The histopathological and immunohistochemical characteristics of pigmentary and cystic glaucoma in the Golden Retriever

Genetic Basis of Pigment Dispersion Syndrome and Pigmentary Glaucoma: An Update and Functional Insights

Pigment Dispersion Syndrome (PDS) and Pigmentary Glaucoma (PG) comprise a spectrum of ocular disorders characterized by iris pigment dispersion and trabecular meshwork changes, resulting in increased intraocular pressure and potential glaucomatous optic neuropathy. This review summarizes recent progress in PDS/PG genetics including rare pathogenic protein coding alterations (PMEL) and susceptibility loci identified from genome-wide association studies (GSAP and GRM5/TYR). Areas for future research are also identified, especially the development of efficient model systems. While substantial strides have been made in understanding the genetics of PDS/PG, our review identifies key gaps and outlines the future directions necessary for further advancing this important field of ocular genetics.

Ophthalmic Disease and Screening in Breeding Dogs

This article describes the history and infrastructure associated with canine breed-related eye screening and certification by Diplomates of the American College of Veterinary Ophthalmologists. Some of the common or otherwise particularly problematic specific inherited ophthalmic conditions are discussed.

The Clinical Approach to Canine Glaucoma

This article provides a simplified approach to diagnosis and clinical decision making in cases of canine glaucoma for the general practitioner. An overview of the anatomy, physiology, and pathophysiology related to canine glaucoma is provided as a foundation. Classifications of glaucoma based on cause are described as congenital, primary, and secondary, and a discussion of key clinical examination findings is provided to guide appropriate therapy and prognostication. Finally, a discussion of emergency and maintenance therapy is provided.

Progressive retrocorneal pigmentation in dogs: A clinical report of 34 cases

OBJECTIVES

To describe the signalment, ophthalmic examination findings, and follow-up of dogs affected with a previously unreported retrocorneal pigmentary lesion.

MATERIALS AND METHODS

Retrospective record evaluation spanning 2009-2019.

RESULTS

Retrocorneal pigmentary lesions were described in 34 patients (46 eyes). German Shepherds (n = 7), Jack Russel terriers (n = 5), and terrier crosses (n = 4) made up 16/34 (47.1%) of the cases. The mean age was 13.5 years (range 1.4-14.2 years), and 16/30 (53.3%) dogs were female. Most dogs were affected unilaterally (22/34 (64.7%)), the others bilaterally, and 5/34 (14.7%) were referred for it while the others were incidentally diagnosed. The lesions affected the ventral, peripheral, inner cornea and had a round/undulated leading edge. The number of corneal clock hours affected was known for 41/46 (89.1%) eyes and involved 1-3 clock hours in 32/41 (78.1%) eyes, 4-6 in 6/41 (14.6%), 7-9 in 2/41 (4.9%), and 10 in 1/41 (2.4%). The central cornea was affected in 9/46 (19.6%) eyes, and in 5/9 (55.6%), the median corneal clarity score was G2 (scale: G0-G4). The commonest additional findings included free-floating uveal cysts (11/34 dogs, 32.4%), cataracts (6/34 dogs, 17.6%), and primary glaucoma (5/34 dogs, 14.7%). Gonioscopy was available in 16/34 (47.1%) dogs and was normal except in primary glaucoma cases. Follow-up was documented in 13/34 (38.2%) dogs with a mean follow-up of 17 months (range: 5-26 months). Lesion progression was documented in 6/13 (46.2%) dogs.

CONCLUSIONS

Retrocorneal pigmentation occurs as a slowly progressive lesion of older dogs that could impact vision. Histological studies of affected eyes are warranted.

Golden retriever pigmentary uveitis: Vision loss, risk factors for glaucoma, and effect of treatment on disease progression

OBJECTIVE

In previous reports, almost half of Golden Retrievers with Pigmentary Uveitis (GRPU) have lost vision in an eye within a year of diagnosis. The purpose of this study was to determine the proportion of GRPU affected dogs with vision loss, risk factors for the development of glaucoma, and effect of treatment on disease progression.

