Royal Canin.
I researched the AAFCO nutrition standards and found that cats need a minimum of 0.2% sodium and 0.3% chloride in their daily food intake. Our cat food (RC Fit 32) has 0.5% and 0.6% respectively. There is no prescribed maximum level at the moment.
I also found out that cats that are dehydrated from diarrhoea and vomitting, as well as cats with kidney stones and urinary tract infections are supposed to eat food with higher levels of salt. Dehydrated cats need salt replenishment, and UTI needs the pet to drink more water, which salt causes them to do.
The bad reviews about Science Diet (they are everywhere on the internet), is not so much about the salt level, but about the fillers. These fillers (corn etc.) are actually carbohydrates that the cat cannot process and therefore becomes fats on the cat. I guess that is why many cats that eat SD are usually obese. Cute, but obesity also causes health problems and shortens the cat’s life.
Sodium chloride toxicity is actually rare, and more likely to happen because of lack of fresh water, rather than unhealthy levels in pet food.
So in short – salt is okay in cat food, fillers make your cat fat if they are sedentary.
Want a cat that is muscle-heavy instead of fats-heavy? Feed meat, canned food, protein-rich grain-free dry diets.The current brand in the market that has the highest level of protein in their dry diets is Innova Evo. But that is expensive.
Ultimately, find a balance between your cat’s requirement, his preference, and your budget.