Adrenal Gland Cancer (Pheochromocytoma) in Dogs
Key takeaways
Pheochromocytomas in dogs are tumors arising from the cells of the adrenal medulla, which produce large amounts of hormones, such as epinephrine.
- Nearly half of all cases are asymptomatic and the tumor isn’t detected until a post-mortem examination
- Symptoms are vague and nonspecific and may include sporadic collapse, weakness, lethargy, muscle tremors, and difficulty breathing
- Diagnosis involves a physical examination, bloodwork, urinalysis, diagnostic imaging, and biopsy
- Treatment typically involves surgical removal of the affected adrenal gland, although medical management is used when surgery is not an option
- When the tumor is diagnosed early, the overall prognosis is guarded to fair, as many dogs experience complications during or after surgery that can be life-threatening
- Dogs that survive surgery have a good prognosis, with many living for years after surgical removal
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A closer look: Adrenal Gland Cancer (Pheochromocytoma) in Dogs
The adrenal glands sit on top of the kidneys and function to produce hormones involved in metabolism, stress response, immune responses, and blood pressure. This broad range of coverage means that disorders affecting the adrenal gland can have nonspecific and difficult to pinpoint symptoms.
Pheochromocytomas are tumors that develop in the adrenal medulla, the central part of the adrenal gland which produces hormones called catecholamines. The most well-known catecholamine is epinephrine, also known as adrenaline. The tumor cells produce high levels of epinephrine, which results in the symptoms associated with this condition.
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Risk factors
Adrenal tumors are more common in older dogs though they are uncommon overall. While pheochromocytomas are uncommon they can cause life-threatening symptoms or sudden death. Dogs showing symptoms require immediate veterinary attention to reduce their blood pressure and prevent serious complications.
Possible causes
No underlying cause has been identified for the formation of adrenal gland cancer.
Main symptoms
Most cases of pheochromocytoma are initially asymptomatic and the tumor is identified at necropsy after the animal suddenly collapses.
Symptoms are vague and nonspecific and may wax and wane. Most occur as a result of high blood pressure.
Testing and diagnosis
Diagnosis of pheochromocytomas involves:
- Physical examination
- Bloodwork
- Blood pressure testing
- Electrocardiogram (ECG)
- Diagnostic imaging, such as X-rays or ultrasound to identify the adrenal mass
- Measurement of catecholamines in the urine Biopsy
Steps to Recovery
Treatment primarily involves surgical removal of the affected adrenal gland. In some cases, pheochromocytomas can invade major blood vessels in the abdomen, which makes surgery extremely risky. When surgery is not an option, medications that counteract the effects of catecholamines on the body may reduce symptoms.
The overall prognosis for dogs who are diagnosed early is guarded to fair. The mortality rate for dogs who are critically ill at the time of surgery is 50%. Complications include bleeding out internally, extremely low blood pressure, or peritonitis (abdominal inflammation) during and immediately following surgery. Dogs that survive the period immediately after surgery have a good prognosis, with many surviving more than 3 years after surgical removal of the mass. Cases treated with medication alone have a shorter expected lifetime, with many surviving only up to a year after diagnosis.
Prevention
Similar to many tumors, there is no preventative measure for pheochromocytomas. Having routine examinations by a veterinarian helps identify symptoms of pheochromocytomas early, which may allow for treatment before invasion into vessels occurs.
Pheochromocytomas are not contagious.
Is Adrenal Gland Cancer (Pheochromocytoma) in Dogs common?
Pheochromocytomas are uncommon in dogs.
Typical Treatment
Surgical removal
