Chronic Glaucoma in Dogs: Relationships Between Histologic Lesions and the Gonioscopic Diagnosis of Pectinate Ligament Dysplasia.

Pectinate ligament dysplasia (PLD) is a common cause of canine glaucoma and the definitive clinical diagnosis is based on gonioscopy. Although the histologic lesions of PLD have been described, it has not been determined whether these changes are specific for PLD or if similar histologic changes can develop as a consequence of secondary glaucoma. The filtration angles of 61 enucleated canine globes with chronic glaucoma were evaluated with light microscopy by 3 examiners who were masked to the clinical history, signalment, and gonioscopic results. A histologic diagnosis of PLD versus non-PLD was determined by each examiner based on previously reported morphologic criteria and compared with the clinical gonioscopic diagnosis. Of the 61 enucleated glaucomatous eyes, 40 were clinically diagnosed with PLD. For all 3 examiners, a histologic diagnosis of PLD corresponded poorly with the clinical diagnosis of PLD (range of kappa score: 0.149-0.269; range of AUC: 0.592-0.621). There was no difference between examiners in their ability to correctly diagnose PLD histologically (P = .978). A fair degree of agreement was noted among examiners in obtaining their suspected histologic diagnosis of PLD (kappa score 0.256). No individual or sets of histologic ICA features were consistent with clinical PLD. The results indicate the histologic ICA changes proposed to be characteristic of PLD are also noted in canine globes affected with chronic secondary glaucoma. Therefore, using routine histologic evaluation, a histologic diagnosis of PLD is not possible in the face of chronic canine glaucoma.

Retinopathy of Great Pyrenees dogs: fluorescein angiography, light microscopy and transmitting and scanning electron microscopy.

OBJECTIVE: Investigation of the pathogenesis of Great Pyrenees retinopathy. ANIMALS: One male and two female puppies of parents who were affected with Great Pyrenees retinopathy and one 4-year-old affected adult male Great Pyrenees dog. PROCEDURE: The puppies were examined daily from 7 weeks of age by indirect ophthalmoscopy and their fundi were photographed until the lesions were static. Fluorescein angiography was completed at 7 weeks of age, within 24 h of detection of ophthalmoscopic lesions, and then weekly. The eyes of a 4-year-old and two 20-week-old puppies were examined with light microscopy, and transmitting and scanning electron microscopy. RESULTS: Blocked choroidal fluorescence was detected at 7 weeks of age. The blocked fluorescence enlarged, when the characteristic serous retinal detachments developed at 11 weeks of age. The detachments enlarged in size and number until the puppies were approximately 20 weeks old. Fluorescein pooling confirmed the presence of transient retinal pigment epithelial detachments. Leakage of dye into serous retinal detachments was not detected in this study. Light microscopy and transmitting and scanning electron microscopy confirmed the presence of multifocal serous retinal detachments with focal retinal degeneration that extended to the inner nuclear layer in a 4-year-old dog. The retinal detachments were accompanied by hypertrophy, hyperplasia, increased pigmentation, and vacuolation of the retinal pigment epithelium. CONCLUSIONS AND CLINICAL RELEVANCE: Great Pyrenees retinopathy is manifested by multifocal serous retinal and retinal pigment epithelial detachments. These detachments are similar to those noted with central serous retinopathy of humans. The sudden development of multifocal retinal and retinal pigment epithelial detachments, and the serous nature of these detachments, supports a theory that they develop secondary to focal secretion and absorption defects in retinal pigment epithelial cells. Given the age of the puppies when the blocked choroidal fluorescence was noted and maturation of the dog retina at 8 weeks postpartum, this retinopathy is considered to be a retinal pigment epithelial dysplasia. This unique inherited retinopathy offers an opportunity to study retinal pigment epithelial secretion.

Unilateral proptosis and orbital cellulitis in eight African hedgehogs (Atelerix albiventris).

Eight African hedgehogs (Atelerix albiventris) were presented with unilateral proptosis. Six animals presented specifically for an ocular problem, whereas two had concurrent neurologic disease. Enucleation and light microscopic examination of tissues was performed in five animals, and euthanasia followed by complete postmortem examination was performed in three animals. Histopathologic findings in all hedgehogs included orbital cellulitis, panophthalmitis, and corneal ulceration, with perforation in seven of eight eyes. The etiology of the orbital cellulitis was not determined, but it appeared to precede proptosis. Orbits in hedgehogs are shallow and the palpebral fissures are large, which may predispose them to proptosis, similar to brachycephalic dogs. This clinical presentation was seen in 15% (8/54) of African hedgehogs presented to the Western College of Veterinary Medicine over a 2-yr period from January 1995 to December 1996 and warrants further investigation.

Intravascular lymphoma presenting as bilateral panophthalmitis and retinal detachment in a dog.

