Inherited retinal dysplasia and persistent hyperplastic primary vitreous in Miniature Schnauzer dogs

Congenital ocular malformations in dogs and cats: 123 cases

OBJECTIVE

Provide epidemiological data regarding the prevalence of congenital ocular malformations in dogs and cats.

ANIMALS STUDIED

A population of 32 974 dogs and 13 977 cats that presented for consultation at the veterinary teaching hospital.

PROCEDURES

Medical records from 2011 to 2018 were reviewed. A retrospective and prospective epidemiological clinical study addressing congenital ocular malformations was conducted. Signalment, medical history, reason for presentation, clinical findings, vision impairment, and treatment options were analyzed.

RESULTS

From the total of cases analyzed, 103 dogs (0.3%) and 20 cats (0.1%) met the inclusion criteria. The majority of dogs were mixed breed, the most common breed being the French Bulldog, while the majority of cats were European domestic shorthair. The median age of diagnosis was 12 months for dogs and 6 months for cats. Sex predisposition was not found. The most frequently identified abnormalities were as follows: congenital cataract (dogs: 31.1%; cats: 30.0%), microphthalmia (dogs: 35.0%, cats: 25.0%), and persistent pupillary membrane (dogs: 27.2%, cats: 40.0%). Some of the concurrently observed malformations were significantly associated. A statistically significant association was found between ocular dermoids and the French Bulldog breed (P < .001).

CONCLUSIONS

Even though congenital ocular malformations are uncommon, knowledge about their prevalence is important, since they can cause vision impairment or even blindness. Moreover, some human ocular disease phenotypes are similar to the ones presented by dogs and cats, so they can be used as models to investigate pathophysiology and therapeutic approaches.

In vivo imaging comparison of unilateral circular retinal plaques in retriever dogs to dysplasia and detachment in the English Springer Spaniel

PURPOSE

To compare the scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT), and fluorescein angiography (FA) findings in retrievers with a single unilateral circular retinal plaque to those of an English springer spaniel with bilateral retinal dysplasia.

PROCEDURES

A retrospective record review identified three dogs with circular retinal plaques that underwent SLO and OCT; in two of the three dogs, FA was also completed. Morphologic changes, lesion measurements, and angiogram characteristics were documented. An English springer spaniel with bilateral retinal dysplasia that had undergone SLO, OCT, and FA was used for comparison.

RESULTS

Scanning laser ophthalmoscopy of the retriever dogs revealed circular retinal plaques with a dark periphery located in the tapetal retina. OCT revealed a thickening of the nerve fiber layer corresponding to the circular pattern observed on SLO. Within the circular plaque, the retina was predominantly of normal architecture. FA revealed variable hypofluorescence of both the rim and the center of the circular lesion throughout the early angiogram phases. In the late recirculation phase, small multifocal areas of hyperfluorescence were observed. OCT of geographic retinal dysplasia in the English springer spaniel revealed disorganization of both inner and outer retinal layers, and retinal detachment.

CONCLUSIONS

Circular plaques observed in the tapetal retina are predominantly formed by a thickening of inner retina, while retinal dysplasia has disorganization of both inner and outer retinal layers. Further etiologic research is needed, including pedigree mapping to determine whether retinal plaques are an acquired or inherited condition.

Molecular genetics of congenital cataracts

Congenital cataracts, the most common cause of visual impairment and blindness in children worldwide, have diverse etiologies. According to statistics analysis, about one quarter of congenital cataracts caused by genetic defects. Various mutations of more than one hundred genes have been identified in hereditary cataracts so far. In this review, we briefly summarize recent developments about the genetics, molecular mechanisms, and treatments of congenital cataracts. The studies of these pathogenic mutations and molecular genetics is making it possible for us to comprehend the underlying mechanisms of cataractogenesis and providing new insights into the preventive, diagnostic and therapeutic approaches of cataracts.

Oculo-skeletal dysplasia in five Labrador Retrievers

OBJECTIVE

To describe the clinical features and diagnostic findings of Labrador Retrievers with oculo-skeletal dysplasia (OSD).

ANIMAL STUDIED

Five privately owned dogs.

PROCEDURES

Medical records of dogs diagnosed with OSD from 2008 through 2018 were reviewed. Patients were excluded if lacking disease confirmation through genetic testing (Optigen RD/OSD). Information collected included signalment, physical and ophthalmic examination findings, results of ocular ultrasound and electroretinogram, and digital radiographs of forelimbs and pelvis.

