Immunohistochemical characterization of normal feline adrenal tissue and adrenal tumors secreting aldosterone

It is suggested that primary hyperaldosteronism (PHA) is an under-diagnosed cause of systemic hypertension in cats. No immunohistochemical markers of aldosterone synthesizing tissues have been identified, meaning that endocrine function cannot be inferred from examining feline tissues. In humans, expression of CYP11B2 (aldosterone synthase) is used for this purpose, but cats have a single CYP11B enzyme responsible for the terminal steps in synthesis of both aldosterone and cortisol, precluding its use as an indicator of steroidogenic function. This study aimed to identify immunohistochemical markers of aldosterone producing tissues. In addition, since there are no existing guidelines for classification of feline adrenal tumors as benign or malignant, this study aimed to investigate potential markers of adrenal tumor malignancy in PHA. Normal adrenals (n = 9) and adrenal tumors secreting aldosterone (n = 31) or cortisol (n = 4) were immunolabeled for steroidogenic enzymes (CYP11B, CYP17A1, and CYB5A), the zona glomerulosa (including KCNJ5 visinin-like 1 (VSNL1), and neuron-specific enolase (NSE)), and proliferation markers (Ki67). Histochemical staining for reticulin was also performed. Transcriptomes of normal (n = 4) and aldosterone secreting tumors (n = 5) were compared. Weak or absent CYP17A1 in conjunction with strong KCNJ5 or VSNL1 immunolabeling was present in aldosterone producing tissues from normal and tumorous cat adrenals. CYP17A1 RNA expression was lower in aldosterone producing tumors compared with normal adrenals (P < .0001). VSNL1 and NSE were not specific markers of aldosterone producing tissue. CYB5A and CYP17A1 were not expressed within the zona reticularis, suggesting minimal adrenal production of androgens. Ki67 proliferative index and reticulin network disruption were not predictive of malignancy.

Use of a Harmonic scalpel for laparoscopic adrenalectomy in two cats

Case series summary

Adrenal tumors are rare in cats and reports of laparoscopic adrenalectomy in cats are limited. This case series describes two cats that underwent laparoscopic adrenalectomy using a Harmonic scalpel for dissection and coagulation. Both surgeries were successful, with minimal hemorrhage, smoke production and lateral thermal damage. Vessels were appropriately sealed and surgical times were appropriate. Both cats recovered without complications postoperatively.

Relevance and novel information

To our knowledge, this is the first veterinary report to describe the use of the Harmonic scalpel for laparoscopic adrenalectomy as the sole device in cats. Owing to the absence of hemorrhage, there was no indication for irrigation, suction or hemostatics. The Harmonic scalpel is an ultrasonic vessel-sealing device with benefits over conventional electrosurgery, including less lateral thermal damage, less smoke production and improved safety due to the lack of an electrical current. This case report aims to highlight the usefulness of ultrasonic vessel-sealing devices for laparoscopic adrenalectomy in cats.

Feline comorbidities: Recognition, diagnosis and management of the cushingoid diabetic

PRACTICAL RELEVANCE

Diabetes mellitus (DM) is a common feline endocrinopathy, and is often driven by underlying insulin resistance with associated pancreatic beta (β)-cell dysfunction. Although spontaneous hyperadrenocorticism (HAC) with hypercortisolemia (hypercortisolism) is relatively uncommon in cats, it is a well-established cause of insulin resistance and is routinely associated with DM in this species.

CLINICAL CHALLENGES

Many of the clinical signs associated with feline HAC are subtle and may be attributed to concurrent DM or the aging process. Failure to recognize HAC in the diabetic cat can impact patient wellbeing and predispose the patient to progressive compromise. Unfortunately, it can be difficult to establish a diagnosis of HAC, as test results may be influenced by poor diabetic regulation, and protocols are different to those used in canine patients. Treatment options depend on the underlying cause, and often require careful, ongoing assessment and modulation of both adrenal function and insulin requirements. However, various approaches have been shown to either improve glycemic control in cats with sustained insulin dependence, or facilitate diabetic remission.

