Biomedical subjects

K.N. Gelatt

Publications and source records attributed to K.N. Gelatt.

11 recordsLinked to original sources

PubMed2000

Evaluation of tear film proteinases in horses with ulcerative keratitis.

Ulcerative keratitis is a common and potentially blinding ocular disease of horses, capable of progressing to corneal perforation in as little as 24 h. This rapid stromal degeneration is mediated in part by exogenous and endogenous proteinases. We measured and compared the concentrations of two matrix metalloproteinases (MMP-2 and MMP-9) and a serine proteinase (neutrophil elastase) present in the precorneal tear film of normal horses and horses with rapidly progressing ulcerative keratitis. Precorneal tear film samples were collected from 23 ulcerated and 21 unaffected eyes of 23 horses with unilateral ulcerative keratitis, and from 33 normal eyes of 17 control horses. MMP-2, MMP-9, and neutrophil elastase were identified by casein and gelatin zymography and quantified by computerized image analysis. Median MMP-9 levels were significantly higher in the precorneal tear film of young control horses vs. older control horses (P = 0.005). Median MMP-2, MMP-9, and neutrophil elastase levels were significantly higher in the precorneal tear film of ulcerated eyes when compared to age-matched normal controls (P = 0.004, P = 0.001, and P = 0.012, respectively). Median MMP-2 levels were also significantly higher in the precorneal tear film of contralateral eyes of affected horses when compared to age-matched normal controls (P = 0.004). No significant differences in median proteinase levels were detected between 'sterile' ulcers and those from which bacteria or mixed infections (bacteria and fungi) were isolated. However, median MMP-2 and neutrophil elastase levels were significantly higher in the precorneal tear film of eyes with 'sterile' ulcers when compared with ulcerated eyes from which fungi were isolated (P < 0.05). The results of this study support the use of topical antiproteinase therapy which targets both MMPs and serine proteinases in progressive equine ulcerative keratitis.

Journal Article↗

PubMed2000

Editorial.

Explore the source record for details and available documents.

Journal Article↗

PubMed2000

Ulcerative keratitis caused by beta-hemolytic Streptococcus equi in 11 horses.

Purpose To describe 11 clinical cases of ulcerative keratitis in horses associated with beta-hemolytic Streptococcus equi in Florida, USA. METHODS: Retrospective clinical study (1996-99). RESULTS: Beta-hemolytic Streptococcus equi was cultured from 11 horses with deep ulcers, descemetoceles or iris prolapse (n = 8), a suture abscess found with a penetrating keratoplasty for a stromal abscess (n = 1), and ulceration that developed following keratectomy/irradiation for corneal squamous cell carcinoma (n = 2). Beta-hemolytic Streptococcus equi subspecies zooepidemicus was found in 10 eyes and subspecies equi in one. Marked signs of uveitis including miosis and hypopyon were present in 8/11 (72.7%) eyes. Keratomalacia was severe in all eyes. The mean diameter of the ulcers associated with beta-hemolytic Streptococcus was 10.2 +/- 6.1 mm. Eight of the eyes required conjunctival flap surgery (four grafts dehisced) and one eye corneal transplantation. Two eyes were treated with medication only. Isolate sensitivity to antibiotics included ampicillin (6/11), bacitracin (11/11), cephalothin (11/11), chloramphenicol (11/11), gentamicin (5/11), polymyxin B (2/11), and tobramycin (1/11). All isolates were resistant to neomycin. The average healing time was 44.7 +/- 26.7 days. The visual outcome was positive in 8/11 eyes, and the globe retained in 9/11 eyes. CONCLUSIONS: Although Gram-positive bacteria predominate in the normal conjunctival microflora of horses throughout the world, Gram-negative bacteria and fungi are more often isolated from equine ulcers. Beta-hemolytic Streptococcus spp. are associated with a very aggressive ulcerative keratitis with the capability to digest conjunctival graft tissue. Clinical signs are pronounced. Aggressive surgical and intensive medical therapy with topical antibiotics and protease inhibitors is indicated.

Journal Article↗

PubMed2000

Rose bengal positive epithelial microerosions as a manifestation of equine keratomycosis.

