Living with a dog diagnosed with Cushing's disease can be challenging, but understanding the condition can help you better care for your furry friend. Cushing's disease is a common endocrine disorder in dogs, affecting about 1 in 100 canines.
The condition causes the adrenal gland to produce too much cortisol, leading to a range of symptoms.
Dogs with Cushing's disease often experience increased thirst and urination, as their bodies try to flush out excess cortisol.
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Understanding Cushing's in Dogs
Cushing's Disease causes a dog's adrenal glands to produce too much cortisol, a stress hormone that puts stress on the cardiovascular system, causes insulin resistance, and weakens the immune system.
Dogs with Cushing's Disease often exhibit symptoms such as eating and drinking a lot, panting, and peeing a lot in the short term.
The most common cause of Cushing's disease in dogs is a pituitary gland adenoma, a benign tumor that grows slowly and secretes ACTH, which stimulates the adrenal glands to produce cortisol.
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Cushing's disease can also be caused by an adrenal gland mass, such as a benign adenoma or a cancerous carcinoma, or by long-term use of corticosteroids like prednisone.
Certain breeds, including Poodles, Yorkshire Terriers, and Dachshunds, may be predisposed to Cushing's disease due to genetics.
Here are the common clinical signs of Cushing's Disease:
- Polydipsia (excessive thirst)
- Polyuria (excessive urination)
- Polyphagia (excessive appetite)
- Heat intolerance
- Lethargy
- Abdominal enlargement (potbellied appearance)
- Muscle weakness
- Weight gain
- Panting
- Alopecia (hair loss, especially on the trunk)
- Hyperpigmentation (darkening of the skin)
A definitive diagnosis of Cushing's disease can be challenging, but it's often based on a combination of clinical signs, lab results, and imaging tests.
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Predilection and Clinical Signs
Cushing's disease tends to affect older dogs, with increased odds past the age of twelve. Both forms of endogenous HAC have a predilection for older dogs, making age a significant risk factor.
Overweight dogs are also more likely to develop Cushing's disease. Both forms of endogenous HAC seem to develop more commonly in overweight dogs.
ADH tends to occur in middle to large breed dogs, with a predisposition to be in females 60-65% of the time. On the other hand, PDH occurs commonly in small dogs, particularly Dachshunds, Beagles, Poodles, Terrier breeds, and Miniature Schnauzers.
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The most common clinical signs of HAC include polydipsia, polyuria, polyphagia, heat intolerance, lethargy, abdominal enlargement, muscle weakness, weight gain, panting, alopecia, and hyperpigmentation. These symptoms are caused by cortisol interfering with antidiuretic hormones, leading to polyuria, and increasing appetite, resulting in polyphagia and weight gain.
Here's a summary of the common clinical signs of HAC:
- Polydipsia (excessive thirst)
- Polyuria (frequent urination)
- Polyphagia (increased appetite)
- Heat intolerance
- Lethargy
- Abdominal enlargement (potbelly appearance)
- Muscle weakness
- Weight gain
- Panting
- Alopecia (hair loss)
- Hyperpigmentation
Keep in mind that 5-10% of patients with HAC have concurrent diabetes mellitus, which may exhibit weight loss instead of weight gain.
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What Causes
Cushing's disease in dogs is often caused by a benign tumor in the pituitary gland, which secretes a hormone that stimulates the adrenal glands to produce cortisol.
This type of tumor is the most common cause of Cushing's disease, and it's a slow-growing one.
Dogs who receive corticosteroids, such as prednisone, to treat another medical condition can also develop Cushing's disease, known as iatrogenic Cushing's.
This is because the medication affects the body in a similar way to cortisol, and symptoms are typically reversible by discontinuing the medication under veterinary supervision.
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Certain breeds, including Poodles, Yorkshire Terriers, and Dachshunds, may be predisposed to Cushing's disease due to their genetics.
Cushing's disease predominantly occurs in middle-aged to older dogs, typically between 7 and 12 years old.
