Results of adrenalectomy in 36 dogs with hyperadrenocorticism caused by adreno-cortical tumour

Short- and long-term survival after adrenalectomy in 53 dogs with pheochromocytomas with or without alpha-blocker therapy

OBJECTIVE

To report data related to the short- and long-term survival of dogs undergoing adrenalectomy for pheochromocytoma, and to determine the influence of preoperative alpha-blocker therapy.

STUDY DESIGN

Retrospective.

ANIMALS

Fifty-three dogs.

METHODS

Medical records were reviewed for dogs diagnosed with pheochromocytoma and treated with adrenalectomy between 2010 and 2020. Preoperative management, imaging studies, intraoperative cardiovascular instability, complications, and procedural information were recorded. When applicable, duration of survival and cause of death, time to recurrence or metastasis, and postoperative complications were recorded.

RESULTS

During anesthesia, a hypertensive episode was documented in 46/53 dogs and arrhythmias were recorded in 16/53 dogs. Of these, 37/46 hypertensive dogs and 11/16 dogs with arrhythmias were treated with an alpha-blocker before surgery. Intraoperative systolic blood pressures reached higher levels by a magnitude of nearly 20% in dogs that were treated preoperatively with an alpha-blocker (P = .01). All dogs survived surgery and 44 survived to discharge. Follow up ranged from 6 to 1653 days (median 450 days). Median survival time for dogs discharged from the hospital was 1169 days (3.2 years). Recurrence and metastasis were suspected in 3 and 8 dogs, respectively.

CONCLUSION

Most dogs survived the immediate postoperative period and achieved long-term survival with a low reported incidence of tumor recurrence or metastasis. Preoperative alpha-blocker therapy was not associated with increased survival.

CLINICAL SIGNIFICANCE

The favorable outcomes reported in this study should be taken into consideration when discussing treatment options for dogs with pheochromocytomas. This study provides no evidence to support preoperative alpha-blocker therapy.

Circulating MicroRNAs as Non-invasive Biomarkers for Canine Cushing's Syndrome

Canine Cushing's syndrome (hypercortisolism) can be caused by a pituitary tumor (pituitary-dependent hypercortisolism; PDH) or a cortisol-secreting adrenocortical tumor (csACT). For both cases, non-invasive biomarkers that could pre-operatively predict the risk of recurrence after surgery would greatly impact clinical decision making. The aim of this study was to determine whether circulating microRNAs (miRNAs) can be used as diagnostic (presence of PDH or csACT) and/or prognostic (disease recurrence, histological grade) non-invasive biomarkers for canine Cushing's syndrome. After a pilot study with 40 miRNAs in blood samples of healthy dogs (n = 3), dogs with PDH (n = 3) and dogs with a csACT (n = 4), we selected a total of 20 miRNAs for the definitive study. In the definitive study, these 20 miRNAs were analyzed in blood samples of healthy dogs (n = 6), dogs with PDH (n = 19, pre- and post-operative samples) and dogs with a csACT (n = 26, pre-operative samples). In dogs with PDH, six miRNAs (miR-122-5p, miR-126-5p, miR-141-3p, miR-222-3p, miR-375-3p and miR-483-3p) were differentially expressed compared to healthy dogs. Of one miRNA, miR-122-5p, the expression levels did not overlap between healthy dogs and dogs with PDH (p = 2.9x10-4), significantly decreased after hypophysectomy (p = 0.013), and were significantly higher (p = 0.017) in dogs with recurrence (n = 3) than in dogs without recurrence for at least one year after hypophysectomy (n = 7). In dogs with csACTs, two miRNAs (miR-483-3p and miR-223-3p) were differentially expressed compared to healthy dogs. Additionally, miR-141-3p was expressed significantly lower (p = 0.009) in dogs with csACTs that had a histopathological Utrecht score of ≥ 11 compared to those with a score of <11. These results indicate that circulating miRNAs have the potential to be non-invasive biomarkers in dogs with Cushing's syndrome that may contribute to clinical decision making.

Utility of contrast-enhanced ultrasound in differential diagnosis of adrenal tumors in dogs

This prospective case study aimed to clarify the clinical significance of contrast-enhanced ultrasound (CEUS) for the differential diagnosis of canine adrenal tumors. Forty-three client-owned dogs with adrenal tumors were included. All dogs underwent CEUS, which was evaluated qualitatively and quantitatively. The peak signal intensity (PI), time to peak signal intensity (TPI), mean transit time (MTT), upslope, and downslope were calculated for each time-intensity curve. The histopathological diagnosis of each resected mass was compared with the CEUS findings and parameters. Enhancement distribution, vascularity, tortuous nourishing vessels, enhancement pattern, and late-phase enhancement did not differ significantly between adrenal cortical adenoma (CA), adenocarcinoma (CAC), and pheochromocytoma (PHEO) in qualitative assessment. In PHEO, the TPI was significantly more rapid compared with that in CA (P=0.0287) and CAC (P=0.0404). The MTT in PHEO was significantly shorter than that in CA (P=0.0016) and CAC (P=0.0003). Upslope in PHEO was larger than that in CAC (P=0.0406). Downslope in PHEO was significantly larger than that in CA (P=0.0048) and CAC (P=0.0018). A receiver operating characteristic curve analysis demonstrated that the area under the MTT curve yielded 0.91 for distinguishing PHEO from adrenocortical tumors in dogs; an MTT cut-off value less than 6,225 msec yielded a sensitivity of 69%, specificity of 94%, and likelihood ratio of 12.46. CEUS appears to be clinically applicable for the differential diagnosis between cortical and medullary origins of primary adrenal tumors in dogs.

