Tina J. Owen

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

OBJECTIVEnTo 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.nnnDESIGNnRetrospective case series.nnnANIMALSn150 dogs with unilateral (n=58) or bilateral (92) CCL rupture.nnnPROCEDURESnMedical 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.nnnRESULTSnDogs 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.nnnCONCLUSION AND CLINICAL RELEVANCEnResults 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.

Transsphenoidal surgery using a high definition video telescope for pituitary adenomas in dogs with pituitary dependent hypercortisolism: Methods and results

OBJECTIVEnTo (1) establish a technique for transsphenoidal removal of pituitary adenomas in dogs with pituitary dependent hypercortisolism (PDH) using a high definition video telescope, and (2) report initial outcomes.nnnSTUDY DESIGNnProspective case series.nnnANIMALSnDogs with pituitary dependent hypercortisolism (PDH; n = 26) with suprasellar masses.nnnMETHODSnPituitary tumors were removed using a modification of a transoral transsphenoidal approach. Surgery was observed using a high definition video telescope (VITOM™) and localization of the sella was performed by drilling pilot holes in the basisphenoid bone followed by computed tomography (CT).nnnRESULTSnDogs had PDH confirmed by urinary cortisol to creatinine ratio (UCCR) and endogenous ACTH assays, and tumors confirmed by MRI. There were no postoperative cerebrospinal fluid leaks, wound dehiscence, or surgical site infections. Overall postoperative mortality was 19% with no mortality observed in the last 16 dogs, indicating an initial learning curve followed by good surgical results. All dogs that survived the immediate postoperative period (1 week) returned to their owners in good health, on hormonal replacement therapy. Follow-up ranged from 3 to 36 months. Sustained tumor control and hormonal remission based on normalized ACTH and UCCR measurements were observed in 20/21 (95%) dogs at 1-year follow-up.nnnCONCLUSIONSnModifications of a trans-oral transsphenoidal technique for surgical removal of pituitary tumors provides a safe and effective strategy for long-term remission of PDH with acceptable morbidity and mortality.

Severe respiratory compromise secondary to cervical disk herniation in two dogs.

Two dogs presented with acute tetraparesis, hypoventilation, and bradycardia with a second-degree atrioventricular heart block. Neurological examination localized both lesions to the cervical spine. Diagnostic imaging revealed a ventral extradural compression at the second to third cervical (C(2)-C(3)) region in one dog and at the third to fourth cervical (C(3)-C(4)) region in the other. Following surgical correction of the extruded disk, the hypoventilation and bradycardia resolved. Cervical disk extrusions are a common cause of acute tetraparesis in the dog. This report shows that respiratory and cardiac complications may occur concurrently. The authors recommend screening dogs with cervical myelopathies for respiratory and cardiac dysfunctions and treating appropriately. Prompt surgical intervention and supportive care can improve the prognosis.

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

OBJECTIVEnTo determine the influence of nail characteristics on bacterial counts on the fingers of surgery personnel.nnnSTUDY DESIGNnRandomized nonblinded controlled crossover study design.nnnSAMPLE POPULATIONnVeterinary students, small animal surgery technicians, small animal surgery interns/residents, and small animal surgery faculty in a veterinary teaching hospital (nu2009=u200921).nnnMETHODSnSubjects 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 Students t test and presence or absence of bacteria were compared using Fishers exact test.nnnRESULTSnTBC, 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.nnnCONCLUSIONnNail 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.

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

OBJECTIVEnTo 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.nnnSTUDY DESIGNnExperimental cadaveric study.nnnANIMALSnTen canine cadavers.nnnMETHODSnComputed 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.nnnRESULTSnThe rostral and caudal margins of the pituitary fossa provided 2 target points per cadaver. The median target error (interquartile range) for all target sites (nu2009=u200920) was 3.533 mm (range, 2.013-4.745).nnnCONCLUSIONnThis stereotactic system allowed the surgeon to locate the rostral and caudal margins of the pituitary fossa with clinically acceptable accuracy and confidence.nnnCLINICAL SIGNIFICANCEnUsing the Brainsight neuronavigation system for localization during transsphenoidal hypophysectomy may decrease morbidity and surgical time.

