Superficial, nonhealing corneal ulcers in horses: 23 cases (1989-2003)

Objective To characterize superficial, nonhealing corneal ulcers in the horse and to assess the affect of age, breed, sex, inciting cause of the ulcer, and treatment on healing time of these ulcers. Design Retrospective study. Animals Twenty‐three horses with superficial, nonhealing corneal ulcerations. Procedure Medical records from 1989 to 2003 of horses diagnosed with superficial, nonhealing corneal ulcers were reviewed. Signalment, duration of clinical signs, ophthalmic abnormalities, treatment and response to treatment were recorded. Horses were treated, in addition to medical therapy, using debridement, debridement and grid keratotomy, superficial keratectomy, and superficial keratectomy with conjunctival graft placement. Results Mean age ± SD of horses was 13.7 ± 5.8 years. The mean time of presence of the corneal ulceration was 38.9 ± 21.3 days. Mean time to complete re‐epithelialization of the corneal ulcers after treatment was 20 ± 14.7 days. Horses treated with debridement alone, grid keratotomy and superficial keratectomy healed in a mean time of 15.3 ± 14.6 days, 16 ± 12.6 days, and 22.8 ± 6.7 days, respectively. Conclusions and clinical relevance Horses treated with a single debridement at initial evaluation healed in a significantly shorter time period than horses treated with grid keratotomy or superficial keratectomy. The latter two procedures may be beneficial in the treatment of nonhealing ulceration in horses, but the results of this study suggest that these procedures should only be performed following failure of the ulcer to heal after epithelial debridement.     

Response of Corriedale and Crioula Lanada Sheep to Artificial Primary Infection with Haemonchus Contortus

Clinical, parasitological and biochemical parameters were evaluated in Corriedale and Crioula Lanada sheep after a single experimental infection with Haemonchus contortus. Ten 4-month-old worm-free lambs, of each breed, were infected with 200 L₃ H. contortus per kg live weight and four uninfected animals of each breed were used as controls. Every week, the animals were weighed and blood and faecal samples were collected for measurement of packed cell volume (PCV), total serum protein (TSP) and albumin (ALB), and the number of eggs per gram of faeces (EPG), respectively. Twelve weeks after infection, the animals were slaughtered. The worm burden was determined and samples of the abomasal mucosa were processed for determination of the number of eosinophils, mast cells and globule leukocytes. No significant differences in PCV, TSP, ALB, parasite burden or the cell populations of the abomasal mucosa were observed between breeds, but Crioula lambs had a lower EPG count. The comparison of the infected groups with their respective controls revealed significant alterations in PCV, TSP and ALB in the Corriedale lambs and in PCV, TSP, ALB and the density of eosinophils and mast cells in the Crioula lambs.     

Accumulation of Sapogenin Conjugates and Histological Changes in the Liver and Kidneys of Lambs Suffering from Alveld,a Hepatogenous Photosensitization Disease of Sheep Grazing Narthecium ossifragum

Sixteen lambs exhibiting hepatogenous photosensitization (alveld) after grazing pasture containing Narthecium ossifragum and seven nonphotosensitized lambs grazing the same pastures were studied. All the alveld-affected lambs revealed liver damage dominated by single cell necrosis, portal fibroplasia and bile duct proliferation. Crystalloid clefts were demonstrated in the bile ducts of two and in the hepatocytes and Kupffer cells of nine photosensitized lambs. Plasma bilirubin concentration was severely increased in ten of the cases of alveld whereas the activity of aspartate aminotransferase was moderately to severely increased in seven cases. The activity of glutamate dehydrogenase was moderately elevated in one of the photosensitized lambs. The main histopathological findings in the kidneys from the alveld-affected lambs were dilated tubules, often with eosinophilic material in the tubular lumina. Regenerative changes were seen in a large proportion of the renal sections. Elevated plasma concentrations of urea and creatinine, and the renal histopathological changes, suggested that the photosensitized lambs had been through a phase of renal injury. Analysis of the free and conjugated sapogenin content in liver tissue and bile was performed by gas chromatography–mass spectrometry. There were significantly higher concentrations of conjugated episapogenins in both the liver and bile in the alveld-affected lambs than in the nonphotosensitized lambs.     