Safety of percutaneous ultrasound-guided fine-needle aspiration of adrenal lesions in dogs: Perception of the procedure by radiologists and presentation of 50 cases

Background

Percutaneous ultrasound (US)‐guided fine‐needle aspiration (FNA) of adrenal gland lesions is controversial in veterinary medicine.

Objective

To evaluate the frequency and radiologists' perception of the risk of the procedure as well as determining the incidence of complications.

Methods

Retrospective study. A first survey was submitted by e‐mail to all board‐certified radiologists of the American College of Veterinary Radiology (ACVR) and European College of Veterinary Diagnostic Imaging (ECVDI). A second survey was sent to radiologists who declared having performed the procedure at least once in their career (observational cross‐sectional case study).

Results

The first survey was sent to 977 diplomates and answered by 138. Of 138 diplomates, 40 currently performed the procedure and 98 did not; 44 of the 98 gave the hypertensive crisis risk in pheochromocytoma as a reason. To the second survey, 12 of 65 responded positively; 50 dogs with 58 lesions were recruited, including 23 pheochromocytomas. Complications were reported in 4 of 50 dogs; 3 hemorrhages (1 mild and 1 moderate) and 1 death from acute respiratory distress syndrome (possibly related to laryngeal paralysis). No hypertensive crisis was reported. There was no relationship between the method of FNA/type of needle used and occurrence of complications. Based on the recollection of these 65 radiologists, who performed approximately 200 FNA of adrenal lesions, a death rate of approximately 1% was estimated.

Conclusions and Clinical Importance

Percutaneous US‐guided FNA of adrenal lesions can be considered a minimally risky procedure, despite the negative perception by radiologists.

Survival analysis of 219 dogs with hyperadrenocorticism attending primary care practice in England

BACKGROUND

Hyperadrenocorticism is an endocrine disease routinely encountered within primary care practice; however, few studies evaluating survival beyond diagnosis have studied this population.

METHODS

This retrospective cohort study analysed the electronic patient records of 219 cases of hyperadrenocorticism from a sample of dogs attending primary care practices in England. Kaplan-Meier plots examined the cumulative survival and Cox proportional hazard regression modelling identified factors associated with the hazard of all-cause mortality.

RESULTS

In the analysis, 179/219 (81.7 per cent) hyperadrenocorticism cases died during the study period with a median survival time from first diagnosis of 510 days (95% CI 412 to 618 days). Trilostane was used in 94.1 per cent of cases and differentiation between pituitary-dependent and adrenal-dependent disease was made in 20.1 per cent of cases. In the multivariable analysis, dogs weighing greater than or equal to 15 kg (HR 1.51, 95% CI 1.06 to 2.15, P=0.023) and those diagnosed greater than or equal to 13 years of age (HR 3.74, 95% CI 2.29 to 6.09, P<0.001) had increased hazards of all-cause mortality. Dogs that had their initial trilostane dose increased had a favourable prognosis (HR 0.49, 95% CI 0.32 to 0.76, P=0.015).

CONCLUSION

This study shows that survival from diagnosis of hyperadrenocorticism appears fair for many dogs and provides primary care practitioners with relatable benchmark prognostic figures.

Molecular markers of prognosis in canine cortisol-secreting adrenocortical tumours

Hypercortisolism is caused by a cortisol‐secreting adrenocortical tumour (ACT) in approximately 15%‐20% of cases in dogs. Little is known about which molecular markers are associated with malignant behaviour of canine ACTs. The objective of this study was to identify molecular markers of prognosis, which could be useful to refine prognostic prediction and to identify potential treatment targets. Cortisol‐secreting ACTs were included from 40 dogs, of which follow‐up information was available. The ACTs were classified as low risk of recurrence tumours (LRT; n = 14) or moderate‐high risk of recurrence tumours (MHRT; n = 26), based on the novel histopathological Utrecht score. Normal adrenals (NAs) were included from 11 healthy dogs as reference material. The mRNA expression of 14 candidate genes was analysed in the 40 ACTs and in 11 NAs with quantitative RT‐PCR. The genes' expression levels were statistically compared between NAs, LRTs and MHRTs. Univariate and multivariate analyses were performed to determine the association of the genes' expression levels with survival. Seven genes were differentially expressed between NAs and ACTs, of which pituitary tumour‐transforming gene‐1 (PTTG1) and topoisomerase II alpha (TOP2A) were also differentially expressed between LRTs and MHRTs. In survival analyses, high expression levels of Steroidogenic factor‐1 (SF‐1), PTTG1 and TOP2A were significantly associated with poor survival. In conclusion, we have identified several genes that are part of the molecular signature of malignancy in canine ACTs. These findings can be used to refine prognostic prediction, but also offer insights for future studies on druggable targets.

