Equus caballus papillomavirus Type 7 is a rare cause of equine penile squamous cell carcinomas.

Penile squamous cell carcinomas (SCCs) are common, potentially life-threatening neoplasms of horses. They are well-recognized to be caused by Equus caballus papillomavirus (EcPV) type 2, although EcPV2 cannot be detected in all cases. A 23-year-old standardbred gelding developed multiple penile in situ and invasive SCCs that contained histological evidence of PV infection. By using both consensus and specific PCR primers, these lesions were found to contain EcPV7 DNA, but not DNA from EcPV2 or any other PV type. To determine how frequently EcPV7 is present in equine penile SCCs, specific primers were used to detect EcPV2 and EcPV7 in a series of 20 archived samples. EcPV7 was the only PV detected in one, both EcPV2 and 7 were detected in five, and only EcPV2 was detected in 14 SCCs. EcPV7 DNA was also detected in three of 10 archived oropharyngeal SCCs, although only as a co- infection with EcPV2. This is the first report of EcPV7 causing disease in horses. These results suggest EcPV7 could cause a subset of equine penile SCCs, and this is the first evidence that PV types other than EcPV2 can cause these neoplasms. The detection of EcPV7 in the oropharyngeal SCCs suggests a potential role of this PV type in the development of these SCCs. There were no clinical or histological features that differentiated lesions containing EcPV7 DNA from those containing EcPV2 DNA. If EcPV7 causes a proportion of equine penile SCCs, vaccines to prevent EcPV2 infection may not prevent all equine penile SCCs.

Treatment of limb wounds of horses with orf virus IL-10 and VEGF-E accelerates resolution of exuberant granulation tissue, but does not prevent its development.

Bandaging of limb wounds in horses leads to formation of exuberant granulation tissue (EGT) that retards healing due to protracted inflammation, aberrant vascularisation and delayed epithelialisation. EGT is not observed if wounds are left undressed or when wounds are on the body. A previous study showed that short-term administration of proteins derived from orf virus dampened inflammation and promoted epithelialisation of open wounds in horses. Here, we investigated the impact of orf virus interleukin-10 and vascular endothelial growth factor-E on the development and resolution of EGT. Excisional wounds were created on the forelimb of four horses, and bandages were maintained until full healing to induce EGT formation. Matching body wounds were created to ensure EGT was limited to the limb, and to differentiate the effects of the viral proteins on normal healing and on EGT formation. Viral proteins or the hydrogel vehicle control were administered topically to site-matched wounds at day 1, with repeat administration at day 8. Wound healing and EGT formation were monitored macroscopically. Wound margin samples were harvested at 2, 7 and 14 days, and at full healing, with histology used to observe epithelialisation, immunofluorescence used to detect inflammatory cells, angiogenesis and cell death, and qPCR to measure expression of genes regulating inflammation and angiogenesis. Limb wounds developed EGT, and exhibited slower healing than body wounds. Viral protein treatment did not accelerate healing at either location nor limit EGT formation in limb wounds. Treatment of limb wounds did however increase epithelialisation and angiogenesis, without dampening inflammatory cell infiltration or gene expression. The healed wounds also had less occlusion and death of blood vessels and fewer epidermal rete ridges following viral protein treatment. These findings indicate that the viral protein treatment does not suppress wound inflammation or EGT formation, but does promote vascular and epidermal repair and EGT resolution.

Short-term treatment of equine wounds with orf virus IL-10 and VEGF-E dampens inflammation and promotes repair processes without accelerating closure.

Healing is delayed in limb wounds relative to body wounds of horses, partly because of sustained inflammation and inefficient angiogenesis. In laboratory animals, proteins derived from orf virus modulate these processes and enhance healing. We aimed to compare immune cell trafficking and the inflammatory, vascular, and epidermal responses in body and limb wounds of horses and then to investigate the impact of orf virus interleukin-10 and vascular endothelial growth factor-E on these processes. Standardized excisional wounds were created on the body and forelimb of horses and their progression monitored macroscopically until healed. Tissue samples were harvested to measure the expression of genes regulating inflammation and repair (quantitative polymerase chain reaction) and to observe epithelialization (histology), innate immune cell infiltration, and angiogenesis (immunofluorescence). Delayed healing of limb wounds was characterized by intensified and extended pro-inflammatory signaling and exacerbated innate immune response, concomitant with the absence of anti-inflammatory eIL-10. Blood vessels were initially more permeable and then matured belatedly, concomitant with retarded production of angiogenic factors. Epithelial coverage was achieved belatedly in limb wounds. Viral proteins were administered to wounds of one body and one limb site/horse at days 1-3, while wounds at matching sites served as controls. Treatment dampened pro-inflammatory gene expression and the innate immune response in all wounds. It also improved angiogenic gene expression, but primarily in body wounds, where it altered blood vessel density and myofibroblast persistence. Moreover, the viral proteins increased epithelialization of all wounds. The short-term viral protein therapy did not, however, improve the healing rate of wounds in either location, likely due to suboptimal dosing. In conclusion, we have further detailed the processes contributing to protracted healing in limb wounds of horses and shown that short-term administration of viral proteins exerts several promising though transient effects that, if optimized, may positively influence healing.

