Dogs get many diseases or conditions that are the
same or similar to diseases caught or developed by their owners. Some of these
maladies are genetic; others are acquired through infections or parasites or as
a result of other abnormalities, diseases, injuries, or old age.
Heart conditions can be inherited in dogs as they
are in people. Dogs can also be victims of cancer, tick-borne diseases,
autoimmune conditions, arthritis, liver or kidney disease, thyroid disease,
irritable bowel syndrome, and even diabetes.
There are two canine diseases known as diabetes:
diabetes mellitus, similar to the human disease, and diabetes insipidus. Both
are endocrine diseases – that is, they result from defects in the body system
that produces hormones. Diabetes insipidus is caused by a lack of vasopressin,
the antidiuretic hormone that controls water resorption by the kidneys. Diabetes
mellitus is characterized by a deficiency of insulin, the hormone that plays a
critical role in sugar metabolism, and is the most common of the two types.
Canine diabetes mellitus can be further divided
into two categories: a congenital type that is similar to juvenile-onset (Type
I) diabetes in humans; and an acquired type that is similar to adult-onset (Type
II) diabetes in humans. Most canine diabetes mellitus is insulin-dependent Type
II, also known as IDDM.
Animals eat food that the body changes to energy
for growth, maintenance, and daily activity. Digestive enzymes convert food
nutrients to chemicals that can be used by the organs to carry on body functions
and leave some energy for running, playing, working, and looking for
tomorrow’s dinner. The bloodstream then carries these chemicals to the cells
for fuel. Glucose, a simple sugar, is the body’s main fuel and is thus a
critical product of the metabolic process, but the mere presence of glucose
isn’t enough – it must be moved from the blood to the cells for use.
Insulin is the key. This essential hormone not
only opens the pathways for glucose to get from the blood to the cells, it helps
prevent the liver from producing an excess amount of glucose and aids the body
in storing the sugar for future energy use. Diabetes mellitus occurs when the
endocrine system fails to produce enough insulin to do all three jobs. The
result is too much glucose in the blood and too little in the cells, a condition
that forces the cells to seek energy elsewhere and seriously disrupts body
Insulin is manufactured in the pancreas, a small
organ near the bottom of the stomach and the small intestine. The pancreas
produces both hormones and digestive enzymes. When the insulin-producing cells
are damaged or destroyed by disease or affected by genetics, diabetes mellitus
is the result.
Onset of IDDM is marked by excessive hunger (polyphagia),
excessive thirst (polydipsia), and excessive urination (polyuria). If the
disease remains undiagnosed, the dog will lose weight as his body breaks down
fats and proteins to get needed energy.
Continued failure to seek treatment brings
lethargy, loss of appetite, depression, and vomiting. Affected dogs may have
decreased resistance to bacterial and fungal infections and may develop liver
and bladder problems and cataracts.
Diagnosis depends on evaluation of early symptoms,
a physical examination, and lab tests to ascertain the amount of glucose in the
blood and urine. Ketones, organic compounds produced by the liver as a result of
insulin insufficiency, may also be found in blood or urine. Excessive ketone
production leads to ketoacidosis, a serious, life-threatening condition.
Ketoacidosis can occur if IDDM is not treated or if the treatment is inadequate.
A single test for hyperglycemia (excess blood
glucose levels) may not be sufficient, especially if the levels are only
slightly elevated, so veterinarians may want to run more than one.
Injection of insulin is the treatment; several
insulins are available. Short-acting insulins are are effective for one-to-four
hours. Medium-range insulins last from four to 24 hours, and long-range versions
last from eight to 28 hours.
Short-acting insulins are the most powerful and
are often used initially to regulate glucose in dogs with ketoacidosis.
While insulin can keep IDDM under control so that
the dog lives a normal life, the most effective type of insulin for each dog
depends on its individual body and the stage of its disease. In addition, some
dogs will do well with a single injection each day and others will need two
The type of insulin and the most effective
maintenance dose can vary, so an owner must work with his veterinarian to
stabilize his pet’s condition and bring the pet back to the clinic for
recommended periodic blood tests.
Because the dog must receive daily doses of insulin, owners must learn to do the injections and store the insulin properly. Veterinarians can prescribe the particular type of insulin, teach owners to do the injections, and provide instructions for storage