As a cat owner, it is likely that you don't think much about your cat's weight. If you take her to the vet for annual vaccinations and check-ups, the vet probably weights her then and notes it down. But if she is healthy it is unlikely that he will say anything about it. And most cats, once they reach maturity, manage to stay at almost exactly the same weight for most of their adult life. So why should it be important to weigh your cat? Well, as with humans, there are some medical conditions for which the first symptom is weight loss. And, again like humans, putting on weight is not so good either, since obesity can predispose to all sorts of complaints. Let us take a look at each of these in turn.

Weight Loss in Cats

There are many possible reasons for weight loss in cats. Older cats losing weight is relatively common, but it shouldn't be assumed to just be due to the cat getting old. It may well be a symptom of something more serious. Diabetes, Kidney disease, and hyperthyroidism all have weight loss as a symptom. For all of these there are likely to be other symptoms too, but this should not be assumed to be the case.

Your cat may go off her food, which will result in weight loss. Often owners do not notice if a cat is eating less, particularly in multi-cat households. Perhaps the cat turns up at mealtimes as usual, as cats are creatures of habit, but she hardly eats. This can have psychological causes, such as anxiety, stress, or depression. Situations that may have upset your cat include excessive noise, other animals in the feeding area, dirty food dishes, or proximity of the food dish to the litter tray. Your cat may also be reluctant to eat due to toothache, and since cats rarely complain, weight loss may be the only thing alerting you to the fact that your cat needs dental treatment.

There are a number of gastrointestinal conditions which cause weight loss, even if the cat is eating well. Other symptoms of these conditions may include diarrhoea, lack of appetite, and vomiting – but not necessarily. Common gastrointestinal problems that produce weight loss in cats include inflammatory bowel disease, food allergies, or certain infections.

Other reasons for weight loss include cancer and FIP, but thankfully these are rare.

Weight Gain in Cats

Weight gain in cats is most commonly due to the cat eating too much and/or not having enough exercise. But this is not always the case. There are a few medical conditions which cause a cat to gain weight. Pregnancy is one of them, so if your female cat has not been spayed, don't go putting her on a diet just because she is becoming pot bellied. She may be expecting kittens!

Apparent weight gain can also be due to fluid retention, which can occur with FIP, heart disease, and some other conditions. Some prescription drugs can also cause cats to gain weight.

Monitoring Your Cat's Weight

it should be clear from the above that it is a good idea to keep note of your cat's weight, perhaps more often than is possible with a yearly vet check. Of course, you can take your cat to the vet to get her weighed if you are concerned about weight loss or gain, and this is definitely a good idea. But it may be useful for the vet to know more about this weight change, such as when it occurred, how long it has been going on, and so on. You will only know the answers to this if you have been regularly weighing your cat at home. So can you do this? You certainly can, and it is a very good idea.

How and When To Weigh your Cat

Simply using your bathroom scales will not work, as they are not accurate enough. For instance, if a five kilo cat loses half a kilo, this is equivalent to ten per cent of its body weight, or about the same as a seventy kilo person losing seven kilos! You would certainly want to know about this, but it will hardly show up at all on your bathroom scales, and certainly not with any degree of precision. You need to get something more accurate for weighing your cat. It is possible to buy pet scales, but scales designed for weighing babies work very well, and they are not expensive. They are accurate enough, and usually large enough that you can persuade your cat to stand on them.

How often should you weigh your cat? It certainly isn't a good idea to do it too often, as for humans who are trying to lose or gain weight, since small fluctuations in weight always occur. Weighing your cat weekly is OK, or maybe fortnightly, but at least monthly. Keep a note of her weight, and see if it changes. Don't worry too much about changes of a hundred grams or so, but rapid weight loss or gain, or losses or gains that continue over a period, should be noted. Of course, if you know the reason and know what to do about it, that is fine. For instance, if your cat is steadily putting on weight but isn't seriously obese yet, giving her a little less food, or substituting 'light' food in place of her usual diet, or persuading her to have more exercise through play, may be all that is needed. If your cat is obviously losing weight due to stress, then try to find out the cause of the stress and eliminate it.

However, if the solution is not that obvious, then is the time to see the vet. It will help him significantly if you take along your weight chart so that he knows how long the weight loss or gain has been going on, and he can then identify the reason.

Hopefully the cause will be something simple, and the vet will be able to sort everything out. And you will be very thankful that you identified the problem early by regularly weighing your cat!