Diabetes Insipidus
Despite its name, diabetes insipidus is not related to the more commonly known diabetes mellitus, and it does not invilve insulin or sugar metabolism. Diabetes insipidus and diabetes mellitus are unrelated, although they can have similar signs and symptoms, like excessive thirst and excessive urination. Diabetes insipidus is the inability to produce a concentrated urine due to a deficiency of antidiuretic hormone (ADH) (cranial diabetes insipidus), or, kidney resistance to ADH (renal diabetes insipidus).
Patients usually have increased thirst (polydipsia) and increased urination (polyuria).
Your dog's body has a complex system for balancing the volume and composition of body fluids. The kidneys remove extra body fluids from the bloodstream. This fluid waste is stored in the bladder as urine. If the fluid regulation system is working properly, the kidneys make less urine to conserve fluid when the body is losing water. The kidneys also make less urine at night when the body's metabolic processes are slower.
The hypothalamus makes antidiuretic hormone (ADH), which directs the kidneys to make less urine. In order to keep the volume and composition of body fluids balanced, the rate of fluid intake is governed by thirst, and the rate of excretion is governed by the production of antidiuretic hormone (ADH), also called vasopressin. This hormone is made in the hypothalamus, a small gland located in the base of the brain. ADH is stored in the nearby pituitary gland and released from it into the bloodstream when necessary. When ADH reaches the kidneys, it directs the kidneys to concentrate the urine by returning excess water to the bloodstream and therefore make less urine. DI occurs when this precise system for regulating the kidneys' handling of fluids is disrupted.
There two broad types of diabetes insipidus: cranial or central diabetes insipidus and
nephrogenic diabetes insipidus. With central diabetes insipidus, the pituitary gland does not secrete enough of this hrmone; In nephrogenic diabetes insipidus, it's the kidneys which do not respond normally to the hormone.
Central DI (CDI) Damage to the pituitary gland can be caused by different diseases as well as by head injuries, neurosurgery, or genetic disorders. To treat the ADH deficiency that results from any kind of damage to the hypothalamus or pituitary, a synthetic hormone called desmopressin can be taken by an injection, a nasal spray, or a pill.
Nephrogenic DI (NDI) The kidneys' ability to respond to ADH can be impaired by drugs and by chronic disorders including polycystic kidney disease, sickle cell disease, kidney failure, partial blockage of the ureters, and inherited genetic disorders. Sometimes the cause of nephrogenic DI is never discovered.
Dipsogenic DI
A third type of DI is caused by a defect in or damage to the thirst mechanism, which is located in the hypothalamus. This defect results in an abnormal increase in thirst and fluid intake that suppresses ADH secretion and increases urine output. Desmopressin or other drugs are not used to treat dipsogenic DI because they may decrease urine output but not thirst and fluid intake. This fluid "overload" can lead to water intoxication, a condition that lowers the concentration of sodium in the blood and can seriously damage the brain.
Causes In about 30% of cases the causes cannot be identified. Other common causes are head injury and pituitary tumours. Heritable forms are extremely uncommon. In some cases, the disorder may be triggered by an infectious disease, such as infectious meningitis or encephalitis or drugs.
Prognosis Congenital NDI is a chronic condition requiring life-long treatment.
Because of the excretion of abnormally large volumes of dilute urine, he may quickly become dehydrated if he does not drink enough water. You must see that the dog has a continuous supply of drinking water. Even with medication, the urge to urinate can come on very suddenly, and in most cases, the dog will not be able to go more than an hour or so without urinating. A "dog door" leading outside may help to prevent accidents.
At least a quarter of all dogs euthanized or turned into shelters are given up because of behavior-related issues. Near the top of the list of reasons for euthanasia and being turned into shelters is house soiling.[i] Therefore, whenever an inappropriate elimination behavior develops, look first for an underlying medical condition before starting training or behavior modification exercises.
For More Information on DI
1. Diabetes Insipidus In Our Best Friends by Susan Thorpe-Vargas and John Cargill (http://www.diabetesinsipidus.org)
2. Nephrogenic Diabetes Insipidus Foundation
3. The Diabetes Insipidus and Related Disorders Network
Go Pets America recommends seeking the advice of your local veterinarian for the most appropriate vaccination program and for the diagnosis and treatment of your pet's health problems. For vaccination requirements please contact your state and local licensing authorities.
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