Diabetes Mellitus in Dogs
Diabetes mellitus is a disease of the endocrine system. This is the system that is responsible for the regulation of hormones in the body. In diabetes mellitus, there is dysregulation of the glucose metabolism in the body, because of a lack of insulin. Insulin is a hormone produced by the pancreas, with its role being to move glucose into the cells and out of the blood stream, tightly regulating the blood glucose levels. A lack of insulin leads to excessive sugar in the blood stream, known as hyperglycaemia.
This disease is most prevalent in middle aged to older patients. The most common symptoms seen include excessive drinking, increased urination, increased appetite, lethargy, and weight loss. The underlying cause of the onset of Diabetes mellitus involves a complex interplay between the genetic make up of your pet, the environment, and multiple other factors. Usually, no specific inciting cause is identified, but it is ultimately because of destruction of the cells present in the pancreas that are responsible for producing insulin.
Consequences of uncontrolled Diabetes mellitus include Diabetic ketoacidosis, which can be life threatening. This occurs when the body begins producing ketones as fuel, leading to electrolyte abnormalities and a build-up of acidity in the body. Other comorbidities include conditions such as cataracts, urinary tract infections and pancreatitis, to name a few. It is important to closely monitor food intake and symptoms in your pet, as early intervention is key in these cases.
This disease requires lifelong management as it is incurable in canines, with the treatment involving subcutaneous (under the skin) injections of insulin twice a day. Each patient is different and will need a dose tailored to their needs. As a result of this, frequent visits to repeat glucose curves are necessary, until good glycaemic control is achieved. This involves achieving as close to normal glucose levels in the blood as possible, without putting your pet in danger of becoming hypoglycaemic, where the blood glucose levels fall to a low level.
Glucose curves involves measuring the level of blood glucose every 2 hours, after receiving the usual morning dose of insulin. Depending on the values seen, a decision regarding the effectiveness of the current insulin dose is made. Ideally, a re-evaluation should be performed a week after discharge. If a dose needs to be adjusted, a repeat check is recommended in 7 to 15 days. The ideal timeline for rechecks should be: one at 1 week post-discharge, at 2-3 weeks post-discharge, 6-8 weeks post discharge and then 10-12 weeks post-discharge. The frequency can then be reduced to every 4 months, unless there are concerns during this period. Other monitoring tools include the FreeStyle Libre, a device inserted into the skin to constantly monitor glucose levels, which lasts about 1-2 weeks once installed, depending on the compliance of your pet.
Insulin is administered using specific insulin syringes. The commonly used syringes are the same as the ones used by people. These syringes are marked in international units, the measurement used when referring to insulin doses. A very small amount of insulin is required, with even small overdoses leading to catastrophic consequences. It is particularly important to understand the amount your pet needs and how to administer it. A demo is the best way for clarifying this, which is ideally performed at a discharge appointment. Ideally, the person who will be administering the insulin should be present for this discussion. The insulin is injected under the skin. This is performed by lifting a portion of the skin, parting the hair, and injecting in this area. Insulin should remain in the fridge and the bottle should be gently inverted a few times before injection, to ensure no separation of the medication occurs. Do not repeat this dose if there are any hiccups when injecting, as this can lead to excessive amounts of insulin, leading to the blood sugar dropping low. Please contact your vet if any issues occur, and never decide to repeat the injection or increase the dose, without instruction from your vet.
Other important management tools include diet and exercise. It is important, that as insulin is administered twice daily, your pet eats twice daily, to correspond with the insulin injections. There are specific diabetic prescription diets available, which can assist in achieving better glucose control. Ideally, your pet should eat in conjunction with the insulin administration. If this is not the case, and one meal is missed, insulin should still be administered, but if the inappetance persists and there are other concerns, a vet should be contacted to discuss the way forward, as administering insulin in a pet that is persistently not eating, can lead to low blood glucose levels. Exercise is important to maintain a good weight and to promote cardiovascular health. Strenuous exercise should be avoided, with walking being the best option for these patients.
Low blood glucose (hypoglycaemia) is a common complication seen. Signs that this is occurring include weakness, dizziness, increased appetite and disorientation and agitation. In very severe cases, hypoglycaemia can result in collapse and even seizures. If you suspect that your pet has low blood glucose, apply honey onto the gums, as this will increase the blood glucose levels. If symptoms persist despite intervention, a veterinarian should be consulted, and the low blood glucose should be investigated.
References: Textbook of Veterinary Internal Medicine, Eight Edition (Ettinger, Feldman, & Cote, 2017)