The endocrine system plays a very important part in the regulation and control of all the other systems with the body. This is true for any type of animal, including us as humans. The endocrine system is comprised of different organs and tissues that actually produce the hormones in the body, which in turn regulate all the other body functions from brain functioning through to reproduction.
There are several different disorders or conditions that can occur in dogs that are located within the tissues and organs of the endocrine system. Most of these conditions will be genetically inherited and most of them are recessive conditions. This means that both parents had to have one gene for the condition and had to contribute this bad gene to the genetic pair when conception occurred. It does not necessarily mean that every puppy in the litter will have the condition, some will be carriers just like the parents and will not show any signs of the condition. There are tests that can be performed for many of these inherited endocrine disorders and if you are breeding and there is a history in either breed or line these tests are very highly recommended. Some breed associations are moving towards mandatory DNA testing for some of these genetic conditions in an attempt to breed out the recessive problems within the pedigree lines.
Cushing's Syndrome is one of the more common of the endocrine disorders found in dogs. There are some breeds that are more prone to the condition than others, which is why an inherited genetic condition is suspected. The most commonly diagnosed breeds with Cushing's Syndrome include all sizes of Poodles, Labradors, German and Australian Shepherds, Maltese, Boxers, Yorkshire Terriers and Dachshunds. It is not exclusive to dogs however, horses, cats and humans can all develop this condition. There is some evidence that it can be inherited, however there are other diseases and even medications that can increase the likelihood of the condition occurring. The condition, when inherited, is caused by an abnormality in the pituitary gland or a tumor within the adrenal glands. When this happens the body overproduces the hormone cortisone, which we more commonly know as cortisol, a stress related hormone. However dogs and other species can also get the condition if they are treated for prolonged periods of time with any type of steroids, also known as glucocorticoids. Cancerous tumors in the brain, pituitary and adrenal glands may also cause Crushing's Syndrome as well as other symptoms.
Typically this condition develops very slowly as higher and higher levels of cortisol form in the body. When it is noticed the dog is generally over six years of age and is very lethargic with poor appetite, a distended abdomen as may be seen with high worm infestations as well as very thin skin and excessive hair loss. Treatment may include surgical removal of the tumor or medications to block the production of cortisol in the endocrine system. Management is often very successful although improvements may take several months to reverse the condition. Treatment on medications will need to continue for life to avoid the condition from reoccurring.
Diabetes mellitus is a condition that, like Cushing's Syndrome, can occur in almost all other species including humans. It is an inappropriate response of the pancreas to produce the insulin needed to keep the blood sugars balanced within the body. While diabetes can have an inherited aspect, poor nutrition and lack of exercise, particularly in obese dogs, will be the trigger for the onset of diabetes.
Any dog breed can develop diabetes mellitus, however there are some breeds that are more prone to this endocrine disorder. The medium and large breeds such as German Shepherds, Labs, Golden Retrievers, Old English Sheepdogs, Chows, Keeshonds, Malamutes and Dobermans are at high risk as are the smaller breeds of Miniature Schnauzers, English Springer Spaniels, Cocker Spaniels and West Highland White Terriers.
Inherited forms of diabetes mellitus may be missed in growing puppies if owners are not aware of the condition. Typically these puppies do very poorly and tend to have chronic diarrhea and increased food and water consumption right from the switch to food from the mother. They grow very slowly and tend to have lots of other health problems and conditions. Some inherited forms of the disease don't occur until later, which typically is first noted by rapid increases in drinking and eating while the dog seems to become less and less healthy and energetic. Weight loss, trouble breathing and even vomiting along with chronic urinary tract infections are often the first sign that owners note in mature dogs developing diabetes mellitus.
Thankfully in most cases diabetes mellitus can be managed by monitoring food consumption and switching to high fiber, lower protein type foods, increasing exercise and providing insulin as required throughout the day to keep blood sugar levels balanced. In emergency situations the dog should be immediately taken to a vet and provided with IV treatment of fast acting insulin. Dogs can go into a coma if left untreated and can suffer significant neurological damage or even death.
Hypothyroidism occurs in several breeds and is very difficult to diagnose because it looks like so many other conditions. It is a condition in which the thyroid gland begins to shut down and stops producing the normal thyroid hormones. It typically starts to become noticeable when the dog is between 4 to 10 years and many owners, especially with the older dogs in the range, simply assume it is old age behaviors, at least initially. The dog begins to become very sedate and has no energy, shortly after than you will notice problems with constipation, constant infections, problems with tolerating cold temperatures and hair loss in symmetrical patterns on the coat. In some dogs the skin will become very dark where the hair is shed. Both females and males will become infertile and will not show any interest in breeding. Often dogs have significant weight gain during this time even though their feed ration has not changed.
As with many of the endocrine disorders, once diagnosed hypothyroidism can be treated with hormone supplements. The success rate for treatment of the condition is very good, as long as other chronic health conditions have not also developed. Typically the treatment takes several months to reverse the physical symptoms and the dog will need to stay on the hormone replacement medications for life.
Any dog showing any type of endocrine disorder should be immediately removed from breeding programs. Since many of the disorders don't fully develop until the dogs are mature, it is essential to keep good records and only breed into lines with no history of these conditions.