Purpose To describe the clinical appearance of corneal epithelial cell microerosions associated with keratomycosis in the horse. METHODS: Retrospective clinical study. RESULTS: Multifocal, punctate, superficial corneal opacities with positive rose bengal retention were noted in six horses with presumed 'viral keratitis'. Faint fluorescein staining was also present in three cases. Equine herpesvirus tissue culture inoculation was negative for a cytopathic effect in three cases. Aspergillus (n = 3), Curvularia (n = 1), and an unidentified fungus (n = 1) were cultured in five horses, and hyphae found on corneal cytology from the sixth. Mixed bacterial infections were present in three eyes. The eyes of two horses with Aspergillus progressed to deep melting corneal ulcers that required surgical therapy. The microerosions remained superficial, but persistent in the other four eyes. Natamycin was utilized topically in all six horses. Transmission electron microscopy from case 6 revealed mucin layer disruption, an intact corneal epithelial cell layer, and fungal attachment to degenerating epithelial cells. The visual outcome was positive in all six horses, although healing was prolonged (48.5 +/- 14.5 days on average in the horses with no surgery; 62 days on average in the two horses that required surgery). CONCLUSIONS: Complete removal or full-thickness penetration of the corneal epithelial cell barrier may not be necessary to allow fungal adherence and initiation of keratomycosis in the horse. Prior to colonization and invasion of the horse cornea, fungi may induce changes in the mucin layer of the tear film that result in or are associated with rose bengal positive microerosions of the superficial corneal epithelium. Horses with painful eyes, and eyes with superficial, multifocal corneal opacities should have their corneas stained with both fluorescein and rose bengal as fungal microerosions may stain weakly, or not at all, with fluorescein, and may thus be mistaken for presumed 'viral keratitis' of the horse.

Journal Article↗

PubMed2000

Posterior lamellar keratoplasty for treatment of deep stromal absesses in nine horses.

OBJECTIVE: To describe and evaluate the use of posterior lamellar keratoplasty as a surgical treatment for deep corneal stromal abscesses in horses. Animals studied Nine horses of various breeds and ages that presented with corneal stromal abscesses located in the posterior one-third of the cornea. Procedure Retrospective medical record study. RESULTS: Nine horses had deep corneal stromal abscesses that were treated with posterior lamellar keratoplasty. Median patient age was 3 years. Six patients were females and three were geldings. Medical therapy alone had been attempted prior to surgery in all nine animals. Corneal abscess culture and histopathology were performed in 8/9 horses. Cultures were positive for an infectious etiology in 4/8 (50%). Histopathology was positive for an infectious etiology in 5/8 (62.5%). Mean surgical time was 71.0 +/- 18.8 min and the average healing time was 23.7 +/- 5.2 days. Visual outcome was positive in 8/9 cases. Conclusion Posterior lamellar keratoplasty is a promising procedure for treatment of deep corneal stromal abscesses in horses. The procedure resulted in considerable shorter surgery time and healing time than had been observed with full-thickness penetrating keratoplasty. Scar formation with this procedure was not significantly different than with penetrating keratoplasty.

Journal Article↗

PubMed2000

Disease of the equine posterior segment.

The appearance of the equine fundus is reviewed from the perspective of differentiating normal variations from disease, and the descriptions have been updated to include recently published ocular fundic abnormalities. Most pathological lesions are identified near the optic nerve head, and typically involve depigmentation or hyperpigmentation. Depending upon configuration and appearance, linear pigmented bands may reflect the course of the vortex veins, the transition from tapetal to nontapetal fundus, or indicate chorioretinitis or equine motor neuron disease. Choroidal vasculature is readily apparent in color-dilute (subalbinotic) horses and must be differentiated from hemorrhage. Retinal hemorrhages in foals are common and may occur independently to hypoxic ischemic encephalopathy. Retinal cysts may signal more significant disease in the eye such as anterior segment dysgenesis. Prominence of gray or tan-colored material on or near the optic nerve head may represent traumatic optic neuropathy, benign optic neuropathy, proliferative optic neuropathy or actual neoplasia.

Journal Article↗

PubMed2000

Editorial.

Explore the source record for details and available documents.

Journal Article↗

PubMed1999

Doppler imaging of the ophthalmic vasculature of the normal dog: blood velocity measurements and reproducibility.

The purpose of this study was to assess the feasibility and reproducibility of color Doppler imaging (CDI) of the vasculature of the normal canine orbit and eye. Eight normal Beagles were evaluated by Doppler imaging. The goals of the study were to determine the location, spectral waveform morphology, specific blood velocity parameters, and reproducibility for the ophthalmic and orbital vessels most frequently identified in the normal dog. Vessels identified a majority of the time (> 50%) included: external ophthalmic artery, dorsal external ophthalmic vein, ventral external ophthalmic vein, internal ophthalmic artery, anterior ciliary artery and vein, short and long posterior ciliary arteries, primary retinal arteries, and vortex veins. Other vessels imaged less frequently included: external ethmoidal artery (50%), and primary retinal veins (25%). For each blood vessel the time averaged velocity, peak systolic velocity, minimum diastolic velocity, pulsatility index, and resistive index were determined. The ophthalmic and orbital vessels have unique spectral waveforms and velocities which serve as a basis for identification. Reproducibility of the most commonly imaged vessels of the canine eye and orbit with Doppler imaging was high (< 10% variation). Doppler imaging has the potential for determining noninvasively and consecutively the blood velocity parameters found in orbital and ocular diseases, including orbital inflammations and neoplasms; intraocular inflammations and neoplasms; vascular diseases including systemic vascular disease (hypertension), vasculopathies, and anemia; the glaucomas; and documentable follow-up after medical and/or surgical treatment of these diseases.