RESULTS

All five dogs were Labrador Retrievers, confirmed to be homozygote for the OSD mutation. The main physical abnormalities were vision deficits (5 dogs), short-limbed dwarfism (5), carpal valgus (4), and color dilution alopecia (4). The main ophthalmic anomalies were cataracts (10 eyes), vitreous syneresis (10), retinal separation (6), persistent hyperplastic primary vitreous (2), lens coloboma (2), microphakia (2), and persistent tunica vasculosa lentis (1). Ocular ultrasound and electroretinogram confirmed the diagnoses of retinal separations and persistent hyperplastic primary vitreous. Radiographic changes included shortening of ulna and curved radius (5 dogs), elbow incongruity and osteoarthritis (4 dogs), hip dysplasia (3), and coxofemoral osteoarthritis (2). Available follow-up information (2 dogs) showed progression of cataract from incipient to mature in one dog, necessitating cataract surgery, and progression of cataract and lameness in another dog.

CONCLUSIONS

The clinical findings of OSD are described in five Labrador Retrievers. DNA testing is critical to diagnose OSD and help eradicate this condition from the breed. Progression of cataracts and osteoarthritis in dogs with OSD warrants yearly monitoring.

Persistent hyperplastic primary vitreous in two piglets

Two Large Yorkshire piglets were diagnosed as persistent hyperplastic primary vitreous (PHPV). In case 1, the white cord-like structure extending from optic disc to lens was observed in the normal-sized right eye. Case 2 showed buphthalmos of the right eye. The internal structure of the right eye was unclear due to bleeding, but a white cord-like structure was slightly observed. In both cases, histological examinations revealed the fibrovascular cord-like structure in hyaloid vitreous. The retina was detached, and dysplastic nervous tissue was observed in anterior vitreous. Immunohistochemistry using various neural markers suggested that dysplastic nervous tissue was derived from the detached neural retina. By the characteristic macroscopic and histopathological features, both cases were diagnosed as PHPV. To our knowledge, this is the first report of swine PHPV.

Phacoemulsification for Cataract Secondary to Persistent Hyperplastic Tunica Vasculosa Lentis and Peristent Hyperplastic Primary Vitreous in a Welsh Corgi

A 7-month-old Cardigan Welsh Corgi was presented with rapid cataract formation. Slit lamp biomicroscopy revealed mature cataract in the left eye. Ultrasonography revealed a microphakic lens and the presence of a cord-like structure extending from the posterior lens to the optic disc. On the basis of ophthalmological examinations, a diagnosis of cataract secondary to persistent hyperplastic tunica vasculosa lentis and persistent hyperplastic primary vitreous was made. Routine phacoemulsifi cation with a capsular tension ring and intraocular lens implantation were performed. Although a blood-fi lled vasculature with focal hemorrhage was observed during surgery, we did not fenestrate the posterior capsule or cut the hyaloid artery. We only polished the posterior capsule carefully for 2 min. At 22 days after surgery, Doppler ultrasonography did not detect blood fl ow within the cord-like structure, and the implanted intraocular lens appeared clear without fi brin formation or posterior capsule opacifi cation. The fi ndings from this case suggest that routine cataract surgery is an optimal surgical treatment for persistent hyperplastic tunica vasculosa lentis and persistent hyperplastic primary vitreous. To the best of our knowledge, this is the fi rst case report of phacoemulsifi cation with intraocular lens implantation for persistent hyperplastic tunica vasculosa lentis and persistent hyperplastic primary vitreous in a Welsh Corgi.

Intraocular sarcoma associated with lens capsule rupture and persistent hyperplastic primary vitreous in a dog

This case report describes the clinical findings and ocular pathology in an adult Golden Retriever diagnosed with an intraocular sarcoma. Nineteen s prior to diagnosis with a lens capsule rupture and intraocular sarcoma, the dog was diagnosed with persistent hyperplastic primary vitreous and uveitis based on clinical signs and the ultrasonographic appearance of the eye. Two years after enucleation, there was no evidence of metastatic spread of the sarcoma. The immunohistochemical characteristics of the tumor as well as the limitations and supportive evidence used in attempting to identify the histogenesis of the tumor are outlined.

The genetics of inherited retinal disorders in dogs: implications for diagnosis and management

Dogs are affected by many hereditary diseases just as humans are. One group of these diseases comprises of retinal disorders, which are a growing problem in canine breeding. These disorders are heterogeneous, with diverse causative mutations and modes of inheritance. Some affect only one breed, while others may affect many breeds; some breeds are affected by only one disease, while others can be affected by two or more. Dog breeders should take into account the presence of any deleterious alleles when choosing parents for the next generation.

Clinical and histological characteristics of canine ocular gliovascular syndrome

OBJECTIVE

To characterize the clinical, diagnostic, and histopathologic findings in dogs with canine ocular gliovascular syndrome (COGS).