EVIDENCE BASE

This review summarizes the current literature on feline HAC, with a particular focus on cats with concurrent DM. The clinical findings that suggest HAC are discussed, along with an outline of diagnostic options and their limitations. Published outcomes for various medical options, surgical procedures and radiation therapy are provided. The authors also share their thoughts on the safe and effective management of cats with HAC and DM, with an emphasis on the anticipation and recognition of changing insulin requirements.

Feline abdominal ultrasonography: what's normal? what's abnormal? The adrenal glands

PRACTICAL RELEVANCE

Abdominal ultrasound plays a vital role in the diagnostic work-up of many cats presenting to general and specialist practitioners. Ultrasound examination of the adrenal glands can provide important information pertaining to several conditions including hyperaldosteronism and hyperadrenocorticism.

CLINICAL CHALLENGES

Despite ultrasonography being a commonly used modality, many practitioners are not comfortable performing an ultrasound examination or interpreting the resulting images. Even for the experienced ultrasonographer, differentiating between incidental findings, such as adrenal mineralisation, and clinically significant pathological changes can be challenging.

AIM

This review, part of an occasional series on feline abdominal ultrasonography, discusses the ultrasonographic examination of the normal and diseased adrenal glands. Aimed at general practitioners who wish to improve their knowledge of and confidence in feline abdominal ultrasound, this review is accompanied by high-resolution images and videos available online as supplementary material.

EQUIPMENT

Ultrasound facilities are readily available to most practitioners, although the use of ultrasonography as a diagnostic tool is highly dependent on operator experience.

EVIDENCE BASE

Information provided in this article is drawn from the published literature and the author's own clinical experience.

Pressure-Volume Curve during Capnoperitoneum in Cats

Laparoscopy is a growing field in veterinary medicine, although guidelines are lacking. The objective of this study was to evaluate the pressure-volume curve during capnoperitoneum in cats. A total of 59 female cats were scheduled for routine laparoscopy. Pressure and volume data were recorded and processed, and the yield point of the curve was calculated using a method based on a capacitor discharging function. For the remaining 40 cats, a linear-like pressure-volume curve was observed until a yield point with a mean cutoff pressure (COP) of 6.44 ± 1.7 mmHg (SD) (range, 2.72-13.00 mmHg) and a mean cutoff volume (COV) of 387 ± 144.35 mL (SD) (range, 178.84-968.43 mL) was reached. The mean mL/kg CO₂ value in cats was 208 ± 34.69 mL/kg (range, 100.00-288.46 mL/kg). The COV correlated with COP and body weight but not with body condition score (BCS). COP correlated only with the COV. This study suggests that feline patients have a pressure-volume curve similar to that of canine patients, and the same pressure limit recommendations can be used for both species. After a yield point of 6.44 mmHg is reached, the increment in volume decreases exponentially as the intra-abdominal pressure (IAP) increases.

