Cushing’s Disease in Dogs

Cushing’s disease is a commonly diagnosed disorder in older dogs. It’s mostly caused by a benign type of tumor on the pituitary gland that controls the function of the adrenal gland and its production of the hormone cortisol. The symptoms of Cushing’s disease are sometimes not easy to spot, but it’s very important that, when you notice the changes in the dog, you inform the vet in order to do further tests and to make an accurate diagnosis.

If the dog has this disease, he will have to use a certain therapy and visit a veterinarian periodically for the rest of his life. This doesn’t mean that he cannot have a normal and happy life. Read on to find out what is the difference between Cushing’s syndrome and Cushing’s disease, what the symptoms of Cushing’s disease are, how it is diagnosed, what the treatment looks like, and how the disease will affect the life of your dog and your life.

What Is Cushing’s Disease in Dogs – The Difference Between Cushing’s Syndrome and Cushing’s Disease

Cushing’s syndrome is a condition where there is an increased amount of the hormone cortisol in the blood of the dog. Causes of the syndrome can be different. The most common cause is a problem with the pituitary gland, and this type is called Cushing’s disease. There are several other causes of Cushing’s syndrome, like an adrenal tumor, which is known as adrenal dependent Cushing’s syndrome. The third cause is the use of steroid drugs for a long period of time; this type is known as Iatrogenic Cushing’s syndrome.

Cushing’s disease is a specific type of Cushing’s syndrome and the most common form that occurs in dogs, over 80%, and therefore, it’s most often mentioned in veterinary literature. Cushing’s disease is a type of hyperadrenocorticism (excessive secretion of adrenocortical hormones) caused by a pituitary tumor. The tumor causing this disease is in most cases a benign type that doesn’t grow, and it affects the pituitary gland by disrupting its work. The result of such a tumor is an increased secretion of ACTH hormone, which stimulates increased production of cortisol in the adrenal cortex.

Cortisol is a stress hormone that is normally produced in the body and helps the dog’s body when it finds itself in stressful situations and daily in the metabolism of proteins, fats, and carbohydrates. In Cushing’s disease, the level of cortisol in the blood is constantly increased, which results in a disorder of the dog’s metabolism as well as disorders of other processes in the dog’s body.

This condition can disrupt the functioning of the cardiovascular system and lead to an increase in blood pressure (hypertension). It can also cause nervous system disorders and muscle weakness. Elevated hormones affect the filtration of blood that takes place in the kidneys, which results in frequent urination, increased possibility of infection of the urinary tract, as well as increased water intake.

All forms of Cushing’s syndrome cause increased levels of cortisol in the blood and give similar symptoms. Regardless of the cause, when it comes to therapy, sometimes the same medications are used in different types of Cushing’s syndrome, so often the terms Cushing’s syndrome and Cushing’s disease are mixed.

Symptoms of Cushing’s Disease in Dogs

This disease occurs in middle-aged and older dogs, rarely in younger ones. Also, Cushing’s disease develops gradually and slowly, and the symptoms at the very beginning of the disease are not easy to notice.

Some of the symptoms of Cushing’s disease in dogs are:

• Excessive thirst (polydipsia)
• Increased urination (polyuria)
• Increased appetite (polyphagia)
• Thinner skin
• Hair loss
• Susceptibility to skin infections
• Decreased activity and fatigue
• Enlarged stomach or pot belly

It’s not easy for vets to diagnose Cushing’s disease, so it’s very important that you observe your dog. The symptoms mentioned above are not easy to spot, but any change that deviates from your dog’s normal behavior can be a sign that something is wrong. For example, if your dog usually pees 3 – 4 times a day and suddenly starts doing it 6 – 10 times a day, it indicates that there might be a problem. Also, excessive food intake creates a larger supply of fat in the abdomen, so due to metabolic and hormonal changes dogs with Cushing’s take on a specific appearance of thin limbs and pot belly If you notice any symptoms or changes mentioned above in your dog, inform the veterinarian in detail about the dog’s health condition.

Breeds that are prone to Cushing’s disease:

• Dachshund
• Schnauzer
• Boxer
• Beagle
• Boston Terrier
• Yorkshire Terrier

Also, in the conducted gender-related study, females had a higher risk of developing Cushing’s disease than males.¹Carotenuto G, Malerba E, Dolfini C, Brugnoli F, Giannuzzi P, Semprini G, Tosolini P, Fracassi F. Cushing’s syndrome-an epidemiological study based on a canine population of 21,281 dogs. Open Vet J. 2019 Apr;9(1):27-32. doi: 10.4314/ovj.v9i1.5. Epub 2019 Feb 15. PMID: 31086762; PMCID: PMC6500859. But this hormonal disorder is one of the most common in dogs, and any dog can develop it, regardless of age, breed or gender.

Diagnosis of Cushing’s Disease in Dogs

This disease is not easy to diagnose, especially at the beginning because sometimes only one or two symptoms occur sporadically. If you suspect that your dog has Cushing’s disease, the most important thing is to monitor the abnormalities that occur in the dog so you can inform your vet about them.

