Cytologic features of canine melanotroph and corticotroph pituitary adenomas.

BACKGROUND: The introduction of intraoperative cytology revolutionized neurosurgical procedures in human medicine, providing real-time diagnostic guidance to surgeons and contributing to improved patient outcomes. In the realm of veterinary medicine, the understanding of pituitary tumors in dogs and cats remains limited due to challenges in obtaining antemortem samples of central nervous system lesions. OBJECTIVES: The aim of this study was to describe the cytologic features of pituitary adenomas in 12 dogs that underwent hypophysectomy. METHODS: The series included nine melanotroph adenomas and three corticotroph adenomas. Definitive diagnosis was based on histopathology and immunohistochemistry. RESULTS: Cytologically, the adenomas had high numbers of bare nuclei and intact cells that were round to polygonal and situated individually or in small clusters. The intact cells had round to oval, eccentric nuclei with finely stippled chromatin and one to three prominent nucleoli and ample to abundant lightly basophilic to amphophilic, grainy cytoplasm with distinct borders, and variable numbers of discrete vacuoles. Mild-to-moderate anisocytosis and anisokaryosis, occasional binucleation, rare and atypical mitotic figures, and nuclear molding were also observed. CONCLUSIONS: The results suggest that intraoperative cytology of canine pituitary adenomas holds promise as a valuable diagnostic tool, aiding swift differentiation from other sellar masses before histologic confirmation. Cytologic characterization of pituitary adenomas in dogs is exceptionally rare in the scientific literature, making this study one of the first to offer a comprehensive description of these cytologic features.

Clinical characteristics and outcome in 15 dogs treated with transsphenoidal hypophysectomy for nonfunctional sellar masses.

OBJECTIVE: To characterize the clinical features, neurological examination findings, diagnostic imaging results, histopathological findings, and outcome following transsphenoidal hypophysectomy (TSH) in dogs with nonfunctional sellar masses (NFSM). STUDY DESIGN: Multi-institutional retrospective study. METHODS: Medical records of dogs that underwent TSH for a NFSM were reviewed for clinical signs, physical and neurological examination findings, diagnostic imaging results, endocrine testing, surgery reports, and outcome. Magnetic resonance (MR) imaging was rereviewed, and tumors were classified using the previously described system according to pituitary tumor extension and vascular involvement. Owners of dogs that survived to discharge were contacted. RESULTS: The majority of dogs presented for mentation change (12/15). The mean pituitary to brain ratio (P/B ratio) was 1.05 (0.6-1.4). Eight dogs had a tumor imaging classification of 5B. Eleven dogs were diagnosed with a nonfunctional pituitary adenoma (NFPA). Perioperative mortality was 33% (5/15). The median survival for all dogs was 232 days (0-1658). When dogs that did not survive to discharge were excluded, the median survival time was 708 days. Seven of 10 dogs that survived the perioperative period received adjunctive therapy. Owner assessment of outcome was excellent (6/7) to good (1/7). CONCLUSION: The common presenting complaint for dogs with large NFSM causing mass effect was mentation changes. Dogs with NFPA that survived to discharge and received adjunctive therapy had good to excellent outcomes. CLINICAL SIGNIFICANCE: Transsphenoidal debulking with adjunctive therapy can be considered for the treatment of NFSM causing clinical signs of mass effect in dogs. Successful long-term outcomes are possible.

Feline Pituitary Adenomas: Correlation of Histologic and Immunohistochemical Characteristics With Clinical Findings and Case Outcome.

Pituitary glands from 141 feline autopsy cases were reviewed histologically. Adenoma and hyperplasia were the most common lesions at 13 cases each. Pituitary adenoma was more likely than hyperplasia to be associated with clinical evidence of endocrinopathy or an intracranial mass (P < .001). A histochemical and immunohistochemical panel was applied to 44 autopsy- or hypophysectomy-derived pituitary adenomas in 43 cats from 2 diagnostic laboratories. Adenomas were differentiated from hyperplasia by the presence of disrupted reticulin fibers. One cat had a double (somatotroph and melanotroph) adenoma. Twenty somatotroph adenomas consisted of periodic acid-Schiff (PAS)-negative acidophils that expressed growth hormone; 16/20 had hypersomatotropism; 17/20 had diabetes mellitus. Eleven melanotroph adenomas consisted of PAS-positive basophils or chromophobes that expressed melanocyte-stimulating and adrenocorticotrophic hormones; 5/11 had hypercortisolism; 6/11 had diabetes mellitus. Eleven gonadotroph adenomas consisted of PAS-negative chromophobes that expressed follicle-stimulating and/or luteinizing hormones. Two thyrotroph adenomas consisted of PAS-negative basophils or chromophobes that expressed thyroid-stimulating hormone. Pituitary-dependent disease was not recognized in cats with gonadotroph or thyrotroph adenomas. The Ki-67 proliferation index in hypophysectomy specimens was lower in somatotroph than in melanotroph adenomas. Fourteen cats with hypophysectomy-treated somatotroph or melanotroph adenoma had an 899-day median survival time versus 173 days in 17 nonsurgical cases. After adjusting for age, adenoma size and type, hypophysectomized cats had an overall better survival time than nonsurgical cases (P = .029). The study results underscore the value of hypophysectomy and trophic hormone immunohistochemistry in the treatment and classification of feline pituitary adenomas.

