Ocular manifestations of equine motor neuron disease.

The characteristics of the ocular manifestations of equine motor neuron disease (EMND) are described. Forty-two horses with histories, clinical signs and necropsies compatible with EMND were the subjects of this study. Ophthalmoscopic lesions that varied in severity were found in 40 of 42 horses and appeared as a distinct pigmented reticulated pattern at the tapetal-nontapetal junction or throughout the fundus, depending upon severity. The pattern colours ranged from yellow brown to black. Areas of hyperreflectivity formed mosaic patterns in the tapetal fundus. ERG B-wave amplitudes were usually at least 50% reduced and many animals showed extinguished amplitudes. None of the horses had apparent visual impairment. Histopathologically, all 42 horses had retinal pigment epithelial (RPE) congestion with ceroid-lipofuscin. Retinal degeneration was variable even within the eyes. Thin layer chromatography (TLC) analysis of the RPE and neural retina identified both green and orange emitting fluorescent compounds not found in normal horses. All unsupplemented horses had plasma vitamin E levels <1.0 microg/ml. The potential significance of this report is the pathognomonic role the ocular manifestations exhibit in helping to diagnose equine motor neuron disease.

Tetracycline and niacinamide for the treatment of sterile pyogranuloma/granuloma syndrome in a dog.

A sterile pyogranuloma/granuloma syndrome in a dog is described. Diagnosis was based on cytological examinations of the skin and lymph nodes and histopathological examinations of the skin and nictitans. Although the condition initially was responsive to large doses of glucocorticoids, it subsequently was treated successfully with tetracycline and niacinamide. The excellent responses of this dog suggest that this drug combination may be a viable therapeutic option for dogs in which glucocorticoids cannot be used.

Retinoblastoma in a dog.

OBJECTIVE: To describe and classify a retinal tumor found in a dog that histologically resembles human retinoblastoma and to discuss the molecular mechanisms of retinal oncogenesis. METHODS: A dog eye with a retinal tumor was examined histologically. Studies including immunocytochemical analysis for retinal S-antigen and glial fibrillary acidic protein, enzyme histochemical analysis for carbonic anhydrase, and nick-end DNA labeling were used to characterize the tumor. Normal retina from another dog and other tumors from dogs, including 2 ciliary body medulloepitheliomas and a brain medulloepithelioma, were examined as controls. RESULTS: The retinal tumor disclosed characteristics typical of human retinoblastoma, including Flexner-Wintersteiner rosettes. It showed strong immunoreactivity with S-antigen and glial fibrillary acidic protein. Carbonic anhydrase activity also could be shown in the tumor. Apoptosis was found to be the predominant method of cell death as shown by nick-end DNA labeling. In contrast to the other tumors examined, this tumor contained areas with retinal photoreceptor and glial differentiation. CONCLUSIONS: The histopathologic findings and differential staining characteristics in this retinal tumor are compatible with retinoblastoma, making this, to our knowledge, the first documented case of spontaneous retinoblastoma in an animal.

Intraocular bacterial contamination during cataract surgery in dogs.

Prevalence of intraoperative contamination of the eyelids, conjunctival sac, and aqueous humor of 50 canine eyes that underwent elective cataract surgery was determined, and the short-term outcomes for contaminated and noncontaminated eyes were compared by scoring media clarity, pupil size and shape, and behavioral evidence of vision during the initial 30-day postoperative period. Results of bacteriologic culture of anterior chamber samples were positive for 12 of the 50 (24%) eyes, but anterior chamber contamination was unrelated to results of bacteriologic culture of eyelids or conjunctival sac swab samples. Eyes undergoing phacoemulsification were less likely to be contaminated than were eyes undergoing intra- or extracapsular extraction. Eyes undergoing intra- or extracapsular extraction and eyes with anterior chamber contamination had a greater likelihood of developing glaucoma postoperatively. We did not detect an association between intraocular contamination and the surgeon performing the operation, the need for postoperative administration of tissue plasminogen activator, or the presence or absence of diabetes mellitus. Also, we did not detect any differences in outcome between eyes with and without intraocular contamination. Despite intraoperative bacterial contamination of the anterior chamber, bacterial endophthalmitis did not develop in any of the eyes.

Ocular manifestation of systemic histiocytosis in a dog.

