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Difficult Diabetic Cat – Could Acromegaly Be To Blame?

I know, it’s kind of a funny sounding word. But if you have a diabetic cat that your vet just can’t seem to stabilise, it’s definitely not a laughing matter. Acromegaly has recently been found to affect up to a quarter of diabetic cats in the UK, many more than previously thought, so it’s worth talking about. It’s also probably underdiagnosed, which means your vet may not think to look for it, so if you’ve been told that your cat’s diabetes is particularly difficult to control, read on! What is acromegaly? The name acromegaly actually comes from human medicine, because in people, it causes abnormally large hands, feet and facial features. Although you can see similar signs in cats (a broad face with a protruding lower jaw and larger than normal feet), it’s much less common so another term you may see used is ‘hypersomatotropism’ which literally means an excessive production of growth hormone. It’s caused by a benign (ie, unlikely to spread to other tissues) tumour on the tiny pituitary gland, situated at the base of the brain. The pituitary gland secretes lots of useful hormones that control all sorts of functions in the body, but in this case it’s growth hormone produced in huge quantities by the growing tumour that causes the problem. The majority of affected cats are males unlike in dogs, where acromegaly is usually caused by changes in the mammary gland and is therefore seen almost exclusively in females that haven’t been spayed. What’s the connection between acromegaly and diabetes? Too much growth hormone floating around the body decreases its sensitivity to insulin, which is the hormone that controls sugar metabolism. If the body doesn’t respond very well to insulin, the blood sugar gets too high and the cat becomes diabetic. This causes the typical diabetic clinical signs of drinking a lot and urinating a lot, along with a greater than average appetite. Despite the big appetite, a normal diabetic cat will often lose weight until their disease is controlled. However due to the other effects of growth hormone, cats with concurrent diabetes and acromegaly tend to gain weight even if their diabetes isn’t well controlled. And because the acromegaly makes insulin less effective, it often takes huge doses of insulin injections to bring the diabetes under control (some normal cats can be controlled on 1-2 units of insulin twice a day, while cats with concurrent acromegaly may require up to 35 units twice a day!). Even with that much insulin, they may never be well-controlled and are much more likely to suffer from frequent episodes of ketoacidosis, a dangerous condition that occurs when the body is simply overwhelmed by too much blood sugar. What are some of the other signs of acromegaly? In addition to the effects on sugar metabolism mentioned above, excessive growth hormone also causes a rise in something called insulin-like growth factor-1 (IGF-1). This IGF-1 causes excessive tissue growth, not just in the face and feet mentioned above, but also in internal tissues such as the throat (causing breathing problems) and the heart (causing a murmur). It may also cause the internal abdominal organs to feel bigger on the vet’s exam but this can be really difficult to detect. Cats with acromegaly also seem prone to high blood pressure, and rarely, the tumour itself can grow so large that it causes changes in behaviour or other neurological signs. Interestingly, it can also affect the joints so arthritis symptoms can be seen. Sadly, the effects on the heart can sometimes be so severe that the cat develops congestive heart failure. How is it diagnosed? Despite the fact that acromegaly is quite common in cats, there is currently no simple test to prove that a cat has the disease. Your vet may start to suspect it if your cat is gaining weight despite the fact that their blood sugar is not under control, or if your cat requires larger than average doses of insulin to stabilise. If acromegaly is suspected, there is a blood test for the IGF-1 peptide, however the results of this test can be misleading especially in the early stages of the disease. A more expensive and complicated but perhaps more accurate test would be a CT or MRI scan of the brain, which may be able to show the tumour on the pituitary gland directly, but even this isn’t a perfect test. It is important to try to distinguish between acromegaly and another condition called hyperadrenocorticism which can have similar symptoms and even look the same on a scan. How do you treat it? So diagnosing acromegaly is difficult, and unfortunately treating it isn’t any easier. Because it’s caused by a tumour, the choices are the same as many other tumours and include an intensive (and expensive) course of radiotherapy or specialist (ie, also expensive) surgery to remove the tumour itself. With treatment, the tumour can shrink and the diabetes itself can even resolve, along with preventing some of the other common side effects of the disease. However there isn’t currently any way of predicting how well a particular cat will respond to treatment or for how long the recovery will last. If no treatment for the pituitary tumour is given, the only other option is to continue treating the resulting diabetes as best as you can, with large doses of insulin and frequent check-ups with the vet to discuss progress and quality of life, similar to cats that were never diagnosed in the first place. But it’s worth finding out if your cat has the disease, as you’ll be more prepared to diagnose and treat the other side effects such as joint pain, high blood pressure and heart disease. Cats with concurrent acromegaly and diabetes don’t tend to respond as well to routine treatment and may be euthanized sooner as a result, although some cats may do well despite their disease. Because we have only recently realised how common the condition is, new testing and treatments are being developed as we speak and hopefully our options will improve as time goes on. If your diabetic cat isn’t responding well to their treatment and you think they may have acromegaly, you should speak with your vet about it, bearing in mind that many of us don’t know much about the condition because it used to be considered so rare. Diagnosis and treatment aren’t easy, but they are possible and could potentially result in a happier, healthier cat. Hopefully a few years from now the story will have an even happier ending!

Sammy’s Story – Feline Diabetes Isn’t As Scary As It Sounds!

