One may accustom an adult cat that gets one sort of food during the day to eat all the food in its cup during half an hour. For that one should take the cup away when the time is over. Beside this, a cat eats its food faster in presence of other cats. But for cats it's more natural to feed little by little several times a day, leaving a part of food for later and returning to it after some hours. If a food doesn't go bad because of heat or flies it is appropriate to leave it for a day if you like. Goods containing much water go bad quick, as a rule; dry fast food and half-dry one may leave easily, to make them accessible for a cat any time it likes.
To understand the matter on should carefully watch his cat. If you notice that a cat declines leavings of previous meal then it's better to feed it with smaller portions but more often.
Is it permissible to give a cat as much water as it wants?
In short - yes, you may do this if only a cat doesn't vomits.
Every time (except for rare physiological disorder), when cat drinks, it merely fills up the lack of water in the organism. If one to prohibit a cat to restore this shortage either it's a usual demand or a lack caused by disorder (diarrhea, vomit), its organism becomes dehydrated. A considerable shortage of water may lead to disorders (and even death) much quicker than a lack of any other nourishment component (fats, protein). That's why cat's cup for water must be always full.
An animal that is permanently thirsty suffers some disorder obviously and needs to be taken to a vet. In such case its organism loses water faster and is incapable to hold it, so that the cat urinates more than usually.
Often cats are unable to keep from urinating (during night, for instance) and begin asking to go out or go to their box. Some owners erroneously think that they can train their cat not to do this by limiting the amount of water. At that they fail to take into account the fact that such limitation prevents an animal to fill up considerable loss of water, which redoubles disorder. Every time when a cat begins to drink more water than usual, show it to a veterinary.
Take water away only when a cat begins to vomit. A vomit usually is evoked by an irritation of stomach walls, that throws it's contents out. Loss of water and salts during vomiting causes thirst. An animal is thirsty, but water coming inside the stomach provokes sequential vomiting. This may turn into a cyclic process: drinking water - vomiting, which results in serious dehydration and possibly coma.
That's why by sings of vomiting take water and food away for at least two hours. Then give it some water (cupful). If this will not cause vomiting, one may give one portion per hour. If vomit appears again, one should wait a bit longer (8-12 hours) and only then give a cat water and food. If at that time a cat will still be vomiting, take it to a vet.
Translated by Tatiana Karpova (Moscow)
(MSU, Biology faculture, Dep. zoology and ecology).