Anaesthetic management and complications of canine adrenalectomies: 41 cases (2007-2017)

Little information is available about the management of adrenalectomies in veterinary anaesthesia. The aim of this study was to describe the anaesthetic techniques, the complication rate and outcome of these cases. Data were collected retrospectively from patients' records. Descriptive statistics were performed with Student's t-tests and Chi-square tests where appropriate. Forty-one cases were included. The mean age was 124.7 ± 29.4 months and the median body weight was 23.1 kg (5.3-69 kg). Carcinoma was the most common diagnosis (34.1%). Premedication was most commonly achieved with methadone alone (70.7%) IV. Propofol was the most common induction agent (39%). An infusion of opioids (80.4%) and an epidural injection of morphine (70.7%) were the most common analgesic techniques. Hypotension was the most common complication observed (51.2%). The mortality rate was 14.6%. The lowest recorded oesophageal temperature was statistically associated with the incidence of haemorrhage (P = 0.025). The invasion of the vena cava (P = 0.001) was significantly associated with haemorrhagic complications. The survival rate was better when patients received hydrocortisone intra-operatively (P = 0.026). This study highlights some possible association between the anaesthetic management and the outcome of the procedure.

Treating canine Cushing's syndrome: Current options and future prospects

Naturally occurring hypercortisolism, also known as Cushing's syndrome, is a common endocrine disorder in dogs that can be caused by an adenocorticotrophic hormone (ACTH)-producing pituitary adenoma (pituitary-dependent hypercortisolism, PDH; 80-85% of cases), or by an adrenocortical tumor (ACT; 15-20% of cases). To determine the optimal treatment strategy, differentiating between these two main causes is essential. Good treatment options are surgical removal of the causal tumor, i.e. hypophysectomy for PDH and adrenalectomy for an ACT, or radiotherapy in cases with PDH. Because these options are not without risks, not widely available and not suitable for every patient, pharmacotherapy is often used. In cases with PDH, the steroidogenesis inhibitor trilostane is most often used. In cases with an ACT, either trilostane or the adrenocorticolytic drug mitotane can be used. Although mostly effective, both treatments have disadvantages. This review discusses the current treatment options for canine hypercortisolism, and considers their mechanism of action, efficacy, adverse effects, and effect on survival. In addition, developments in both adrenal-targeting and pituitary-targeting drugs that have the potential to become future treatment options are discussed, as a more selective and preferably also tumor-targeted approach could have many advantages for both PDH and ACTs.

Feasibility of single-port retroperitoneoscopic adrenalectomy in dogs

OBJECTIVE

To evaluate the feasibility of single-port retroperitoneoscopic adrenalectomy (SPRA) in dogs.

STUDY DESIGN

A pilot experimental study.

ANIMALS

Eight healthy beagle dogs.

METHODS

SPRA was performed on the left and right sides (4 dogs each). Resection of the adrenal gland was performed through a SILS port using a retroperitoneal approach. Operative time was defined from skin incision to the completion of skin suture. Postoperative pain was evaluated by using 3 pain scores. Integrity of the adrenal gland capsule was evaluated by histologic assessment.

RESULTS

Mean time taken to complete the SPRA was 44.1 minutes (range, 37-51) and was significantly longer on the right side than on the left side (P < .05). There were no complications intraoperatively or during 14 days of postoperative monitoring. The adrenal gland capsule was found to be injured in 3 of the 8 dogs by histologic assessment.

CONCLUSION

This is the first report of SPRA in the veterinary literature. With this technique it is possible to perform adrenalectomy with some risk of capsule penetration and with excellent visibility.

CLINICAL SIGNIFICANCE

This study suggests that SPRA is feasible and can be used to resect small adrenal tumors with minimal complications.

Preoperative Differential Diagnosis of Canine Adrenal Tumors Using Triple-Phase Helical Computed Tomography

OBJECTIVE

To characterize the computed tomography (CT) findings for canine adrenal tumors, including cortical adenoma, cortical adenocarcinoma, and pheochromocytoma, and to evaluate the feasibility and usefulness of preoperative triple-phase helical CT for differentiation of tumor types and surgical planning.

STUDY DESIGN

Retrospective study.

ANIMALS

Dogs with adrenal tumors (n=36).

METHODS

All dogs underwent triple-phase helical CT, followed by adrenalectomy and histopathological diagnosis of the resected mass. Precontrast images, arterial, venous, and delayed phase images were obtained. In all cases, morphological characteristics and CT values and calculations, including the percentage enhancement washout ratio, relative percentage washout, enhancement washin, and enhancement washout, were analyzed and compared among the tumor types.

