Diabetes with other disorders in Cats


Diabetic cat with possible hyperthyroidism

Question: Baron is a 20+ domestic Short hair who weighs about 18 lbs, has had diabetes the past 4 years. He is on 5 units of insulin twice daily and seems to be doing quite well. Last curve was a little high @ 340/191/ 266. 4 weeks prior he was about 240. 150/200 (app) Note: T4 has been steadily rising. Last reading was 7.5 and one before that was 6 (which was up from 5.5) In the past he has had levels up to 5, but they decreased. I speculate that the glucose levels papably increase for two reasons: I allowed him to eat regular Science diet senior along with RD. He had been RD almost exclusively before. We have him taking cosequin (sic) for arthritis at 1 tablet per day (he probably only ingests about 50-75% because I mix it with his soft food. The elevating t4 level is the big one. Our Doctor (of more than 25 years) recommends that we start him on a low dose of topozil (1/2 of a 5 mg tablet twice daily). I normally never question our Doctor, but I am baffled by the high T4 since Baron is showing none of the classic symptoms. 1. He is not overly active--activity level is normal for an older cat--he sleeps a lot 2. He is not eating ravenously--eating has even decreased slightly in warm summer weather 3. His coat (all white) looks great and he grooms himself regularly--in fact he grooms enough to vomit hairballs even though we brush him twice daily. 4. He is alert, responsive, and a little playful 5. Past blood work up to 3 months ago (last general panel) were well within normal limits (BUN etc.). If treatment is justified, a 5 hour trip to the nearest facility and a week alone would probably harm him greatly, so medication is the only option we can consider. He also has not tolerated medications well (upset stomache) My questions are as follows: 1. Can the glucosmine elevate blood sugar levels significantly? 2. Is it possible the higher glucose levels are creating the high T4 levels 3. What other diagnostic options are available to confirm the diagnosis 4. What are the risks involved with topozil and the diabetic feline? This last one is particularly of concern. I fear that adding this to his regimen will throw him into a spiral and out of control. We are taking him for another full panel on Tuesday and plan to visit further with our Doctor. As always, thank you for your assistance. Don Answer: Don- 1) Based on our clinical experiences we think that administering glucosamine can make it hard to accurately measure the blood glucose in some cats. This feeling is not supported by research and has been refuted by one research study -- although this study was funded by one of the manufacturers of these products. We don't think that there is an actual elevation in blood glucose, based on the symptoms of the cats we are testing and based on the fact that in at least two cats, when stopped the glucosamine for a few days, without changing insulin levels, the blood results improved. So this is a case in which it wouldn't hurt to stop the glucosamine to see what happens to the glucose curve if you want to based on suspicion, but where the only current information suggests that it won't change things. 2) It is more likely that the higher T4 levels are creating the higher glucose levels. It is notoriously difficult to regulate insulin levels in cats with hyperthyroidism. I do not know of any research or information that suggests the opposite situation occurs where glucose levels rise and cause increases in T4. 3) The most accurate test for hyperthyroidism without going to a great deal of trouble is a free T4 by equilibrium dialysis test. This can be be done by Michigan State University's lab and is available from Antech and probably other commercial veterinary labs. There are three other tests that can confirm hyperthyroidism but involve much more work -- the T3 suppression test, nuclear scintigraphy (using radioactive iodine and a camera that can detect it to show that the thyroid is overactive) and thyroid biopsy. In reality, the total T4 test is very accurate for hyperthyroidism and it is not likely that the test results are wrong, though. If your veterinarian can palpate an enlarged thyroid gland and the total T4 is elevated, the odds of an incorrect diagnosis based on these findings is really low. 4) I don't know of any special risks associated with methimazole (Tapazole Rx) and diabetes, except that adequate control of the hyperthyroidism, based on testing T4 levels, doesn't always control the adverse effect that hyperthyroidism has on controlling blood glucose. I do not know why that is the case. However, it is best to control hyperthyroidism before losing control of the glucose levels, if possible, because it lessens the long term impact of the resistance to insulin that hyperthyroid cats seem to develop over time. We have had pretty good luck using transdermal methimazole in cats with sensitive stomachs. These are special gels that methimazole is mixed with that are applied topically (usually to the hairless tissue on the inside of the ear) and are absorbed through the skin. This system for delivering the methimazole does not work for all cats but the results are measurable, so it is possible to monitor the success of the medication and to change to another form, if necessary. Compounding pharmacies can make methimazole into transdermal gels. It can also be helpful just to put the methimazole tablet into a small gel capsule that you can buy at a pharmacy, to lessen the chance of a reaction based on the bitterness of the pill itself. It is not too unusual to have cats who have hyperthyroidism without any clinical signs except gradual weight loss and increased heart rate (some don't even have this sign). Good luck with this. Mike Richards, DVM 9/03/2003