Approximately 85% of dogs with naturally occurring hyperadrenocorticism have pituitary-dependent hyperadrenocorticism, while 15% have a cortisol-producing adrenal tumor.
In dogs, a sex predilection has been reported, with approximately 75% of affected dogs being female.
However, some studies have failed to find an association with sex in dogs.
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Diagnosis
Diagnosis of Cushing's disease in dogs can be a complex process, but it's essential to get it right to ensure proper treatment. The diagnosis should be based on clinical signs, followed by supporting minimum database abnormalities, such as high cholesterol concentration or increased ALP activity.
A physical exam and a thorough conversation with your veterinarian about your dog's symptoms are the first steps in diagnosing Cushing's disease. If your veterinarian suspects Cushing's disease, diagnostic testing can be done.
Two main tests are used to diagnose Cushing's disease in dogs: the low-dose dexamethasone suppression test (LDDST) and the ACTH stimulation test. The LDDST involves administering a low dose of dexamethasone to your dog and then measuring cortisol levels at specific intervals.
The ACTH stimulation test involves injecting synthetic ACTH into your dog and then measuring cortisol levels before and after the injection. An abnormal response could suggest Cushing's disease.
Urinalysis and urine culture might also be part of the diagnostic process to rule out other possible conditions. The urine cortisol:creatinine ratio (UCCR) is a highly sensitive test to differentiate healthy dogs from those with hyperadrenocorticism.
Here's a summary of the diagnostic tests used to diagnose Cushing's disease:
Note that no single test or combination of tests is 100% accurate to diagnose Cushing's disease. A diagnosis should be based on a combination of clinical signs, laboratory abnormalities, and diagnostic test results.
Treatment and Management
Surgery is an option for Cushing's disease, but it's not always the best choice due to potential complications and limited availability.
Medical management is a viable alternative, and two main drugs are used to treat the condition: mitotane and trilostane.
Mitotane works by selectively destroying the cortisol-producing cells in the adrenal glands, while trilostane blocks the production of cortisol.
Regular blood tests and monitoring are necessary while using either medication, and the dosage may need to be adjusted over time.
A low-fat diet is typically recommended for dogs with Cushing's disease, and potential diet options include Royal Canin Adult Low Fat Diet or Hill's Prescription Diet i/d.
Dogs with Cushing's disease should have continued monitoring, such as bloodwork and ACTH stimulation tests, for the remainder of their life to ensure the medication dosage is appropriate and symptoms are controlled.
Medications like mitotane and trilostane require regular checkups and blood tests to ensure the dosage is correct and symptoms are under control.
Here are some common medications used to treat Cushing's disease in dogs:
- Mitotane: Selectively destroys cortisol-producing cells in the adrenal glands.
- Trilostane (Vetoryl): Blocks the production of cortisol.
Regardless of the medication chosen, it's essential to closely follow your veterinarian's instructions to ensure the best possible outcome for your dog.
Prognosis and Lifespan
The prognosis for dogs with Cushing's Disease varies, but treatment can prolong survival time. In one study, medical management with trilostane increased survival time compared to no treatment. Median survival for dogs that underwent a unilateral adrenalectomy was 992 days from discharge.
A dog's survival time can vary significantly, with an average of about two years. Only 10% of patients live beyond four years. However, with proper treatment and care, many dogs can live normal lives for several years.
Cushing's Disease can lead to complications after a year or two if left untreated. These complications can include an increased risk of infection, a higher likelihood of developing diabetes, and reduced life expectancy. With treatment, these risks can be mitigated.
The effectiveness of treatment depends on various factors, including the dog's age, overall health, and the type of treatment used. Some treatment options, like radiation therapy, can impact the prognosis and should be discussed with a veterinarian.
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Here are some general statistics on the survival time of dogs with Cushing's Disease:
It's essential to work closely with a veterinarian to develop a tailored treatment plan and monitor the dog's condition regularly. With proper care and management, many dogs with Cushing's Disease can live normal lives for several years.