RESULTS

Of the 36 dogs with adrenal masses, cortical adenocarcinoma was most commonly diagnosed (16 dogs), followed by pheochromocytoma (13 dogs), and cortical adenoma (7 dogs). The precontrast minimum CT value and enhancement washout between venous and delayed phases in the cortical adenoma were significantly higher than those in the cortical adenocarcinoma. The maximum CT values of the precontrast image and arterial and venous phases, the enhancement washin and washouts, percentage enhancement washout ratio, and relative percentage washout in the pheochromocytomas were significantly higher than those in cortical adenocarcinoma.

CONCLUSION

The differential diagnosis of canine adrenal tumors was feasible based on triple-phase CT findings, including morphological features, CT values, and intratumoral contrast attenuation. Preoperative diagnosis using triple-phase helical CT may be useful for surgical planning in dogs with adrenal tumors.

Cortisol-secreting adrenocortical tumours in dogs and their relevance for human medicine

Spontaneous cortisol-secreting adrenocortical tumours in pet dogs are an attractive animal model for their human counterparts. Adrenal morphology and function are similar in dogs and humans, and adrenocortical tumours have comparable clinical and pathological characteristics. Their relatively high incidence in pet dogs represents a potential source of adrenocortical tumour tissue to facilitate research. The molecular characteristics of canine cortisol-secreting adrenocortical tumours suggest that they will be useful for the study of angiogenesis, the cAMP/protein kinase A pathway, and the role of Steroidogenic Factor-1 in adrenal tumourigenesis. Pet dogs with spontaneous cortisol-secreting adrenocortical tumours may also be useful in clinical testing of new drugs and in investigating the molecular background of adrenocortical tumours.

Insulin-like growth factor--phosphatidylinositol 3 kinase signaling in canine cortisol-secreting adrenocortical tumors

Background

Hypercortisolism is a common endocrine disorder in dogs, caused by a cortisol‐secreting adrenocortical tumor (AT) in approximately 15% of cases. In adrenocortical carcinomas of humans, activation of the phosphatidylinositol 3 kinase (PI3K) signaling pathway by insulin‐like growth factor (IGF) signaling represents a promising therapeutic target.

Objectives

To investigate the involvement of PI3K signaling in the pathogenesis of ATs in dogs and to identify pathway components that may hold promise as future therapeutic targets or as prognostic markers.

Animals

Analyses were performed on 36 canine cortisol‐secreting ATs (11 adenomas and 25 carcinomas) and 15 normal adrenal glands of dogs.

Methods

mRNA expression analysis was performed for PI3K target genes, PI3K inhibitor phosphatase and tensin homolog (PTEN), IGFs, IGF receptors, IGF binding proteins and epidermal growth factor receptors. Mutation analysis was performed on genes encoding PTEN and PI3K catalytic subunit (PIK3CA).

Results

Target gene expression indicated PI3K activation in carcinomas, but not in adenomas. No amino acid‐changing mutations were detected in PTEN or PIK3CA and no significant alterations in IGF‐II or IGFR1 expression were detected. In carcinomas, ERBB2 expression tended to be higher than in normal adrenal glands, and higher expression of inhibitor of differentiation 1 and 2 (ID1 and ID2) was detected in carcinomas with recurrence within 2.5 years after adrenalectomy.

Conclusions and Clinical Importance

Based on these results, ERBB2 might be a promising therapeutic target in ATs in dogs, whereas ID1 and 2 might be valuable as prognostic markers and therapeutic targets.

Animal models of adrenocortical tumorigenesis

This comparative review highlights animal models of adrenocortical neoplasia useful either for mechanistic studies or translational research. Three model species-mouse, ferret, and dog-are detailed. The relevance of each of these models to spontaneous and inherited adrenocortical tumors in humans is discussed.

Complete surgical removal of a very enlarged pituitary corticotroph adenoma in a dog

A 13 yr old castrated male vizsla was referred to the authors' institute because of polyuria, polydipsia, polyphagia, and weight loss. Pituitary-dependent hypercortisolism (PDH) was diagnosed by hormone testing and adrenal and pituitary imaging. Computed tomography (CT) revealed a pituitary mass measuring 21 mm in width. Medical therapy was initiated with trilostane. Despite adequate control of the hypercortisolemia, the polyuria and polydipsia persisted and the dog developed neurologic signs due to the pituitary mass effect. Pituitary transsphenoidal debulking surgery was performed and immunocytochemistry confirmed a corticotroph adenoma. The dog survived for 13 mo after surgery. Postmortem examination revealed an empty fossa without pituitary remnants and the presence of a malignant pheochromocytoma in the right adrenal gland. This case report demonstrates, for the first time, that a large pituitary adenoma in the dog may be treated successfully by pituitary surgery.

Intercostal approach for right adrenalectomy in dogs

OBJECTIVE

To describe an intercostal (IC) approach to the right adrenal (RA) gland in dogs.

STUDY DESIGN

Cadaveric study and case series.

ANIMALS

Dogs with right adrenal (RA) tumors (n = 11) and normal canine cadavers (6).

