Cushing’s Disease in Dogs: What You Should Know About It
Cushing’s disease in dogs is a dangerous condition that primarily affects canines in their middle and elderly years. When your dog’s body produces too much cortisol, it develops Cushing’s syndrome.
Cortisol aids in stress management, weight control, infection resistance and blood sugar regulation. However, too much or too little might create problems.
Cushing’s disease, also known as hypercortisolism or hyperadrenocorticism, is challenging to diagnose, as it shares symptoms with other conditions. The purpose is to inform your veterinarian of any changes in your pet’s behavior.
Let’s take a closer look into Cushing’s disease in dogs, its forms and symptoms, treatment and care.
Table of Contents
- What Is Cushing’s Disease in Dogs?
- What Causes Cushing’s Disease?
- Which Are the Clinical Signs of Cushing’s Disease in Dogs?
- How to Diagnose Cushing’s Disease?
- How to Treat Cushing’s Disease in Dogs?
- How Long Do Dogs with Cushing’s Disease Live?
- The Takeaway
- Nutrition Strength Adrenal Support for Dogs
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What Is Cushing’s Disease in Dogs?
Cushing’s disease in dogs, also known as hyperadrenocorticism, is a disorder in which the body’s cortisol levels are abnormally high. Cortisol is a natural steroid produced by the body, and it is essential for many basic activities.
The adrenal glands are small glands that sit adjacent to the kidneys and create cortisol, adrenaline and a variety of other hormones that produce cortisol.
There are two forms of hyperadrenocorticism in dogs: pituitary-dependent (PDH) and adrenal-dependent (ADH). Like many other hormone functions in the body, the amount of hormone produced is tightly regulated.
The pituitary gland in the brain produces a hormone called adrenocorticotropic hormone (ACTH). This hormone controls cortisol production from the adrenal glands.
When enough cortisol has been released into the bloodstream, the adrenal glands reduce the quantity of cortisol produced, resulting in a drop in ACTH production.
What Causes Cushing’s Disease?
Cushing’s in dogs are divided into three categories, each with its own etiology. Each form of cancer is treated differently and has a different prognosis (expected outcome).
Tumor of the Pituitary Gland
Cancer of the pituitary gland is the most prevalent cause of canine Cushing’s disease (85 – 90 percent of cases) (located at the brain base). The tumor might be benign (harmless) or malignant (harmful, cancerous).
The pituitary gland produces too much of a hormone called ACTH, which encourages the adrenal glands to create cortisol. When the pituitary detects elevated cortisol levels, it makes less ACTH, which reduces cortisol production.
Pituitary gland tumors may range in size from microscopic to big. Other clinical indications may be present depending on the size of the cancer since a giant tumor may push on or interfere with surrounding tissues.
With proper medicine and adrenal gland activity management, many dogs with Cushing’s disease may enjoy daily lives for many years. If the pituitary tumor spreads, it will impact the brain, causing neurological symptoms and a poor outlook for the dog.
Tumor of the Adrenal Gland
A benign or malignant tumor of the adrenal gland itself might cause Cushing’s disease (adenoma or carcinoma, respectively). If the tumor is benign, it may be surgically removed and the condition will be cured. If the tumor is cancerous, surgery may provide temporary relief but a poor prognosis.
Cortisol Overproduction Due to Steroid Usage
Iatrogenic Cushing’s disease is the third type of condition. This condition develops when an oral or injectable steroid is used in excess. Although the steroids were usually provided for a good purpose, their overuse caused damage to the patient in this instance.
Which Are the Clinical Signs of Cushing’s Disease in Dogs?
Cushing’s disease symptoms vary greatly from dog to dog. The most frequent symptom is an increase in thirst and urination. Also, your dog may seem plump around the abdomen yet skinny in the limbs because cortisol induces muscular weakening and breakdown.
Some dogs seem frail throughout, as though their muscular mass is eroding. Hair loss is quite common, particularly on the back and tail.
Cortisol affects sugar metabolism in the body. If your dog is diabetic, his sugar levels will become uncontrollable and challenging to manage if he gets Cushing’s disease. When Cushing’s illness is detected, some dogs may acquire diabetes, either temporarily or permanently.
Cushing’s illness may also result in reversible liver abnormalities. Cushing’s disease in dogs is often suspected when regular blood testing reveals elevated liver enzymes.
Urine tests might show that the urine is more dilute than usual. Cushing’s disease may also cause a protein to flow into the urine.
If left untreated, Cushing’s disease in dogs may lead to life-threatening complications. Because cortisol influences insulin action, patients with diabetes may get gravely unwell.
Excess cortisol may stress the kidneys, resulting in blood pressure irregularities and substantial protein loss. Cushing’s disease also increases the risk of a blood clot developing in the wrong place and obstructing a major blood artery. Thankfully, these life-threatening effects are uncommon.
How to Diagnose Cushing’s Disease?
When Cushing’s disease in dogs is suspected, routine tests such as a complete blood count (CBC), chemical profile and urine analysis are often performed. These tests are used to examine any changes that may have happened due to Cushing’s disease and the patient’s general health.
Cushing’s disease in dogs may be diagnosed using a variety of blood tests. No one test is 100 percent correct since Cushing’s disease is a hormonal disorder, and hormones vary due to stress and other diseases.
As a result, confirming Cushing’s diagnosis might require two tests. Cushing’s disease cannot be ruled out by a single negative blood test. It might be aggravating to repeat costly tests to confirm a diagnosis.
