Keratometry, biometry and prediction of intraocular lens power in the equine eye

OBJECTIVE: To determine ocular dimensions (A- and B-scan ultrasound) and corneal curvature (radius of corneal diameter determined in B-scan ultrasound) in the equine eye and to calculate the appropriate dioptric power for a posterior chamber intraocular lens (IOL) necessary to achieve emmetropia in the eyes of horses undergoing lens extraction. ANIMALS: Fourteen clinically normal adult horses of various breeds. Additionally, for comparison, one American Miniature colt foal, and one 2.5-year-old Shire gelding were examined. PROCEDURE: B-scan ultrasound was performed on one eye from each horse. One eye from both the Shire and the American Miniature were examined for comparison. Data from ultrasound (globe measurements and corneal curvature), and the estimated postoperative IOL positions were entered into theoretical IOL formulas (Binkhorst and Retzlaff theoretical formulas) in order to calculate the predicted IOL strength required to achieve emmetropia after lens extraction in horses. Results: Mean axial length of globes was 39.23 mm +/- 1.26 mm, mean preoperative anterior chamber depth (ACD) was 5.63 +/- 0.86 mm, and mean lens thickness was 11.75 +/- 0.80 mm. Predicted postoperative ACD (PACD) was calculated as the ACD plus 50% of the lens thickness. Additionally, PACD 2 mm anterior and 2 mm posterior to the center of the lens were calculated in order to evaluate the effect of IOL position on its required refractive power. Required IOL strength calculated, using the three values for the predicted postoperative ACD, was 29.91 D +/- 2.50, 29 D +/- 2.52 (center of lens); 27.13 D +/- 2.27, 26.33 D +/- 2.20 (2 mm anterior to center of lens); and 33.18 D +/- 2.78, 32.24 D +/- 2.68 (2 mm posterior to center of lens) with the Binkhorst and Retzlaff theoretical formulas, respectively. CONCLUSIONS: An IOL of substantially lower diopter strength than that needed in either dogs or cats is required to achieve emmetropia after lens extraction in adult horses. IOL strength of approximately 30 D, depending on where the IOL ultimately comes to rest, will probably be required.     

Frequency of latent equine herpesvirus type-1 infection among a sample of horses in the central North Island of New Zealand

ABSTRACT

Aim: To estimate the frequency of infection with equine herpesvirus type-1 (EHV-1) among horses from the central North Island of New Zealand, including the frequency of detection of the D₇₅₂ genotype.

Methods: Samples of retropharyngeal lymph nodes (RLN) and submandibular lymph nodes (SLN) were dissected from the heads of 63 horses that were humanely killed for various unrelated reasons between March and November 2015. DNA extracted from these tissues was subjected to enrichment for EHV-1 sequences by hybridisation with biotin-labelled EHV-1 specific probe, followed by recovery of EHV-1 sequences on streptavidin-coated magnetic beads. Enriched samples were tested for the presence of EHV-1 using nested quantitative real-time PCR. The EHV-1 amplicons were sequenced to determine the genotype of the virus.

Results: The median age of the horses was 6 (min 2, max 30) years, and 47/63 (75%) were Thoroughbreds. EHV-1 DNA was detected in RLN samples from 6/63 (10%) horses, and three of these horses were also positive for EHV-1 DNA in SLN. The remaining horses were negative for EHV-1 DNA in both RLN and SLN samples. The N₇₅₂ genotype was detected in all positive samples and the D₇₅₂ genotype was not detected in any of the samples.

Conclusions: EHV-1 continues to circulate among horses in New Zealand. The frequency of latent EHV-1 infection among sampled horses may have been underestimated due to the sensitivity limit of the assay or because of the limited anatomical sites sampled in the study. Lack of detection of the D₇₅₂ genotype suggests that infection with this genotype is not common in horses in New Zealand.

Clinical Relevance: If live animals are tested for EHV-1 using SLN biopsy it should be kept in mind that negative results do not rule out the presence of latent EHV-1 infection at other sites inaccessible for testing. The RLN appear to be the preferred sample for detection of EHV-1 DNA in horses following recent euthanasia.     

Combined decongestive therapy including equine manual lymph drainage to assist management of chronic progressive lymphoedema in draught horses

Equine chronic progressive lymphoedema (CPL) is a disabling disorder of draught horse breeds. Combined decongestive therapy (CDT) is the treatment of choice for lymphoedema in man and has been adapted for use in horses. Equine CDT, which includes manual lymph drainage (MLD) and subsequent bandaging with short stretch bandages, was expected to improve the signs of CPL in draught horses because CPL resembles primary lymphoedema in man. Five affected horses ‐ Gypsy cob (n = 1), Clydesdale (n = 1), Shires (n = 3) ‐ were included. Lesions were documented pre‐ and post treatment. Percentage volume loss of the distal legs was calculated using the disc model. Initial plans for daily CDT had to be adapted; intermittent treatment of Chorioptes infections required alternating between CDT and MLD in 4/5 horses. Concurrent pyoderma (1/5 horses) was treated throughout the study. Development of unrelated lameness (hoof abscess) allowed limited CDT treatment only in one horse. Marked softening of previously firm tissue indicated the change from ‘brawny’ to pitting oedema in 2/5 horses. Fibrotic nodules and folds in the pasterns became markedly softened and smaller in 2/5 horses. Skin surface notably improved in all horses: hyperkeratosis decreased, erosions and ulcerations healed completely and crusts disappeared. After 2 weeks, a mean volume reduction of 11.25% was seen, ranging from 4.75–21.74% and quality of movement improved. This pilot study documents evidence that CDT assists management of CPL. Current CPL management is limited to palliative treatments of secondary infections. Whilst not a permanent treatment, CDT offers a promising tool to manage horses with CPL, improving their quality of life and potential usefulness. More extensive and prolonged studies with a larger number of horses are warranted to evaluate the full potential of CDT.     