Megacolon treatment in diabetic Cat - cisapride (Propulsid Rx)

Question: My diabetic calico cat continues with her megacolon problem. She is about 10. After her cleanout last week she was like a kitten again, but that was short-lived ... after one bowel movement the day after clean-out, she didn't exhibit peristalsis (sp) again.

I gave her an enema with PetEnema Saturday which did stimulate her, and again on Monday. And again yesterday, wed.

today she had some diarrhea on her own.

My specialist only sees the colon surgery if she doesn't get her ability back. I don't want to go that way ... since she is diabetic I should think it will really mess up her water balance.

I am giving her up to 15 cc of lactulose a day.

I didn't try the Iams low-residue food, should have done that.

She was doing pretty well on sheba and Wysong dry until I neglected to give her lactulose ... I got busy and thought maybe we could skip it. Wrong!

But I was only giving her about 4 cc a day ...

Anyway, any new ideas on treatment, and how to subscribe again.

Thank you very much. Jill

Answer: Jill-

It is still possible to get cisapride (Propulsid Rx) from compounding pharmacies and many vets feel that it is helpful for megacolon problems. An alternative medication is ranitidine (Xantac Rx), which seems to have similar effects in some cats. The usual dosage of cisapride is 1.25 to 2.5mg given 15 to 30 minutes prior to eating and the dosage of ranitidine is 1 to 2mg/kg every 12 hours.

We have not used the low residue diet much (two patients) but it is still getting good reviews on the veterinary information sites, such as the Veterinary Information Network (tm).

It sounds like it will be possible to get back to a situation in which things are a little more controlled. I sure hope so.

Mike Richards, DVM 1/15/2001

Elevated liver enzymes in diabetic older cat

Question: Dear Dr. Mike, I have written to you before regarding my 18 year old diabetic cat regarding his licking behavior, etc. I thought he was doing really well with his insulin ( 5 units 2x per day, Humulin N 100). However, he had a follow up blood test done on Monday. The results came back OK regarding the diabetes and the kidneys. His liver enzymes were "off the scale" (his words). He called it hepatitis and stated that while the liver test was high before, they are very high now. Given his age, he felt that a biopsy or anything invasive would be a bad idea. I agreed. He suggested a bland diet with a Vitamin B complex. The unusual thing is that his appetite is still quite healthy and he is still demanding his food as well as home made boiled chicken. This is unusual in liver disease as I have been reading. The vitamin complexes that I have seen contain corn syrup or sucrose. He is diabetic so this is a problem. My vet said that there is absolutely nothing I can do but keep him comfortable and eating. He also could not say how this "hepatitis" developed and said it may be connected to the diabetes. He has always been an indoor cat. I would appreciate your thoughts on this.

Thank you so much for your time Barbara

Answer: Barbara-

We have seen several cats in our practice with hyperthyroidism that seemed to be causing elevations in liver enzymes. These cats have a very good appetite, in most cases, despite the presence of the high liver enzymes. Sometimes liver enzymes are elevated when only part of the liver is damaged, which can happen with blood clots disrupting circulation or when a tumor is occupying only a portion of the liver. In these cases pets tend to feel well despite elevations in liver enzyme levels. I tend to think that it is worth considering diagnostic testing, such as ultrasound exam and/or biopsy of the liver, but that is a judgment call and your vet knows the overall situation better than I do. Testing for hyperthyroidism is minimally invasive, since only a blood sample is necessary and I think that is worth considering, too. If hyperthyroidism is present, treatment will often help the liver a great deal.