ANIMALS STUDIED

Client owned Golden Retrievers.

PROCEDURES

Two complete ophthalmic examinations were performed at least 6 months apart. Visual status, presence of glaucoma, GRPU score, and treatment were recorded. A proportional odds (ordinal logistic) model was fitted to determine whether the use of topical steroidal or non-steroidal (NSAID) ophthalmic preparations was associated with a change in GRPU scores.

RESULTS

Twenty-nine Golden Retrievers, 58 eyes, were included. One eye was enucleated after the first examination. On first examination, 57/58 (98.3%) eyes and 29/29 (100%) dogs were visual. At the second examination, 48/57 (84.2%) eyes and 25/29 (86.2%) dogs were visual. Vision loss in 7/9 (77.8%) eyes was secondary to glaucoma. Posterior synechia and fibrinous material in the anterior chamber were significant risk factors for the development of glaucoma (P < .001). There was no significant difference in the change in GRPU score between eyes receiving topical steroids and topical NSAIDs (P = .14). Time between examinations was a significant factor in disease progression (increased GRPU score; P = .016).

CONCLUSION

The number of eyes and dogs that retained vision was higher than previous reports. No topical treatment was superior in slowing disease progression. Golden Retriever Pigmentary Uveitis is a slowly progressive disease.

Golden retriever pigmentary uveitis: Challenges of diagnosis and treatment

Pigmentary uveitis (PU), also known as Golden Retriever Pigmentary Uveitis (GRPU), is a common ocular condition of Golden Retrievers that has severe, vision-threatening ocular complications and can require surgical intervention. In order to ensure consistency in the diagnosis of GRPU between examiners, a specified set of diagnostic criteria must be applied. This is critical to ensure owners, breeders, and veterinary ophthalmologists maintain confidence in the ocular certification process. Therefore, current and former members of the American College of Veterinary Ophthalmologists' Genetics Committee came together to draft this Viewpoint Article on the challenges of diagnosis and treatment of Golden Retriever Pigmentary Uveitis for veterinary ophthalmologists, Golden Retriever owners, and Golden Retriever breeders.

Bilateral Anterior Uveitis in a Northern Saw-whet Owl (Aegolius acadicus) With a Metastatic Pectoral Malignant Mesenchymoma

A captive, adult, male northern saw-whet owl (Aegolius acadicus) was examined for blepharospasm of the left eye. The owl was diagnosed with bilateral anterior uveitis and a corneal ulceration in the left eye. It was treated with oral and topical nonsteroidal anti-inflammatory medications and a topical antibiotic. Multiple recheck examinations and medication adjustments were performed over the next 4 months, at the end of which time the bilateral anterior uveitis was controlled with a topical nonsteroidal anti-inflammatory applied 3 times per week to both eyes. The owl was re-examined 2 months later after 2 suspected neurologic episodes. On physical examination, the owl was quiet and had difficulty standing and ambulating. Five firm multilobular and immobile masses were identified overlying the pectoral muscle and sternum. Fine-needle aspiration from 1 mass revealed neoplastic cells consistent with a sarcoma. The owl was euthanatized. On the basis of results of histopathologic examination, the mass was diagnosed as a pleomorphic spindle cell sarcoma with features of rhabdomyosarcoma, liposarcoma, and osteosarcoma. Numerous tumor cells were immunopositive for myoglobin and desmin, indicating striated muscle origin. Although a metastatic lesion was present in 1 adrenal gland, lesions of inflammation or neoplasia were absent in either eye on histopathologic examination. This report describes an apparent ocular manifestation of systemic disease in an avian species with clinically diagnosed recurrent anterior uveitis.