Orf virus interleukin-10 and vascular endothelial growth factor-E modulate gene expression in cultured equine dermal fibroblasts.

BACKGROUND: Wounds in horses often exhibit sustained inflammation and inefficient vascularization, leading to excessive fibrosis and clinical complications such as "proud flesh". Orf virus-derived proteins, vascular endothelial growth factor (VEGF)-E and interleukin (ovIL)-10, enhance angiogenesis and control inflammation and fibrosis in skin wounds of laboratory animals. HYPOTHESIS/OBJECTIVES: The study aimed to determine if equine dermal cells respond to VEGF-E and ovIL-10. Equine dermal cells are expected to express VEGF and IL-10 receptors, so viral protein treatment is likely to alter cellular gene expression and behaviour in a manner conducive to healing. ANIMALS: Skin samples were harvested from the lateral thoracic wall of two healthy thoroughbred horses. METHODS: Equine dermal cells were isolated using a skin explant method and their phenotype assessed by immunofluorescence. Cells were treated with recombinant proteins, with or without inflammatory stimuli. Gene expression was examined using standard and quantitative reverse transcriptase PCR. Cell behaviour was evaluated in a scratch assay. RESULTS: Cultured cells were half vimentin(+ve) fibroblasts and half alpha smooth muscle actin(+ve) and vimentin(+ve) myofibroblasts. VEGF-E increased basal expression of IL-10 mRNA, whereas VEGF-A and collagenase-1 mRNA expression was increased by ovIL-10. In cells exposed to inflammatory stimulus, both treatments dampened tumour necrosis factor mRNA expression, and ovIL-10 exacerbated expression of monocyte chemoattractant protein. Neither viral protein influenced cell migration greatly. CONCLUSIONS AND CLINICAL IMPORTANCE: This study shows that VEGF-E and ovIL-10 are active on equine dermal cells and exert anti-inflammatory and anti-fibrotic effects that may enhance skin wound healing in horses.

Medical and surgical management of an intra-abdominal abscess of hepatic origin in a horse.

CASE DESCRIPTION: A 4-year-old Arabian-cross mare was examined because of a 48-hour history of pyrexia, lethargy, and signs of abdominal discomfort. CLINICAL FINDINGS: On initial evaluation, the horse was in good body condition, but febrile, tachycardic, tachypneic, and icteric and had signs of colic. Findings on CBC and serum biochemical analysis indicated marked systemic inflammation and hepatocellular damage. Serial abdominal ultrasonographic examinations revealed progressive, localized hepatic parenchymal abnormalities in the left ventral aspect of the abdomen in proximity to the left liver lobes, and eventual identification of an irregularly marginated, hyperechoic walled region of heterogenous echogenicity consistent with an encapsulated hepatic abscess. TREATMENT AND OUTCOME: Medical treatment was initiated with administration of doxycycline and flunixin meglumine. After 7 days, the horse's clinical signs and hematologic values improved. After 14 days, the horse was discharged from the hospital and prescribed continuation of doxycycline treatment for 14 days. One week following hospital discharge, the horse was reevaluated for recurrent signs of colic and pyrexia. The horse was sedated, and the region overlying the caudal aspect of the seventh rib was desensitized with an inverted L nerve block by local infiltration with 2% lidocaine. While the horse was standing and sedated, drainage of an encapsulated intra-abdominal abscess was followed by rib resection and removal of a portion of necrotic left lateral liver lobe. The development of a pneumothorax following rib resection represented the only major surgical complication. Twelve months later, the horse was clinically normal and had returned to its previous level of performance. CLINICAL RELEVANCE: Rib resection in standing sedated horses, together with appropriate medical management, should be considered an option for removal of well-encapsulated cranially located intra-abdominal abscesses that are adherent to the ventrolateral aspect of the body wall in horses.