A 3-year-old sexually intact female Bernese Mountain Dog was referred for treatment of a descemetocele of the left eye. Physical examination revealed bilateral exophthalmos and scleral thickening, multiple cutaneous nodules, and mandibular paralysis in addition to ulcerative keratitis associated with a Pseudomonas infection. One year prior to examination, a biopsy specimen of the episcleral tissue from the right eye had been interpreted as nodular granulomatous episclerokeratitis (fibrous histiocytoma). Immunosuppressive treatment prior to referral had not resulted in remission of the ocular lesions. When we examined the biopsy specimen, we interpreted the lesions to represent episcleral involvement of systemic histiocytosis. Because of the poor prognosis, the dog was euthanatized.

Tibetan terrier model of canine ceroid lipofuscinosis.

Over a 10-year period, we have studied the Tibetan terrier's visual electrophysiology, light and electron microscopic (EM) retinal characteristics of a slowly evolving inherited ceroid lipofuscinosis (CL). The retinal degeneration with CL inclusions (rdi) in the inner nuclear layer (bipolar cells) and nerve fiber layer (ganglion cells) has been called "rdi" to differentiate the visual abnormality from typical early retinal degeneration (erd) reported also in the Tibetan terrier. The unique "rdi" electroretinogram (ERG) gives a predominant P III wave at age 7 weeks but becomes more characteristically depressed in all phases over several years. Nyctalopia is the only functional abnormality for the first 5 to 6 year of life. Signs are remarkably few considering the pathology. Microscopic studies of the retina show accumulations, increasing with age, of autofluorescent dense inclusion particles which stain intensely by Luxol fast blue, PAS, and acid-fast procedures. Ultrastructural studies of the retina show the dense particles to be lamellar membranes repeating every 2 to 4 nm, consistent with ceroid lipofuscin. The inner retinal layers were always the target layer to be affected first and most severely. The ganglion cells were most frequently involved. The photoreceptors eventually degenerated but relatively few particles were found in this layer. The cytosomes in the cerebral cortex and brainstem neurons resemble lipofuscin, containing granular, lamellar, and globular components. Different pigment bodies were present in the cerebellar Purkinje cells. Neuronal loss which was moderate in the cerebellum and mild in the cerebrum was accompanied by astrogliosis and a striking presence of macrophages.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of a persistent corneal erosion in a boxer dog.

A dog was presented to the New York State College of Veterinary Medicine with a one-month history of corneal ulceration. The corneal lesion was diagnosed as a persistent corneal erosion (PCE) and treated initially with debridement and supported with a contact lens. One week later, the corneal erosion remained unepithelialized. Following debridement, multiple anterior stromal punctures were performed. Within 10 days, the erosion was healed as evidenced by coverage of the cornea with adherent, uninterrupted epithelium. The proposed etiology and management of PCE in dogs is discussed.

An epizootic of blindness and encephalitis associated with a herpesvirus indistinguishable from equine herpesvirus I in a herd of alpacas and llamas.

Blindness characterized by dilated unresponsive pupils and funduscopic evidence of varying degrees of vitritis, retinal vasculitis, retinitis, chorioretinitis, and optic neuritis developed in 21 alpacas and 1 llama within a 30-day period. The animals were part of a group of approximately 100 animals imported from Chile one year earlier. The animals had spent 6 months in quarantine and then, for the 6 months preceding the epizootic, were housed at an exotic animal import-export farm, where the disease developed. Four of the affected animals also had signs of neurologic dysfunction. A herpesvirus indistinguishable from equine herpesvirus I was isolated from 4 of the affected animals, and antibody titers diagnostic for equine herpesvirus I were demonstrated in the serum of all but one of the affected animals.

Healing of experimentally induced corneal ulcers in horses.

Corneal ulcers to the depth of the anterior third of the stroma were created surgically in both eyes of 10 ponies. One eye in each pony was treated topically with chloramphenicol and 1% atropine ophthalmic ointments 3 times per day; the contralateral eye was not treated topically. All ponies were given phenylbutazone orally for relief of ocular pain. Fluorescein-stained ulcers were measured once a day. The median healing time of the treated eyes (11 days) and the median healing time of the nontreated eyes (13.5 days) were found not to be significantly different. Clinically, however, more severe complications arose in the nontreated eyes.

