FR
ENWhat is Cushing's syndrome?
Cushing's syndrome (hyperadrenocorticism, HAC) is caused by a chronic excess of cortisol in the body. Cortisol is vital in small amounts, but in prolonged excess it disrupts metabolism, the immune system, the skin, muscles, and vital organs. There are three distinct forms depending on where the problem originates.
Pituitary-dependent (PDH)
A (usually benign) tumor of the pituitary gland at the base of the brain secretes too much ACTH, which stimulates the adrenal glands to overproduce cortisol. This is the most common form.
Adrenal tumor (ADH)
A tumor forms directly on one adrenal gland (near the kidney). About half of these tumors are malignant (carcinomas). The tumor produces cortisol autonomously, without regulation.
Iatrogenic (medication-induced)
Caused by prolonged administration of steroid medications (prednisone, dexamethasone...). The body behaves as if it is overproducing cortisol. This form resolves with gradual tapering of the medication.
Predisposed breeds and profiles
Excess cortisol acts like a hammer on the entire body: it weakens muscles, thins the skin, overloads the liver, disrupts insulin, compromises immunity, and raises blood pressure. The longer the disease goes undiagnosed, the more complications accumulate; early diagnosis makes all the difference.
Signs and symptoms
Cushing's signs develop slowly, often over months, sometimes years. Many owners attribute them to normal aging. The progression is insidious: recognizing early signals allows you to act before complications set in.
Early stage
- •Increased thirst (polydipsia)
- •Frequent urination (polyuria)
- •Excessive appetite (polyphagia)
- •"Pot belly" (pendulous abdomen)
- •Recurrent skin infections (pyoderma)
Intermediate stage
- •Enlarged liver (hepatomegaly)
- •Thinning of the skin
- •Symmetric hair loss (trunk)
- •Excessive panting, lethargy
- •Very dilute urine
Advanced stage
- •High blood pressure
- •Easy bruising
- •Blackheads (comedones) on skin
- •Frequent urinary tract infections
- •Heat intolerance, muscle weakness
Excess cortisol acts on the entire body simultaneously. That is why Cushing's presents with so many varied symptoms: it is not several diseases, it is one hormone disrupting everything.
When to seek immediate help?
Certain Cushing's-related situations constitute veterinary emergencies. Bring your dog in immediately if you observe:
- Severe respiratory distress: uncontrollable panting, labored breathing, mouth breathing at rest
- Sudden collapse or inability to stand
- Intense or uncontrollable trembling
- Uncontrollable vomiting and diarrhea with prostration
- Intense pain: whimpering, hunched posture, reluctance to move
- Seizures or epileptic episodes
- Loss of consciousness or coma
How is the diagnosis made?
There is no single definitive test for Cushing's. The diagnosis relies on a combination of evidence: clinical presentation, specialized bloodwork, and imaging. The goal is threefold: confirm Cushing's, identify the form (pituitary or adrenal), and assess whether any tumor is benign or malignant.
Clinical suspicion
The presence of several characteristic signs (polydipsia, polyphagia, pot belly, symmetric hair loss, recurrent skin infections) in an older dog strongly suggests Cushing's. The veterinarian also takes a detailed medication history.
Specialized hormonal tests
Three main tests: the ACTH stimulation test (adrenal response capacity), the low-dose dexamethasone suppression test (cortisol suppression), and the urine cortisol/creatinine ratio (screening tool). None is perfect alone; they complement each other.
Imaging: ultrasound and CT scan
Abdominal ultrasound evaluates the size and appearance of both adrenal glands. An enlarged adrenal may indicate a tumor. CT scan (or MRI) is used to locate a pituitary or adrenal tumor, assess if it is benign or malignant, and look for metastases.
Distinguishing pituitary vs adrenal
The high-dose dexamethasone suppression test and imaging findings help differentiate the two forms. This is crucial: treatment and prognosis differ significantly depending on the form.
