Canine orbital meningiomas: a review of 22 cases

Clinical and pathologic features of primary orbital meningiomas in the dog were reviewed. Twenty-two meningiomas, confined to the orbit, were identified from the Comparative Ophthalmic Pathology Laboratory of Wisconsin from 1981 to 1997. The dogs ranged in age from 3 to 17 years (mean = 9.2 years). The clinical presentation, reported in 20 cases, was indicative of a retrobulbar mass and included exophthalmos and orbital swelling (18/20), and papilledema or abnormalities of the posterior segment (7/20). Visual acuity was reported in 15 cases; of those, 12 dogs were blind in the affected eye. Follow-up information was obtained on 17 cases; six dogs developed local recurrence of the neoplasm. Two dogs with recurrent neoplasms simultaneously developed blindness in the opposite eye. Extension along the optic nerve to the optic chiasm was suspected. No metastasis was found at the time of the study. Enucleation with excisional biopsy was effective therapy to date in 11 cases (0.2–4.5 years follow-up time). All neoplasms were located within the vicinity of the optic nerve and, when sectioned through the optic nerve head, appeared to completely envelope the nerve. The neoplastic cells were arranged in tight whorls and bundles characteristic of meningiomas. Most tumors had islands of chondroid and osseous metaplasia (17/22). Ocular invasion was limited to small foci in the posterior choroid or optic nerve head of six dogs. Immunoperoxidase stains on 10 cases were positive for vimentin and S-100, but negative for cytokeratin. Electron microscopy revealed complex interdigitations between cell membranes and few desmosomal intercellular attachments. Primary orbital meningiomas have a characteristic histologic appearance and may recur locally after surgical excision.     

A case of orbital hemangiopericytoma in a dog

A 7-and-a-half-year-old-dog was presented with progressive unilateral exophthalmos. Computed tomography imaging revealed an orbital mass that was surgically excised by lateral orbitotomy to preserve vision. The tumor was diagnosed histologically as a hemangiopericytoma. Twelve months postoperatively there were no signs of a local recurrence. This is the first case report of a hemangiopericytoma involving the orbit of a dog.     

Canine and feline retinal lymphoma: a retrospective review of 12 cases

This retrospective study identified 12 cases (6 canine and 6 feline) of ocular lymphoma with extensive retinal involvement and relative sparing of other ocular tissues. Our objectives were to describe the morphologic and immunohistochemical features of retinal lymphoma, assess the degree of correlation to the human counterpart, assign subtypes based on the veterinary‐adapted WHO classification system, and promote accurate reporting of retinal involvement in cases of intraocular lymphoma. Our findings suggest that a distinct retinal tropism is quite rare, representing approximately 1% of all cases of canine and feline ocular lymphoma. No breed or sex predispositions were identified. The mean age of the affected animal was 7 years (range 4–10) and 11 years (range 6–19) for dogs and cats, respectively. Nine cases (5 canine and 4 feline) were classified as diffuse large B‐cell lymphoma (DLBCL) subtype. The remaining cases were classified as peripheral T‐cell lymphoma (PTCL).     

Unilateral orbital lacrimal gland abscess in a horse

A 20-year-old Thoroughbred gelding presented for evaluation of a periorbital dorsal swelling of the left eye that had been intermittently present for 3 months. Upon ocular examination, a firm, non-painful swelling was identified under the upper eyelid in the region of the orbital lacrimal gland, and was noted to extend anteriorly from underneath the dorsal orbital rim. Ultrasonographic examination revealed a mixed echogenic mass along the dorsal orbital rim that followed the contour of the globe. CT scan showed a moderately contrast enhancing mass that was contiguous with the eyelid. Differential diagnoses included neoplasia, inflammatory lesions such as a granuloma, foreign body or abscess. Surgical exploration and excision of the mass revealed a lobular structure with a purulent center. Histopathology identified the mass as the orbital lacrimal gland with concurrent severe dacryoadenitis. Culture of the purulent center of the mass revealed beta-hemolytic Staphylococcus aureus. The patient was maintained on supportive care and antibiotic treatment based on sensitivity postoperatively. No recurrence was reported 40 months later. This paper aims to identify bacterial dacryoadenitis as a cause for unilateral periorbital swelling in the horse. Differential diagnoses for this presentation, as well as successful surgical management are discussed. To the author's knowledge, this is the first case of bacterial dacryoadenitis and subsequent abscessation of the orbital lacrimal gland in the horse.     