METHODS

Cadavers had an IC (n = 3) or paracostal (3) approach to the RA. The relative spatial position of the RA to the incision was evaluated. Medical records (June 2007-December 2012) of dogs that had an IC approach to the RA were reviewed. Perioperative data were recorded and described.

RESULTS

In cadavers, the RA was closer to the cranial aspect of the surgical incision after an IC approach compared with a paracostal approach. The IC approach for right adrenalectomy was successfully performed in 11 dogs (6 adrenocortical carcinomas, 4 pheochromocytomas, and 1 osteosarcoma) with a mean anesthesia duration of 242 minutes and mean surgical of 144 minutes. Dogs had vascular invasion into the phrenicoabdominal vein (n = 11) and caudal vena cava (6). There were no significant intra- or postoperative complications. One dog was euthanatized intraoperatively. Median survival time for all dogs was 786 days.

CONCLUSIONS

The IC approach for right adrenalectomy offers superior exposure of the RA compared with a paracostal approach.

Diagnosis of spontaneous canine hyperadrenocorticism: 2012 ACVIM consensus statement (small animal)

This report offers a consensus opinion on the diagnosis of spontaneous canine hyperadrenocorticism. The possibility that a patient has hyperadrenocorticism is based on the history and physical examination. Endocrine tests should be performed only when clinical signs consistent with HAC are present. None of the biochemical screening or differentiating tests for hyperadrenocorticism are perfect. Imaging can also play a role. Awareness of hyperadrenocorticism has heightened over time. Thus, case presentation is more subtle. Due to the changes in manifestations as well as test technology the Panel believes that references ranges should be reestablished. The role of cortisol precursors and sex hormones in causing a syndrome of occult hyperadrenocorticism remains unclear.

Recent advances in the diagnosis of Cushing's syndrome in dogs

Hypercortisolism is a common condition in dogs and can be defined as the physical and biochemical changes that result from prolonged exposure to inappropriately high plasma concentrations of (free) cortisol, whatever its' cause. This disorder is often called Cushing's syndrome, after Harvey Cushing, the neurosurgeon who first described the human syndrome in 1932.

Adrenocortical carcinoma in a dog with incomplete excision managed long-term with metastasectomy alone

A 10 yr old bichon frise presented with a 3 mo history of polyuria, polydipsia, and hind limb weakness. Serum biochemistry revealed persistent hypokalemia. A left adrenal gland mass with right adrenal atrophy was detected ultrasonographically. Basal serum cortisol concentration was at the low end of normal (30 nmol/L; reference range, 30-140 nmol/L) and adrenocorticotropic hormone (ACTH)-stimulated cortisol concentration was low (199 nmol/L; reference range, 220-470 nmol/L). Basal serum 17-α-OH progesterone concentration was also low (0.03 ng/mL; reference range, 0.06-0.30 ng/mL), but the aldosterone concentration 2 hr after the ACTH stimulation was elevated (> 3,000 pmol/L; reference range, 197-2,103 pmol/L). A left adrenalectomy and nephrectomy were performed. Histopathology revealed an adrenocortical zona glomerulosa carcinoma. Surgical excision was considered incomplete; however, clinical signs resolved. Two years later, basal and ACTH-stimulated aldosterone concentrations were elevated. Computed tomography demonstrated a mass effect in the liver. The left lateral and left medial hepatic lobes were removed. Histopathology confirmed metastatic endocrine carcinoma. The patient was stable 1,353 days postsurgically (when this report was prepared). This is the first case report of a metastatic adrenal carcinoma that was successfully managed surgically for > 3 yr.

Animal models of adrenocortical tumorigenesis

Over the past decade, research on human adrenocortical neoplasia has been dominated by gene expression profiling of tumor specimens and by analysis of genetic disorders associated with a predisposition to these tumors. Although these studies have identified key genes and associated signaling pathways that are dysregulated in adrenocortical neoplasms, the molecular events accounting for the frequent occurrence of benign tumors and low rate of malignant transformation remain unknown. Moreover, the prognosis for patients with adrenocortical carcinoma remains poor, so new medical treatments are needed. Naturally occurring and genetically engineered animal models afford a means to investigate adrenocortical tumorigenesis and to develop novel therapeutics. This comparative review highlights adrenocortical tumor models useful for either mechanistic studies or preclinical testing. Three model species - mouse, ferret, and dog - are reviewed, and their relevance to adrenocortical tumors in humans is discussed.

Metabolic complications of endocrine surgery in companion animals

Metabolic complications of endocrine surgery occur commonly and precautions should be taken to avoid potentially life-threatening situations and to lessen expense associated with a more extended hospital stay. Common complications of endocrine surgery as well as prevention strategies will be reviewed for pancreatic, parathyroid, and adrenal surgery.

