What is Cushing's disease in dogs?

Cushing's disease in dogs can be a serious threat to your pet's overall health and longevity. In today's blog, our Mechanicsburg veterinary team explains the causes of this serious condition, as well as complications that can arise and treatments.

What causes Cushing's disease in dogs?

If your dog has a pituitary tumor, this can cause an excess of cortisol in its body, resulting in Dependent Cushing's disease or Hyperadrenocorticism. This serious condition can put your dog at risk for a variety of other diseases and conditions.

Is Cushing's disease fatal in dogs?

Cushing's disease (hyperadrenocorticism) is a serious health condition that occurs in dogs when the adrenal glands overproduce cortisol (cortisol). Excess cortisol can put a dog at risk for a variety of serious conditions and illnesses, ranging from kidney damage to diabetes, and can be fatal.

Does Cushing's cause breathing problems in dogs?

Blood clots that block the lungs' vessels, known as thromboembolism, can make breathing difficult. Cushing's disease is more common in dogs, and the condition can lead to life-threatening heart and lung problems.

Symptoms & Complications of Cushing’s Disease

Cushing's symptoms are often vague, making it critical to see your veterinarian as soon as possible if you notice any of them. Cushing's disease increases the risk of kidney damage, high blood pressure, blood clots, and diabetes in dogs. If your dog has Cushing's disease, it may exhibit any of the following symptoms:

How is Cushing's disease diagnosed in dogs?

Your vet will only be able to use blood tests to diagnose Cushing’s disease. The tests used to diagnose the cause of your dog's symptoms can include but are not limited to, a urinalysis, urine culture, adrenal function tests (low dose and high dose dexamethasone suppression test, and potentially ACTH stimulation test), full chemistry panel, and complete blood panel.

At Silver Springs Clinic in Mechanicsburg, our vets have access to state-of-the-art diagnostic imaging tools and treatment methods to identify and manage these issues.

In combination with a physical exam to look for signs of the disease, these tests can help your vet arrive at a diagnosis. Keep in mind that adrenal function tests can result in false positives when another disease with similar clinical signs is present.

Though an ultrasound can aid in the diagnosis of Cushing's disease, it is more useful in ruling out other conditions that could be causing your dog's symptoms. Tumors in the spleen or liver, bladder stones, gallbladder disease, gastrointestinal disease, and chronic inflammatory liver disease can all cause similar symptoms.

An ultrasound may not be able to detect adrenal enlargement, since patient movement or interference due to gas in the overlying intestine can influence test results. Most vets prefer magnetic resonance imaging (MRI) - an effective but expensive diagnostic imaging procedure that allows your vet to assess your dog’s adrenal glands.

What are the medications for Cushing's disease in dogs?

There are two main drugs that can be used to treat Cushing disease in your dog. A form of the insecticide DDT (drug names include Lysodren® and mitotane) can destroy the cells in the adrenal glands that produce cortisol. In addition, medications like trilostane help reduce the amount of cortisol produced by the adrenal glands. This is achieved by inhibiting specific steps in the cortisol production process. Trilostane and mitotane are both effective at treating and controlling the symptoms of Cushing's disease.

Discuss which may be the most effective treatment for your dog, and follow your vet's instructions diligently.

After the induction phase with mitotane, you will need to bring your dog to our clinic for an ACTH stimulation test, which “stimulates” the adrenal gland. This test can be done on an outpatient basis to help your vet determine the starting point for a mitotane maintenance dose. If the mitotane works, the adrenal gland will not overreact to the stimulation.

Though you won’t need an induction phase for trilostane, dogs often require small adjustments to trilostane doses early in treatment. Over their lifetime, routine monitoring of blood tests may indicate that other adjustments need to be made. How well clinical symptoms of Cushing’s disease can be controlled can also mean changes are required.

No matter which medication your vet feels is best for your pooch, your dog will likely be on it for the long term and may require periodic adjustments in doses. He or she will need to come in for ACTH stimulation tests as often as monthly until we can control the excessive production of cortisone. Regular testing will be needed.

Could there be any adverse reactions to my dog's treatment for Cushing's?

Cushing's disease symptoms can be reduced with careful monitoring and long-term management. Medication for Cushing's disease can be very effective in treating the condition when given in the correct dosage. However, the incorrect dose can result in mild to severe side effects.

With blood test monitoring, it’s unusual for adverse reactions to appear. But if they do, they may include the following:

• Lethargy or depression
• General weakness
• Stomach upset (Gastrointestinal symptoms - diarrhea or vomiting)
• Picky eating or decreased appetite

If you spot any of these symptoms, discontinue the medication and call your veterinarian right away.

While medication costs and the need for frequent blood monitoring can make Cushing’s disease expensive to manage, diligent follow-up care and monitoring for adrenal function can make for a good prognosis.

Pets who do not receive adequate monitoring and follow-up often experience relapses and severe illness or death, as a result of complications.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.