A seven-year-old, spayed female boxer was presented for sudden blindness and red eyes of one week's duration. Ophthalmic examination revealed bilateral uveitis with complete bullous retinal detachments. Initial diagnostic testing failed to reveal evidence of systemic disease. Cytopathology of subretinal aspirates confirmed the presence of macrophages with intracytoplasmic retinal pigment, epithelial and choroidal pigment, and monocytes. Tentative diagnoses were idiopathic uveitis and retinal detachment. The dog was treated with immunosuppressive doses of prednisone. The retinas reattached and vision returned. By two months, the dog became blind and systemically ill. Postmortem and histopathological examinations revealed intravascular lymphoma in multiple organs, including the eyes.

Equine phacoclastic uveitis: the clinical manifestations, light microscopic findings, and therapy of 7 cases.

This retrospective clinical study describes the clinical manifestations, light microscopic findings, and diagnosis and treatment of acute and chronic lens rupture in the horse. Rupture of the lens capsule in the horse usually results in a chronic, blinding inflammation (phacoclastic uveitis) unless prompt surgical and medical therapies are implemented. The clinical manifestations of acute lens capsule rupture included: cataract; intralenticular displacement of iridal pigment; lens cortical fragments attached to the perforated lens capsule, iris, and corneal endothelium; miosis; aqueous flare; and usually a corneal or scleral perforation with ulceration or focal full thickness corneal edema and scarring. The clinical signs of chronic phacoclastic uveitis include blindness, phthisis bulbi, and generalized corneal opacification related to scarring, vascularization, pigmentation, and edema. In one horse, acute phacoclastic uveitis was successfully treated with phacoemulsification to remove the ruptured lens and medical therapy to control the accompanying inflammation. The affected eyes of the horses with chronic phacoclastic uveitis were enucleated because of persistent clinical signs of nonulcerative keratitis and uveitis, despite long-term medical management. The clinical manifestations and lack of improvement with medical therapy are similar in the horse, dog, cat, and rabbit. However, the histologic findings in equine phacoclastic uveitis differ significantly from those in the dog, and rabbit.

Equine orbital neoplasia: a review of 10 cases (1983-1998).

The clinical manifestations, laboratory findings, and survival times of 10 horses with orbital neoplasms are reported. In all cases, orbital neoplasms were malignant and locally invasive with no defined surgical circumscribed edges. It was often difficult to identify the primary cell type of the neoplasia in histologic specimens due to the poorly differentiated, anaplastic nature of the majority of cases. All except one horse were eventually euthanized 2 mo to 5 y after diagnosis due to poor response to treatment, metastasis, or unrelenting orbital neoplasia. Mean survival time increased with surgical treatment, but no significant difference was found among no treatment, chemotherapy, surgical mass removal, or exenteration/enucleation. Equine practitioners should be aware of the marked difference in prognosis of orbital neoplasms compared with ocular or localized eyelid neoplasia.

Ulcerative keratitis associated with qualitative tear film abnormalities in cats.

Three cats with indolent corneal ulcers and one cat with bilateral corneal sequestration and normal aqueous tear production were found to have rapid tear break-up times (BUTs). Tear BUTs in clinically affected cats averaged 2.5 +/- 1.29 s and 2.33 +/- 0.58 s for the right and left eyes, respectively. Palpebral conjunctival biopsies were harvested from consistent sites from each eye of affected cats (n = 7 affected eyes), and age-and breed-matched controls (n = 2 unaffected eyes). Light microscopy revealed a marked decrease to complete absence of conjunctival goblet cells (average goblet cell (GC):epithelial cell (EC) density = 18:50), conjunctival epithelial dysplasia, squamous metaplasia, and neutrophilic and mononuclear cell submucosal infiltration in affected cats. Specimens from the control cats had an average GC:EC density of 34:50, and minimal submucosal inflammatory infiltrate. The corneas (n = 7 eyes) healed following surgical keratectomy with (n = 2 eyes) or without (n = 1 eye) conjunctival pedicle flaps, superficial keratectomy and striate keratotomy with (n = 2 eyes) or without (n = 2 eyes) third eyelid flaps, and mucinomimetic tear supplementation (n = 5 eyes). Goblet cell regeneration was confirmed after 5 months of mucinomimetic supplementation (n = 2 eyes). The etiology for these mucin deficiencies remains unknown.

The use of immunohistochemistry and the polymerase chain reaction for detection of feline leukemia virus and feline sarcoma virus in six cases of feline ocular sarcoma.