Elective and Emergency Surgical Management of Adrenal Gland Tumors: 60 Cases (1999–2006)

Sixty-one adrenal gland tumors were surgically removed from 60 dogs. Fifty-two dogs underwent elective adrenalectomy and 8 dogs underwent emergency adrenalectomy for acute adrenal hemorrhage. Size of adrenal tumors ranged from 10 mm to 80 mm. Histopathology confirmed a diagnosis of adrenocortical tumor in 47 dogs, 26 of which were malignant. Pheochromocytoma was diagnosed in 11 dogs. Six dogs had tumor invasion of the caudal vena cava. Of the seven dogs that did not survive the perioperative period, four underwent emergency adrenalectomy. No dogs with tumor invasion of the caudal vena cava died perioperatively. Perioperative morality rates were 5.7% for dogs that underwent elective adrenalectomy and 50% for dogs that underwent emergency adrenalectomy for acute adrenal hemorrhage. Median survival time was 492 days for the 53 dogs that survived the perioperative period. Of the factors analyzed, only adrenal tumor size and the presence of acute adrenal hemorrhage had predictive values for perioperative mortality. Those dogs that survived the perioperative period had extended survival times of up to 1,590 days. The mortality rate associated with elective adrenalectomy in dogs may be lower than previously reported. Dogs with very large tumors or acute adrenal hemorrhage may have a more guarded prognosis.

A comparison of factors that influence survival in dogs with adrenal-dependent hyperadrenocorticism treated with mitotane or trilostane

BACKGROUND

Trilostane is a recognized treatment for canine pituitary-dependent hyperadrenocorticism (PDH); however, its efficacy in dogs with adrenal-dependent hyperadrenocorticism (ADH) is unknown.

OBJECTIVES

To examine factors that might influence survival in the medical management of ADH, with particular emphasis on treatment selection.

ANIMALS

Thirty-seven animals referred to 4 centers over a period of 12 years that had been diagnosed with ADH and treated with either trilostane (22/37), mitotane (13/37), or both (2/37).

METHODS

Retrospective analysis of clinical records.

RESULTS

There was no statistically significant difference between the survival times of 13 dogs treated only with mitotane when compared with 22 dogs treated only with trilostane. The median survival time for animals treated with trilostane was 353 days (95% confidence interval [CI] 95-528 days), whereas it was 102 days (95% CI 43-277 days) for mitotane. Metastatic disease was detected in 8 of 37 dogs. There was a significantly lower probability of survival for dogs with metastatic disease when compared with those without metastatic disease (P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

The choice of medical treatment for ADH may not have a major effect on survival times. However, the presence of metastatic disease considerably decreases survival time regardless of the choice of medical treatment.

Evaluation of gradual occlusion of the caudal vena cava in clinically normal dogs

OBJECTIVES

To devise a technique for gradual occlusion of the caudal vena cava in dogs and determine effects of complete occlusion of the caudal vena cava.

ANIMALS

8 mixed-breed hounds that weighed between 25 and 30 kg.

PROCEDURE

Baseline evaluation of dogs included serum biochemical analyses and determination of glomerular filtration rate (GFR) with dynamic renal scintigraphy and plasma clearance analysis. An occluder was placed around the vena cava in the region cranial to the renal veins. The occluder was attached to a vascular access port. The vena cava was gradually occluded over 2 weeks. The GFR was measured every 2 weeks after surgery, and venograms were performed every 3 weeks after surgery. Blood samples were collected every 48 hours for the first week and then weekly thereafter to measure BUN and creatinine concentrations and activities of alanine transaminase, alkaline phosphatase, and creatinine kinase. Dogs were euthanatized 6 weeks after surgery, and tissues were submitted for histologic examination. The GFR and biochemical data were compared with baseline values.

RESULTS

Gradual occlusion of the caudal vena cava was easily and consistently performed with this method, and adverse clinical signs were not detected. Formation of collateral vessels allowed overall GFR to remain constant despite a decrease in function of the left kidney. Measured biochemical values did not deviate from reference ranges.

CONCLUSIONS AND CLINICAL RELEVANCE

Gradual occlusion of the caudal vena cava may allow removal of adrenal gland tumors with vascular invasion that would otherwise be difficult or impossible to resect.

Surgical management of adrenal gland tumors with and without associated tumor thrombi in dogs: 40 cases (1994-2001)

OBJECTIVE

To compare pathologic findings and results of adrenalectomy for adrenal gland tumors in dogs with and without vena caval tumor thrombi.

DESIGN

Retrospective study.

ANIMALS

40 dogs with adrenal gland tumors.

PROCEDURE

Medical records were examined. An exact logistic regression analysis was used to evaluate associations between tumor type or right-sided versus left-sided tumor involvement and development of caval tumor thrombi and associations between tumor thrombi, tumor type, or right- versus left-sided location and perioperative complications and mortality rate. Survival was compared between dogs with and without tumor thrombi.

RESULTS

Caval thrombi were detected in 25% of dogs, including 3 of 28 (11%) dogs with an adrenocortical tumor and 6 of 11 dogs with a pheochromocytoma. A caval tumor thrombus was detected in 6 of 17 right-sided and 4 of 20 left-sided tumors. Sensitivity and specificity of abdominal ultrasonography for detection of caval thrombi were 80 and 90%, respectively. Intraoperative and postoperative complications developed in 15 and 51% of dogs, respectively. The mortality rate was 22%. There were no significant differences in perioperative morbidity and mortality rates between dogs with and without tumor thrombi.

