Distinctive histopathologic features of canine optic nerve hypoplasia and aplasia: a retrospective review of 13 cases

Canine optic nerve hypoplasia (ONH) and aplasia (ONA) are significant neuro-ophthalmologic disorders that have been reported in several species. The purpose of this study was to describe the distinctive histopathologic features of ONH and ONA in canine patients identified from a collection of 20 000 ocular submissions at the comparative ocular pathology laboratory of Wisconsin from 1989 to 2006. The following information about ONH and ONA cases was collected: signalment, and clinical and gross findings, including unilateral vs. bilateral involvement. Microscopic evaluation was performed, with attention to optic nerve malformation, retinal ganglion cell (RGC) and nerve fiber layer (NFL) loss, and retinal disorganization. The distribution of retinal vasculature was recorded and a search for unusual findings of ONH and ONA was performed. Information and histologic documentation was available for 13 cases. Eight cases of ONH and five cases of ONA were identified. The average group age was 20.2 months and 16.1 months, respectively. The most common breed was the Shih Tzu (3/13). ONH usually presented bilaterally (7/8); all ONA cases presented as a unilateral disease (5/5). The morphologic findings in the optic nerve (ON) in ONH included variable degrees of ON hypoplasia and gliosis, as well as ectopic vestigial ON remnants within orbital nerves and connective tissues. The NFL was detected in the majority of the ONH cases; however, RGCs were rare or absent. Mild retinal disorganization was seen occasionally. Most cases of ONH were associated with regional peripheral retinal blood vessel extension into the vitreous, leaving the peripheral retina avascular. In ONA cases the retinal blood vessels, NFL and RGCs were totally absent and retinal disorganization was severe. Distinctive microscopic features encountered in ONA included anterior segment dysgenesis in some cases. The retina in these cases was stretched across the posterior lens capsule, never making contact with the posterior pole of the globe. The current study reviews the human and veterinary literature pertaining to ONH and ONA, compares ONH and ONA in dogs, and presents related ophthalmic histopathologic findings that have not been reported previously.     

A matched observational study of canine survival with primary intraocular melanocytic neoplasia

A retrospective histopathologic study was performed to evaluate the effect of primary intraocular melanocytic neoplasia on canine survival. Tumor size, location within the globe, extent of infiltration, and mitotic index were analyzed for their potential to predict survival. A total of 244 cases of dogs with melanocytic tumors submitted to the Comparative Ocular Pathology Laboratory of Wisconsin from 1988 to 1998 were evaluated. Histopathologic criteria (mitotic index, cytologic features of anaplasia) were used to differentiate 188 benign melanocytomas from 56 malignant melanomas. Signalment evaluation of age, sex, and breed revealed similarities in both tumor populations, with the majority of tumors discovered in 9-year-old, female/spayed, mixed-breed dogs. A greater percentage of left eyes (66%) vs. right eyes (47%) was found in the melanoma population, but an equal distribution was found in the melanocytoma population (48% and 52%, respectively). The majority of tumors arose from the anterior uveal tract (79% in the melanocytoma and 95% in the malignant melanoma populations). The German Shepherd breed was predisposed in the limbal distribution. At the time of enucleation, most tumors had invaded the sclera, but did not show extrascleral extension (51% in the melanocytoma and 61% in the malignant melanoma populations). Survival analysis showed a significant difference in survival between control and malignant melanoma populations ( P  = 0.0081) and was suggestive of a difference between the melanocytoma and melanoma populations ( P  = 0.031). Tumor extension, tumor size, and mitotic index were not found to be reliable predictors of survival.     

Bilateral traumatic optic nerve avulsion in a Thoroughbred gelding

This report describes an unusual case of acute blindness following traumatic head injury in a mature horse. The horse fell over backwards and subsequently presented with bilateral blindness and epistaxis. Vision did not return following medical supportive therapy and euthanasia was elected. Post mortem findings revealed a basisphenoid fracture and bilateral optic nerve avulsion rostral to the optic chiasm, an uncommon presentation of traumatic blindness not previously reported in the horse.     

Reactive histiocytosis of the orbit and posterior segment in a dog

We present a case of reactive histiocytic disease involving the orbit, optic nerve, retina, and choroid in a Border Collie dog initially presenting for vision loss. Long-term partial return of vision has been achieved with systemic immunosuppression. Anterior segment and ocular surface manifestations of reactive histiocytic disease in dogs are relatively common. Posterior segment and orbital involvement, however, are minimally documented in the existing literature. To the authors' knowledge, this is the first report of disease confined to the orbit and posterior segment as well as the first report of vision loss as a presenting complaint for reactive histiocytic disease. Clinical, magnetic resonance imaging, cytologic, and histopathologic findings are reviewed.     