Uveitis associated with poliosis and vitiligo in six dogs.

Idiopathic panuveitis with retinal detachment was associated with facial poliosis, vitiligo, and alopecia in 6 dogs; 4 were adult males. Dermatohistologic examination of affected facial sites from all dogs revealed a lichenoid dermatitis and unusual histiocytic cells. Intensive topical and systemic corticosteroid and topical mydriatic/cycloplegic therapy was successful in controlling uveitis in all dogs for variable periods. Three dogs, monitored for 12, 30, and 46 months, retained useful vision despite infrequent recurrence of uveitis. One dog was lost for subsequent examination. Two dogs were euthanatized and necropsied. Ocular histologic examination of these dogs revealed extensive granulomatous iridocyclitis and choroiditis, with retinal detachment and lenticular degeneration.

Multiple congenital ocular defects in the Akita dog.

Microphthalmia, congenital cataracts, posterior lenticonus, and retinal dysplasia were observed in members of 3 litters of Akita puppies thought to be related to a common male ancestor. The electroretinograms of 3 clinically affected puppies were normal. Histological examination of 6 microphthalmic animals revealed nuclear and cortical cataract with multiple retinal folds and rosettes predominantly overlying the tapetum lucidum. Posterior lenticonus was observed histologically in 3 of the 6 puppies.

Effect of flunixin meglumine on prostacyclin accumulation in the equine eye.

A study was performed to identify prostacyclin (PGI2) in equine aqueous humor, demonstrate an increase in PGI2 following anterior chamber paracentesis, and determine the effects of subconjunctival injection of flunixin meglumine on PGI2 accumulation. Twenty ponies were found to be normal upon ocular examination and were placed under general anesthesia. Anterior chamber paracentesis was performed in both eyes (right and left); immediately afterward, 25 mg of flunixin meglumine was injected (subconjunctivally) in the left eye. Aqueous paracentesis was performed 1.5 hours later (both eyes). Aqueous humor samples were assayed for 6-keto PGF1alpha, the stable, inactive metabolite of PGI2. Eyes treated with flunixin meglumine contained less 6-keto PGF1alpha than did control eyes.

Enucleation in birds of prey.

Enucleation in birds requires special consideration. Two case reports are presented as examples of 2 techniques for enucleation in raptors. The first technique utilizes a transaural approach and is suitable only in owls that have extensive external ear openings. The major advantage of this technique is that it allows complete histologic examination of the globe. The second technique is a globe-collapsing procedure that is suitable for any avian species. This technique precludes complete histologic examination.

Biomicroscopic and histologic pathology of the eye in riboflavin deficient rainbow trout (Salmogairdneri).

Quadruplicate lots of 35 fingerling rainbow trout (mean body weight 11.2 g) were fed for 20 weeks a complete diet or one deficient in riboflavin. Five fish from each low were examined for ocular lesions each week. At the end of the experiment eyes of three fish form each lot were examined histologically. Beginning with the 14th week, epithelial changes were present in the cornea; they appeared as thickening of the stroma and endothelium and resulted in clouding. Opacity of the lens originated in the posterior subcapsular cortex and progressed to lens fiber autolysis and liquefaction.

Vitamin E deficiency retinopathy in dogs.

Dogs fed purified diets developed retinopathy consistently when the nutrition was deficient in vitamin E. Deleting DL-methionine along with vitamin E and selenium (groups 3 dogs) varied the development minimally. Supplementation of vitamin E to a selenium-deficient diet (group 1 dogs) protected the retina from changes. Ethoxyquin added to a diet deficient in vitamin E, but supplemented with National Research Council levels of selenium or 10 times the National Research Council levels, induced no beneficial recognizable changes in the retinopathy. the characteristic retinopathy was ophthalmoscopically visible as early as 3 months (group 2 to 9 dogs). Typical lesions developed first in the central, outer layers and progressed slowly toward the periphery. The tapetal retina was more extensively involved, showing a color change and mottling. Microscopically, a yellow autofluorescent pigment accumulated in large amounts within the retinal epithelium. Later stages of retinopathy showed this pigment was present in migrating cells in all the retinal layers. The early disappearance of a recordable electroretinogram, night blindness, and eventual severe day visual impairment makes this retinopathy similar to some aspects of degenerations described for persons and pure breed dogs.