Diabetes mellitus is a hormonal metabolic condition in which a dog is unable to control the glucose, or
sugar, level in its blood. It is a relatively common condition, and may affect up to 1 in 100 dogs. There are
three types of this condition:
Type 1: Insulin-dependent diabetes mellitus (IDDM).
Type 2: Non-insulin-dependent diabetes mellitus.
Type 3: Secondary diabetes mellitus, which is the result of another primary disease.
Most dogs suffer from type 1 diabetes (insulin-dependent diabetes mellitus).
A dog’s blood sugar levels are controlled by a hormone called insulin. This hormone is produced by the
pancreas, an organ that lies close to the stomach and is also responsible for producing some digestive
enzymes. A dog with diabetes mellitus suffers either from a shortfall in the amount of insulin that its body
needs, or it produces enough insulin but its body tissues do not respond to its actions. The result is higher
than normal blood sugar levels.
Primary diabetes mellitus (Type 1 and 2) is thought to be caused by failure of the pancreas to produce
sufficient insulin, as a result of an inherent abnormality of the pancreas or through deterioration in the
pancreas associated with ageing.
Secondary diabetes mellitus (Type 3) is thought to be caused by any one of the following factors:
inflammatory diseases of the pancreas, hormonal imbalances that influence the function of insulin, longterm administration of certain drugs, obesity and immune-system disorders that cause body tissues to
resist the action of insulin.
Is it serious? YES. If left untreated, a dog will become depressed, vomit, breathe more rapidly than normal,
eventually stop passing any urine at all, slip into a coma and die.
Dogs at risk: Cocker and King Charles spaniels, Dachshunds, Doberman pinschers, German Shepherds,
Golden and Labrador retrievers, Miniature poodles, Pomeranians, Rottweilers, Samoyeds, dogs over 8
years old, unspayed bitches and obese dogs.
Uncomplicated Diabetes Mellitus.
Increased blood sugar levels result from impaired glucose utilization, increased sugar production by the
body’s efforts trying to correct the blood sugar levels, and increased breakdown of glycogen (sugar
reserves) by the liver. The increased blood sugar levels then create an increased absorption of water into
the blood vessels, which dehydrates the body and manifests as increased thirst and water drinking, as well
as increased urine output. The latter is a result of increased sugar levels in the blood that draw water with
it, via the kidneys and bladder.
In addition to the above, the satiety centre in the hypothalamus (brain area) is unable to utilize the sugar in
the blood, and together with the nutrient loss via the urine, the body is starved, resulting in an increased
appetite with concurrent weight loss.
Insulin is an anabolic hormone, which means that when it is deficient, the body will go into a state of protein
breakdown, which further contributes to weight loss and muscle wastage. The proteins are also broken
down into amino acids which are utilized by the liver in order to produce new sugars, which are needed by
the starving tissues; however, the latter aggravates the already high levels of blood sugars.
One of the many functions of the hormone insulin is to suppress fat breakdown. Thus, in its absence, fat
breakdown is actually stimulated contributing to weight loss.
Complicated (Ketoacidotic) Diabetes Mellitus
With time, the abnormal levels of fat breakdown within the liver start to produce excessive amounts of
ketones (acidic by-products of fat metabolism). These substances then reach the blood stream and begin
affecting electrolyte levels contributing towards dehydration, loss of intravascular fluid volume, widespread
acid state within body fluids and shock. Furthermore, once the ketones reach the brain, they can cause
nausea, anorexia and subsequent vomition. The state of shock also predisposes the kidneys to premature
kidney failure. The body then goes into stress mode, and starts producing stress hormones (cortisol and
epinephrine), which contribute to the already high blood sugar levels, creating a vicious cycle of events that
are to the detriment of the dog.
The precise treatment regime will be determined with the help of your veterinarian and depends on the type
of diabetes mellitus, and its cause.
It is important to remember that diabetes mellitus is a disease that needs to be managed closely
with your veterinarian, and in most cases, for the rest of the dog’s life. That means, that in most
cases cure is not possible, requiring that the condition of the dog is carefully monitored and
managed at all times as to allow an acceptable quality of life for the patient.
The following are all common elements of therapy:
1. Withdrawal of other drugs – any drug treatment that could be a cause of the condition should be
stopped as soon as possible.
2. Treatment of a specific cause – if an underlying primary condition is diagnosed, specific and
prompt treatment is implemented.
3. Weight reduction – this is important in overweight animals.
4. Spaying of a bitch – done as soon as the bitch is fit enough for surgery.
5. Insulin – injected on a regular schedule, usually at the time of feeding.
6. Dietary modification – may be required if maintenance of sugar levels becomes very difficult to
7. Exercise – consistent level of mild daily exercise is ideal and bouts of strenuous exercise should
be avoided.
With careful veterinary management, about 70% of dogs suffering from diabetes mellitus can be stabilized
as in-patients. The majority of these dogs will go on to enjoy a good quality of life for between 1 and 5
years on average, although some patients have experienced much longer periods of successful disease
management and longevity.
Many of the causes of diabetes mellitus cannot be prevented, but the one important step that you can take,
is to ensure that your dog is not overweight. Dogs already diagnosed with diabetes mellitus need to be
monitored for weight gain as well, to prevent complications in the management of the condition.
Monitoring Insulin Therapy at home
The most important indicators of insulin treatment efficiency are changes in the patient’s appetite, attitude,
body condition, amounts of water taken in and amounts of urine produced in relation to each other.
Monitoring Insulin Therapy in the Long-term
Once the diagnosis has been made by your veterinarian and initial blood sugar levels have been stabilized,
evaluating insulin therapy once weekly for up to a month may be required. Thereafter, serial blood sugar
level readings are done as recommended by your veterinarian, based on body weight assessment and
resolution of clinical signs that may develop with time.
The normal blood sugar levels are between 3.3 – 5.5 mmol/l, which the body maintains at all times through
a number of different mechanisms, but most importantly, through the actions of the hormone insulin.
There are many different sources and products, which are made available for insulin therapy in dogs. The
treatment routine depends largely on the type of diabetes that the patient is suffering, but also by the
response of the patient to these products. Generally a twice daily insulin treatment routine is used.
In a diabetic patient that range is modified to between 4 – 12mmol/l. It is actually rare to obtain a perfect
glucose curve (sugar level profile), like the graph below. The vertical axis represents the blood sugar
levels, measured in a 24 hour period (horizontal axis).
The goal of our therapy is to maintain the patient’s sugar levels between the two horizontal red lines and
avoid the complications of diabetes mellitus. Too high, as well as too low blood sugar levels will both lead
to a state of coma and death as the ultimate complications. Learning to monitor the patient’s everyday
habitus (demeanour), appetite, water intake and urine production becomes crucial.
Causes of Elevated Blood Sugar Levels
Insufficient insulin dosage.
Insufficient duration of insulin action.
Outdated, inactive insulin.
Inaccurate or ineffective administration.
 Overfeeding.
 Stress.
 Insulin resistance caused by other diseases and medication.
Causes of Too Low Blood Sugar Levels
Insulin overdose.
Concentrated insulin (old).
Overlap of insulin action.
Transient diabetes.
Anorexia caused by oral disease or ketoacidosis.
Maldigestion due to pancreatic insufficiency or bacterial overgrowth.
Malabsorption due to inflammatory bowel disease, lymphoma, etc.
Diabetes mellitus is a common disease in animals which can only be managed successfully with the help of
your veterinarian, allowing for a good quality of life for our beloved pets. Knowing more about the disease
and understanding it, makes the management of the condition thereafter much easier, cheaper, and less