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  • Author or Editor: Richard R. Dubielzig x
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Abstract

Objective—To determine whether cyclooxygenase-2 (COX-2) is expressed in benign or malignant canine uveal melanocytic neoplasms and whether expression correlates with malignancy.

Sample Population—Tissue sections from 71 globes; 57 with benign (n = 15), malignant (34), or mixed (8) uveal melanocytic neoplasms; 10 with nonneoplastic disease; and 4 with no abnormalities.

Procedures—Bleached sections from all globes and canine kidney were incubated with mouse monoclonal antibody directed against rat COX-2 protein or mouse antibody isotype control. Location, intensity, and percentage of immunolabeled cells were scored.

Results—Expression of COX-2 was detected in all but 5 globes, all of which contained neoplasms. Expression of COX-2 was detected in regions infiltrated by neoplasia in 21 globes; however, definitive labeling of tumor cells was detected in only 2 of those. In the remaining 19 globes, COX-2 expression was detected in areas also labeled in globes without disease and globes with nonneoplastic disease, especially the aqueous outflow tract and ciliary body. However, only globes with uveal malignant melanomas had detectable COX-2 expression in the iris. Expression of COX-2 was detected in the ciliary body of more globes with uveal malignant melanoma (20/34) than in those without disease (1/4), with nonneoplastic disease (4/10), or with melanocytoma (3/15) or mixed neoplasms (3/8).

Conclusions and Clinical Relevance—Canine globes with uveal melanocytic neoplasia appeared to express COX-2 in similar sites and with similar intensity as globes without neoplasia. Differentiation of benign from malignant canine uveal melanocytic neoplasms was not possible.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of acute (clinical history of glaucoma for ≤ 2 days) and chronic (clinical history of glaucoma for 7 days) goniodysgenesis-related glaucoma on various stress-inducible proteins in canine retinas.

Sample Population—15 canine retinas (5 from control eyes, 5 from eyes with acute glaucoma, and 5 from eyes with chronic glaucoma).

Procedures—Globes were obtained from the Comparative Ocular Pathology Laboratory of Wisconsin. Eyes were characterized on the basis of clinical history. The distribution of glial fibrillary acidic protein (GFAP), heat shock protein (HSP) 60, and hypoxia-inducible factor (HIF)-1α was determined by use of immunohistochemical analysis.

Results—Intensity of GFAP staining increased with temporal progression of glaucoma. In specimens from eyes with acute glaucoma, staining for HSP 60 was more variable among eyes, compared with that of the control eyes, whereas specimens from eyes with chronic glaucoma typically had less HSP 60 staining than was evident in the control eyes. Neither the control eyes nor specimens from the eyes with acute glaucoma had nuclear staining for HIF-1α in the retinas. Four of 5 specimens from eyes with chronic glaucoma had nuclear staining for HIF-1α in cells of the outer nuclear layer. Staining for HIF-1α was distributed segmentally in regions of more severe atrophy and disorganization.

Conclusions and Clinical Relevance—Results of the study reported here supported a clinically evident, rapidly progressive disease with a shift in cell regulation between acute and chronic glaucoma and also supported ischemia as a mechanism of retinal injury in this disease.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate cellular death in the neurosensory portion of the retina during the first 7 days after onset of clinical signs of overt primary angle-closure glaucoma (PACG) in dogs.

Sample Population—14 globes from dogs with PACG and 2 normotensive globes from dogs with PACG in the opposite eye.

Procedures—Retinas were examined via light microscopy and terminal deoxynucleotidyl transferase- mediated biotin-dUTP nick end-labeling.

Results—Necrosis of ganglion cells and segmental degeneration of the nerve fiber layer rapidly progressed to scattered full-thickness retinal attenuation and disorganization. Apoptosis was detectable within 1 day after onset of PACG and was prominent by 3 days. Necrosis of ganglion cells was significantly greater in retinas affected for ≤ 1 day, compared with retinas affected for > 1 day. In contrast, apoptosis in the ganglion cell layer was significantly greater in retinas affected for > 1 day, compared with retinas affected for ≤ 1 day. End-stage retinal atrophy was seen by day 7.

Conclusions and Clinical Relevance—The presence of necrotic ganglion cells within 1 day after onset of clinical signs suggests a narrow window of opportunity to initiate effective therapy in overt PACG. Photoreceptor death is an important and striking aspect of neurosensory retinal degeneration after acute onset of PACG. (Am J Vet Res 2002;63:257–261)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether retinal damage in dogs with primary glaucoma (PG) is consistent with ischemia-induced glutamate toxicosis.

Sample Population—Retinal tissue sections from 25 dogs with PG and 12 normotensive control dogs.

Procedure—Retinal sections from control and glaucomatous dogs were stained for morphometric and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) analyses to determine whether retinal damage was consistent with glutamate toxicosis. Immunohistochemical analysis was performed to detect ischemia-like loss of glutamate from neurons in damaged areas.

