Obesity is a growing epedemic among the cat and dog population and has become the most common nutritional disorder seen in cats. Between 40-60% of cats living in the Australia, the UK and US are obese. That is a staggering number and frighteningly it the situation is getting worse.
A cat is considered to be overweight if his weight is 15% over his optimal weight, and he is obese if he is 30% above his optimal weight.
It's easy to ignore obesity because for the most part, an obese cat doesn't look or act sick, but this is a slow and insidious problem which over time has a detrimental to his overall health and quality of life.
When cats gain weight, the fat accumulates beneath the skin (subcutaneous fat) which is what most people think of, but there is another type of fat which can be found within the abdominal cavity, surrounding the organs such as the kidneys, pancreas and liver. This is known as visceral or intra-thoracic fat. What is known in humans is that it is the major culprit in many health problems associated with obesity. This type of fat is active and it is now believed to be an important endocrine organ. It releases pro-inflammatory chemicals and hormones which lead to inflammation, insulin resistance and even hunger. That's right, visceral fat can make you feel hungry.
Some cats have a small paunch at towards the back of their belly and just in front of their hind legs. This is not associated with obesity, it is known as the primordial pouch and is just a loose flap of skin (see image below).
What are the causes of obesity in cats?
The biggest factors associated with obesity in cats is overfeeding (particularly free-feeding and high carbohydrate diets) and not enough energy expenditure (calories in vs calories out). If the calories consumed exceed calories burned then the cat will put on weight.
Dry food has been seen as the holy grail of food for two decades now. There is some movement away from this belief, but dry food is still hugely popular. I am not saying we shouldn't feed any dry food, but is it as good for our cats as has been touted by pet food manufacturers and a number of veterinarians?
1) High carbohydrate food. The cat by nature requires a high protein diet and most dry foods are high in plant carbohydrates. Cats synthesize protein and fat to use as energy, carbohydrates are converted to fat. Have a look at the ingredients list on dry cat food, they are always listed in order of weight, with the first ingredient being the most abundant one. On dry food, this is often cereal based which is cheap compared to meat. Cats in the wild would obtain a tiny amount of grains and vegetables by eating the stomach content of their prey, but the bulk of their food came in the form of protein. More information on reading cat food labels can be found here.
2) Another disadvantage of dry diets is they are very calorie dense, with only 10% water content. Not only are cats getting excess calories, but they are not getting enough water (which is also filling). A diet in the wild (ie; small rodents or birds) would consist of up to 70% water. This can also have a serious health on their urinary tract health because many cats don't compensate for this lack of water in their diet by drinking more.
3) Dry diets are generally left out for cats to 'free feed' and while most cats won't scoff down their food in the same fashion as many dogs do, not all cats are going to self-moderate. It is very convenient for cat owners to put a scoop of dry food in the bowl and forget about it until it is empty.
4) Carbohydrates aren't as filling as protein, therefore it is much easier for cats to over eat.
I also have to wonder if a part of this is down to human behavior. Often people equate food to love and care. Are we quite literally over-loving our cats to death by our reluctance to say no? It may be as simple as giving them more food at meal times to make them happy, giving in to their cries for more food or sharing our snacks with our feline companions.
This may be a controversial one, but so many pet owners are keeping their cats indoors now for their own safety. However most pet owners don't compensate for this by ensuring indoor cats still remain active, with daily play sessions.
Certain medications can lead to weight gain in cats. Glucorticoids are the most common type of medication and can induce excessive hunger (known as polyphagia) in cats.
The thyroid gland is located in the neck and is responsible for producing thyroid hormone which regulates metabolism. Hypothyroidism is a rare disease in cats that is caused by an underactive thyroid gland.
Cushing's Disease (hyperadrenocorticism)
Caused by excessive production of the hormone cortisol in the adrenal gland, Cushing's disease can cause weight gain due to an increased appetite caused by excessive cortisol levels.
As the cat moves into his senior years his metabolic rate slows down, joints may become more painful and the senior cat will be less active. A slowed down metabolic rate and decrease in activity can both lead to obesity in cats if we don't modify their diet.
Just as with people, some cats are more genetically prone to putting on weight than other cats. This is more common in certain dog breeds (such as Cocker Spaniels and Labradors for example) than cats, but it still exists. Domestic shorthairs are the most commonly represented breed and it is believed that neutered males are affected more than females (see below).
I don't want anybody to avoid desexing their cat for fear of weight gain. The importance of spaying and neutering all non-breeding cats can not be over emphasised. Cats who have been desexed are slightly more prone to weight gain than entire cats due to a lower basal metabolic rate. However, this can easily be corrected by simply adjusting their diet accordingly just as we should with ageing cats. It should be remembered that while desexed cats may be more prone to weight gain, there are a number of health risks associated with not desexing such as testicular and mammary cancer.
What problems does obesity cause in cats?
Most pet owners just don't realise the serious health complications associated with obesity which is why it is not taken more seriously. Very few pet owners would knowingly allow something harmful happen to their cat.
- Diabetes - Insulin is a hormone produced by the pancreas, which is needed to transport glucose (from food) into the cells (I always think of insulin as a key to unlock a door to the cell allowing glucose to enter). Glucose is needed by the cells for energy, growth and repair. Obesity leads to 'insulin resistance' in which means glucose levels build up in the blood, but is not able to enter the cells, meaning they are unable to function as they should.
- Arthritis - Is a painful disorder of the joints where cartilage (the smooth coating at the ends of the joints which helps them glide over one another) wears down. Excess weight places undue strain on the joints which over time causes the smooth coating to wear away.