Pulmonary fibrosis and gammaherpesvirus infection in horses

Pulmonary fibrosis is a devastating and often progressive condition leading to exercise intolerance and frequently the demise of the animal. Although uncommonly encountered in horses, the condition is intensely researched both in human medicine and animal models. Viral infections have long been suspected to play a part in the development of pulmonary fibrosis and neoplastic conditions in other species. In 2007, an association between equine herpesvirus 5 (EHV‐5) infection and nodular pulmonary fibrosis in horses was suggested and the name equine multinodular pulmonary fibrosis (EMPF) was introduced. Recently, the presence of EHV‐5 in equine lymphoma has also emerged. The case report by Schwarz et al. in this issue describes a horse suffering from concurrent T cell leukaemia and EMPF in association with EHV‐5. This article summarises current knowledge about EMPF and EHV‐5 infections in horses, recent developments in the understanding of pulmonary fibrosis in man and the proposed contribution of viral infections to pulmonary fibrosis and neoplastic conditions.     

Equine mammary gland disease with a focus on botryomycosis: A review and case study

Mammary gland problems occur incidentally in horses and one of the rarer conditions is botryomycosis (bacterial pseudomycosis, bacterial granuloma, staphylococcal pseudomycetoma). This article includes a short review of equine mammary gland problems inappropriate lactation, mastitis and neoplasia and botryomycosis, and additionally 2 clinical cases of botryomycosis of the udder resulting from Staphyloccocus aureus infection will be discussed. Both cases involved nonpregnant, nonlactating mares referred for chronic mammary inflammation with draining abcessation. In both mares, botryomycosis caused by S. aureus was confirmed by histopathology and a bacterial culture. Both mares recovered fully after surgical hemimastectomy under general anaesthesia.     

Clinical presentation,treatment and possible causes of persistent endometrial cups illustrated by two cases

Persistent endometrial cups are relatively rare in the mare and the occurrence in 2 successive pregnancies, as described in this issue, is an intriguing finding. This article describes an additional 2 cases of endometrial cups persisting in excess of 12 months in mares that had experienced pregnancy loss. Both mares demonstrated irregular ovarian activity in the form of repeated formation of haemorrhagic anovulatory follicles. A definitive diagnosis was made by visualisation of cup tissue by hysteroscopy and demonstration of equine chorionic gonadotropin (eCG) in the mares' serum. Biopsy of endometrial cups was made under visual direction and the mares were treated by chemical curettage with kerosene. The clinical presentation, treatment and possible causes of persistent endometrial cups are reviewed and discussed.     

Assessment of quality of life in equine patients

Reasons for performing study: Assessing patients' quality of life (QOL) is a core part of clinical decision making. Various methodologies for assessing patients' QOL have been developed in human medicine and small animal veterinary disciplines. In contrast, the lack of aids for QOL assessment in equine veterinary practice leaves practitioners reliant on subjective assessments of QOL, which may be prone to avoidable errors. Objectives: This paper suggests pragmatic ways in which QOL may be enhanced, while remaining appropriate for the time, financial and owner‐based constraints within equine practice. Methods: Through interdisciplinary research, this paper identifies, adapts and applies insights from several areas of research and practical experience in order to develop an overarching approach to making QOL‐based decisions in clinical cases. Results: The paper identifies 6 steps involved in QOL‐based decision making and provides examples of how these steps may be practically applied. These include deciding what each clinician feels is important; deciding how to evaluate it, including taking owners' views into consideration; making decisions about each case and achieving the desired clinical outcomes. Conclusions: Practitioners can draw their own conclusions on how they may improve QOL assessment in practice and may usefully share these with colleagues. Reporting cases and sharing practical examples of QOL tools used on the ground are vital to the development of this field and appropriate methodologies. Potential relevance: Improvements in QOL assessment are relevant to all areas of equine veterinary practice, and several areas of research. Further research may develop QOL assessment in practice, but more important are the personal improvements that each practitioner may achieve. See also correspondence by Grove     

马流感病毒血凝素基因甲病毒复制子重组表达质粒的构建及其免疫效力评价

为评价马流感病毒(EIV)HA基因核酸免疫效果,本研究以甲病毒复制子载体pSFV1CS分别构建了表达EIV H3N8亚型的美洲型和欧洲型HA基因的重组真核表达质粒。并将其转染293T细胞,经间接免疫荧光鉴定表明HA基因获得表达;以重组质粒免疫的BALB/c鼠能够检测到特异性抗体产生,而且HI抗体水平持续升高,同时小鼠体内IFN-γ、IL-4分泌水平也有所升高。攻毒后小鼠表现轻度临床症状,但病毒分离和RT-PCR均未检测到病毒。上述结果表明,该重组质粒pSFV1CS-EIV-HA具有良好的免疫原性并且可以诱导免疫动物产生较高免疫应答的能力。