Transsphenoidal surgery: accuracy of an image-guided neuronavigation system to approach the pituitary fossa (sella turcica).

OBJECTIVE: To determine the accuracy of locating the pituitary fossa with the Brainsight neuronavigation system by determining the mean target error of the rostral (tuberculum sellae) and caudal (dorsum sellae) margins of the pituitary fossa. STUDY DESIGN: Experimental cadaveric study. ANIMALS: Ten canine cadavers. METHODS: Computed tomography (CT) and MRI were performed on each cadaver with fiducials in place. Images were saved to the neuronavigation computer and used to plan the drilling approach. The cadavers were placed in the surgical head clamp of the Brainsight system and positioned for a transsphenoidal approach. On the basis of the planning, 2 localization points were drilled, 1 each at the rostral and caudal margins of the pituitary fossa, and CT was repeated. Error was assessed from the difference in millimeters between the targets identified during Brainsight planning and the actual location of the 2 points drilled on each cadaver skull as identified by postdrilling CT. RESULTS: The rostral and caudal margins of the pituitary fossa provided 2 target points per cadaver. The median target error (interquartile range) for all target sites (n = 20) was 3.533 mm (range, 2.013-4.745). CONCLUSION: This stereotactic system allowed the surgeon to locate the rostral and caudal margins of the pituitary fossa with clinically acceptable accuracy and confidence. CLINICAL SIGNIFICANCE: Using the Brainsight neuronavigation system for localization during transsphenoidal hypophysectomy may decrease morbidity and surgical time.

Transsphenoidal Surgery for Pituitary Tumors and Other Sellar Masses.

Transsphenoidal surgery is an option for dogs and cats with functional and nonfunctional pituitary masses or other sellar and parasellar masses. An adrenocorticotropic hormone-secreting tumor causing Cushing disease is the most common clinically relevant pituitary tumor in dogs, and the most common pituitary tumor seen in cats is a growth hormone-secreting tumor causing acromegaly. Transsphenoidal surgery can lead to rapid resolution of clinical signs and provide a cure for these patients. Because of the risks associated with this surgery, it should only be attempted by a cohesive pituitary surgery group with a sophisticated medical and surgical team.

Magnetic resonance imaging versus computed tomography to plan hemilaminectomies in chondrodystrophic dogs with intervertebral disc extrusion.

OBJECTIVE: To determine the influence of preoperative computed tomography (CT) versus magnetic resonance (MR) on hemilaminectomies planned to treat thoracolumbar (TL) intervertebral disc (IVD) extrusions in chondrodystrophic dogs. STUDY DESIGN: Prospective clinical study. SAMPLE POPULATION: Forty chondrodystrophic dogs with TL IVD extrusion and preoperative CT and MR studies. METHODS: MR and CT images were randomized and reviewed by 4 observers masked to the dog's identity and corresponding imaging studies. Observers planned the location along the spine, side, and extent (number of articular facets to be removed) based on individual reviews of CT and MR studies. Intra-observer agreement was determined between overall surgical plan, location, side, and size of the hemilaminectomy planned on CT versus MR of the same dog. RESULTS: Similar surgical plans were developed based on MR versus CT in 43.5%-66.6% of dogs, depending on the observer. Intra-observer agreement in location, side, and size of the planned hemilaminectomy based on CT versus MR ranged between 48.7%-66.6%, 87%-92%, and 51.2%-71.7% of dogs, respectively. Observers tended to plan larger laminectomy defects based on MR versus CT of the same dog. CONCLUSION: Findings from this study indicated considerable differences in hemilaminectomies planned on preoperative MR versus CT imaging. Surgical location and size varied the most; the side of planned hemilaminectomies was most consistent between imaging modalities.

The effect of nail characteristics on surface bacterial counts of surgical personnel before and after scrubbing.