Other Considerations
Dogs with Cushing's disease can live for several years with proper treatment, but their lifespan is often shorter than that of dogs without the condition.
Their weight can fluctuate significantly, making it essential to monitor their diet and exercise to prevent obesity and related health issues.
With a life expectancy of 1-3 years after diagnosis, it's crucial to make the most of the time you have with your furry friend.
Other Conditions
Cushing's Disease can have a significant impact on your dog's overall health, leading to various medical conditions and complications.
Kidney problems are a common side effect, caused by high blood pressure and protein loss through the urine, which can lead to kidney infections and bladder stones.
The liver can also be affected, with vacuolar hepatopathy causing abnormal holes to develop in liver cells, potentially leading to liver dysfunction.
Diabetes is another common issue, as excessive cortisol can disrupt blood sugar regulation, increasing the risk of developing diabetes.
Chronic skin conditions are a common symptom, including thin or fragile skin, hair loss, and recurrent skin infections.
High blood pressure and blood clots are also potential complications, with even life-threatening conditions like pulmonary thromboembolisms possible in severe cases.
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Iatrogenic
Iatrogenic is a term that refers to a condition caused by medical treatment. In dogs, Iatrogenic Cushing's Disease is a serious condition that can be caused by long-term use of steroids.
This condition occurs when the excessive use of steroids artificially elevates cortisol levels in the body. Steroids are commonly prescribed to treat inflammation and certain medical conditions.
Managing Iatrogenic Cushing's Disease requires the guidance of a veterinarian. They may recommend gradually reducing the dosage of your dog's steroid medication while monitoring its health.
This can help your dog's adrenal glands to regain normal function and prevent further complications associated with elevated cortisol levels.
Frequently Asked Questions
What are the signs of worsening Cushing's disease in dogs?
Watch for signs of worsening Cushing's disease in dogs, including increased thirst, urination, appetite, and panting, as well as skin issues and hair loss. If you notice any of these symptoms, consult your veterinarian for proper diagnosis and treatment
When should you euthanize a dog with Cushing's disease?
Euthanasia is typically considered when a dog with Cushing's disease can no longer walk due to permanent paraplegia. This usually occurs within 6 months to 3 years after diagnosis.
What are the final stages of Cushing's disease in dogs?
**Final Stages of Cushing's Disease in Dogs:** If left untreated, Cushing's disease can lead to severe polydipsia and polyuria, frequent urinary tract infections, and a weakened immune system. These symptoms can indicate a worsening of the disease, requiring prompt veterinary attention.
Sources
- Canine Hyperadrenocorticism (iowaveterinaryspecialties.com)
- 2023 AAHA selected endocrinopathies of dogs and cats guidelines (doi.org)
- Survival of dogs with pituitary-dependent hyperadrenocorticism treated twice daily with low doses of trilostane (doi.org)
- Effects of disease on the results of diagnostic tests for use in detecting hyperadrenocorticism in dogs (doi.org)
- Frequency and risk factors for naturally occurring Cushing's syndrome in dogs attending UK primary-care practices (doi.org)
- Epidemiology of hyperadrenocorticism among 210,824 dogs attending primary-care veterinary practices in the UK from 2009 to 2014 (doi.org)
- Canine hyperadrenocorticism associations with signalment, selected comorbidities and mortality within North American veterinary teaching hospitals (doi.org)
- Cushing's syndrome—an epidemiological study based on a canine population of 21,281 dogs (doi.org)
- A comparative study by age and gender of the pituitary adenoma and ACTH and alpha-MSH secretion in dogs with pituitary-dependent hyperadrenocorticism (doi.org)
- Surgical treatment of adrenocortical tumors: 21 cases (1990-1996) (doi.org)
- Adrenalectomy in dogs with adrenal gland tumors: 52 cases (2002–2008) (doi.org)
- Vetoryl (chewy.com)
- Cushing's Disease in Dogs: Causes, Signs & Treatment (bettervet.com)
- FDA (fda.gov)
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