Cushing’s Disease in Dogs

Cushing’s disease is a condition caused by a tumor in the pituitary gland, which very often ends up without a diagnosis. It often causes frequent urination with high urine volume and excessive thirst, even though these are also known as symptoms of other conditions as well.

Causes of Cushing’s disease

Cushing’s disease occurs when the body produces too much cortisol. It is produced by the endocrine system, which secretes hormones in the body. If it is secreted in normal amounts, cortisol helps the body respond to stress stimuli and regulate the immune system, but if it is present in large amounts, cortisol can cause numerous damages. It can also be caused by taking excessive amounts of dexamethasone over long periods of time. In quite rare cases, it can still be triggered by ear drops for various problems, which contain steroids.

Symptoms of Cushing’s disease

Chronic cortisone excesses in dogs can lead to a variety of symptoms. Not all dogs have the same symptoms, but most of them have at least two or three of the common symptoms seen.

The most commonly observed symptoms include the following:

• Excessive development and increase of urine volume. Many of these dogs urinate for longer periods of time than normal or urinate too often. Some produce so much urine that something similar to leakage will appear while the animal sleeps. Many dogs start to urinate in the house. According to the production of excess urine, there is also excess thirst, which is not usually as worrying for owners as the problem with urine.
• Hair loss without any regeneration. Hair loss is most commonly seen along the back, tail, and back of the back legs. Hair loss can lead to a thin coat or cause complete hair loss with a bald appearance. Dogs with Cushing almost never lose hair on their head or front legs.
• Muscle weakness. This can be seen in a dog who has trouble climbing the stairs or difficulty in jumping off furniture or in/out of a car. Muscle weakness can cause these dogs to be unable to go for long walks, for no apparent reason, similar to discharged batteries. This can cause it to have difficulty in standing up after it has been lying down for a long time.

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Dogs with Cushing’s syndrome have a great and sometimes even abnormally high appetite for some foods. In contrast, these dogs rarely have problems with vomiting or diarrhea. They often pant excessively. However, there are a number of symptoms that you should be very careful about and contact a veterinarian when you notice them:

• Excessive thirst
• Excessive urination
• Increased appetite
• Weight gain
• Swollen abdomen
• Obesity
• Hair loss
• Lack of energy
• Infertility
• Skin irritations
• Thinning of the skin

Breeds that have a higher risk factor for Cushing’s disease

As a rule, this condition occurs in animals over the age of 8 years. Certain breeds of dogs are at a higher risk of developing this disease, including:

• Caniche/Poodle
• Teckel
• Boston terrier
• Boxer
• Beagle

Diagnosis of Cushing’s disease

Diagnosing Cushing’s disease is not easy, and many tests may be needed to determine the presence of the disease. These include blood and urine tests. If the urine is diluted and the alkaline phosphatase liver enzyme is growing, Cushing’s disease testing is necessary.

A test to simulate the hormone adrenocorticotropic may be used, for which a blood sample will be needed. An injection of adrenocorticotropic will be given, after which a blood sample will be taken every two hours. If cortisol levels rise a little, it is a normal phenomenon. However, if this level increases more and more, the diagnosis of Cushing’s disease is confirmed.

Another way to detect the disease is with the help of an injection of steroidal dexamethasone. In a healthy animal, cortisol levels drop within a few hours due to the steroid that suppresses the adrenal, so the automatic cortisol production. If the disease is present, cortisol levels do not decrease following this test.

Not all dogs respond in the same way to high cortisol concentrations, so making a diagnosis of hyperadrenocorticism is a real challenge.

However, the dosage of cortisol in the blood is vital for the diagnosis and monitoring of dogs with Cushing’s syndrome.

Specific endocrine functional tests: Cortisol-creatinine ratio, low-dose dexamethasone suppression test, ACTH stimulation test.

• The cortisol/urinary creatinine ratio is a rapid screening test for suspected hyperadrenocorticism, which may rule out this diagnosis. This test is recommended because of its high sensitivity, almost all dogs with this syndrome are detected positive.
• The low-dose dexamethasone suppression test is based on the fact that the administration of exogenous glucocorticoids suppresses the production of ACTH from the pituitary and, therefore, cortisol from the adrenal gland. Suppression persists in normal dogs for about 16 to 24 hours. The advantage of this test is that it can differentiate pituitary and adrenal Cushing syndrome.
• The ACTH stimulation test is based on the assumption that hyperplastic or neoplastic adrenal glands often have abnormally high reserves of cortisol and therefore they respond excessively to maximum stimulation with ACTH. The disadvantage of this test is that it does not provide the necessary information to classify the type of Cushing’s syndrome: Pituitary or adrenal.

ACTH – the adrenocorticotropic hormone is a hormone secreted by the pituitary gland, which stimulates the formation and secretion of glucocorticoids, especially cortisol, in the adrenal cortex.

Treatment in Cushing’s disease

To be able to treat this disease, it is essential for your veterinarian to be able to detect whether it is accompanied by any type of tumor and where it is located. It is estimated that up to 90% of cases of Cushing’s disease are accompanied by a pituitary tumor. Also, depending on the cause of this disease, your veterinarian will prescribe treatment in this regard. If corticosteroid medications are responsible, they will be removed from the animal’s medication, but gradually. If removed suddenly, the animal could be in danger.

If it is a tumor, your veterinarian will prescribe a drug for its reduction for a period of several months, and after the surgery has been done.

Hyperadrenocorticism can interfere with the quality of life of both the dog and the owner. If patients are not treated, they become more susceptible to life-threatening complications such as urinary tract infections, diabetes, pancreatitis, thromboembolism, or systemic hypertension. Treatment of canine hyperadrenocorticism improves clinical signs and reduces the risks associated with the disease.

In the case of adrenal-dependent hyperadrenocorticism (ADH), the treatment of Cushing in dogs includes two options:

Surgical: For adrenal tumors that cause hyperadrenocorticism, excision is recommended. If the tumor cannot be removed surgically, medical treatment is used.

Medicinal: Vetoryl, Lysodren, Anipryl, and Nizoral are the options for the treatment scheme. Typically, Vetoryl and Lysodren are the most commonly used.

Vetoryl Capsules reduce cortisol production. 10-14 days after starting the treatment scheme, repeat the tests again;

Lysodren is chemotherapy for human use that destroys the adrenal gland layers that produce cortisol but is not effective in peripheral Cushing’s syndrome.

Anipryl is recommended only in cases of pituitary-dependent disease without complications;

Nizoral/Ketoconazole inhibits cortisol secretion and blocks androgen receptors.

Prognosis of Cushing’s disease in dogs

Any treatment given to animals for Cushing’s disease can have side effects, which is why you should prepare yourself for what will follow. You need to pay attention to all the symptoms your dog may have, from lack of energy, lack of appetite, vomiting, to difficulty in walking. All of these are side effects of the prescribed treatment, which means you should consult your veterinarian. Throughout the course of treatment, but also sometime after it is completed, you should monitor the level of cortisol in the dog’s blood. If its level drops too much, the animal risks getting sick again.

The prognosis and progression of the disease in dogs with Cushing’s syndrome can be satisfactory, especially in the cases that were diagnosed before the aggressive clinical signs occurred, such as insulin resistance or kidney disease. It is extremely rare for this disease to be cured, but with the right treatment, the dog can live for many years, having an almost normal life. The average life span after a dog was diagnosed with Cushing’s disease is about 3 years.

Preventing Cushing’s disease in dogs

In order to prevent this disease, the animal has to avoid overconsuming drugs containing corticosteroids. It is the only way to prevent the disease because the rest of the causes are natural and can occur no matter what we do.