Caracterização clínica e histopatológica de bulbos oculares de cães e gatos (2005-2015)

RESUMO: Objetivou-se realizar a caracterização clínica e histopatológica de bulbos oculares de cães e gatos, removidos cirurgicamente por indicação clínica, no período entre 2005-2015. Foram realizados 101 procedimentos de remoção do bulbo ocular, 93 enucleações (92%) e 8 exenterações (8%). Os procedimentos foram realizados em 80 cães, (79% dos casos) e em 21 gatos (21% dos casos). Os cães submetidos à intervenção cirúrgica apresentavam perfurações oculares (n=31, 39%), glaucoma (n=19, 24%), protrusão ocular (n=13, 16%), diagnósticos sugestivos de neoplasia (n=10, 12,5%) e outros (n=3, 2,97%). Dentre os gatos os diagnósticos clínicos compreenderam perfuração ocular (n=9, 49%), glaucoma (n=3, 14,2%), microftalmia (n=3, 14,2%), sugestivo de neoplasia (n=2, 9,5%), protrusão ocular (n=2, 9,5%) e outros (n=2, 9,5%). Vinte e sete amostras de bulbos oculares foram submetidas para avaliação histopatológica, sendo 23 provenientes de cães e quatro de gatos. Dentre as amostras de origem canina, sete exibiram achados histopatológicos compatíveis com glaucoma, sete perfurações oculares, seis neoplasias intraoculares, duas panoftalmites e um quadro de Phthisis bulbi. Nos bulbos oculares de gatos foram diagnosticadas duas neoplasias intraoculares, uma microftalmia e uma perfuração ocular. Constatou-se que o glaucoma secundário, as neoplasias e as perfurações oculares estão entre as principais causas de enucleação em cães, e associadas a alterações primárias como a ceratoconjuntivite seca e as uveítes. Estas afecções, diferentemente das neoplasias, podem ter êxito terapêutico mediante diagnóstico e tratamento precoces, prevenindo a cegueira e a remoção do bulbo ocular.

Isolation and cultivation of canine uveal melanocytes

OBJECTIVES

To establish a method for isolation and culture of canine uveal melanocytes.

ANIMALS STUDIED

Uveal explants from five mixed-breed dogs.

PROCEDURES

Donor globes were dissected, and the anterior uvea removed. The uveal explants were placed in trypsin solution for enzymatic digestion. Extracted cells were cultured in modified F12 media. Immunocytochemistry was performed to confirm the identity of the extracted cells.

RESULTS

Melanocytes were successfully isolated from uveal explants. Contaminating cell types were not observed. Repeated passaging of the melanocytes resulted in a gradual decrease in intracellular pigment. Melanocyte cell lines could be cryopreserved, thawed, and cultures successfully reestablished.

CONCLUSIONS

This extraction technique allows for generation of large populations of canine uveal melanocytes in a relatively short period of time. This technique could be a useful tool for future studies investigating both normal cellular characteristics and alterations found in melanocytes from dogs with ocular melanocytic disorders.

Immunohistochemical Characteristics of Normal Canine Eyes

Immunohistochemistry is widely utilized in diagnostic laboratories to study neoplastic and nonneoplastic diseases. Knowledge of the immunohistochemical characteristics of normal tissue is essential for interpretation of immunoreactivity in pathologic conditions. In this study, immunohistochemistry was performed with a broad panel of diagnostically relevant antibodies on 4 normal canine globes—namely, vimentin, pan-cytokeratin (AE1/AE3), cytokeratin 7, cytokeratin 8/18, cytokeratin 20, α–smooth muscle actin, muscle specific actin, desmin, Melan-A, microphthalmia transcription factor, S-100, glial fibrillary acidic protein, triple neurofilaments, neuron-specific enolase, chromogranin A, synaptophysin, laminin and CD31. Results include cytokeratin immunoreactivity limited to the conjunctival epithelium, corneal epithelium, and retinal pigment epithelium; distinct patterns of immunopositivity of muscle markers; and widespread immunoreactivity for vimentin and most neural/neuroendocrine markers. These findings in normal eyes provide the basis for interpretation of ocular immunohistochemistry in dogs. Published immunophenotypes of primary ocular neoplasms are also reviewed.