Peculiarities of feline hyperadrenocorticism: Update on diagnosis and treatment

Practical relevance: Hyperadrenocorticism (HAC) is a relatively uncommon endocrinopathy of older cats, with a mean age at diagnosis of 10 years. In addition to pituitary-dependent and adrenal-dependent hypercortisolism, clinical signs of HAC can result from adrenal sex steroid-producing tumours. Clinical challenges: While HAC in cats has many similarities to canine HAC, there are key differences in presentation, diagnosis and response to therapy. Most, but not all, cats with HAC have concurrent diabetes mellitus, which is often insulin resistant. Up to a third of cats with HAC have extreme skin fragility and are at high risk of debilitating iatrogenic skin tears during diagnostic or therapeutic interventions. Infections of the skin and nail beds, and urinary, respiratory and gastrointestinal tract, secondary to cortisol-induced immune suppression, are also common. Cats respond differently to dogs to adrenal function tests including adrenocorticotropic hormone (ACTH) stimulation and dexamethasone suppression tests; a 10-fold higher dose of dexamethasone is recommended in cats to screen for HAC. Curative treatment options include adrenalectomy or transsphenoidal hypophysectomy. Radiation or medical treatment may improve clinical signs. The response to mitotane therapy is poor. While trilostane is the medical treatment of choice based on retrospective studies, investigations into the pharmacokinetics of this drug in cats are lacking. Global importance: Feline HAC occurs worldwide and is not associated with any purebreed predisposition. Although uncommon, adrenal sex steroid-producing tumours have a higher prevalence in cats than in dogs. Evidence base: The information in this review is drawn from over 180 reported cases of feline HAC. Reports investigating clinical presentation, clinicopathological findings and treatment outcomes are observational, retrospective multiple case series (EBM grade III) or single case reports (EBM grade IV). While most endocrine testing studies for diagnosis are cohort controlled analytical studies (EBM grade III), prospective, randomised, placebo-controlled studies have been performed (EBM grade I).

Anaesthetic management of a unilateral adrenalectomy of an adrenocortical tumour in a dog

Adrenalectomies in dogs are being more commonly performed, however anaesthetic management of such cases can be challenging due to the multiple aetiologies of adrenal tumours and the physiological role of adrenal glands. This case report describes the anaesthetic management of a dog with clinical signs of hyperadrenocorticism that underwent unilateral adrenalectomy via laparotomy and discusses anaesthetic preparedness, protocol selection and management of complications for dogs undergoing adrenalectomy.

Adrenocortical tumor in a cat secreting more than one type of corticosteroid

CASE SUMMARY

A 14-year-old, spayed female domestic shorthair cat was evaluated because of a right adrenal mass. The referring veterinarian had started treatment for hypokalemia and systemic arterial hypertension. During the initial evaluation the cat was alert and responsive, and serum potassium concentration was within the reference range. Serum concentrations of aldosterone and progesterone were increased. Atrophy of the contralateral adrenal and an exaggerated response of cortisol to stimulation with adrenocorticotropic hormone suggested hypersecretion of cortisol. Unilateral adrenalectomy was performed and recovery was uneventful. Histologic examination of the mass revealed an adrenocortical tumor. After surgery, clinical signs of hypercortisolism, hyperaldosteronism and hyperprogesteronism were no longer observed, and neither potassium supplementation nor antihypertensive treatment were needed.

RELEVANCE AND NOVEL INFORMATION

In cases with an adrenocortical tumor, clinicians should investigate whether the tumor hypersecretes glucocorticoids, mineralocorticoids, sex steroids or combinations of these. Hypersecretion of more than one adrenal hormone may occur in a cat with an adrenocortical tumor.

Complications and Conversion from Endoscopic to Open Surgery

Endoscopic surgery is a rapidly expanding modality of diagnosis and treatment of small animal patients. The development of skills, equipment, and minimally invasive means of correcting complications may be of great importance in decreasing the incidence of conversion from endoscopic to open surgery; however, conversion to an open approach should never be seen as a failure. Conversion should be considered at any time that it is of the greatest benefit for the patient. This concept is important enough to warrant discussion with the owner before surgery and acceptance of the need to convert without further consultation during the procedure.

Cardiopulmonary Effects of Laparoscopic Ovariectomy of Variable Duration in Cats

OBJECTIVE

To evaluate the cardiopulmonary effects of low-pressure (6 mmHg) peritoneal insufflation of varying duration in healthy cats during ovariectomy (OVE).

STUDY DESIGN

Prospective, randomized study.

ANIMALS

Female cats (n = 24).