Canine limbal melanoma: 30 cases (1992-2004). Part 1. Signalment, clinical and histological features and pedigree analysis

OBJECTIVES: (1) To review the signalment, clinical, and histological features of canine limbal melanoma; (2) to perform pedigree analysis on breeds predisposed to limbal melanoma to establish if common ancestry exists; and (3) to investigate if any ancestral relationship exists between canine limbal melanoma and canine anterior uveal melanoma (CAUM). DESIGN: Retrospective study. ANIMALS STUDIED: Thirty dogs with limbal melanoma. METHODS: Medical records of patients were reviewed. Follow-up information was obtained by re-examination of patients or telecommunications with the referring veterinary surgeons or the owners. Pedigrees were analyzed for common ancestry amongst affected dogs. RESULTS The mean age (+/- SD) at diagnosis was 6.2 (+/- 2.75) years with a range from 1 to 11 years. There was a bimodal distribution of ages with a peak at 3-4 years and a peak at 7-10 years. There was no eye predilection or predisposition for sex or coat color. Twenty-five (83%) of the limbal melanomas occurred within a dorsal arc from the dorsomedial to the ventrolateral limbus. Golden retrievers were four times more common in the melanoma group compared to the Animal Health Trust population (P < 0.0001). Labrador retrievers were three times more common in the melanoma group (P=0.01). Pedigree analysis on eight Golden retrievers [limbal melanoma (n=5), CAUM (n=2) and diffuse ocular melanosis (n=1)], revealed a pattern of inter-relatedness consistent with the condition(s) being caused, at least in part, by a genetic mutation(s). A similar level of inter relatedness was evident in six Labrador retrievers (limbal melanoma (n=2) and CAUM (n=4)). In 5/22 cases (23%), histological features suggestive of malignancy were present including intratumor necrosis in 4/22 cases (18%) and cellular atypia in 1/22 cases (5%). CONCLUSIONS: In Golden and Labrador retrievers there is evidence that limbal melanomas, CAUM and ocular melanosis are at least in part heritable and that the same genetic mutation(s) may be causally associated with melanocytic disease at different ocular sites. The same genetic mutation(s) may be present in these two breeds. Histology should be performed on all cases to identify those with greater malignant potential.     

CASE REPORT: Bilateral vision loss in a captive cheetah (Acinonyx jubatus)

The following case report describes a 1‐year‐old female cheetah (Acinonyx jubatus) with bilateral blindness and unresponsive pupils. For comparison, a second healthy 2.5‐year‐old male cheetah without visual deficits was also examined. Clinical examination of both animals included biomicroscopy, indirect ophthalmoscopy, tonometry, and electroretinography. The young female cheetah showed no menace response, no direct or indirect pupillary light reflex, and no dazzle reflex in either eye. Fundus lesions, as detected by indirect ophthalmoscopy, are described for the female animal. In both eyes, the fundus color was green/turquoise/yellow with multiple hyperpigmented linear lesions in the tapetal area around the optic nerve. The optic nerve head was dark gray and about half the normal size suggesting bilateral optic nerve hypoplasia and retinal dysplasia or differentially optic nerve atrophy and chorioretinal scarring. The ERG had low amplitudes in the right eye but appeared normal in the left eye compared with the male cheetah. Blood levels did not suggest current taurine deficiency. This is addressed to some degree in the discussion. Bilateral optic nerve hypoplasia or optic nerve atrophy is a rare anomaly in cats and has not yet been described in a cheetah.     

ULTRASONOGRAPHIC FINDINGS IN CANINE GASTRIC NEOPLASIA IN 13 PATIENTS

The ultrasonographic findings in 13 canine patients with histopathologically proven gastric tumors were reviewed. The echogenicity of gastric wall lesions was variable and independent of the type of tumor. All dogs had an increase in gastric wall thickness and in only one dog was the wall layering intact. Regional lymph node involvement was a common finding, but abnormalities within the liver were seen in only one patient. Gastric neoplasia was observed most commonly in middle-aged and old, medium- to large-sized dogs. Carcinoma was the most common tumor found. In this study, with a limited number of animals and limited tumor types, it appeared that thickening of the gastric wall, accompanied by loss of gastric wall layering and enlargement of regional lymph nodes were ultrasonographic signs likely to be found with gastric neoplasia. In this limited study the histologic type of gastric tumor could not be predicted on the basis of the ultrasound examination.     

犬黑色素瘤治疗研究进展

犬黑色素瘤是一种恶变率和转移率高的肿瘤,且多发生于口腔,由于疾病发展迅速,如果不尽早治疗,在疾病发展后期,患犬的生存期和生存质量会显著下降。另一方面,现有临床传统肿瘤治疗方法,如手术、化疗及放疗,对于犬黑色素瘤的治疗效果不尽如人意,且在实际应用中受限。论文通过结合人医和兽医黑色素瘤的研究进展,对目前关于犬黑色素瘤的免疫疗法、靶向治疗、细胞因子和溶瘤病毒等新型治疗方法进行总结及分析,期望能够对我国小动物临床应用和科研工作有所启发。