Journal Article↗

PubMed1999

Comparative Doppler imaging of the ophthalmic vasculature in normal Beagles and Beagles with inherited primary open-angle glaucoma.

The objective of this study was to compare orbital and ocular vasculature velocity, measured by Doppler imaging, in normal Beagles and Beagles with inherited primary open-angle glaucoma. Eight normal Beagles and 13 Beagles with different stages of primary open-angle glaucoma were evaluated twice with a 2-4-week period between measurements. Doppler imaging was performed with the dogs anesthetized, and the Doppler transducer applied directly on the corneal surface. The majority of the orbital vasculature (external ethmoidal artery; internal ophthalmic artery and vein; and external ophthalmic artery and vein) and ocular blood vessels (anterior ciliary artery and veins; long posterior ciliary arteries; short posterior ciliary arteries; primary retinal arteries; and the vortex veins) were identified and Doppler blood velocity parameters were determined. The glaucomatous dogs demonstrated significant differences in the Doppler velocity parameters of several orbital vessels (external ethmoidal, external ophthalmic, and internal ophthalmic arteries), and several ocular vessels (anterior ciliary, short posterior ciliary, and long posterior ciliary arteries). These differences included decreased blood velocities, and increased pulsatility and resistive indexes. The Doppler blood flow velocities of the primary retinal arteries were unchanged between the normal and glaucomatous dogs. In the glaucomatous dogs, the Doppler imaging suggests increased vascular resistance downstream in both the orbital and ocular vasculature. These blood velocity parameter changes may be primary or secondary, and may offer therapeutic opportunities to increase perfusion, prolong the retina and optic nerve head function, and maintain vision in the canine glaucomas.

Journal Article↗

PubMed1998

Intraocular pressure in normal dairy cattle.

Intraocular pressure (IOP) was measured in normal dairy cows by applanation tonometry. In the first study of 15 Holstein and 17 Jersey cows the mean IOP by Mackay-Marg tonometry was 27.5 +/- 4.8 mmHg (range 16-39 mmHg); no significant differences (P < 0.92) were observed between the Holstein and Jersey breeds. In the second study of 15 Holstein and 12 Jersey cows, the mean IOPs by Mackay-Marg and TonoPen-XL tonometry were 28.2 +/- 4.6 mmHg (range 19-39 mmHg) and 26.9 +/- 6.7 mmHg (range 16-42 mmHg), respectively. Comparisons of the Mackay-Marg and TonoPen tonometers indicated no significant differences (P < 0.16). The mean and range of IOP in normal dairy cows within 2 SD (95% of the population) is 27 mmHg with a range of 16-36 mmHg.

Journal Article↗

PubMed1998

Distribution of intraocular pressure in dogs.

Intraocular pressure (IOP) was measured by four different applanation tonometers in normal dogs. By MacKay-Marg tonometry in 391 dogs (772 eyes) the mean +/- SD IOP was 18.8 +/- 5.5 mmHg (range 8-52 mmHg). Using Tono-Pen XL tonometry in 421 dogs (823 eyes) the mean IOP was 19.2 +/- 5.9 mmHg, and the range was 4.42 mmHg. With MMAC-II tonometry in 80 dogs (158 eyes), the mean IOP was 15.7 +/- 2.8 mmHg with a range of 10-30 mmHg. By pneumatonograph tonometry in 135 dogs (255 eyes), the mean IOP was 22.9 +/- 6.1 mmHg and the range was 10-47 mmHg. In this study 53 breeds were represented. Of those breeds with six animals or more, no significant differences were detected in IOP between breeds (P > 0.353) or sex (P > 0.270). There was a significant decline of 2-4 mmHg (P > 0.0001) in IOP as age increased from less than 2 years to greater than 6 years of age. This trend was present with all of the four tonometers. There were no significant differences between the MacKay-Marg and TonoPen-XL tonometers (P > 0.198), but significant differences with the MMAC-II (P > 0.001) and pneumatonograph (P > 0.001) tonometers existed compared to the first two instruments. Based on this study and the literature, the mean IOP for the normal dog is 19.0 mmHg with a range of 11 (5%) and 29 (95%) mmHg.

Journal Article↗