Ocular sarcoma was diagnosed by light microscopic examination in enucleated globes (n = 4), orbital tissue biopsy (n = 1) and ocular evisceration contents (n = 1) from six cats. To determine if feline leukemia virus (FeLV) or a replication-defective FeLV, feline sarcoma virus (FeSV), was present in these ocular sarcomas, immunohistochemistry (IHC) and polymerase chain reaction (PCR) for FeLV were utilized. Immunohistochemical staining for FeLV glycoprotein 70 (gp70) was performed on all six formalin-fixed, paraffin-embedded tumors using an avidin-biotin complex technique. DNA was extracted from each specimen and a 166 bp region of the FeLV long-terminal repeat (LTR) was amplified by PCR. All tumors were composed primarily of spindle cells; two neoplasms had PAS-positive basement membrane enveloping areas of spindle cells. All tumors involved the uvea and five of six tumors showed transcleral extension, one of which invaded the optic nerve. Immunohistochemical staining for FeLV gp 70 was negative. PCR to amplify a portion of the FeLV LTR was negative. Based on these findings of these limited number of cases, FeLV/FeSV may not play a role in the tumorigenesis of feline ocular sarcomas. However, additional tumors representing all morphological subtypes should be investigated for the presence of viral antigen and DNA. It is important to determine the etiology and pathogenesis of these malignant ocular sarcomas. If the cell of origin and pathogenesis involve ocular and lenticular injury, and FeLV/FeSV is not present, then the clinical management of cases of feline ocular trauma, uveitis and glaucoma may prevent the development of this tumor.

Incomplete nasomaxillary dysplasia in a foal.

Atresia of the nasal punctum is the most common congenital anomaly for the equine nasolacrimal system. Nasomaxillary dysplasia has not been previously documented in foals, is of unknown etiology, and appears to be a rare condition. Conjunctivomaxillary sinostomy was successful in resolving the epiphora.

Oscillatory potentials and light microscopic changes demonstrate an interaction between zinc and taurine in the developing rat retina.

Our objective was to investigate whether zinc interacts with taurine to influence the development of retinal structure and function. Virgin female Sprague-Dawley rats were bred overnight and assigned to one of four treatments in a 2 x 2 factorial design with two levels of zinc (50 micrograms/g through gestation and 50 micrograms/g after parturition; 15 micrograms/g through gestation and 7.5 micrograms/g after parturition) and two levels of taurine (2 or 0 mumol/g). The control diet contained 50 micrograms/g zinc and 2 mumol/g taurine. Guanidinoethyl sulfonate (10 g/L), a taurine transport inhibitor, was added to the drinking water of the rats receiving 0 mumol/g taurine. At postnatal d 23, male pups (n = 10) were weaned onto their respective diets. Pup eyes were examined by biomicroscope and indirect ophthalmoscope at 4 and 7 wk; retinal folds and choroidal atrophy were detected in the pups deficient in zinc and taurine. Analysis of plasma zinc and tibial zinc concentrations revealed a significant interaction in these tissues (P < 0.05). Dark-adapted oscillatory potentials (OP) were recorded at 7.5-8.5 wk. Two-way ANOVA showed a significant interaction between zinc and taurine for OP2 and OP3 amplitudes; marginal zinc deficiency decreased the amplitude of the OP only when rats were also deficient in taurine. A significant depressing effect of marginal zinc deficiency was noted for OP1 amplitude. Taurine deficiency significantly depressed the amplitude of OP1 and OP4. Histological examination of the retinas from rats deficient in both zinc and taurine revealed photoreceptor degeneration and confirmed retinal dysplasia. These data provide evidence for an interaction between zinc and taurine in retinal morphology and function.

Conjunctival mycobacteriosis in two emus (Dromaius novaehollandiae).

Avian tuberculosis was diagnosed in two young adult female commercial emus (Dromaius novaehollandiae) with granulomatous conjunctivitis. Histologically, the granulomas appeared typical of avian tuberculosis. Caseonecrotic cores were surrounded by a broad ring of palisading epithelioid macrophages and multinucleate giant cells with a moderate admixture of heterophils, lymphocytes, and plasma cells. One conjunctival granuloma had multifocal mineralization. At necropsy, granulomas were also found in visceral organs of both birds. Acid-fast bacilli were demonstrated in all lesions using Ziehl-Neelsen or Fite's stains. Culture confirmed the bacilli to be Mycobacterium avium (complex).

Thymoma in a geriatric rabbit with hypercalcemia and periodic exophthalmos.

An 8-year-old rabbit was referred to an ophthalmologist because of intermittent bilateral exophthalmos and prolapse of the nictitating membranes. Both eyes could be retropulsed normally, and the exophthalmos was induced with ventroflexion. The rabbit had moderate hypercalcemia and a large mediastinal mass that could be seen on thoracic radiographs. The rabbit's condition was unchanged for 5 months. It was reexamined because of weight loss and paroxysmal coughing and, at that time, was thin and tachypneic, and had reduced thoracic compliance. Thoracotomy was performed, and a 5-cm-diameter encapsulated mass, subsequently determined histologically to be thymoma, was removed. The rabbit was euthanatized after surgery because of complications. The periodic exophthalmos and hypercalcemia in this rabbit were believed to be paraneoplastic syndromes.

Epiphora associated with dacryops in a dog.

A six-month-old basset hound was presented with unilateral right epiphora and medial canthal and maxillary bone swelling. Skull radiographs and dacryocystorhinography revealed a nasal cyst, right nasolacrimal duct dilatation, and obstruction. Laboratory examination of the cyst confirmed the diagnosis of dacryops, a cyst of lacrimal gland origin. The cyst was treated successfully with surgical drainage and curettage.