Surgical excision of a feline orbital lacrimal gland adenocarcinoma with adjunctive cryotherapy and carboplatin‐impregnated bead implantation

The purpose of this report was to discuss the diagnosis, treatment, and outcome of a cat with an orbital lacrimal gland adenocarcinoma. A 14.5‐year‐old spayed female domestic shorthair cat was evaluated for a firm swelling at the left dorsotemporal orbital rim. The orbital mass was excised with preservation of the globe, and adjunctive cryotherapy was performed. A definitive diagnosis of lacrimal gland adenocarcinoma was obtained after histopathologic evaluation and histochemical staining with periodic acid–Schiff and mucicarmine. Thirteen months postoperatively, tumor regrowth occurred with a much larger osteolytic lesion, and a second surgery was performed consisting of tumor excision with implantation of carboplatin‐impregnated calcium sulfate hemihydrate beads. The cat has remained free of recurrence 11 months after the second surgery (26 months after initial diagnosis and surgery). A feline orbital lacrimal gland adenocarcinoma was successfully managed utilizing globe‐preserving surgical excision with adjunctive cryotherapy and subsequent carboplatin‐impregnated bead implantation. Orbital lacrimal gland adenocarcinoma in cats may not be as aggressive as other forms of periocular, head, and neck adenocarcinomas.     

Dacryops of the lacrimal gland in a dog

A case of congenital lacrimal cyst or dacryops of the lacrimal gland in an 8‐month‐old Neapolitan Mastiff dog is reported. The dog presented with a swelling dorsolateral to the left globe, which had been present since birth. In addition, hyperplasia and prolapse of the superficial gland of the left nictitating membrane, and bilateral macropalpebral fissure and ‘diamond eye’ conformation were apparent. On manual eversion of the upper eyelid, a subconjunctival mass was visible that was translucent and pink and affected the upper conjunctival fornix. B‐mode ultrasonography revealed the presence of an echolucent thin‐walled cystic structure measuring 15 by 12 mm and containing an echodense border and a distended tubular fluid‐filled structure that extended posteriorly. A viscous and transparent fluid was aspirated from the lesion. Surgery was performed to excise the lesion, reposition the nictitans gland, and correct the morphology of the palpebral fissure. Histopathology confirmed the mass to be a cyst and distended duct of the lacrimal gland. Although tear secretion was compromised, resection of the cyst was curative.     

Zygomatic gland adenoma in a dog: histochemical and immunohistochemical evaluation

Orbital epithelial tumors in dogs are rare and most frequently malignant. Distinguishing their origin from the lacrimal or zygomatic gland is often challenging and is based mostly on tumor location. A case of adenoma involving the orbit in a 13-year-old, female, standard Schnauzer is reported. Histologically, the neoplasm was characterized by nests and cords of epithelial cells mostly forming small glandular structures. The origin of the tumor from the zygomatic gland was determined by histochemical characteristics (alcian blue pH 1 positive staining) of a small remnant of normal gland included within the tumor capsule. The benign nature of our finding was confirmed by follow-up information: 2 years after complete surgical removal of the mass no tumor recurrence or metastases was recorded.     

Use of a sclerosing agent (1% polidocanol) to treat an orbital mucocele in a dog

A case of a salivary gland mucocele in a dog causing nonpainful exopthalmos with dorsolateral deviation of the globe and protrusion of the third eyelid. Diagnosis was made via ultrasound and confirmed with computed tomography. Aspiration of the cystic material along with injection of a sclerosing agent, 1% polidocanol (Aethoxysklerol), was used to destroy the mucocele. Follow-up monthly examination post injection confirmed resolution of clinical signs to date, namely abnormal globe position, with no complications observed.     