The usual diets recommended for liver disease are low protein diets, such as Hill's l/d or k/d diets and Purina's NF diet, among others. There may also be benefits to the liver in using ursodiol (Actigal Rx), which increases bile flow and in using SAMe (Denosyl-SD4 tm), a supplement that seems to help some liver patients.

It is good that your cat continues to have an appetite and to do well with the insulin regulation. It is challenging to keep up with all the problems that can occur in older cats but it is often possible to make them feel much better and to live longer with good quality of life, so it is rewarding, too.

Good luck with this.

Mike Richards, DVM 12/16/2000

Hernia in adult cat with diabetes

Question: Dear Dr. Mike,

My diabetic 14-year-old kitty, Oliver, has developed an umbilical hernia. My vet says she's never seen this in an adult cat before and thinks it may have been caused by over exertion. It's large enough that he needs it surgically repaired. His hind legs have been weak ever since he's been dx'ed with diabetes, and I know this is neuropathy. Do you have any idea if the neuropathy could cause the umbilical hernia as well? Also, have you ever seen this kind of hernia in an adult cat?

Thank you for your past responses and your ever informative news letters! Judy

Answer: Judy-

I know of no association between diabetic neuropathy and the formation of umbilical hernias and I could not find any references to this in the Veterinary Information Network database or the surgical texts that I have. I think this must be just one of those strange things that happen sometimes. The good thing is that it is usually possible to repair an umbilical hernia with very good hope for it to remain repaired for life and that it is usually a short surgical procedure, which is also a good thing from a surgical and anesthetic standpoint, so Oliver's prognosis is good.

Just in case there has been a mix-up, we do sometimes see inguinal hernias in older pets, both dogs and cats, although much less commonly in cats. It is harder to get a strong repair when fixing an inguinal hernia. These are most commonly seen in older dogs that are coughing a lot but muscular weakness in the rear limbs might contribute to the formation of an inguinal hernia due to stress in the inguinal region when the legs are not supporting weight properly. I have about a 60 to 70% success rate repairing inguinal hernias (about 30 to 40% of pets have recurrences). I am not sure if that is a normal average or below normal average for success in repairing these hernias. If this were the hernia present the prognosis wouldn't be as good for a long term successful repair but the need to try to repair the hernia is greater since inguinal hernias are more likely to cause strangulation of the hernial sac contents, which can cause death.

Hopefully you got the name right and Oliver has an umbilical hernia.

Mike Richards, DVM 12/6/2000

Asthma and diabetes

Question: Dear Dr. Richards,

This question pertains to our 6.5 year old indoor cat Lucia. Here's a not so brief case history.

On returning from a week long trip several years ago, we found Lucia to have difficulty breathing, so much so we brought her to an emergency room where she stayed overnight. At this point she was diagnosed with asthma and given Prednesone and a bronchidilater. All was well for several years (we stopped the medicine after a week or two and used as needed) until this spring, when her asthma reappeared with a vengeance. She was given Prednesone again for a two week period and again her asthma subsided. After returning from a weekend away this June, we noticed that Lucia had lost weight, was not eating much, and was very lethargic. We brought her to the Vet and was told that she had very high glucose levels and keytones in her urine, so much so that she stayed the weekend for IV treatment and glucose curves. After several weeks on Insulin and Cypro (for the asthma) she seemed well on her way to recovery. Her eating habits, however, changed significantly. She would no longer eat her Nine Lives that she had eaten all her life. In fact she would cycle through different types of food that she would or wouldn't eat. At one point she ate 4 cans of fancy feast a day, but will not eat that anymore. She incessantly begs for table scraps, something she never did before. She seems to cycle between times of not eating at all and eating quite a bit. After her Insulin shot, her ears tend to get very warm and she likes to lay down on cool surfaces (tile, hardwood), as opposed to our bed, where she used to sleep. When we leave for a weekend, she seems to not want to eat at all. At this point, I don't think she has been completely regulated for the correct Insulin level (we're doing 5 units per day of Insulin U), but I can't help but feel there is something else wrong with her. Having read about Pancreatisis, it seems like she might have several of the symptoms.

