What is Cushing's Disease in Dogs?
Cushing's disease, formally known as hyperadrenocorticism, is a serious health condition caused by an excessive concentration of the stress hormone cortisone in your pup's body. Cushing's disease weakens your dog's immune system and increases their risk of developing serious conditions such as diabetes and kidney disease.
While there are two types of Cushing's diseases seen in our canine companions, pituitary-dependent Cushing's disease is the most common, making up about 80-85% of all cases of Cushing's seen in dogs. This form of the disease is caused by the development of benign or malignant tumors in the pituitary gland at the base of your dog's brain.
The remaining 15-20% is made up of cases of Cushing's disease caused by the growth of tumors in one or both of your dog's adrenal glands.
How can I Tell if My Dog has Cushing's Disease?
Symptoms of Cushing's can be vague, and can also be an indication of other common conditions seen in dogs. This makes it essential that your furry friend see a qualified veterinarian as soon as possible to diagnose the issue. Dogs with Cushing’s disease face an increased risk of kidney damage, high blood pressure, blood clots and diabetes. If your dog is suffering from Cushing's they may display one or more of the following symptoms:
- Hair loss
- Excessive thirst or drinking
- Increased urination
- Thin, fragile skin
- Muscle weakness
- Pot belly, enlargement of the abdomen
- Excessive panting
- Reduced activity
- Increased appetite
- Recurring skin infections
Contact your veterinarian right away if your four-legged friend is displaying any of the symptoms listed above.
How is Cushing's Disease Diagnosed?
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 VRCC in Englewood, our board certified Internal Medicine Specialist are experienced in the diagnosis and treatment of a wide range of internal medicine conditions. We 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 may help diagnose Cushing’s disease, it’s more valuable in helping to rule out other conditions that could be causing your dog’s symptoms. Other diseases that may cause similar symptoms include tumors in the spleen or liver, bladder stones, gallbladder disease, gastrointestinal disease, chronic inflammatory liver disease.
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 is the Treatment for Cushing's Disease in Dogs?
There are two main drugs that can be used to treat your pup's Cushing’s disease. A form of the insecticide DDT (drug names include Lysodren® and mitotane) can destroy the cells that produce cortisone in the adrenal glands. Also, medications such as trilostane help decrease the amount of cortisone that the adrenal glands produce. This accomplishes this goal by inhibiting specific steps in the cortisone production process. Both trilostane and mitotane can effectively treat and control the signs 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 is working, 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.
Are there any Common Adverse Reactions to Treatment for Cushing's Disease?
Symptoms related to Cushing’s disease can be minimized with diligent observation and long-term management. When provided in the proper dosage, medication for Cushing’s disease can prove very effective in treating the condition. However, the wrong dose can cause mild or severe side effects.
With blood test monitoring, it’s unusual for adverse reactions to appear. But if they do, they may include:
- 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.
What is the Prognosis for Dogs with Cushing's Disease?
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.