The Burns Chicken & Rice and Duck & Rice are both low in sodium (0.13%), Potassium (0.35%) and Magnesium (0.10%). There are no flavourings added (salt is commonly added to many of the cereal based foods to add some flavour!) and therefore these Burns foods could be used in place of the expensive HILLS H/D or ROYAL CANIN "Early Cardiac" (Sodium 0.13%, Potassium 0.80%, Magnesium 0.15%).
Of course it is also necessary to control the weight - the Burns has 8% fat whereas the Royal Canin has 20%.

See the Burns Alternative Selector