Partial orbital rim resection, mesh skin expansion, and second intention healing combined with enucleation or exenteration for extensive periocular tumors in horses

Ocular and periorbital sarcoids and squamous cell carcinoma are common in equine practice. Extensive involvement of periorbital tissues often necessitates removal of the globe if the function of the eyelids can not be maintained with tumor removal alone. This report describes a modification of the standard enucleation or exenteration technique for cases in which there is insufficient skin to achieve primary closure following complete surgical excision. The caudal portion of the dorsal orbital rim is protuberant; partial excision with an osteotome facilitates skin closure by decreasing the size of the wound. Mesh expansion of skin via multiple rows or parallel stab incisions can also be used as an adjunct to facilitate closure. Four horses underwent enucleation or exenteration using the orbital rim resection and mesh skin expansion techniques for extensive periocular tumors that were unresponsive to prior treatments. Follow-up intervals ranged from 6 to 42 months and no horses had tumor regrowth.     

Bacterial infection of the lower respiratory tract in 34 horses

OBJECTIVE: To investigate associations between the bacteriology and aspects of history, clinical presentation, outcome and pathology of lower respiratory tract disease of 34 horses. PROCEDURE: Detailed aerobic and anaerobic bacteriological investigations were performed on clinical specimens from horses with pneumonia, lung abscessation and necrotic pneumonia with or without pleurisy in an attempt to identify those bacteria that might contribute to the initiation and progression of infection. RESULTS: Bacteria were cultured from 33 of the 34 horses. In ten cases, only aerobic/facultatively anaerobic isolates were cultured while aerobic/facultatively anaerobic bacteria and obligately anaerobic bacteria were isolated in the other 23 cases. Moderate to large numbers of anaerobic bacteria were isolated only when the estimated duration of illness was at least five days. Bacteria were not cultured from 12 of the pleural fluid samples but were always cultured from pulmonary samples (either transtracheal aspirates from live horses or pulmonary lesions at necropsy). Streptococcus equi subsp zooepidemicus was isolated in the three cases where only one bacterial species was cultured. In the other 30 cases, multiple species were isolated. These included most often and in greatest numbers, Streptococcus equi subsp zooepidemicus, Pasteurellaceae, Escherichia coli, anaerobic cocci, Eubacterium fossor, Bacteroides tectum, Prevotella heparinolytica, Fusobacterium spp, and pigmented members of the genera Prevotella and Porphyromonas. Aerobic/facultatively anaerobic organisms were isolated from 97% of horses, while obligately anaerobic organisms were cultured from 68% of horses. CONCLUSION: There was no association between the isolation of any specific bacterium and the outcome of disease. However, obligately anaerobic bacteria (such as anaerobic cocci, Bacteroides tectum, P heparinolytica and Fusobacterium spp) and the facultatively anaerobic species Escherichia coli, were recovered more commonly from horses that died or were euthanased than from those that survived. There was an association between failure of horses to recover from pleuropneumonia and delay in diagnosis and initiation of treatment.     

An Outbreak of Gangrenous Syndrome among Buffaloes and Cattle in West Bengal: Clinicopathological Studies

Gangrenous syndrome/Degnala disease was recorded in a large number of buffaloes and cattle in Murshidabad district of West Bengal, India. Fusarium spp. had been isolated from the mouldy paddy straw which were fed to the animals. There was a reduction in the incidence of the disease following withdrawal of the mouldy paddy straw. Histopathological examination showed necrosis and loss of architectural details in the skin.     

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.     

