Surgical findings and outcomes after unilateral adrenalectomy for primary hyperaldosteronism in cats: a multi-institutional retrospective study.

CASE SERIES SUMMARY: Twenty-nine cats from different institutions with confirmed or highly suspected primary hyperaldosteronism treated by unilateral adrenalectomy were retrospectively included in this study. The most frequent clinical signs were lethargy (n = 20; 69%) and neck ventroflexion (n = 17; 59%). Hypokalaemia was present in all cats, creatinine kinase was elevated in 15 and hyperaldosteronism was documented in 24. Hypertension was frequently encountered (n = 24; 89%). Preoperative treatment included potassium supplementation (n = 19; 66%), spironolactone (n = 16; 55%) and amlodipine (n = 11; 38%). There were 13 adrenal masses on the right side, 15 on the left and, in one cat, no side was reported. The median adrenal mass size was 2 × 1.5 cm (range 1-4.6 × 0.4-3.8); vascular invasion was present in five cats, involving the caudal vena cava in four cats and the renal vein in one. Median duration of surgery was 57 mins. One major intraoperative complication (3%) was reported and consisted of haemorrhage during the removal of a neoplastic thrombus from the caudal vena cava. In 4/29 cats (14%), minor postoperative complications occurred and were treated medically. One fatal complication (3%) was observed, likely due to disseminated intravascular coagulation. The median duration of hospitalisation was 4 days; 97% of cats survived to discharge. The potassium level normalised in 24 cats within 3 months of surgery; hypertension resolved in 21/23 cats. Follow-up was available for 25 cats with a median survival of 1082 days. Death in the long-term follow-up was mainly related to worsening of comorbidities. RELEVANCE AND NOVEL INFORMATION: Adrenalectomy appears to be a safe and effective treatment with a high rate of survival and a low rate of major complications. Long-term medical treatment was not required.

Stereotactic body radiation therapy as an alternative to adrenalectomy for the treatment of pheochromocytomas in 8 dogs.

The objective of this report is to describe the use and outcome of stereotactic body radiation therapy (SBRT) for treatment of pheochromocytomas in 8 dogs. Pheochromocytomas are an uncommon but challenging tumour to manage. Adrenalectomy is the standard of care for treatment of pheochromocytomas in both animals and humans; however, unpredictable catecholamine secretion from the tumour and vascular and local invasion of the tumour and thrombi can pose life-threatening perioperative and anaesthetic risks. SBRT has been investigated as an alternative to adrenalectomy in human patients with pheochromocytomas. Eight dogs with clinical signs, an adrenal mass, and cytology and/or urine normetanephrine/creatinine ratios consistent with pheochromocytoma were treated with SBRT in lieu of adrenalectomy. Three dogs presented with acute hemoabdomen. Seven dogs had caval tumour invasion, 3 with extension into the right atrium. Following SBRT, all dogs had complete resolution of clinical signs and reduced urine normetanephrine/creatinine ratio and/or tumour size. No significant anaesthetic complications were encountered. Acute radiation toxicity was limited to grade I gastrointestinal signs in 3 dogs and resolved within 1-2 days of symptomatic therapy. Five of 8 dogs were alive at the time of follow up, with a median follow up time of 25.8 months. SBRT resulted in a favourable outcome and mitigated the life-threatening risks of adrenalectomy in these 8 dogs. SBRT may be a safe and effective alternative to adrenalectomy for pheochromocytomas in dogs with non-resectable tumours, or for owners averse to the risks of surgery.

Glucocorticoid-deficient hypoadrenocorticism secondary to intravascular lymphoma in the adrenal glands of a dog.