PROCEDURES

The archives at the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW) were used to identify eyes with COGS. Histopathological inclusion criteria included: a neovascular membrane extending from the optic nerve head or retina, clusters of spindle cells lacking vascularization within the vitreous, and histological signs of glaucoma. Special and immunohistochemical (IHC) staining techniques were performed. Clinical data, treatments, and outcomes were obtained from case records and information provided by submitting veterinarians.

RESULTS

Thirty-seven eyes of 36 dogs were identified with COGS. The average age at diagnosis was 8.8 years (±2.2). The relative risk for a Labrador retriever affected by COGS was significantly greater (9.3 times) (P < 0.0001) when compared to all other dog breeds within the COPLOW database. Most dogs presented with hyphema and secondary glaucoma; average intraocular pressure was 39 mmHg (±19). Average time to enucleation or evisceration was 27 days. Vitreal cells stained positive with IHC for glial fibrillary acidic protein in 14 of 17 globes, and vascular endothelial growth factor was expressed in the vitreal cells in five of five globes.

CONCLUSIONS

We have defined a syndrome associated with vitreal glial cell aggregates and neovascular proliferation from the optic nerve or retina, which leads to neovascular glaucoma. The inflammation and secondary glaucoma resulting from this syndrome appear poorly responsive to conventional medical therapies. The exact etiology of COGS remains undetermined, but a systemic etiology is unlikely.

Relative quantification of white blood cell mitochondrial DNA and assessment of mitochondria by use of transmission electron microscopy in English Springer Spaniels with and without retinal dysplasia

OBJECTIVE

To compare relative amounts of WBC mitochondrial DNA (mtDNA; assessed via real-time PCR assay) and morphology of lymphocyte mitochondria (assessed via transmission electron microscopy [TEM]) in blood samples collected from English Springer Spaniels with and without retinal dysplasia.

ANIMALS

7 and 5 client-owned English Springer Spaniels (1 to 11 years old) with and without retinal dysplasia, respectively.

PROCEDURES

Blood samples were obtained from affected and unaffected dogs via venipuncture. Genomic DNA was extracted from WBCs of the 7 affected and 5 unaffected dogs, and relative quantification of the cytochrome c oxidase subunit 1 gene (COX1) was determined via analysis of real-time PCR results. White blood cells from 3 affected and 4 unaffected dogs were embedded in epoxide resin for TEM; cross sections were examined for lymphocytes, which were measured. The mitochondria within lymphocytes were quantified, and the mitochondrial surface area per lymphocyte cross section was calculated. A masked technique was used to compare mitochondrial morphology between the 2 groups.

RESULTS

Compared with the smallest measured quantity of mtDNA among unaffected dogs, mtDNA amounts varied among unaffected (1.08- to 4.76-fold differences) and affected dogs (1- to 2.68-fold differences). Analysis of lymphocyte measurements and mitochondrial surface area, morphology, and quantity revealed no significant differences between affected and unaffected dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

No significant differences were detected in relative amounts of WBC mtDNA or the size, number, or morphology of lymphocyte mitochondria in English Springer Spaniels affected with retinal dysplasia, compared with results for unaffected control dogs.

Ophthalmic examination findings in a group of retired racing Greyhounds

OBJECTIVE

To characterize the frequency and types of ophthalmic findings in a group of retired racing Greyhounds.

MATERIALS AND METHODS

Complete ophthalmic examinations of both eyes of 100 retired racing Greyhounds were performed. Anterior segment examinations were performed by slit-lamp biomicroscopy. Tear production was measured by Schirmer tear test. Intraocular pressures were obtained by applanation tonometry. The posterior segments were examined by binocular indirect ophthalmoscopy following pharmacologic dilation. A photographic record of abnormalities was obtained whenever possible.

RESULTS

Mean tear production by Schirmer tear test was 21 mm/min (range 11-30 mm/min). Mean intraocular pressure by applanation tonometry was 16 mmHg (range 9-28 mmHg). The most prevalent anterior segment findings were cataracts (17% dogs, 11% eyes), corneal degeneration/scarring (6% dogs, 4% eyes), and suspected typical and atypical 'pannus' (total 4% dogs, 4% eyes). The most prevalent posterior segment abnormalities were vitreal degeneration (31% dogs, 38% eyes) and chorioretinal degeneration/scarring (7% dogs, 4% eyes). Other findings included anterior chamber vitreal strands, stretched lens zonules, periocular alopecia, a case of mild unilateral chemosis, and a distichium.

CONCLUSIONS

Ophthalmic abnormalities are not uncommon in retired racing Greyhounds.