- Hepatic Lipidosis (fatty liver disease) - This is a painful and life threatening condition in which develops when a cat stops or greatly reduces his food intake. To make up for the shortfall, the body uses up stored fat, sending it to the liver to be processed. As the liver is not very good at processing fat, it quickly becomes overwhelmed affecting its ability to function properly.
- Exercise intolerance - The larger your cat becomes, the harder it is for him to exercise which then becomes a vicious cycle, as he exercises less, he is likely to put on even more weight.
- Skin problems - Obese cats are more prone to developing skin problems, a large cat may find it difficult to groom himself as effectively as a lighter cat.
- Greater risk during anaesthesia and surgery.
- Heart disease due to excessive weight placing extra strain on the heart.
Other less talked about health risks associated with obesity include certain cancers such as bladder, mammary and transitional cell carcinoma, reproductive disorders and urinary tract disease. Risk factors in obese dogs include greater risk of heatstroke, cardio respiratory disease, decreased immune function and high blood pressure. Certain medical tests are made more difficult in obese cats such as abdominal palpitation, ultrasound, . These should be considered as potential risk factors in cats too.
The good news is that if a cat is allowed to lose this weight, their health risks can either be greatly reduced or in some cases completely reversed.
How can I tell if my cat is obese?
It is always best to ask your veterinarian if he/she believes your cat is obese. Cats come in all shapes and sizes and therefore it is difficult to determine a standard weight which covers all cats and their differences. For example, a Singapura would be expected to weigh less than a Maine Coon.
However, a general guide to determining if your cat is overweight is the following:
Feel along the side of the cat. You should be able to feel the ribs, with a slight layer of fat covering them.
Stand above the cat, you should be able to see a waist, and have an hourglass figure.
There is a noticeable bulge on either side of the tail head.
What will my vet do?
Veterinarians are there to help your cat and you. If you are unsure that your cat is overweight, book an appointment with your veterinarian. They can guide and help you all the way.
Your veterinarian will perform a physical examination of your cat. He/she will also want to perform some blood tests to rule out a medical cause of obesity such as an underactive thyroid (hypothyroid) as well as evaluate your cat's overall health with standard tests including complete blood count, biochemical profile and urinalysis.
A physical examination will be performed to evaluate your cat's physical health including looking for signs of arthritis. Obesity can exacerbate the problem, making your cat even more inactive, which in turn leads to more weight gain.
How is obesity treated in cats?
Weight loss is something which requires close veterinary supervision. If it is done too quickly it can lead to hepatic lipidosis, which is life threatening. Therefore NEVER attempt a weight reduction diet on your own. A safe guide is 1 to 1.5% weight loss per week. You and your veterinarian will work closely to ensure weight loss is achieved safely. Regular check ins will be necessary.
- Increase exercise: There are plenty of interactive toys on the market which will encourage your cat to exercise. You should aim for 20-30 minutes of exercise a day, this can be split into two or three sessions. There are many types of cat toy on the market, buy a variety and try them all out on your cat. Some love to play fetch, others love to stalk and attack a wand toy. A favourite of my cats was Da Bird. I would recommend starting out with shorter exercise sessions but more frequently initially. Jackson Galaxy recommends working with your cat's hunt, kill, eat drive. A cat in the wild would stalk his prey, once caught he would kill and then eat it. Make your cat earn his dinner by mimicking what he would do in the wild. Allow him to stalk his prey (again, a wand toy is great for this), don't let him catch it immediately, but make him work for it. After his play session, feed him (if it's dinner time). This has so many benefits. It is time spent with your cat, it exercises his body as well as his mind and he earns his supper.
- Take your cat for a walk: Another option is to train your cat to walk on a harness so he can get outside and explore the world while getting some exercise. Some cats take to a harness well, other cats will have nothing to do with it. Follow your cat's lead (pardon the pun), and don't force the issue if he clearly hates it.
- Decrease caloric intake: There are prescription diets on the market specifically for cats, your veterinarian will be able to recommend the right diet for your cat. As discussed above, it is now well known that many dry foods contain excessive quantities of carbohydrates which can lead to obesity. So switching to either canned or raw food should be discussed with your veterinarian and it should be done gradually over several days. Cats can be extremely fussy when it comes to changes in their diet and if that happens, they can develop the potentially life threatening hepatic lipidosis.
- Give him food he has to work at eating. This will slow down the eating process and keep him occupied. Chicken wings or necks, cheap cuts of beef which have to be really gnawed on.
- Water only: Once weaned, cats have no nutritional requirement for milk. Overweight cats in particular should be provided with fresh, clean water, milk contains unnecessary calories.
- No treats: It's easy to slip the odd treat to your cat, but this needs to be stopped completely.
- Consider getting your cat a feline companion. Two cats are more likely to play than a cat on their own.
- Feed 3-4 smaller meals per day instead of filling the bowl and leaving it down for your cat to graze on.
If the cause is medical and not diet related, treating the condition should hopefully resolve the obesity.
Have one person in charge of feeding your cat, it's too easy for cats to double up on meals otherwise. Just this morning my cat who had already been fed by me tried hitting my son up for a second breakfast.
Once your cat has reached his target weight, maintain this by feeding a balanced diet which meets but does not exceed his calorific requirements. Remember, the older and less active the cat, the fewer calories he requires. As a general rule of thumb, I like to remove uneaten food after 20-30 minutes.
What is the prognosis for cats who have lost weight?
The prognosis is very good. A lot of cats have had their diabetes reversed when they have shifted down to a healthy weight, he greatly reduces his chances of developing hepatic lipidosis and skin problems should resolve.
Unfortunately, arthritis can not be reversed, however there is less pressure on the joints in lighter cats, therefore slowing down progression of the condition.