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.     

Orbital fibroma in a horse

An 11-year-old American Quarterhorse gelding presented for moderate periorbital swelling and exophthalmia of the left eye. The menace response, and direct and consensual pupillary light reflexes were absent in the left eye. Conjunctival hyperemia, blepharedema, a mydriatic pupil, resistance to retropulsion, and an increased intraocular pressure were present. A soft-tissue mass could be palpated in the left retrobulbar space by pressing onto the orbit over the supraorbital fossa. Incomplete surgical resection of the mass was performed and histopathologic evaluation was consistent with a fibroma. Normal pupillary light reflexes and vision returned following surgery. The mass has not recurred 14 months after surgery.     

Hendra (equine morbillivirus)

Hendra has been recognized in Australia as a new zoonotic disease of horses since 1994/5 and subsequent work has shown that the viral agent is endemic in certain species of fruit bat. The Hendra virus is the type species of a new genus within the sub-family Paramyxovirinae, which also contains another newly identified zoonotic bat virus, namely Nipah. It is assumed that contact with bats has led to the Hendra virus being transferred to horses on each of the three separate incidents that have been reported in the last five years. No evidence has been found for widespread subclinical infection of horses.Infected horses can develop a severe and often fatal respiratory disease characterized by dyspnoea, vascular endothelial damage and pulmonary oedema. Nervous signs may also occur. Fatal respiratory disease has been seen in cats and guinea pigs following experimentally induced infections. Transmission of the virus from horses to other horses or man seems to have taken place, but very close contact was required. Three human cases have been recognized, all in association with equine cases. There have been two human fatalities, one due to respiratory failure and the other from a delayed-onset encephalitis. A number of diagnostic methods have been developed, but great care must be taken in obtaining samples from suspected cases.     

MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF THE FOOT IN HORSES WITH PALMAR FOOT PAIN AND CONTROL HORSES

Palmar foot pain is a common cause of lameness. Magnetic resonance imaging (MRI) has the potential to detect damage in all tissues of the equine foot, but an understanding of the differences in magnetic resonance (MR) images between feet from horses with and without palmar foot pain is required. This study aimed to describe MR findings in feet from horses with no history of foot-related lameness, and to compare these with MR findings in horses with lameness improved by palmar digital local analgesia. Thirty-four limbs from horses euthanized with a clinical diagnosis of navicular syndrome (ameness >2 months duration, positive response to palmar digital nerve blocks and absence of other forelimb problems) (Group L), and 25 feet from age-matched horses with no history of foot pain (Group N) were examined. For each anatomic structure, MR signal intensity and homogeneity, size, definition of margins, and relationships with other structures were described. Alterations in MR signal intensity and homogeneity were graded as mild, moderate, or severe and compared between Groups L and N. Results revealed that there were significant differences in MR images between Groups N and L. Multiple moderate-severe MR signal changes were present in 91% of limbs from Group L and moderate (none were graded severe) in 27% of limbs from Group N. In most Group L limbs, more than three structures and frequently six to eight structures were abnormal. Concomitant abnormalities involved most frequently the deep digital flexor tendon, distal sesamoidean impar ligament, navicular bone, collateral sesamoidean ligament, and navicular bursa (with significant associations in severity grade between these structures), sometimes with involvement of the distal interphalangeal joint and/or its collateral ligaments. It was concluded that findings on MR images were different between horses with and without foot pain, and that pain localized to the foot was associated with MR changes in a variety of structures, indicating that damage to several structures may occur concurrently and that MR imaging was useful for evaluation of foot pain.     

SCINTIGRAPHIC EVALUATION OF THE STIFLE IN NORMAL HORSES AND HORSES WITH FORELIMB LAMENESS

We tested the hypotheses that mature horses without lameness have a repeatable radiopharmaceutical uptake pattern in the stifle, which is bilaterally symmetric; immature horses have a different radiopharmaceutical uptake pattern; and forelimb lameness alters the radiopharmaceutical uptake pattern in the stifle. The objectives of the study were to describe the normal radiopharmaceutical uptake patterns using region of interest (ROI) analysis; to compare uptake patterns between left and right stifles of the same horse and between mature and immature horses; to compare radiopharmaceutical uptake in mature normal horses with those with forelimb lameness. Lateral scintigraphic images of the stifle from 51 horses aged 2-16 years were evaluated using seven ROIs and a reference site (midfemur). After subtraction of a background count, ratios between the mean counts per pixel for each ROI to the reference site were calculated. There was a repeatable radiopharmaceutical uptake pattern in mature normal horses that was bilaterally symmetrical. The caudoproximal aspect of the tibia and the patella had the highest ratios. Radiopharmaceutical uptake patterns in horses with forelimb lameness were not significantly different. Immature normal horses had a different symmetric pattern, with greatest radiopharmaceutical uptake ratios in the caudoproximal aspect of the tibia and the tibial crest. It was concluded that there are symmetric, repeatable radiopharmaceutical uptake patterns in both immature and mature horses, which are not altered by forelimb lameness.     

马传染性贫血病毒驴白细胞弱毒疫苗株囊膜基因的优化及其DNA疫苗体外瞬时表达研究

马传染性贫血病毒(Equine infectious anemia virus,EIAV)的密码子使用频率与哺乳动物间存在着明显差异。为此,对马传染性贫血病毒驴白细胞弱毒疫苗株(DLA-EIAV)囊膜全长基因按照哺乳动物优势密码子的使用原则进行了重新设计和合成,并以此为基础通过重叠延伸PCR、限制酶切等方法得到结合型和分泌型囊膜基因,将其插入含有鸡beta-actin/兔beta-globin复合启动子(AG)的高效表达载体pCAGGS中,构建了EIAV驴白细胞弱毒疫苗株结合型和分泌型囊膜基因的DNA疫苗质粒pCAGGS-opti-bou-env、pCAGGS- opti-sec-env。将构建的质粒纯化后分别转染293T细胞,以间接免疫荧光和Western blot方法检测转染48 h后细胞及上清中囊膜蛋白的表达。结果显示,两种表达质粒均可正确表达EIAV囊膜蛋白,与相对应未优化的表达载体pCAGGS-wt-bou-env和pCAGGS-wt-sec—env相比,密码子优化的基因体外瞬时表达水平有极为显著的提高,而且蛋白表达部位也与预期的结果符合。这一结果为EIAV囊膜蛋白的单抗制备、表位鉴定、免疫试验、新疫苗的开发等奠定了基础。