Sammy catSammy is a lovely, and much loved, 13 year old moggie who has always been the picture of health. Healthy appetite, healthy weight and body condition – and he seemed pretty happy too. But a few months ago his owner noticed him at the water bowl more than she used to. At first she didn’t think anything of it, but with the extra drinking came extra urination, and it also seemed to be associated with an increase in appetite. But still she assumed that this was normal as the weather was getting colder and he was spending more time inside. However, at his next annual check-up with me, we found out that he had actually lost almost a pound in the past year. I recommended a blood and urine test and his owner agreed, and when the results came back the answer was clear – Sammy was diabetic. His owner was in tears. How could she possibly cope with a diabetic cat? She works full time and has two small children, and besides, she has no medical training so how on earth would she be able to give an insulin injection twice a day? She even thought about having him put to sleep because she simply wasn’t going to be able to handle his condition. But we had a nice long chat about what it means to be diabetic and what the treatment would and wouldn’t entail, and by the end of the conversation she was willing to give it a try. What is diabetes? This gets a bit complicated, but I’ll do my best to explain it. Sugar in the blood (also called glucose) is a very important source of energy for the body and without it the body’s organs (particularly the brain) run out of fuel and start to shut down resulting in lethargy, confusion, fits, coma and even death. Too much of it however can also be harmful and diabetes is a condition that results in the cat’s blood sugar being too high. Most of the time this is because the body doesn’t produce enough insulin, the hormone responsible for lowering and stabilising blood sugar. High blood sugar in turn results in lots of very sugary urine which leads to more frequent urination, and the increased urination causes increased thirst and drinking. A lack of insulin also means that the body’s cells can’t use the glucose, even if there’s lots of it in the blood, so the body starts to break down other tissues such as fat and protein for energy. This then causes weight loss, but also an increase in appetite as the body tries to compensate. Therefore, the four most common symptoms of diabetes are: Amber drinking 1. Drinking more than normal 2. Urinating more than normal 3. Eating more than normal 4. Weight loss Diabetes is not the only disease that causes these symptoms, but if all four come together, it puts diabetes at the top of the list. How is diabetes diagnosed? Diagnosing diabetes sounds like it should be pretty easy – if a cat has high blood sugar, it has diabetes, right? Not quite. Cats can have high blood sugar for a couple of different reasons, the most common being stress. And what cat isn’t stressed by the time it gets to the vet, let alone has its blood taken for testing? It is therefore important for your vet to make sure that it isn’t just stress causing the high blood sugar. One of the easiest ways to do this is to test the urine for sugar as well – if there is sugar in the urine, chances are the cat is truly diabetic but this still isn’t a perfect test. If your vet suspects that your cat may have diabetes, a second blood test will typically be run. This could either be, depending on your vet’s personal preference, a single test called fructosamine, or a series of glucose measurements over several hours called a glucose curve. Fructosamine measures the average amount of glucose in the blood over the past 2 weeks (thus making it a more accurate test than a single glucose measurement) whilst a glucose curve measures both the highest and the lowest blood sugar levels on a curve over the course of a day. Both tests are used commonly and both can help the vet diagnose and treat diabetes. And now the scary bit – how is diabetes treated? Because diabetes usually means the body doesn’t make enough insulin, the best way to treat diabetes is to give the body more insulin. This may sound easy, but unfortunately insulin can only be given by injection with a needle under the skin. And it has to be given every day, usually twice a day, at about the same time each day so a regular routine is essential. The good news is that the needles are very very small, and so is the volume that needs to be injected. Therefore most of the time the cat doesn’t even seem to notice, especially once they get used to the process. The bigger concern for the cat is having to go into the vet periodically for check-ups and blood tests to see how their body is coping with the treatment, but even that isn’t too bad and once their condition is stabilised these checks can often be done less often. Another thing that may help is a change of diet to something that is high in protein and low in carbohydrates (the nutrient that gets broken down into glucose after digestion). It is important to monitor your cat’s diet when they are on insulin, as if they do not eat regularly, the insulin could actually hurt them. Similarly, weight loss can help the body better regulate its glucose metabolism so losing excess weight in a controlled manner could make a big difference to their treatment and in some cases may even result in the disease resolving completely. If your cat is diagnosed with diabetes treatment is essential. It is not generally acceptable to allow the disease to go untreated as it can cause significant discomfort and severe problems for the cat. With insulin therapy, a well-managed diabetic cat can go on to live many healthy, happy years. Insulin, however, is not without risks itself, as giving too much of it can result in a condition called hypoglycaemia, or blood sugar that is too low. As mentioned above, this is a life threatening condition that can result in lethargy, confusion, fits, coma and even death. You should speak with your vet about what symptoms to look out for and how best to manage them should they arise and it’s very important that you let your vet know immediately if you think your cat may be hypoglycaemic. I am happy to say that both Sammy and his owner are doing very well today. His owner gives him two injections a day, which she has fit into the family routine and no longer sees it as a bother, just something else that has to be done. She has even offered to speak with other owners of newly-diagnosed diabetic cats to give them the confidence they need to get through the initial diagnosis and first few weeks of treatment. So if you find yourself with a diabetic cat, don’t be discouraged, it’s not actually that scary and yes, you can do it! If you are worried that your cat is showing the symptoms described above, please talk to your vet or try our Interactive Cat Symptom Guide to help decide what to do next.
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