METHODS

After anesthesia induction, cats had short (Short LAP; n = 8) or long duration (Long LAP; n = 8) laparoscopic ovariectomy, or Open OVE (Open; n = 8) for comparison. Hemodynamic and pulmonary measurements were recorded after induction of anesthesia (T0), 5 minutes after abdominal insufflation had reached 6 mmHg of pressure (T1), after the 2nd ovary had been resected (T2), after abdominal decompression (T3), and at the end of anesthesia, after abdominal closure (T4). Hemodynamic and pulmonary variables were compared between groups.

RESULTS

Low-pressure abdominal insufflation caused cardiopulmonary changes in cats. At T1 and T2, Long LAP and Short LAP caused a significant change in PvCO2 and RC when compared with Open. During T3, RC was lower only in Long LAP. At T2, there was decrease in SV, but not CO for Long LAP when compared with Open.

CONCLUSIONS

Duration of insufflation was associated with worsening of negative cardiopulmonary effects; however, these effects were reversible and resolved by the end of the procedure.

Treatment of aldosterone-secreting adrenocortical tumors in cats by unilateral adrenalectomy: 10 cases (2002-2012)

Background

Primary hyperaldosteronism (PHA) in cats occurs as a consequence of excessive hormone production by an adrenocortical tumor. Median survival time, association between tumor type and prognosis, and the likelihood that cats require continued medical therapy after surgery have not been systematically evaluated.

Objectives

To determine the median survival time of cats with PHA treated by unilateral adrenalectomy. To examine if tumor type, anesthesia time, or tumor location (left or right side) affect survival and if affected cats require continued postoperative treatment for persistent hypertension or hypokalemia.

Animals

Ten client‐owned cats.

Methods

Retrospective study. Cats were diagnosed with PHA based on clinical signs, increased plasma aldosterone concentration, and advanced imaging. Cats underwent unilateral adrenalectomy. Survival time (days alive after surgery) was determined for each cat. Factors affecting median survival time were investigated, including histopathology, anesthesia time, and location (side) of the tumor.

Results

Eight of 10 cats survived to discharge from the hospital post adrenalectomy. Overall median survival was 1,297 days (range 2–1,582 days). The only significant factor affecting median survival time was anesthesia time >4 hours. Tumor type and location (side) did not significantly affect median survival time. No cats required continued medical treatment for PHA.

Conclusions and Clinical Importance

Although PHA in cats is still considered an uncommon condition, it should be considered in middle to older aged cats with hypokalemic polymyopathy and systemic hypertension. Surgical correction by unilateral adrenalectomy is a viable approach to definitive treatment of PHA with no need for continued medical management.

Trilostane therapy for treatment of spontaneous hyperadrenocorticism in cats: 15 cases (2004-2012)

BACKGROUND

Medical treatment with trilostane improves clinical signs, causes unclear insulin requirement changes, and variable survival times in cats.

OBJECTIVES/HYPOTHESIS

To characterize the long-term efficacy of trilostane in treating cats with hyperadrenocorticism (HAC).

ANIMALS

Fifteen client-owned cats with spontaneous HAC.

METHODS

Multicenter descriptive retrospective study with a search performed on all medical records for cats diagnosed with spontaneous HAC.

RESULTS

Clinical signs (13 of 15 cats) and ACTH stimulation testing results (13 of 15) improved with trilostane therapy. Diabetes mellitus was reported in 9/15 cases. Insulin requirements decreased by 36% within 2 months in 6/9 diabetic cats. Median survival time was 617 days for all cats (range 80-1,278 days). Complications included weight loss, urinary tract infections, chronic kidney disease, seizures, and recurrent pancreatitis. Hypocortisolemia was documented in 1 case. Cause of death occurred as a result of nonadrenal or nondiabetic illnesses (renal failure, seizures [caused by hypoglycemia or unknown]), or lymphoma.

CONCLUSIONS AND CLINICAL IMPORTANCE

Trilostane ameliorates clinical signs of HAC in cats, is tolerated well in the long term, and can lead to improved regulation of diabetes.