We are bringing her to the Vet for more blood work tomorrow, but so far, they can't find any other problems, aside from the diabetes. Her brother does not have anything wrong with him, so we've ruled out any infectious diseases. Any guidance would be greatly appreciated.

Thanks, John

Answer: John-

Pancreatitis is subtle and difficult to diagnose in cats. It is possible that it is present. Considering the other medical history it is probably more likely that the signs you are seeing are due to the diabetes and/or asthma, though. It is particularly difficult to deal with asthma in a diabetic cat due to the problems with regulating cats when corticosteroids, like prednisone, must be used to treat a secondary condition.

It is a good idea to try to use alternative therapies to limit the amount of prednisone that is necessary to control the asthma. Cyproheptadine is a good thing to try. Bronchodilators help some cats. Having terbutaline (Brethine Rx) on hand to deal with crisis situations might also be a good idea. In most cats with asthma, occasional use of prednisone or some other corticosteroid is likely to be necessary, though.

During the initial few weeks to months of insulin therapy there are often problems with variable appetite and cats will often eat a food one day and then refuse it the next. Over time, as it is possible to adjust the insulin dosage to more closely control the glucose levels, there is usually a point where the cat goes back to a normal eating pattern. Cyproheptadine is an appetite stimulant in cats but it causes depression in the first week or so that it is used in a lot of cats, so that might be part of the problem with the eating pattern, to.

We have not had to deal with sensitivity to insulin very often, but it does occur. We usually have seen pain at the injection site that is consistent, but it would be possible for other signs to occur, such as flushing of the skin, which might be what you are seeing with the ears. Your vet probably would notice this during the time when Lucia is there but do remember to tell him or her about it, too.

One of the hardest problems to deal with in diabetic cats is the effect of things like leaving them at the vets or even when leaving them at home with someone looking out for them. This stresses cats, which makes them release more sugar, changes their eating habits and just makes it generally hard to keep their insulin regulated. This becomes less of a problem over time, as everyone adjusts to the use of insulin, but it is really tough early on when trying to establish the correct insulin dosages.

This is just something that you have to work through and it does take a lot of coordination between you and your vet, so keep in close contact and don't be afraid to ask questions and point out problems. This is going to be doubly true in Lucia's case since asthma requires the same sort of relationship with the vet. Hang in there and things should improve with time.

Mike Richards, DVM 11/4/2000

Diabetes, cushing's and insulin in cat

Q: Dr. Richards, Thank you for responding to my questions. Yesterday I was ready to go with PZI, got a consent form, etc. , but my vet, David Anderson, thinks I am throwing away money. He used to use PZI, but now he is using the Humulin Ultralente. I did switch to Humulin Lente two weeks ago, but have not seen a lot of improvement. I want to try NPH after two more weeks on Lente. I hope he will agree. He believes Calico Cat may have Cushings since she isn't responding. She has a bloated belly. But the tests for Cushings are too costly, etc. So I will try HL and then switch to NPH for a final go. What food do you recommend for diabetic cats? Last night I tried some brewer's yeast, she licked the plate clean. This morning the same. Thanks for the info on the wounds. Wow, that's a big wound you let heal by itself. My vet said he doesn't suture them if they are less than an inch. That was good news. Your news is good too. I like the phrase you gave me, and will most certainly use it hence forth. Thanks for the protocol on that.

A: Jill

I think it is a good idea to give the Lente insulin some time to see how it works. Stabilizing cats on insulin can take some time and changing from one insulin to another too quickly might mean that you will miss an insulin dosage that might have worked.

Cushing's disease is unusual in cats but there have been several recent reports on its occurrence in cats, so it can't be ruled out. It is a cause of insulin resistance. Cats with Cushing's disease sometimes don't lose weight when they are diabetic, which is unusual and serves as an alert that it may be a problem. Acromegaly will also induce insulin resistance in cats. This is an excess of growth hormone. Testing is sometimes the only way to know if acromegaly is present but often there will be a quick progression to neurologic signs (muscular weakness, incoordination, circling or seizures). Also, hyperthyroidism can cause insulin resistance. Cats with both diabetes and hyperthyroidism usually lose a lot of weight but that can also happen with either disease alone so it isn't as good an indication of potential problems. Testing for all of these conditions would be somewhat expensive.

