Diabetes mellitus affects between 0.4% and 1.2% of dogs, and about 0.7% of all cats, making it one of the most common diseases of the endocrine, or hormone, system in domestic pets. It can also be one of the most difficult of conditions to manage well, with most diabetic animals having occasional “relapses” where they destabilise. In this blog, we’re going to look at the condition, what it is, how it’s treated, and then look at some of the new approaches we’re pioneering here at USVC!
What is diabetes mellitus?
Also known as sugar diabetes (to distinguish it from a different endocrine disease, water diabetes), diabetes mellitus occurs when the dog’s or cat’s body is no longer able to manage its own blood sugar. Blood sugar is really important because it’s the basic fuel all cells need to function normally, and levels that are too high or too low can both be harmful. In dogs and cats (like humans), blood sugar levels are controlled by the pancreas, an organ in the abdomen. If the sugar goes too low, the pancreas releases the hormone glucagon, which tells the liver to make more. If it goes too high, insulin is released which tells all the cells in the body to absorb sugar from the blood - in fact, without insulin, cells cannot absorb sugars at all. It’s this system that goes wrong in the diabetic patient.
Traditionally, human doctors have divided diabetes into Type 1, insulin insufficiency (where not enough insulin is being made) and Type 2, or insulin resistance (where the cells “ignore” the insulin signal). While modern research suggests that in fact there are actually at least 5 different types, this distinction can be helpful in animals.
Diabetes in dogs is usually due to the pancreas shutting down (possibly due to a mistake by the body’s immune system) leading to insulin insufficiency (quite similar to Type 1 in humans). While they can develop obesity-related insulin resistance diabetes, it’s less common.
Cats (of course!) do things differently; in some respects, their form of the disease starts off with insulin resistance (which is why obesity is such a high risk in cats), with the tissues ignoring insulin signals. However, after a few weeks or months, the pancreas may stop working properly (essentially, it gives up in disgust!), leading to insulin insufficiency as well.
Understanding these differences can be really helpful to understanding the disease, and how we can treat it.
What are the symptoms?
Whichever type of diabetes they have, the symptoms are essentially the same, and typically include:
- Weight loss (because the cells cannot use sugar for energy).
- Increased hunger (because the body is starving, no matter how much they eat!).
- Increased urination and thirst (as sugar levels rise, the kidneys struggle to reabsorb it, and end up losing more water).
- Increased susceptibility to infections (especially urinary infections) as the excess sugar encourages bacteria to grow.
However, diabetes can easily - and rapidly - become more than unpleasant, but life-threatening. Both dogs and cats can develop a condition called ketoacidosis where the blood turns to acid, leading to dehydration, lethargy, loss of appetite, collapse, vomiting, and ultimately death if not rapidly treated.
Occasionally, the blood glucose may go so high that the brain is affected - this is called a hyperosmotic coma, as the sugar in the blood draws water out of the brain. The symptoms include abnormal behaviour, collapse, coma, seizures and ultimately death.
How can it be diagnosed?
While a one-off blood sugar reading can in some cases be enough to diagnose the condition, in many situations it cannot prove it (because sugar levels fluctuate naturally, and can be pushed up by many other conditions including stress). In these cases, we use a blood test called fructosamine which allows us to estimate average blood sugar levels over the previous few weeks. We’d also want to rule out other possible conditions that can cause, or mimic, diabetes, such as Cushing’s Disease.
What about treatment?
In dogs, diabetes cannot be cured in the vast majority of cases. Management is therefore a lifelong task. The aim is to give the dog sufficient supplemental insulin to regulate their blood sugars for them. This means injections of insulin - usually twice a day - under the skin, to pull their blood sugar down. To work out what dose of insulin is required, we’ll carry out a Blood Glucose Curve, to test their response to insulin over 6-8 hours. Depending on the results, our vets may increase or lower the dose, and then repeat the curve every week or two until we’re sure they’re stable on the optimal dose for them. Long term management is also dependent on a very rigid timetable, a suitable diabetic diet (low sugar, high fibre, quite high in fat and protein), and careful monitoring at home.
This last point is essential - without accurate monitoring of blood sugar levels, it won’t be possible to control the diabetes.
Cats are a little different. Because in many cases insulin resistance is the initial cause, aggressive treatment in the first few weeks can result in them going into long term remission. The treatment involves very careful control of blood sugar levels with insulin, diet, and monitoring; as well as urgent weight loss. Once in remission, a cat is unlikely to develop diabetic symptoms as long as they stay lean!
Of course, not every cat will go into remission - they may already have entered the insulin insufficiency stage of the disease, in which case management will be the same as in dogs, and again, accurate monitoring is essential.
So, what’s new?
Well, we have some new toys! As we said above, accurately measuring blood sugar levels is essential to effective treatment. However, this means regular blood samples - maybe 7 or 8 in a single day, or even more in unstable patients. This usually involves a needle prick in the ear - but many dogs and especially cats really don’t appreciate being made into a pincushion! As a result, we are pioneering the use of a semi-permanent continuous monitoring system for use in those hard-to-control cases. This is a device that is implanted under the skin, allowing us to just run the scanner over it and read the blood sugar level without any needles! We’re even looking at connecting it up to a phone app so we can monitor them all the time… so watch this space!