An ACTH stimulation test is a 1 – 2 hour test that measures cortisol levels before and after administering a stimulant. The stimulant will cause an excessive reaction in dogs with Cushing’s illness. Once treatment has begun, an ACTH stimulation test assesses responsiveness.
The cortisol response to a hormone suppressing medicine is measured in an 8-hour Dexamethasone suppression test. Dexamethasone is a synthetic version of cortisol that causes cortisol levels in normal dogs to decline. At first, the level may reduce in a dog with Cushing’s disease, but it will rise faster than predicted.
The quantity of cortisol emitted into the urine is measured by the cortisol to creatinine ratio. Excess cortisol is excreted in a dog’s urine with Cushing’s disease. This is a screening tool for Cushing’s disease in dogs.
However, it is not a conclusive test. If the urine cortisol to creatinine ratio suggests Cushing’s disease, most dogs will require a follow-up blood test.
An abdomen ultrasound is often used to determine the size and structure of the adrenal glands, particularly when an adrenal tumor is suspected. It’s also a fantastic way to see whether your liver or other organs have been impacted by Cushing’s illness.
How to Treat Cushing’s Disease in Dogs?
A medicine called Lysodren / mitotane has been the basis of Cushing’s therapy for decades. Lysodren works directly on the adrenal gland’s overgrown cells, causing them to die.
Patients with Cushing’s illness have more prominent adrenal glands than usual and Lysodren is toxic to these cells. The treatment for Cushing’s disease in dogs aims to make the adrenal gland incapable of releasing too much cortisol without causing it to drop too low.
Most dogs will get a daily Lysodren loading dosage for 7 – 10 days before returning for recheck blood testing. Depending on the findings of these tests, an additional loading time may be required, or the dog may be placed on Lysodren twice-weekly maintenance treatment.
As Lysodren works swiftly to reduce cortisol levels in the body, some dogs get unwell after the loading period. It’s critical to keep an eye on pets at home when they’re being loaded with Lysodren.
Contact your veterinarian if you observe lethargy, a loss of appetite, vomiting or diarrhea. Your dog may require a dose of prednisone or dexamethasone to raise cortisol levels. Hospitalization for fluids may be needed in rare cases. When administered by a qualified veterinarian, Lysodren treatment is relatively safe.
Nystatin (ketoconazole) is an antifungal medicine that inhibits the adrenal gland and only treats Cushing’s disease in rare cases. It is less effective than other medications for controlling Cushing’s disease. Still, some doctors prefer it because it lowers cortisol gradually rather than quickly, like Lysodren.
Cushing’s disease is also treated with anipryl (l-depranyl). It causes a slow drop in cortisol levels, similar to ketoconazole. It is sometimes used when close monitoring is not possible.
Both nystatin and anipryl are seldom suggested since they induce less predictable and effective treatment of Cushing’s disease.
Trilostane is a relatively new medicine for Cushing’s disease. It is presently the only FDA-approved medicine for Cushing’s disease therapy. As a result, it is often the first medicine prescribed by veterinarians.
Studies have shown that it is safe and effective in treating Cushing’s disease. This indicates that adverse effects are uncommon and that blood tests show that serum cortisol levels are dropping as expected.
This therapy increases the number of individuals with chronic clinical signs of Cushing’s disease, despite adequate cortisol management in blood tests. As a result, several physicians recommend Lysodren, a non-FDA authorized medicine, over trilostane.
Drug selection is often complex, and it is ultimately up to the patient’s family to make an educated decision. Because trilostane inhibits the synthesis of all adrenal hormones, it must be administered by the patient family members with caution.
Surgery to remove the tumor may be required if Cushing’s disease is caused by an adrenal tumor. Some of these tumors are cancerous. Thus further hospitalization in a clinic for Cushing’s treatment dogs may be necessary.
Pituitary-dependent patients get radiation therapy. Cushing’s disease in dogs has been found to alleviate or eliminate neurological symptoms and the prognosis when treated early. In these patients, the median survival duration is 743 days.
How Long Do Dogs with Cushing’s Disease Live?
The prognosis for Cushing’s disease in dogs is determined by whether the condition is pituitary-dependent or non-pituitary-dependent, as well as if the tumor is benign or malignant.
Pituitary Tumors
Medical therapy may give long-term control with a decent quality of life if the etiology is a tiny pituitary tumor. Patients treated with trilostane or mitotane for pituitary-dependent Cushing’s illness had a median survival period of two to two and a half years.
The prognosis is worse if the pituitary tumor is significant and affects the brain and adjacent tissues.
Adrenal Tumors
In around half of the cases, adrenal tumors are benign, and surgical excision is curative. The other half of adrenal tumors are malignant. They have a terrible prognosis, mainly if they have already spread when diagnosed.
When treated with trilostane, the median survival duration is around one year. Patients with metastases of the initial tumor, local vascular invasion or a tumor larger than 5 cm in length have a poorer prognosis.
The Takeaway
Hyperadrenocorticism, often known as Cushing’s disease, is a hormonal condition in which the body creates too much cortisol. A tumor on the pituitary gland or the adrenal gland is the most common cause.
It causes a slew of symptoms that may seem unrelated at first. A potbellied look is one of the most apparent indications. While the condition cannot be prevented, early identifying it will help your dog’s prognosis.
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Image source: Wikimedia / droid.