A review of orbital and intracranial magnetic resonance imaging in 79 canine and 13 feline patients (2004-2010)

Objective To review the distribution of orbital and intracranial disease in canine and feline patients undergoing magnetic resonance imaging (MRI) following referral to a veterinary ophthalmologist and to correlate results of MRI with pathologic conditions including neoplasia, suspected optic neuritis (ON) and orbital cellulitis. Recognized and emerging imaging techniques are reviewed. Procedure Medical records of 79 canine and 13 feline patients were reviewed. Results Neoplasia was diagnosed in 53/92 (57.6%) of patients. The most prevalent types of neoplasia were carcinoma (16/53, 30.1%), sarcoma (11/53, 20.8%), lymphoma (8/53, 15.1%) and presumptive meningioma (9/53, 17.0%). Carcinomas and sarcomas were characterized by bony lysis and intracranial/sinonasal extension. Lymphoma was generally unilateral, less invasive and originated from the ventromedial orbit. Intracranial masses representing presumptive meningiomas frequently exhibited a ‘dural tail’ sign. Diagnosis of suspected ON was made in 13 of 92 (14.1%) patients. Results of MRI in patients with suspected ON included unilateral optic nerve hyperintensity (3/13, 23.0%), bilateral optic nerve hyperintensity (1/13, 7.7%) and optic chiasmal hyperintensity (3/13, 23.0%). Seven suspected ON patients demonstrated intracranial multifocal patchy contrast enhancement (7/13, 53.8%). Diagnosis of orbital cellulitis was made in 12/92 (13.0%) patients. Conclusions Orbital neoplasia was the most common pathologic condition detected. Essential Roentgen characteristics are helpful when diagnosing pathologic processes and providing prognoses in cases of orbital or intracranial disease. Magnetic resonance imaging comprises an important diagnostic component in cases of suspected ON. Emerging contrast and functional MRI techniques as well as SI data may increase our ability to characterize disease processes.     

Identification and preservation of the parathyroid gland during total thyroidectomy in dogs with bilateral thyroid carcinoma: a report of six cases

Simultaneous removal of bilateral thyroid tumors was performed while preserving the parathyroid gland in six dogs. At least one external parathyroid gland was identified in all dogs. In five cases, the external parathyroid gland and its blood supply were preserved intact. In one dog, the vessels supplying the external parathyroid gland had been invaded by the tumor, and the gland was thus removed and reimplanted into the sternohyoid muscle. That dog required postoperative treatment with oral calcium gluconate and vitamin D₃. Local tumor recurrence was not observed in any of the cases. The mean survival time was 920 days. We found that the external parathyroid gland could be identified and preserved in most dogs undergoing total thyroidectomy.     

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.     

Modified lateral orbitotomy for vision-sparing excision of a zygomatic mucocele in a dog

A 1-year-old Shar Pei presented for recent-onset exophthalmos and right peri-ocular facial swelling. Physical examination revealed the facial mass was of soft-tissue consistency and nonpainful to the dog. Due to inability to retropulse the globe during ophthalmologic examination, it was suspected the mass had impinged into the orbit, resulting in rostral displacement of the globe. Anatomic location suggested the lesion was probably associated with the zygomatic salivary gland. Fine-needle aspiration and subsequent cytological evaluation of fluid extracted from the facial mass was consistent with a diagnosis of zygomatic mucocele. Computed tomography imaging confirmed a single fluid-filled mass was resulting in both the facial distention and the exophthalmos. A modified, lateral orbitotomy surgical approach was selected for excision of the lesion to provide ventral exposure to the orbit, while minimizing trauma to the globe and supporting structures. Histopathology of the excised lesion confirmed a diagnosis of zygomatic mucocele. This case demonstrates utilization of a modified lateral orbitotomy for effective surgical management of a zygomatic mucocele in a dog, with preservation of vision and absence of any significant postoperative complications.