OBJECTIVE: To determine the influence of nail characteristics on bacterial counts on the fingers of surgery personnel. STUDY DESIGN: Randomized nonblinded controlled crossover study design. SAMPLE POPULATION: Veterinary students, small animal surgery technicians, small animal surgery interns/residents, and small animal surgery faculty in a veterinary teaching hospital (n = 21). METHODS: Subjects were randomized into one of 2 groups; group 1 wore nail polish (P) for 1 week and group 2 (control) had nonpolished (NP) fingernails. Each subject changed groups the following week. Fingernail lengths were measured each day and fingernail samples were collected before and after presurgical scrub and after surgery. Total bacterial counts (TBC) and suspected staphylococci were counted on blood agar media and mannitol salt agar. The association between bacterial counts and nail biting, position of the volunteer, duration of the surgery, whether the nail polish was chipped, duration of nail polish application, type of surgery, and handedness was tested. Log-transformed CFU counts were compared with a Student's t test and presence or absence of bacteria were compared using Fisher's exact test. RESULTS: TBC, quantities of staphylococci, other gram-positive organisms, and gram-negative bacilli did not differ between P and NP personnel. The only variable associated with higher bacterial counts consisted of nail lengths greater than 2 mm. CONCLUSION: Nail polish did not influence bacterial counts and types of isolates, but nail length is a risk factor for increased bacterial counts. Based on our results, we recommend that nail length be kept under 2 mm.

Radius and ulna fracture repair with the IMEX miniature circular external skeletal fixation system in 37 small and toy breed dogs: A retrospective study.

OBJECTIVE: To determine outcome and prognostic factors after radius and ulna fracture repair with a modified IMEX miniature circular external skeletal fixation (MCESF) in small and toy breed dogs. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Thirty-seven young small and toy breed dogs with 41 radial and ulnar fractures. METHODS: Records of radial and ulnar fractures repaired with a modified IMEX MCESF were reviewed. Constructs included 3-4 complete rings, 2 threaded rods, 4 mm-diameter nuts and 6-8 transfixation wires. MCESF configuration, type of fracture reduction, dynamization of the apparatus, inclusion of a dowel pin, and implantation of allograft were recorded. Outcome measures included complications, limb alignment, time to clinical union, and functional outcomes, scored as excellent, good, fair, or poor. RESULTS: Radiographic union was achieved in 40/41 fractures. Fractures reached bony union within 33-84 days after repair. Time to union was not influenced by the type of fracture reduction (P = .11), use of a dowel pin (P = .099), or implantation of an allograft (P = .45). Fracture dynamization delayed radiographic union (P = .0005). At implant removal, mean frontal (FPA) and mean sagittal plane alignments (SPA) were 7.9° ± 6.5° and 7.5° ± 5.8°, respectively. Limb alignment did not differ between radiographs obtained immediately after surgery and those obtained at time of radiographic union in the frontal (P = .062) or sagittal (P = .14) planes. Ninety-five percent of cases had good-to-excellent outcomes, based on return to function at final re-evaluations. CONCLUSION: This modified IMEX MCESF construct provided an effective alternative to treat young small and toy breed dogs with radius and ulna fractures.

Comparison of tibial plateau angles in dogs with unilateral versus bilateral cranial cruciate ligament rupture: 150 cases (2000-2006).

OBJECTIVE: To compare tibial plateau angle (TPA) in dogs with unilateral versus bilateral cranial cruciate ligament (CCL) rupture, to compare right versus left TPA in dogs with bilateral CCL rupture, and to determine whether TPA can be used to predict whether a dog with unilateral CCL rupture would subsequently rupture the contralateral CCL. DESIGN: Retrospective case series. ANIMALS: 150 dogs with unilateral (n=58) or bilateral (92) CCL rupture. PROCEDURES: Medical records were reviewed and TPA was recorded. Dogs with unilateral CCL rupture that were not known to have ruptured the contralateral ligament were followed up for a minimum of 2 years. RESULTS: Dogs with unilateral CCL rupture were significantly older (median, 7.0 years) than dogs with bilateral CCL rupture (median, 4.5 years). Median TPA for dogs with unilateral CCL rupture (26 degrees) was not significantly different from median TPA for dogs with bilateral rupture (27 degrees in both the right and left limbs), and right and left TPAs were not significantly different in dogs with bilateral CCL rupture. There was no correlation between TPA and the time interval between diagnosis of the initial and subsequent CCL ruptures in dogs with bilateral CCL rupture. CONCLUSION AND CLINICAL RELEVANCE: Results suggested that TPA in the range studied (mostly<35 degrees) was not a useful predictor of contralateral CCL rupture among dogs with unilateral CCL rupture, although age may be a risk factor for development of bilateral CCL rupture. The incidence of bilateral CCL rupture may be higher than previously reported.