Based on the symptoms, during a clinical examination, a vet will take blood and urine analyses. If the following parameters are increased, there is a good chance that the dog has Cushing’s disease:

• High blood pressure
• High liver enzymes
• Increased white blood cell count
• Proteins in urine
• Reduced urine-specific gravity (diluted urine)

If the results of blood and urine tests show increased parameters, it raises a strong suspicion of Cushing’s disease, and additional tests can be done in order to confirm the disease. Additional tests that veterinarians use to confirm the suspicion of Cushing’s disease are the following:

• Urine cortisol to creatinine ratio (UCCR)
• ACTH stimulation test
• Dexamethasone suppression test (LDDS)

The LDDS screening test is the most common test used by vets. For the purposes of these tests, the dog must stay with the vet for a few hours. Also, if the tests do not give the vet a clear picture, an additional CT or MRI of the dog can be done to accurately locate the problem, which in this disease is located on the pituitary gland.

Treatment for Cushing’s Disease in Dogs

In order to eliminate the cause of Cushing’s disease, it’s necessary to remove the tumor or lesion located on the pituitary gland. As this small gland is located in the dog’s brain, such surgery is very risky and complex and is still studied by specialized vet surgeons and is performed only by highly specialized institutions. Also, in addition to being risky, recovery from such a procedure takes a long time and is very expensive.

Another option is treating this disease with medications, and it is usually the vets’ treatment of choice. Medications for dogs with Cushing’s disease have shown to work very well, and the dog’s life returns to normal very quickly. Although dogs that use medications for this disease will have to take them for the rest of their lives, this option is again more acceptable and cheaper than surgery.

Currently, according to the FDA, two drugs can be used for this disease in the USA:
Anipryl (selegiline) is used exclusively for Cushing’s disease (pituitary-dependent).
Vetoryl (trilostane) is used to treat Cushing’s disease as well as Cushing’s syndrome.

Vets can also prescribe a drug called Lysodren (mitotane), which is intended for human chemotherapy. Vets can legally prescribe this human drug to dogs, but it’s better to use drugs intended for dogs because they can react differently if we give them drugs that are not intended for them.²Treating Cushing’s Disease in Dogs. FDA. Retrieved 24 November 2020.

These medications can be given to dogs only with a prescription and according to the vet’s instructions. By using the medication, the dog’s body and health are brought into balance, but there will never be a complete cure of the disease, and dogs with Cushing’s must use medication for the rest of their lives.

In order to determine the correct dose of medication, dogs often need to visit a vet more often at the beginning of therapy in order to determine the condition of the body with blood tests. Due to the fact that dogs with Cushing’s disease, as well as many other permanent conditions, have to visit veterinarians more often, the question on the owner’s mind is often, how much will this all cost?

The prices of blood and urine findings vary depending on which components are involved, and they range from $150 to $250. Dexamethasone suppression test results cost from $30 to $50, blood cortisol findings from $20 to $30, and ACTH stimulation test from $150 to $200.

Treatment depends on the dose as well as the size of the dog. If the dog is of average size, the therapy can cost from $20 to $50 per month.

Conclusion

According to Washington State University College of Veterinary Medicine, Cushing’s disease, or pituitary-dependent hypercortisolism, is one of the increasingly diagnosed diseases with about 100,000 dogs diagnosed annually. This disease occurs gradually, and since the symptoms are not visible and frequent at the very beginning, it’s sometimes more difficult for vets to establish an accurate diagnosis. It’s very important that if you notice any of the symptoms in your dog, such as increased thirst, increased urination, general weakness, hair loss (alopecia), or a pot belly, contact your vet to do additional tests and to help the dog as soon as possible. If a veterinarian diagnoses this disease, your dog will have to take medication for the rest of his life and visit the vet regularly. To learn more about the treatment, please read the “Treatment for Cushing’s Disease in Dogs” section. And don’t worry, even with Cushing’s disease, your beloved dog can live a long and happy life.

Frequently Asked Questions (FAQs) About Cushing’s Disease

What Are the Final Stages of Cushing’s Disease in Dogs?

Excessive amounts of cortisol in the dog’s body after a long time disrupt the dog’s metabolism and the normal functioning of other systems. The dog is more prone to infections, especially urinary tract infections. Disorders of protein and carbohydrate metabolism leads to changes in the liver, such as an increase in liver volume and in liver enzymes. There are also changes in blood pressure and hormonal imbalance. If left untreated, the dog becomes weak, lethargic, gains weight in the abdomen, and weakens and loses weight in limbs. If left untreated, dogs with Cushing’s disease may die from the effects of the disease.

Is My Dog in Pain with Cushing’s Disease?

If the symptoms of this disease develop and become more frequent, it means that elevated levels of the hormone cortisol in the blood begin to be harmful to organs and to systems in the body, and the dog may feel pain and weakness. To learn more about the symptoms of this disease, please read the section 'Symptoms of Cushing’s Disease in Dogs.'

What Is the Life Expectancy of a Dog with Cushing’s Disease?

If the disease is treated according to the recommendations of a vet, and treatment is accompanied by regular examinations, this disease should not affect the life expectancy of a dog. However, if a disease is caused by a malignant tumor of the pituitary gland, which is very rare, the prognosis is unfavorable. Such tumors grow and have bad effects on the brain and spread to other organs and shorten the life of a dog.

What Is the Best Treatment for Cushing’s Disease in Dogs?

There are two options for treating Cushing’s disease. The first is surgery, in which the cause of the disease can be removed, most often as a benign tumor on the pituitary gland. As this is a very demanding operation that can only be performed by highly specialized institutions and experts, there are a lot of risks, and recovery is long and difficult. The second option is medication treatment, which is the most common choice for Cushing’s disease therapy. Dogs must take prescribed medication for the rest of their lives under the obligatory supervision of a veterinarian. To learn more about the treatment of this disease, please read the section 'Treatment for Cushing’s Disease in Dogs.'