Rare case links Addison’s disease and pheochromocytoma in a dog
Bottom line
A newly highlighted canine case report describes an unusual endocrine-oncology overlap: a 14-year-old Jack Russell Terrier with long-standing primary hypoadrenocorticism was later found to have a unilateral phaeochromocytoma, then successfully treated with left adrenalectomy and right nephroureterectomy, with a good postoperative outcome. The report stands out because primary hypoadrenocorticism in dogs is typically associated with small, atrophic adrenal glands on ultrasound, while phaeochromocytoma is an adrenal medullary tumor more often discussed in the context of hypertension, arrhythmias, and perioperative instability. The coexistence of the two conditions appears to be rare, with prior literature more often describing the reverse scenario, including hypocortisolism caused by bilateral pheochromocytoma or pheochromocytoma occurring alongside other adrenal disorders. (bvajournals.onlinelibrary.wiley.com)
Why it matters: For veterinary professionals, this case is a reminder not to let an established Addison’s diagnosis close the door on later adrenal pathology. In dogs with primary hypoadrenocorticism, ultrasonography often shows thin adrenal glands, and a left adrenal thickness under 3.2 mm has been reported as strongly suggestive of the disease. That makes a later unilateral adrenal mass especially notable, and clinically important, because canine phaeochromocytoma can carry substantial anesthetic and surgical risk. Recent retrospective data suggest dogs treated with adrenalectomy have longer survival than those managed medically alone, and presurgical alpha-adrenoreceptor antagonist treatment was associated with better survival to discharge in surgically managed dogs. (pubmed.ncbi.nlm.nih.gov)
What to watch: Watch for whether the full report prompts more discussion around repeat imaging, blood pressure monitoring, and surgical planning when dogs with established hypoadrenocorticism later develop signs that don’t fit a stable Addison’s picture. (pubmed.ncbi.nlm.nih.gov)
Key facts
- Article type
- Canine case report
- Patient
- 14-year-old Jack Russell Terrier
- Pre-existing condition
- Long-standing primary hypoadrenocorticism
- Later diagnosis
- Unilateral phaeochromocytoma
- Surgery
- Left adrenalectomy and right nephroureterectomy
- Outcome
- Good postoperative results
- Clinical significance
- Rare coexistence of hypoadrenocorticism and phaeochromocytoma in dogs
- Typical imaging in hypoadrenocorticism
- Thin adrenal glands on ultrasound
A new canine case report details a rare diagnostic twist: a dog with pre-existing, long-standing primary hypoadrenocorticism was later diagnosed with unilateral phaeochromocytoma and successfully managed surgically. According to the source summary, the patient was a 14-year-old Jack Russell Terrier that underwent left adrenalectomy and right nephroureterectomy, with good postoperative results. The case adds to a small but clinically important body of literature on dogs with overlapping adrenal disease, especially when one diagnosis might be expected to make the other less likely. (pubmed.ncbi.nlm.nih.gov)
That tension is what makes the report notable. Primary hypoadrenocorticism in dogs is classically linked to destruction or atrophy of the adrenal cortex, and ultrasonography often shows thin adrenal glands; in one study, a left adrenal gland thickness below 3.2 mm was strongly suggestive of the disease. Phaeochromocytoma, by contrast, is a catecholamine-secreting tumor of the adrenal medulla that can present with episodic or persistent hypertension, tachyarrhythmias, weakness, panting, gastrointestinal signs, or be found incidentally during imaging. In other words, the expected imaging and endocrine patterns can point clinicians in very different directions. (pubmed.ncbi.nlm.nih.gov)
The existing literature suggests this combination is uncommon. A 2022 Veterinary Record Case Reports paper described hypocortisolism caused by bilateral pheochromocytoma and called it the first report of that mechanism in a dog. Other case reports have linked canine pheochromocytoma with ectopic Cushing’s syndrome rather than Addison’s disease. Against that backdrop, a unilateral medullary tumor arising in a dog already carrying a long-standing diagnosis of primary hypoadrenocorticism appears to be a distinctly unusual presentation. That inference is based on the scarcity and framing of published case reports, rather than a formal incidence study. (bvajournals.onlinelibrary.wiley.com)
The surgical details in the source summary also fit what clinicians know about these tumors: adrenalectomy for pheochromocytoma can be technically demanding, and adjacent-organ involvement may complicate the procedure. Prior veterinary case literature has described dogs requiring nephrectomy or nephroureterectomy when the adrenal mass is closely adhered to the kidney or surrounding structures. More broadly, retrospective studies show that while perioperative risk is real, many dogs that survive surgery do well long term, with low reported recurrence or metastasis in some series. A 2025 multicenter retrospective analysis of 255 dogs found that adrenalectomy was associated with longer survival than medical management with alpha-adrenoreceptor antagonists alone. (bvajournals.onlinelibrary.wiley.com)
Recent evidence also offers useful context for perioperative planning. In the 2025 multicenter study, 97.8% of surgically treated dogs that received presurgical alpha-adrenoreceptor antagonist therapy survived to discharge, compared with 85.2% of those that did not receive pretreatment. Separate retrospective work has found most dogs survive the immediate postoperative period after adrenalectomy, and anesthesia-focused case reports continue to emphasize the need to anticipate marked blood pressure swings during tumor handling. Newer reports have also explored tools such as clevidipine for intraoperative hypertension control and indocyanine green guidance in adrenal surgery, underscoring how management is still evolving. (pubmed.ncbi.nlm.nih.gov)
Why it matters: For veterinary professionals, the bigger takeaway is diagnostic vigilance. A dog with stable, long-standing Addison’s disease can still develop new adrenal pathology, and the presence of one endocrine diagnosis shouldn’t automatically explain every later clinical change. If a dog with known hypoadrenocorticism develops unexplained hypertension, arrhythmias, abdominal pain, or an adrenal mass on imaging, clinicians may need to widen the differential list to include pheochromocytoma, even if that feels counterintuitive. This case also reinforces the value of coordinated internal medicine, imaging, anesthesia, and surgery input when adrenal disease stops following the usual script. (pubmed.ncbi.nlm.nih.gov)
What to watch: The next thing to watch is whether this report changes how specialists talk about follow-up in chronic hypoadrenocorticism, particularly around when to repeat abdominal imaging or pursue workups for concurrent adrenal neoplasia in dogs whose signs no longer match uncomplicated Addison’s disease. More published case accumulation, rather than a single report, will be needed before practice norms shift. (bvajournals.onlinelibrary.wiley.com)