Results—In severely damaged glaucomatous retinas, all neurosensory layers had focal regions that were thin or disrupted. There was less thinning of the outer nuclear layer (ONL) and inner nuclear layer (INL) in moderately damaged retinas than in severely damaged retinas. Acute signs of damage in the INL included cells with dark, condensed chromatin and lightly stained cytoplasm interspersed with a few TUNELpositive cells, which was consistent with glutamate toxicosis. Glutamate immunoreactivity was reduced in thin areas and in damaged cells of the INL and ONL, which was consistent with glutamate release in damaged areas. Glutamate immunoreactivity was increased in putative Müller cells in damaged areas, which also was consistent with glutamate release.

Conclusions and Clinical Relevance—Retinal damage in dogs with PG differs in intensity in focal areas. Damage in affected regions resembles damage induced by glutamate. Glutamate is lost from damaged neurons and accumulates in Müller cells, which is consistent with increased glutamate release contributing to the damage. Glutamate antagonists may protect INL cells in dogs with glaucoma. (Am J Vet Res 2004;65:776–786)

Full access
in American Journal of Veterinary Research

Abstract

Case Description—6 dogs (10 eyes) with keratitis following long-term topical treatment with a carbonic anhydrase inhibitor (CAI) were evaluated. In 4 dogs (6 eyes), CAI treatment was discontinued. Three dogs (4 eyes) underwent enucleation because of end-stage corneal disease. One dog was treated differently in each eye and thus was represented in both aforementioned groups.

Clinical Findings—Following initiation of treatment with a CAI (ie, brinzolamide or dorzolamide), the median time to development of severe ocular signs was 266 days (range, 133 to 679 days). Clinically severe ocular signs included ulcerative and nonulcerative perilimbal keratitis or severe diffuse keratitis with marked vascularization. The keratitis was refractory to treatment with anti-inflammatory medications. Histologic and immunohistochemical examination of enucleated globes was performed in 3 affected dogs and in 1 dog with keratitis that recovered. Corneal lesions included 2 distinct inflammatory infiltrates with plasma cells predominating in the anterior stroma and both T cells and neutrophils in the epithelium. Stromal plasma cells and overlying epithelium exhibited strong positive immunoreactivity for IgG.

Treatment and Outcome—Topical CAI treatment was discontinued in 4 dogs after a median of 209 days (range, 44 to 433 days), and in these dogs, clinical improvement was evident within 2 to 4 days of CAI treatment cessation. Signs of keratitis resolved in 12 to 25 days in these 4 dogs, and median follow-up time after CAI discontinuation was 25.5 months (range, 6 to 42 months), during which time signs of corneal disease did not recur.

Clinical Relevance—On the basis of this small series, presumed topical CAI-associated keratitis in dogs appeared to be an uncommon immune-mediated disease that was not responsive to corticosteroid treatment. Affected patients improved rapidly, but only after discontinuation of CAI treatment. In dogs with glaucoma, clinicians should consider the development of punctate keratopathy and severe diffuse keratitis as potential adverse effects related to topical administration of CAIs, even after previously uneventful long-term use.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine prevalence, reason for evaluation, treatment, and outcome for dogs and cats with presumed solitary ocular lymphoma (PSOL).

Design—Retrospective case series.

Animals—7 dogs and 2 cats with PSOL.

Procedures—Medical records were reviewed. Progression-free survival time (PFST) and overall survival time (OST) were determined.

Results—Animals with intraocular (4 dogs and 1 cat) or conjunctival (3 dogs and 1 cat) lymphoma represented 0.1% and 0.08% of patients with lymphoma evaluated at the hospital during the study period, respectively. Animals with intraocular lymphoma represented 0.19% of all patients with uveitis; animals with conjunctival lymphoma represented 0.16% of all patients with conjunctivitis. Tumors included B-cell (2 intraocular and 1 conjunctival), non–B-cell, non–T-cell (1 intraocular), and T-cell (3 conjunctival) neoplasms; immunophenotype of 2 uveal lymphomas was not determined. Treatments included enucleation (4 intraocular) and chemotherapy (3 intraocular and 2 conjunctival). All dogs with intraocular lymphoma developed neurologic signs. Lymph node metastasis was detected in 2 patients with conjunctival lymphoma. Median PFST and OST were 178 days for all animals with PSOL, dogs with PSOL, and animals with intraocular lymphoma. Median PFST and OST for animals with conjunctival lymphoma were 221 and 549 days, respectively.

Conclusions and Clinical Relevance—Results indicated PSOL was uncommon, but should be considered a differential diagnosis for animals with uveitis or conjunctivitis. Performance of MRI and cytologic analysis of CSF and regional lymph node aspirate samples may be beneficial for such patients. Prognosis seemed to be better for animals with conjunctival lymphoma than it was for those with intraocular lymphoma.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To characterize the effects of oral administration of a high dose of enrofloxacin to cats.