Treatment and management
Treatment aims to control excess cortisol and improve quality of life; a complete cure is not always possible. The approach depends on the form of Cushing's, the dog's general health, and the nature of the tumor.
Oral medications: first line
- Trilostane (Vetoryl®): blocks a key enzyme in cortisol production. Lifelong treatment, well tolerated, with regular blood monitoring.
- Mitotane (Lysodren®): selectively destroys cortisol-producing cells in the adrenal gland. Effective but requires a precise protocol.
- Monitoring is essential: regular ACTH stimulation tests to adjust dosing and prevent excessively low cortisol.
Surgical removal: selected cases
- Adrenal tumor: adrenalectomy (open or laparoscopic) by a veterinary surgery specialist. Can be curative if the tumor is benign and localized.
- Pituitary tumor: very complex surgery, rarely performed in North America. Reserved for specialized university centers.
- Full pre-operative workup: required to assess cardiovascular, renal, and coagulation status before any procedure.
Radiation: pituitary tumors
- Indication: large or symptomatic pituitary tumors (brain compression). Shrinks the tumor and improves neurological signs.
- Availability: limited to equipped veterinary university centers (Université de Montréal, US universities).
- Possible combination: often paired with oral medical treatment to control cortisol in parallel.
Complementary support
- Liver support: the liver is often enlarged and overloaded. Hepatoprotective supplements may be recommended.
- Phytotherapy / holistic: some holistic vets offer supplements under supervision. Never as a replacement for conventional treatment.
- Comorbidity management: treatment of hypertension, secondary diabetes, or recurrent urinary infections if present.
What to expect long-term?
Prognosis depends on the form of Cushing's, the dog's general condition, the nature of the tumor, and the response to treatment. The disease is not always curable, but it is often very controllable.
Rigorous veterinary follow-up is key. Regular check-ups allow dose adjustments, detection of side effects, and adaptation of the treatment plan as the disease evolves.
Home management tips
Comfort adjustments for your dog
Elevated water and food bowls with constant access to fresh water (dogs drink a lot)
Measured, regular meals to prevent obesity (appetite is excessive)
Cool resting spots; Cushing's dogs struggle in heat
Absorbent bedding or dog diapers for nighttime incontinence
Frequent outings to urinate, especially in the evening (significant polyuria)
Gentle physical activity adapted to the dog's energy level
Essential actions
- Strictly follow the treatment schedule (Trilostane or Mitotane), never double a missed dose
- Daily monitoring: appetite, water intake, urination, defecation, energy
- Weigh the dog regularly to track progress
- Keep all blood monitoring appointments: essential for dose adjustment
- Minimize stress (loud noises, turbulent children, routine changes)
- Avoid steroid medications (prednisone, cortisone) unless explicitly prescribed
- Plan frequent walks if polyuria is significant
- Consult promptly if: sudden weakness, vomiting, anorexia, prostration
- Consider a referral to an endocrinology or internal medicine specialist
- Never change the dosage without consulting your veterinarian
Never do
- Double a missed dose: simply take the next scheduled dose normally
- Stop treatment abruptly without veterinary guidance (risk of Addisonian crisis)
- Give prednisone or other steroids without a prescription
- Ignore signs of under-treatment (symptom relapse) or over-treatment (weakness, anorexia)
Frequently asked questions
My dog has been drinking and eating a lot for a few months. Could it be Cushing's?
Is Cushing's disease painful for my dog?
Will Trilostane treatment cure my dog?
My dog has Cushing's and also diabetes. Are they related?
What is the difference between pituitary and adrenal Cushing's?
Does my dog need surgery?
This guide is provided for informational and educational purposes only. It does not constitute veterinary medical advice and is not a substitute for a consultation with a qualified veterinarian. Every animal is unique and their health must be evaluated individually. If you have concerns about your pet's health, contact our clinic or consult a veterinarian promptly.