Diabetes in dogs is an increasingly recognized and diagnosed health problem. Typically occurring in the later years of life, previously healthy dogs begin to show a variety of symptoms that can suggest diabetes. As with humans, diabetes in dogs is completely treatable, and with good management, it will not affect the quality of life or the lifespan of your dog. However, if the symptoms of diabetes go unnoticed and the disease is left untreated, it can lead to malnutrition, dehydration, and even death.
In both humans and animals, diabetes is caused by a decrease in, or complete lack of, insulin production in the body. Every cell in our bodies requires energy to function. The food we ingest is converted into glucose, which travels through the bloodstream, feeding cells and creating energy. Insulin in the body is the vehicle that allows cells to absorb glucose from the bloodstream.
In healthy animals, cells in the pancreas release insulin automatically when a rise in glucose in the blood is detected. The insulin is then distributed to cells throughout the body, allowing them to capture the glucose and use it for energy.
Almost all diabetes in dogs is caused by type 1, or insulin-dependent diabetes. In these animals, the pancreas stops producing insulin. Many factors can affect and destroy insulin production in the pancreas, including Cushing’s disease, steroid and immune system problems, pancreatic infection, or stress. However, in many cases, the exact cause remains unidentified. Regardless of the cause, without insulin, cells throughout the body cannot absorb glucose from the blood, effectively starving them of energy.
In response to the cells’ distress, the brain sends signals to eat more, so the body can take in more glucose. Meanwhile, glucose levels in the blood steadily rise, unable to be utilized, while the cells continue to demand glucose. This results in the body breaking down fat and muscle protein to be converted into energy by the liver. An unending cycle is quickly created, where more glucose is ingested and produced, but the body cannot utilize it due to the lack of insulin.
Consequences of Untreated Diabetes in Dogs
As the cycle progresses, glucose continues to build up in the body, leaking into the urine and drawing water from cells into the urinary tract. This leads to constant dehydration despite increased water intake.
If diabetes is left unchecked, dogs will begin to suffer from severe malnutrition (as the body cannot utilize the food consumed), muscle wasting (as the body feeds on its own tissue for energy), and dehydration (from glucose drawing water from the body). In addition, diabetic ketoacidosis can develop. As the body begins to break down fat for energy, by-products called ketones are created. If these byproducts continue to accumulate in the blood, they can cause a serious and potentially fatal illness.
Symptoms
The symptoms of diabetes in dogs are similar to those in humans. The early signs most commonly noticed include:
- Drastically increased appetite
- Significant weight loss, even while eating more
- Increased thirst (polydipsia)
- Increased urination (polyuria)
- Lethargy
In diagnosing and treating diabetes, the knowledge and skill of your veterinarian are absolutely essential. After a complete physical exam of your dog, your vet will perform laboratory tests. Since the symptoms of diabetes can often mimic those of other diseases, such as Cushing’s disease and hypothyroidism, only a combination of symptoms and laboratory tests can lead to a definitive diagnosis.
Complete blood work, blood chemistries, and a urine analysis will be performed to measure the amount of glucose present in your dog’s blood and urine. A positive result in the urine and a blood glucose value over 200 mg/dL are indicative of diabetes. Additionally, the level of ketones will be measured to ensure they are not abnormally high.
Once a diagnosis of diabetes has been made, your veterinarian can work with you and your dog to manage the disease. Treatment typically includes insulin injections, dietary adjustments, and possibly lifestyle changes.
Most dogs with insulin-dependent diabetes will require insulin injections to regulate their blood glucose. The most commonly used insulin for dogs is Vetsulin, which is specifically made for pets. However, there are many types of insulin available, and your vet will decide which one works best for your pet. Although many owners are initially apprehensive about giving their dog injections, your veterinarian will help you feel comfortable with the procedure, and it can soon become second nature.
The initial regulation phase may include several “glucose curves,” where an initial dose of insulin is given, and blood glucose is checked immediately after eating, as well as 4-6 more times at 2-hour intervals to monitor the dog’s blood glucose levels throughout the day.
The optimal blood glucose levels for diabetes control are between 90-180 mg/dL. Levels between 180-300 mg/dL are too high, and symptoms of diabetes will start to appear. If blood glucose exceeds 300 mg/dL, it becomes dangerously high, and serious side effects can occur.
It may take several weeks to adjust the insulin dosage, and several glucose curves may be required to find the correct dosage for your dog. At home, you may be asked to use a glucose meter to monitor your dog’s glucose levels, ensuring they do not get too high or too low. Hypoglycemia, or blood sugar levels below 50 mg/dL, is a life-threatening emergency, most often caused by giving a diabetic dog an incorrect dose of insulin or administering insulin when the dog hasn’t eaten. Symptoms of hypoglycemia include severe lethargy, dizziness, loss of bladder control, loss of consciousness, and seizures. If your diabetic pet exhibits these symptoms, immediately try to get them to eat something or spread honey or corn syrup in their mouth for the body to absorb the glucose, and seek immediate veterinary attention.
Since maintaining a constant, well-regulated blood sugar level is the goal of diabetes treatment, your veterinarian may recommend switching your dog to a high-fiber, low-carbohydrate diet to help regulate their blood glucose levels.
With a combination of insulin and dietary changes, the initial regulation of your diabetic dog will help control the disease. Within a few weeks, you should see positive changes in their energy, body condition, and other symptoms. After good regulation has been established, monitoring blood work every 3-6 months will be necessary to ensure your pet’s insulin requirements remain stable and glucose regulation stays on track.
Dogs and Cataracts
One of the most common complications of diabetes in dogs is progressive blindness caused by cataracts. Prolonged high levels of glucose in the blood lead to the formation of cataracts (a white pigmentation of the lens) in the eyes, which can cause blindness. Unfortunately, many dogs with diabetes will develop cataracts and blindness, even with excellent treatment and control. In some cases, surgery can remove the cataract and restore vision, but it is not an option in every case.