CONCLUSIONS AND CLINICAL RELEVANCE

Caval thrombi associated with adrenal gland tumors are amenable to adrenalectomy and thrombectomy without significantly increased perioperative morbidity and mortality rates, assuming the surgeon is experienced in appropriate techniques.

Trilostane treatment of a dog with functional adrenocortical neoplasia

A 13-year-old, crossbreed dog presented with a history of recent onset polydipsia, progressive lethargy, weakness and reduced appetite. Blood tests showed raised concentrations of alkaline phosphatase and alanine aminotransferase with marginally low serum potassium. There was a leucocytosis with a mature neutrophilia and no eosinophils. Endocrine tests showed a normal aldosterone concentration and an exaggerated adrenocorticotropic hormone (ACTH) stimulation test, consistent with a diagnosis of hyperadrenocorticism (HAC). A diagnosis of adrenal-dependent HAC was made, based on the presence of a calcified mass involving the left adrenal gland, and hepatomegaly, on radiography and ultrasonography. The owners declined surgical adrenalectomy. Medical management with trilostane rapidly improved the clinical signs and normalised the serum chemistry. ACTH stimulation tests showed an improvement in post-ACTH cortisol concentrations and were used to make dose adjustments where necessary. At the time of writing, no adverse side effects had been seen and the dog remained well after 80 weeks of treatment.

Surgical treatment of right-sided renal lymphoma with invasion of the caudal vena cava

An eight-year-old, male castrated basset hound presenting with a three-month history of lethargy was examined. Diagnostic tests including radiography and ultrasonography showed a right-sided renal mass. A 99mTc diethylenetriamine penta-acetic acid scan demonstrated that this kidney was non-functional. At surgery, invasion of the caudal vena cava was found, and the renal segment of the vena cava and the right kidney were resected. The left renal vein was anastomosed to the more proximal vena cava using a polytetrafluoroethylene graft, and the dog recovered well. Two days postsurgery, the dog suffered an acute episode of aspiration pneumonia and was euthanased. The renal mass was diagnosed as lymphoma on histopathology.

Nontraumatic rupture of an adrenal gland tumor causing intra-abdominal or retroperitoneal hemorrhage in four dogs

Diagnosis and surgical management of intra-abdominal or retroperitoneal hemorrhage in 4 dogs with rupture of an adrenal gland tumor were determined. All 4 dogs were lethargic and weak with pale mucous membranes on initial examination. Three dogs did not have any history of clinical signs of hyperadrenocorticism or pheochromocytoma prior to examination. In 3 of the dogs, a mass in the area of the adrenal gland was identified with ultrasonography prior to surgery. All dogs developed ventricular premature contractions before or during anesthesia. Three dogs survived adrenalectomy; 1 dog was euthanatized during surgery because of an inability to achieve adequate hemostasis. The remaining 3 dogs all survived more than 5 months after surgery; 1 was euthanatized 9 months after surgery because of rupture of a hepatic mass. On the basis of these results, we suggest that hemodynamic stabilization followed by adrenalectomy is the treatment of choice for dogs with nontraumatic rupture of an adrenal gland tumor and resulting life-threatening hemorrhage.

Ultrasonography of the adrenal glands in the dog, cat, and ferret

Ultrasonography has become an important modality for imaging adrenal glands in small animals. Normal adrenal glands and structural abnormalities, such as changes in size, shape, and echogenicity, can be identified. In the case of adrenal tumors, ultrasonography is a valuable tool for identifying neoplastic masses with local and regional involvement, as well as potential abdominal metastases. When correlated with clinical findings and results of hematologic, serum biochemical and endocrine tests, ultrasonographic findings make a substantial contribution to the diagnosis of adrenal diseases in dogs, cats, and ferrets.

Results of transsphenoidal hypophysectomy in 52 dogs with pituitary-dependent hyperadrenocorticism

OBJECTIVE

To evaluate microsurgical transsphenoidal hypophysectomy in dogs with pituitary-dependent hyperadrenocorticism (PDH).

STUDY DESIGN

Prospective study to evaluate the results (survival and disease-free interval, remission, recurrence) and complications of microsurgical transsphenoidal hypophysectomy by clinical follow-up, computed tomography (CT), and urinary corticoid-to-creatinine (C/C) ratios in dogs with PDH. The effect of surgical experience was investigated by comparing results of hypophysectomy cases 1 through 26 and 27 through 52.

ANIMALS OR SAMPLE POPULATION

52 dogs with PDH.