A lot of vets remember being told in veterinary school or somewhere along the line in their careers that insulin doses of more than 1 unit per pound indicate insulin resistance or that insulin dosage should not exceed 1 unit per pound. I think that the current thinking is that both of these guidelines are incorrect.

It is very difficult to regulate insulin really well without doing glucose curves. To do this, blood is drawn just before the morning insulin dose or as close to it as possible. Then blood is drawn every two to four hours for at least twelve hours. A "curve" is drawn on a chart based on the sugar levels. The peaks and valleys of this curve give an idea of when the insulin is most effective, when it is wearing off and whether or not there is an excess or deficiency in the insulin dose. Surprisingly, high blood sugars at certain times of the day can occur as the result of OVERDOSING insulin --- there is a rebound effect when the sugar level drops very low that will make it go very high later in the day.

Many of our clients, but definitely not all of them, are able to obtain blood samples from their cats or dogs and run blood glucose tests at home using the glucometers that are sold in pharmacies and other places where medical supplies are available. If you can do this it is very helpful in regulating insulin dosage. We find that putting a little vaseline on the edge of the ear, shining a light through the ear and then pricking a visible blood vessel along the ear margin will allow enough blood to be collected from cats to allow testing. The biggest problem is getting the blood onto the little testing machine properly. Sometimes it is necessary to suck up the sample from the ear margin with a small pipet, which does make the process complicated.

I usually think that the best food for diabetic cats is one that they like that they will eat consistently. I think that is more important than most of the other considerations when it comes to diet for diabetic cats. However, people that study these things suggest a diet containing moderate amounts of fiber such as Hill's w/d diet.

We have had a cat in our practice with acromegaly and diabetes but I don't remember one with Cushing's disease.

Good luck with this.

Mike Richards, DVM 7/1/99

Cat with concurrent diabetes and hyperthyroidism

Q: Dear Dr. Mike,

I am a subscriber to Vet Digest and once again require some of your words of wisdom. My cat, Oliver, is one of the unlucky few who went through a treatment of radioactive Iodine to treat his hyper-thyroid condition and ended up being hypo-thyroid. He went from 9 lbs to 11 1bs and was very lethargic. On top of that he's become diabetic. His hypo-thyroid condition is responding somewhat to 1.25 tablets of .05mg levotabs/daily (that's .0625 mg), but he hasn't responded to insulin. His blood and urine glucose are above 400.

Tonight we are increasing his insulin from 2 units twice daily to 3 units twice daily. (100 units/ml insulin)

I'm wondering if the hypo-thyroid condition and treatment interfere with treatment for diabetes. Have you any experience with this? I know that hypo-thyroidism is rare in cats and this may be an unusual case.

Also, is it possible that my cat won't respond to insulin at all?

Many thanks in advance. -Judy

A: Judy-

In human beings, diabetes is more common in patients with hyperthyroidism than it is in the population as a whole. In cats, a study by Hoenig, Petersen and Ferguson showed that hyperthyroidism also influenced glucose tolerance in cats and that hyperthyroid cats were more likely to have diabetes. In addition, their study concluded that treatment for the hyperthyroidism did not really help in the treatment of the diabetes and that it might even make it worse. There was no mention in this study of difficulty in regulating the diabetes in these cats and at least one other study (Rand, et. al 1993) suggests that even though there is a link between hyperthyroidism and diabetes that the treatment for the diabetic condition is still straightforward and should be controllable. We are treating one cat for concurrent diabetes and hyperthyroidism and so far, it is doing well.

Veterinarians are very conservative, most of the time, in initial insulin dosages for cats. There are cats who will experience insulin shock with as little as 1 unit of insulin but who have high glucose levels without any treatment. So most vets are a little nervous about starting out with insulin dosages that approximate the "average" treatment dosage. We have had cats whose insulin requirements were as high as 25 units twice a day --- but it took us several weeks to work up to this dosage because we started out with 1 unit twice a day, too. I was at a seminar on endocrine diseases and the speaker (whose name I can't remember offhand) said that there isn't an upper limit to insulin dosage -- you just give as much as you have to for it to work.

