Diabetes mellitus is one of the most common endocrine diseases in dogs and cats. An estimated 0.5% of all cats and up to 5% of all dogs are affected. The trend is increasing and apparently correlates with the proportion of overweight animals. Like people who wear diabetic socks for men, cats usually have type 2 diabetes, while dogs often have an underlying disease, which leads to diabetes mellitus. In addition to the administration of insulin, feeding a suitable diet is an important part of therapy. In the cat, it can then come in about 30% of cases to remission of diabetes, so that further insulin doses can be dispensed with.
About 80% of all affected cats suffer from a type of diabetes similar to type 2 diabetes in humans. Pathogenetically plays a role on the one hand insulin resistance of the peripheral tissue and on the other hand the limited insulin production of the beta cells of the pancreas. Obesity seems to be the most critical risk factor because overweight cats have a fourfold increased risk of developing diabetes mellitus than normal-weight cats. Other risk factors include increasing age, male gender, castration, and physical inactivity. Older castrated obese males statistically have the greatest risk of developing diabetes mellitus. Other specific types of diabetes (formerly referred to as secondary diabetes mellitus) affect about 20% of cats and are caused, for example, by pancreatitis, pancreatic neoplasia, hypersomatotropism, hyperthyroidism, and the administration of diabetogenic drugs (glucocorticoids, proligeston).
Diestrus often cause in dogs
In dogs, diabetes mellitus cannot be assigned to a type of diabetes as clearly as in cats. As a rule, older animals from the age of eight are affected, most commonly the breeds Spitz, Poodle, Beagle, Middle and Miniature Schnauzer, Rottweiler, Maltese, Yorkshire, Cairn, and Fox Terriers, and Dachshunds. In addition to a genetic disposition, the cause is often diseases that lead to reduced insulin production or reduced insulin effect, e.g. pancreatitis, pancreatic neoplasia, hypercortisolism (Cushing’s disease), the application of diabetogenic drugs and in dogs as a special feature of the diestrus of uncastrated. The progesterone secreted by the ovaries stimulates the formation of somatropin (somatotropic hormone, STH), which acts as an antagonist of insulin. Through castration, i.e. the removal of the ovaries, diabetes is reversible. However, affected have fewer beta cells and are therefore more susceptible to diabetes mellitus than castrated animals.
Different secondary diseases
As in humans, polyuria and polydipsia are often early symptoms of diabetes. Other findings may include weight loss despite polyphagia, unkempt, thinning coat, lethargy, dehydration, and especially in cats, anorexia, and vomiting. Diabetogenic neuropathy with movement disorders occurs in about 10% of affected cats. Typical is a plantigrade foot of the hind limbs, that is, the cat no longer appears only with the toes, but with the entire sole of the foot. Dogs often develop cataracts at an early age. It progresses rapidly, so some pet owners report a “sudden” loss of vision but is partially reversible with early treatment.
Insufficient detection of hyperglycemia
Diagnosis of diabetes mellitus is based on clinical symptoms and persistent hyperglycemia and glucosuria. The standard values may vary slightly depending on the laboratory and examination method:
- Blood glucose dog: 60 to 110 mg/dl
- Blood glucose cat: 50 to 150 mg/dl
Glucosuria occurs when the blood glucose concentration exceeds the renal threshold (175 to 225 mg/dl in dogs and 250 to 350 mg/dl in cats). The blood glucose levels can rise significantly (in supposedly pathological areas) when excited. Cats in particular can show sometimes massive hyperglycemia (and glucosuria when exceeding the renal threshold) due to stress, so if diabetes mellitus is suspected, the fructosamine concentration in the serum should be determined. It reflects the average blood sugar level of the last one to two weeks. The animals should also be examined for concomitant diseases or possible triggering diseases.
If an animal staggers, trembles, or suddenly becomes aggressive, then it is probably just hypoglycemia. Clinical hypoglycemia symptoms include
- Convulsions and coma
Some animals are also just very calm and have no appetite. As an emergency treatment, oral glucose solution or honey (1 g per kg of body weight) should be given immediately. You can smear the honey (or chewed glucose) laterally inside the cheek, gums or tongue. This is particularly useful if the animals have already collapsed and can no longer absorb large amounts of fluid or the risk of aspiration pneumonia is too great. Owners of diabetic animals should always have a source of glucose (dextrose on the way) handy. After successful emergency treatment with oral glucose administration, small amounts of food should be given at one to two hours intervals.
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Oral antidiabetic drugs in cats
While dogs with diabetes usually rely on insulin administration, in some cases cats can be treated with oral antidiabetic drugs. Glipizide, a second-generation sulphonylurea, stimulates insulin secretion and can be administered at an initial dose of 2.5 mg/cat twice daily. After two weeks, the dose may be increased to 5 mg/cat twice daily if hyperglycemia is still present and no adverse reactions occur. Other classes of oral hypoglycemic agents are either ineffective or have not yet been studied in cats. Also, therapy with glipizide is only successful in 30% of cats. In addition, glipizide can lead to an accelerated loss of residual beta cells, so this therapy should only be used if the pet owner is unable to inject insulin regularly.
Pillar 1: Insulin therapy
In addition to a suitable diet, the application of insulin is the drug of choice in the treatment of diabetes mellitus. It takes place subcutaneously, for example, either in the neck or on the lateral chest wall. Approved for dogs and cats is the intermediate insulin Caninsulin, MSD Intervet, a mixture of 30% amorphous (semilente) and 70% crystalline (ultralente) zinc insulin from pigs in an aqueous suspension. Porcine insulin is identical to dog insulin and differs from cat insulin in three amino acids. In cats, caninsulin should be injected subcutaneously twice a day. The once-daily application is usually not sufficient for glycemic control. The required insulin dose can vary greatly from person to person and must be determined by blood glucose daily curves. The administration of insulin glargine (Lantus, Sanofi-Aventis) is also possible. While Lantus is one of the long-term insulins in humans, the effect in dogs and cats is only intermediate, so Lantus® must also be administered twice a day.
Pillar 2: Diet
Weight reduction (about 1% of body weight per week) often leads to a significant improvement in diabetes mellitus in obese animals. In addition, a high-protein, low-carbohydrate diet is important, especially in cats. As pure carnivores, they have only a low activity of hepatic glucokinase and glycogen synthetase, so glucose can only be broken down very slowly. Cats should receive many small meals per day, which is in line with natural feeding patterns and minimizes fluctuations in blood sugar levels. Dogs should be fed twice a day, timed to the maximum effect of insulin. The easiest way is to use commercial diet feed.
Remission in cats possible
Through the combined administration of insulin and diet as well as weight reduction, a remission of diabetic symptoms is possible within a few months in about one-third of affected cats. Therefore, especially in the first few months, close blood sugar control is necessary in order to be able to reduce insulin in time or even discontinue.
Home monitoring recommended
Pet owners can measure their pet’s blood sugar at home in a stress-free environment than in practice. For this purpose, a drop of blood is obtained with a lancet on the ear. To stimulate blood circulation, for example, the ear can be warmed up for two to three minutes with a washcloth to facilitate blood collection. Suitable blood glucose meters are, for example, Ascensia Elite (Bayer) or the AlphaTrak (Albrecht), or g-Pet (Woodley), which have been specially developed for animals. It is recommended to determine fasting blood glucose twice a week and to create a blood glucose curve once a month.