The diagnosis and treatment of periorbital sarcoid in the horse: 445 cases from 1974 to 1999

OBJECTIVE: Diagnosis and management of periorbital sarcoids in horses is a significant clinical challenge for the practicing veterinary surgeon and pathologist. The purpose of this study was to investigate the response of various types of sarcoids to different therapeutic methods. Animals studied Medical records of 445 clinical patients. Procedures This paper retrospectively examines the clinical and histological features of periorbital sarcoids and the treatment of 445 cases. Treatment by surgical excision, cryosurgery, Bacillus-Calmette-Gaérin (BCG) immunomodulation, topical cytotoxic applications, and radiation are described. RESULTS: Six types of sarcoid can be found in the immediate periorbital region and each has some characteristics of other disorders of the skin with which they can be confused. The diagnosis of sarcoids is, however, relatively simple in most cases. The lesions are not necessarily restricted to the dermis and epidermis, but commonly invade into the subcutis and the deeper muscular structures around the eye. Treatment with radiation is expensive and difficult to manage but resulted in the best outcome with almost 100% resolution in 66 cases. By contrast, surgical excision has serious potential complications that arise primarily as a result of the infiltrative nature of periorbital sarcoids. The value of BCG immunomodulation therapy for fibroblastic and nodular lesions described by previous workers is confirmed in this paper, with a good overall response (69%), provided that the material was injected intralesionally. Perilesional injection did not appear to carry a significant benefit. However, treatment of verrucose or occult lesions by this method gave generally poor results. The results of intralesional injection of cisplatin emulsions suggest that this may be an effective method of treatment in cases where other modalities are not feasible. In common with previous reports, failure to resolve the lesions frequently resulted in regrowth of the tumor, and in most cases this recurrence appeared to be more aggressive, with extensive local infiltration and faster growth. Conclusion The periorbital tissues are less tolerant of damage than those at many other sites and therefore certain treatment methods may be contraindicated. This suggests that it is important to select the best possible treatment at the first opportunity. It is a wise precaution to warn owners of horses with periorbital sarcoids of the dangers of leaving them and the particular risks associated with the currently available treatments.     

Equine conjunctival pseudotumors

Five horses presented with unilateral pink, smooth, nonulcerated conjunctival masses with histologic features characteristic of inflammatory pseudotumors, i.e. proliferative inflammatory lesions clinically resembling true neoplasia. Although causes for the inflammatory lesions were not determined, based on the presence histologically of mononuclear (predominantly lymphocytic) inflammatory cell infiltrates and the absence of infectious agents, parasites or foreign bodies, an immune-mediated pathogenesis was suspected. Affected horses ranged from 5 to 8 years of age with no apparent breed or sex predilection. Conjunctival lesions were nodular in two cases and relatively flat and more diffuse in three cases. Third eyelid lesions were present in three cases and two affected eyes had corneal involvement. Based on findings from these five cases, the prognosis for equine conjunctival pseudotumors appears to be good when lesions are treated by partial or complete surgical excision, local administration of anti-inflammatory agents, or a combination of surgery and anti-inflammatory therapy.     

In vitro analysis of antiangiogenic activity of fungi isolated from clinical cases of equine keratomycosis

OBJECTIVE: The goal of this project was to explore the possibility that fungal organisms produce metabolites that inhibit angiogenesis. Procedures Fungal cultures were obtained from cases of keratomycosis, grown in Sabouraud's dextrose broth, and sterile filtered for use in experiments. The Matrigel assay was used to screen the filtrate samples for antiangiogenic activity. Matrigel is a basement membrane matrix that supports the differentiation of human umbilical vein endothelial (HUVE) cells into a capillary-like network of tubules. HUVE cells were cultured using standard techniques and passaged at confluence, with all cells being used at passage 3-6. HUVE cells (40 000 cells) were pipetted into each well of a 24-well tissue-culture plate coated with Matrigel. An aliquot of fungal media filtrate was added to each well and the plates allowed to incubate for 18 h, at which time they were evaluated for tubule formation. RESULTS: Two fungal isolates showed inhibition of tubule formation. The addition of 100, 200 and 400 &mgr;L of the fungal media filtrate from the first isolate (Fusarium sp. 99A34574) produced a consistent and dose-dependent inhibition of tubule formation. The second isolate (Aspergillus sp. 271599) did not show inhibition of tubule formation with 100 or 200 &mgr;L added to the wells, however, it did show inhibition at 400 &mgr;L/well. The remaining three isolates did not cause inhibition at any concentration. CONCLUSIONS: Our findings suggest that certain fungal organisms produce metabolites that inhibit tubule formation in vitro, and that these metabolites may play a significant role in altering the host vascular response to fungal infections of the cornea.