Less known than the more common diabetes mellitus, diabetes insipidus, described by Dr. Susan Thorpe-Vargas as "the other diabetes," can occur in dogs of any age, gender or breed. Diabetes insipidus is a dangerous illness, as its symptoms can go unnoticed in an unobserved dog and dehydration can occur within four to six hours. There are two types of diabetes insipidus: Central diabetes insipidus, also known as vasopressin-sensitive DI, is characterized by a deficit of anti-diuretic hormone, resulting in a water imbalance and the inability to concentrate urine. Nephrogenic diabetes insipidus, or vasopressin-resistant DI, occurs when, although enough anti-diuretic hormone is produced, the kidneys are unresponsive. Both types of diabetes insipidus present with the same symptoms.
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Polydipsia
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Polydipsia is characterized by excessive and continuous fluid intake. Due to excessive urination and dehydration, your dog will become insatiably thirsty, looking for water wherever he can find it. You may observe him drinking from unusual places, like a dripping faucet, the toilet bowl or water puddles. Generally speaking, if your dog is consuming more than 100 ml of fluid per day, this is considered abnormal. Never withhold water from your diabetic dog. Once he has received treatment and his system has regulated, the excessive drinking should cease. Polydipsia can be symptomatic of many different illnesses, so in-depth testing by a qualified veterinarian is necessary.
Polyuria
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Polyuria, or diuresis, is when your dog produces an abnormally large volume of urine, which is the direct result of polydipsia. Polyuria may go unnoticed if your dog lives outdoors or has easy access to the back yard via a doggie door. However, if your dog lives inside, you may notice that she asks to go outside more than usual, or that she is beginning to have accidents in the house. Like polydipsia, polyuria is symptomatic of many conditions, so testing and diagnosis by your veterinarian is needed to confirm diabetes insipidus.
Electrolyte Imbalance
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Electrolytes are salts that are found in body fluids, tissues and blood, and are vital for muscle coordination, the absorption and excretion of fluids, and nerve and heart function. If your dog is suffering from polyuria, he will lose valuable electrolytes through his urine. Symptoms of electrolyte imbalance include increased thirst, lethargy, drowsiness, restlessness, gastrointestinal disturbance, oliguria (decreased urine production) and tachycardia (rapid heartbeat).
Dehydration
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Dehydration occurs when your dog's fluid levels are below normal and can be the direct result of polyuria, polydipsia and electrolyte loss. Dehydration in and of itself can be a life-threatening condition if not treated immediately. Symptoms of dehydration include sunken eyes, dry and tacky gums, thick saliva, lethargy, depression, loss of skin elasticity and tachycardia.
Other Symptoms
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Other symptoms that may indicate diabetes insipidus are disorientation, lack of coordination, unsteady gait, stupor or seizures. These symptoms, like the others, could be indicative of a number of disorders, so veterinary testing and diagnosis is necessary. Through testing, your veterinarian will be able to determine if two other symptoms of diabetes insipidus are present: low levels of ADH, the hormone necessary for urine concentration; and, through urinalysis, a low specific gravity of urine (high water content).
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