Histopathologic Findings in Canine Pituitary Glands

To optimize the histologic evaluation of hypophysectomy specimens, sections of 207 canine pituitary glands (196 postmortem, 11 hypophysectomy specimens) were reviewed. Adenohypophyseal proliferation was the most common (n = 79) lesion. Proliferative lesions were sparsely to densely granulated; the granules were usually basophilic to chromophobic and periodic acid-Schiff-positive. Adenohypophyseal proliferation was classified as hyperplasia (n = 40) if ≤2 mm diameter with intact reticulin network, as microadenoma (n = 22) for 1–5 mm homogeneous nodules with lost reticulin network, or as macroadenoma (n = 17) for larger tumors. Craniopharyngeal duct cysts were common incidental lesions and the only lesion in 15 dogs. Uncommon diagnoses included lymphoma (n = 4), hemorrhagic necrosis (n = 4), metastatic carcinoma (n = 3), hypophysitis (n = 3), ependymoma (n = 2), craniopharyngioma (n = 2), and 1 case each of metastatic melanoma, pituicytoma, gliomatosis, germ cell tumor, meningioma, and atrophy. The pituitary histologic diagnosis was associated with hyperadrenocorticism (HAC; P < .001) and adrenocortical histologic diagnosis (P = .025). Both HAC and adrenocortical hyperplasia showed a positive trend with the degree of adenohypophyseal proliferation. The association of adrenocortical hyperplasia with HAC was not significant (P = .077). Dogs with adenohypophyseal proliferations were older than dogs with normal pituitary glands (P < .05). Brachycephalic breeds were overrepresented among dogs with pituitary macroadenoma or craniopharyngeal duct cysts, but the association was not statistically significant (P = .076). Adenohypophyseal hyperplasia was more common than adenoma among postmortem specimens, but was unexpected in >80% of cases. Pituitary macroadenoma was the most common diagnosis in hypophysectomy specimens.

Immunohistochemical Evaluation of Canine Pituitary Adenomas Obtained by Transsphenoidal Hypophysectomy

Hypophysectomy specimens from 16 dogs with pituitary adenoma were evaluated with periodic acid-Schiff (PAS), reticulin, and immunohistochemistry for adrenocorticotrophic hormone (ACTH), melanocyte stimulating hormone (MSH), growth hormone (GH), and Ki-67. The reticulin network was obliterated in all adenomas. One adenoma expressed ACTH and GH. Eight corticotroph adenomas were basophilic to chromophobic, and PAS- and ACTH-positive. Seven melanotroph adenomas were distinguished from corticotroph adenomas by expression of MSH. Pituitary-dependent hypercortisolism was diagnosed in 5 of 8 dogs with corticotroph and 4 of 7 with melanotroph adenoma. Pituitary height/brain area (P/B) ratio was elevated in all dogs. Previous canine hypophysectomy studies suggested that melanotroph adenomas were larger and carried a worse prognosis than corticotroph adenomas; however, in this study, corticotroph adenomas in comparison to melanotroph adenomas were larger (median P/B ratio: 1.06 versus 0.76), more proliferative (median Ki-67 index: 9.47% versus 1.99%), and associated with shorter survival (median: 300 versus 793 days). Recommended immunohistochemistry for PAS-positive pituitary adenomas includes ACTH and MSH to distinguish corticotrophs from melanotrophs and Ki-67 for proliferation index.

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.

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.

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

OBJECTIVEnTo 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.nnnSTUDY DESIGNnProspective clinical study.nnnSAMPLE POPULATIONnForty chondrodystrophic dogs with TL IVD extrusion and preoperative CT and MR studies.nnnMETHODSnMR and CT images were randomized and reviewed by 4 observers masked to the dogs 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.nnnRESULTSnSimilar 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.nnnCONCLUSIONnFindings 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.