RESULTS

Preoperative CT enabled accurate assessment of pituitary size (24 nonenlarged and 28 enlarged) and localization relative to intraoperative anatomic landmarks. Treatment failures included procedure-related mortalities (five dogs) and incomplete hypophysectomies (four dogs). The 1-year estimated survival rate was 84% (95% confidence interval [CI], 71% to 92%). The 2-year estimated survival rate was 80% (95% CI, 65% to 90%). In 43 dogs, the hyperadrenocorticism went into remission. Hyperadrenocorticism recurred in five dogs. The 1-year estimated relapse-free fraction was 92% (95% CI, 76% to 97%). The main complications were transient, mild, postoperative hypernatremia; transient reduction or cessation of tear production (25 eyes in 18 dogs); permanent (five dogs) or prolonged (nine dogs) diabetes insipidus; and secondary hypothyroidism. Normal tear production had resumed in all but one case after a median period of 10 weeks. In the second case series (27 through 52), the hospitalization period was shorter, the number of dry eyes fewer, the survival fraction greater, and the postoperative mortality lower than in the first series. In 15 dogs in which remission was obtained, postoperative CT images suggested the presence of small pituitary remnants; in 1 of these, hyperadrenocorticism recurred. In 46 dogs, the histological diagnosis was pituitary adenoma.

CONCLUSIONS

Microsurgical transsphenoidal hypophysectomy in dogs with PDH is an effective method of treatment in specialized veterinary institutions having access to advanced pituitary imaging techniques. Postoperative CT findings do not correlate well with remission or subsequent recurrence of hyperadrenocorticism.

CLINICAL RELEVANCE

The neurosurgeon performing hypophysectomies must master a learning curve and must be familiar with the most frequent complications of the operation to recognize them as early as possible and to treat them immediately and effectively. Urinary C/C ratios are sensitive indicators for the assessment of remission and recurrence of hyperadrenocorticism.

Multiple endocrine neoplasias in a dog: corticotrophic tumour, bilateral adrenocortical tumours, and pheochromocytoma

In a 10-year-old ovariohysterectomized standard Schnauzer, the finding of dexamethasone-resistant hypersecretion of cortisol, the results of computed tomography, and elevated plasma concentrations of ACTH suggested the presence of both adrenocortical tumour and pituitary-dependent hyperadrenocorticism. The dog made an uneventful recovery after bilateral adrenalectomy and remained in good health for 31/2 years with substitution for the induced hypoadrenocorticism. Then the enlarged pituitary caused neurological signs and eventually euthanasia was performed. The surgically excised right adrenal contained a well-circumscribed tumour of differentiated adrenocortical tissue and in the left adrenal there were two adrenocortical tumours and a pheochromocytoma. The unaffected parts of the adrenal cortices were well developed and without regressive transformation. At necropsy there were no metastatic lesions. The cells of the pituitary tumour were immunopositive for ACTH and had characteristics of malignancy. The present combination of corticotrophic tumour, adrenocortical tumours, and pheochromocytoma may be called 'multiple endocrine neoplasia' (MEN), but does not correspond to the inherited combinations of diseases known in humans as the MEN-1 and the MEN-2 syndromes. It is suggested that the co-existence of hyperadrenocorticism and pheochromocytoma may be related to the vascular supply of the adrenals. Some chromaffin cells of the adrenal medulla are directly exposed to cortical venous blood, and intra-adrenal cortisol is known to stimulate catecholamine synthesis and may promote adrenal medullary hyperplasia or neoplasia.

Urinary corticoid/creatinine ratios in the differentiation between pituitary-dependent hyperadrenocorticism and hyperadrenocorticism due to adrenocortical tumour in the dog

In a study on the differentiation between pituitary-dependent hyperadrenocorticism (PDH) and hyperadrenocorticism due to adrenocortical tumour (AT), two questions were addressed: 1. Do basal urinary corticoid/creatinine (c/c) ratios have any value in this respect, and 2. what is the reference percentage suppression of the urinary c/c ratios in the high-dose dexamethasone suppression test? Data obtained from 160 dogs with hyperadrenocorticism were analysed. In 49 dogs the diagnosis AT was confirmed by the finding of plasma ACTH concentrations < 40 ng/l, by visualisation of the tumour by ultrasonography and/or computed tomography, and by histological examination of the adrenal tissue obtained at surgery or autopsy. Among the 111 dogs with PDH, there were 31 animals with resistance to dexamethasone suppression, i.e., suppression < 50%. The basal urinary c/c ratios of dogs with PDH and AT did not differ significantly, although urinary c/c ratios > 100 x 10(-6) almost exclusively occurred in association with PDH. Among the dogs with hyperadrenocorticism, the positive predictive value of a basal urinary c/c ratio > 100 x 10(-6) for the diagnosis of PDH was 0.90 (95% CI: 0.74-0.98). Of the 49 dogs with AT, 34 had a urinary c/c ratio after dexamethasone administration higher than the basal urinary c/c ratio. The maximum suppression of the basal urinary c/c ratio in dogs with AT was 43.7%. It is concluded that in dogs with hyperadrenocorticism basal urinary c/c ratios only have predictive value in the differentiation between AT and PDH when the ratio exceeds 100 x 10(-6). The generally accepted criterion of 50% suppression by dexamethasone in the differentiation between PDH and AT is also applicable to the urinary c/c ratio.