CASE REPORT: A 2-year-old neutered male German Shepherd dog was presented with weakness, poor appetite and weight loss. Glucocorticoid-deficient hypoadrenocorticism was diagnosed with undetectable pre- and post-ACTH cortisol concentrations but normal sodium and potassium concentrations. Despite appropriate supplementation with glucocorticoids, the patient's weakness progressed and neurological deficits developed. The patient was euthanased. Histopathological analysis of multiple organs, including the adrenal glands, showed an accumulation of neoplastic lymphocytes within blood vessels, consistent with a diagnosis of intravascular lymphoma. Histologically, in both adrenal glands, the architecture of the zona fasciculata and reticularis was disrupted by blood vessels congested with a neoplastic population of T-lymphocytes; the zona glomerulosa remained intact. CONCLUSION: This is the first report of intravascular lymphoma causing glucocorticoid-deficient hypoadrenocorticism in a dog.

Adrenalectomy and caval thrombectomy in a cat with primary hyperaldosteronism.

A 13-year-old, castrated male, domestic longhaired cat was diagnosed with primary hyperaldosteronism from an adrenal gland tumor and a thrombus in the caudal vena cava. Clinical signs included cervical ventriflexion, lethargy, weakness, inappetence, and diarrhea. Laboratory tests revealed hypokalemia, normonatremia, hyperglycemia, hypophosphatemia, and elevated creatine kinase activity. Hypokalemia worsened despite oral potassium supplementation. An adrenalectomy and caval thrombectomy were successfully performed utilizing deliberate hypothermia followed by progressive rewarming.

Use of abdominal ultrasonography in the diagnosis of primary hyperaldosteronism in a cat.

A 13-year-old castrated male cat was examined because of a 2-week history of weakness, cervical ventroflexion, and dysphagia. Clinicopathologic abnormalities included hypokalemia and high serum creatine kinase activity. Abdominal ultrasonography revealed a 15-mm spherical mass in the area of the left adrenal gland. Plasma aldosterone concentration was high, and plasma renin activity was low. Findings were diagnostic of primary hyperaldosteronism. The cat responded well to intravenous and oral potassium supplementation while in the hospital. The owner declined surgery; therefore, repeated follow-up abdominal ultrasonography was recommended. The cat did well clinically with medical management alone until day 334, when it was lost to follow-up.

Suppression of growth hormone secretion in spontaneous canine hyperadrenocorticism and its reversal after treatment.

The plasma growth hormone response to the provocative agent, xylazine, was assessed in 4 dogs with spontaneous hyperadrenocorticism, before and after therapy. Before treatment of the hyperadrenocorticism, no significant increase in growth hormone concentration occurred in any of the dogs following the administration of xylazine. A significant increase in growth hormone concentrations following xylazine administration occurred in 2 of the 3 dogs with hypophysis (pituitary)-dependent hyperadrenocorticism after treatment with mitotane (o,p'-DDD) and in 1 dog after surgical removal of a hyperfunctional adrenal adenoma. Although the impaired growth hormone response persisted in 1 dog, the administration of xylazine was repeated in this animal after only 3 weeks of mitotane therapy; it is likely that growth hormone unresponsiveness would reverse if the hyperadrenocorticism were controlled for a longer period. These findings demonstrate that in dogs, as in persons, the excessive production of endogenous corticosteroids associated with either hypophysis-dependent hyperadrenocorticism or hyperfunctional adrenal tumor can induce suppression of growth hormone release which is reversible following treatment.

Hypothalamic catecholamine levels in dogs with spontaneous hyperadrenocorticism.

Hypothalamic norepinephrine (NE) and dopamine content was studied in dogs with spontaneous and iatrogenic hypercortisolism and in untreated normal dogs. The concentration of NE in the hypothalamus was subnormal in 4 of 8 dogs with pituitary-dependent hyperadrenocorticism (PDH), whereas long-term administration of corticotropin or cortisone acetate did not result in low hypothalamic NE content. In dogs with hyperadrenocorticism due to adrenocortical tumor subnormal as well as normal and high hypothalamic NE levels were found. Hypothalamic as well as striatal dopamine content did not differ among groups of dogs with PDH, adrenocortical tumor, corticotropin treatment, cortisone treatment and in untreated normal dogs. The subnormal hypothalamic NE levels in dogs with PDH may be involved in the hypersecretion of ACTH found in this disease. The normal hypothalamic dopamine levels in dogs with PDH are not consistent with a dopaminergic-depletion as the cause of PDH.