Animals—24 (12 male and 12 female) young healthy cats.

Procedures—Cats were allocated on the basis of sex into 2 groups (4 males and 4 females/ group) from which 3 subgroups for 3 durations (3, 5, or 7 days) of enrofloxacin (50 mg/kg, PO, q 24 h) or control solution (1 mL of water, PO, q 24 h) administration that began on day −1 were created. Funduscopic examinations were performed daily. Electroretinography (ERG) was performed before and every 2 to 3 days after the start of oral administration. Four cats/study group were euthanized on days 3, 5, and 7, and eyes were collected for light and electron microscopic evaluations.

Results—Neurologic, funduscopic, and ERG abnormalities were evident only in cats administered enrofloxacin. Funduscopic changes (granular appearance or graying of the area centralis) were noticed on or before day 3 (after only 3 days of enrofloxacin administration), with subsequent similar changes along the visual streak. Vascular attenuation (between days 2 and 4) and generalized tapetal hyperreflectivity (between days 5 and 7) followed. Reduction in b-wave ERG amplitude preceded funduscopic changes. Morphologic changes in the photoreceptor layers correlated with duration of enrofloxacin administration, with generalized degenerative changes evident after 3 doses.

Conclusions and Clinical Relevance—The study indicated that a high dose of enrofloxacin (50 mg/kg/d, PO) induced retinal and systemic changes. Enrofloxacin at 10 times the recommended dosage is acutely toxic to the outer retina of clinically normal cats.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To compare results of computed tomography (CT) and radiography with histopathologic findings in tracheobronchial lymph nodes (TBLNs) in dogs with primary lung tumors.

Design—Retrospective case series.

Animals—14 client-owned dogs.

Procedures—Criteria for inclusion were diagnosis of primary lung tumor, use of thoracic radiography and CT, and histologic confirmation of TBLN status. Medical records were reviewed for signalment; history; and physical examination, clinicopathologic, radiographic, CT, surgical, and histopathologic findings.

Results—Tracheobronchial lymphadenopathy was not identified via radiography in any dogs. Tracheobronchial lymphadenopathy was diagnosed in 5 dogs via CT. Six dogs had histologic confirmation of metastasis to TBLNs. Radiographic diagnosis yielded 6 false-negative and no false-positive results for tracheobronchial lymphadenopathy. Computed tomography yielded 1 falsenegative and no false-positive results. Sensitivity of CT for correctly assessing TBLN status was 83%, and specificity was 100%. Positive predictive value was 100%, and negative predictive value was 89%. Dogs with lymphadenopathy via CT, histologic confirmation of TBLN metastasis, or primary tumors with a histologic grade > 1 had significantly shorter survival times than their counterparts.

Conclusions and Clinical Relevance—Results of CT evaluation of TBLN status were in agreement with histopathologic findings and more accurate than use of thoracic radiography for evaluating TBLNs in dogs with primary lung tumors. Computed tomography imaging should be considered as part of the staging process to more accurately assess the TBLNs in dogs with primary lung tumors.

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in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective—To characterize the clinical and morphologic aspects of aqueous humor misdirection syndrome (AHMS) in cats and provide a hypothesis regarding its pathogenesis on the basis of detailed analysis of affected cats.

Design—Retrospective study.

Animals—32 cats (40 eyes).

Procedure—Medical records of cats in which AHMS was diagnosed from July 1997 to August 2003 were reviewed. In certain cats, results of additional diagnostic testing were also obtained, including A-scan, B-scan, and high-resolution ultrasonography; streak retinoscopy; video keratometry; and infrared neutralizing videoretinoscopy as well as results of analysis of flash-frozen sections and histologic examination of enucleated globes.

Results—Cats had a uniformly shallow anterior chamber, intact lens zonules, and a narrowed approach to an open iridocorneal angle. Mean age of affected cats was 11.7 years (range, 4 to 16 years), and female cats were significantly more often affected than male cats. Clinical signs included mydriasis, decreased pupillary light reflex, decreased menace response, and blindness. Glaucomatous changes to the optic nerve, incipient cataracts, and eventual blindness were seen. Intraocular pressure was ≥ 20 mm Hg (range, 12 to 58 mm Hg) in 32 of 40 eyes. Ultrasonography and histologic examination revealed a thickened anterior vitreal face interposed between the lens and ciliary body, partial ciliary cleft collapse, and cavitated vitreal regions. Various treatment modalities were used.

Conclusions and Clinical Relevance—AHMS affects older cats, especially females, and may result in glaucoma, vision loss, and signs of ocular pain. Topical administration of carbonic anhydrase inhibitors decreased intraocular pressure. (J Am Vet Med Assoc 2005;227:1434–1441)

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in Journal of the American Veterinary Medical Association