A: You should be very concerned now. In general, cats not eating for 24 hours, or those consuming less than 50 percent of their normal intake for more than 2-3 days, are of concern to me. As in many things, cats have to be different than humans or dogs. Because cats are true obligate carnivores who were designed to have multiple small meals of birds and rodents, their livers are designed to metabolize high levels of protein all the time. When cats don't eat for a few days, or when they are not taking in enough calories over a period of time, they try to use their fat stores for energy needs and the fat can overwhelm the liver's capacity to metabolize it, clogging up the cells and causing the liver to fail.
If you notice that your cat hasn't eaten for 24 hours or your cat's appetite has been significantly decreased for 2-3 days, it is important to bring your cat in for us to examine and see if we can determine why they aren't eating. We will also need to start nutritional support to prevent fatty liver failure (hepatic lipidosis). Depending upon your cat's condition and length of time not eating, this may involve starting on an appetite stimulant, syringe feeding, or placement of a feeding tube.
Wait! Before you say you would never have a feeding tube placed in your cat because you have seen people have their lives unnecessarily prolonged with extraordinary measures, you need to know that for cats, a feeding tube is a temporary life saver. Many cats are not amenable to being syringe-fed when they are not eating on their own and the process of syringe feeding can create a condition known as food aversion-where just the smell of food can make them drool, become nauseous, and prolong the anorexia. There are several types of feeding tubes and many are well tolerated by the cat. Many of these tubes can be used not for only administering their food but also their medications (which can be a wonderful added benefit for their owners!). Once the cat is eating well on its own, the tube can be removed.
Cats can stop eating for many different reasons. It is one of the few signs that cats will give you that something is wrong (please refer to the Topics of Interest page on this website). Cats are designed to be very stoic animals and they maintain a facade of normalcy for as long as possible. Bloodwork, x-rays, and possibly other tests such as abdominal ultrasound may be needed to determine why a cat is not eating. Sometimes the reason for the initial anorexia cannot be found but they still need to be nutritionally supported until they start eating again - this may be as few as 1-2 days or it could be several weeks.
