There is a bewildering choice of wet and dried cat food available on the market these days, although, as is the case with many of our grocery items, you usually get what you pay for in terms of quality. However, you need to decide which variety is best for your cat, wet or dry, and there are a number of factors to be taken into consideration for each, although sometimes when you acquire a new cat or kitten it may already be set in its eating habits. Sometimes cats just take a liking to one sort of food or the other - and nothing will shift them!
The first thing to remember about your cat is that he or she is a carnivore and needs a high proportion of muscle-based meats in their diet, just as they would have in the wild, as it contains the amino acid 'taurine' which is essential for their well-being. Cats should not be fed dog food (even though it may be tempting as it is frequently cheaper than cat food) as dogs are omnivorous and can break down and digest both vegetable and animal protein, unlike their feline companions.
When dried food (known as 'kibble' in the USA) was first launched many years ago, many thought it related to urinary problems in cats, and, in particular, painful urinary crystals in neutered male cats. It was also thought to be linked to chronic renal failure, inflammatory bowel disease and diabetes due to the low water content. Research showed that the urinary problems were linked specifically to a high magnesium content, and gradually the formulae of dried foods were modified to contain a much lower percentage of magnesium, which nowadays should be less than 230mg per average serving.
There is still a risk of diarrhoea related to the high starch and carbohydrate content, which can also be responsible for acute dehydration, especially as dried food has a moisture content of only 8-10%, compared to an average of 78% in wet food. Fresh water should always be available, especially so for cats who are fed a high proportion of dried food, and it is now widely accepted that cows' milk can cause stomach upsets. A cat fed entirely on dried food is far mote likely to become overweight than one fed solely on wet food, and is also quite likely to eat the food too quickly and then regurgitate it.
However, dried food does have a number of advantages. In the wild, cats live on the prey that they catch, such as birds and small rodents, and pulling fresh meat from the bones helps to prevent the build-up of plaque and tartar that can lead to dental disease. It is not wise to give bones to domestic cats as they can easily splinter, but dried food has the same effect and can help prevent dental problems, especially in breeds such as Siamese and Orientals that are particularly prone to this, and it also strengthens the jaw muscles. If you are out during the day and tend to leave food down when you leave the house, dried food will stay fresh during the day and will not attract flies, whereas wet food tends to dry out becoming rather unappealing to your cat, as well as having quite a pungent smell. Once you've opened a bag of dried food it will stay fresh for quite a while so long as you seal it up again, whereas wet food needs to be used up quite quickly once it's been opened, and cats never seem to find it so appetising if it's been stored in the fridge and is cold.
Wet food can be a lot more expensive than dried food, although there are a huge number of varieties to choose from so you can give your cat a more varied diet. It has a high water content so although your cat still needs access to fresh water, there is not the same risk of dehydration. It is also easier for pet food manufacturers to add the essential minerals that a cat needs into wet food, and if you are trying to add a supplement or medication prescribed by your vet, it is much simpler to hide it in wet food. Wet food also has a far higher percentage of the meat or fish protein that is essential to your cat's diet, without added carbohydrates to bulk it out.
Ideally, a choice of both wet and dry food will provide your cat with everything she needs in her diet, with wet food ensuring she taken sufficient water on board, and dry food helping to keep dental disease at bay. It is less wasteful to provide a bowl of each, rather than mixing them, so that when you come home, you don't need to waste any leftover dried food, which should be acceptable if it's left down for a bit longer.
Cats are very determined creatures, and you will not be able to persuade them to eat something they do not like, even if it is good for them! If you have just one cat, they can afford to be a bit fussier knowing that you will eventually provide the food they like best, but if they have one or more feline companions they will soon learn that what they don't eat at mealtimes will be enjoyed by the others, and that if all the food has gone, you will not necessarily notice straight away that one has not eaten. But you will still need to monitor the amount of food you leave out (based on the number, size and physical output of your cats), and they should not be allowed to overeat as, contrary to popular belief, cats can be quite greedy and can become obese.
Most cat food has quite a long 'use by' date provided it is kept sealed, and you should aim to buy the best quality wet and dried food you can afford - it's always worth looking out for bargains in your local pet store, and stocking up in bulk whilst it is at a lower price. You will also often find good bargains at the trade stands if you go to a cat show.