Hope this helps.

Mike Richards, DVM 6/1/99

Diabetic cat with megacolon

Q: Hello Dr. Mike. I have a 13 year old male cat who I love dearly. Unfortunately he now has a dual medical problem He is a diabetic and has been so for almost 3 years, and I have had a difficult time regulating his blood glucose. I use insulin of course - Humulin -U 100 ultralente, and have been experimenting with the dosage. 4 months ago he developed megacolon, perhaps related to the diabetes, perhaps independently caused. I have been treating the megacolon with lactulose ( 2 x daily) and Propulsid. Dietary regulation is near impossible becasue the cat is finicky and I must get him to eat in order to give him his insulin. Of late the medication has not been working too well and he has been getting enemas as frequently as once a week. At those times he does not eat and he once went into insulin shock, a scary thing, but we saved him in time. I have spoken to several surgeons and there is a split in their suggestions- some say operate now - it is an easy operation and an 85 % chance of full recovery depite the fact that he is a diabetic. Others say use caution and try things such as adding bran to his diet. The latter group say this is a high risk surgery for a geriatric (13) diabetic and only use it as an absolute last resort. They say try everything possible before surgery. I am in a quandary as to what to do and which group to believe. Is this indeed high risk surgery to be avoided if possible? or is it relatively safe and routine and should I plunge ahead? I would appreciate any advice that you can give me. Thanks.

A: I am guessing that you have two questions.

First, is the subtotal colectomy a reasonably safe procedure and does it work?

This is fairly easy to answer. This surgery involves removing nearly the entire colon and then suturing the two ends that are left back together to form a much much shorter colon. This ends the fecal impaction problem in almost all cats in which this surgery is performed. Several studies have shown success rates greater than 90% which means that these patients are both surviving and doing well. Because of the complexity of the procedure and potential for serious complications it probably ranks as medium risk surgery. The benefits seem to outweigh the risks for any cat no longer responding to medications such as lactulose. Even when the medications are working this surgery is reasonable to consider.

Second, are there increased surgical risks due to the diabetes and difficulties regulating it in my cat?

Yes, there are. Do they outweigh the benefits? I'm not sure, but I lean towards thinking they do, providing the surgery is performed by someone willing to take the measures necessary to protect the health of a diabetic patient.

Diabetics have special needs when it comes to surgery. Surgery is always stressful to some degree. Stress can cause problems in diabetic patients. The surgeon must be prepared to deal with these problems and must have the full cooperation of the pet owner. Preoperative labwork may be optional for some surgical patients but not for diabetics. It is important to identify any pre-existing problems. It is usually better to try to determine what is causing problems with blood glucose regulation and to try to achieve stabilization of the insulin dosage prior to surgery but megacolon can become a serious enough problem all by itself. You may have to elect to proceed with surgery even if good insulin regulation has not been achieved -- but try to get that done with the help of your vet prior to surgery.

Anesthetics are generally not a problem in diabetic patients except that it probably isn't a good idea to use xylazine (Rompun Rx) as an induction agent.

Find a surgeon who is familiar with operating on diabetic patients and has experience doing subtotal colectomies. This may mean traveling to a surgical referral hospital or veterinary school. You should receive pretty specific instructions about the insulin dosages to administer on the day of surgery and the surgeon should be equipped to check electrolyte levels, glucose levels and to treat for low or high blood sugar during surgery and recovery. Diabetic patients may be a little more prone to infection and may heal a little more slowly than non-diabetic patients but a surgeon familiar with the problems should take measures to protect against them, if it appears to be necessary.

If you take these steps it is only slightly more risky to operate on a diabetic patient than on a "normal" patient. The limiting factor in your cat's case is the current lack of control of the insulin levels. If you can get control of this problem with the help of your vet or perhaps a specialist your vet can recommend, then surgery becomes a simpler choice. If you can not gain control over the insulin regulation prior to surgery it is likely that you will not have control after surgery. Since this is a serious problem in its own right, it adds a complication to the decision making.

It is easy to see why you are in a quandary. I hope that this has helped and not made it worse!

Mike Richards, DVM

Last edited 01/30/05


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...