Intralesional bovine papillomavirus DNA loads reflect severity of equine sarcoid disease

Reasons for performing study: Sarcoids are nonmetastasising, yet locally aggressive skin tumours that constitute the most frequent neoplasm in equids. Infection by bovine papillomaviruses types 1 and 2 (BPV‐1, BPV‐2) has been recognised as major causative factor in sarcoid pathogenesis, but a possible correlation of intralesional virus load with disease severity has not been established thus far. Hypothesis: Given the pathogenic role of BPV‐1 and BPV‐2 in sarcoid disease, we suggest that intralesional viral DNA concentration may reflect the degree of affection. Methods: Severity of disease was addressed by recording the tumour growth kinetics, lesion number and tumour type for 37 sarcoid‐bearing horses and one donkey. Viral load was estimated via quantitative real‐time PCR (qPCR) of the E2, E5, L1 and L2 genes from the BPV‐1/‐2 genome for one randomly selected lesion per horse and correlated with disease severity. Results: Quantitative PCR against E2 identified viral DNA concentrations ranging from 0–556 copies/tumour cell. Of 16 horses affected by quiescent, slowly growing single tumours or multiple mild‐type lesions, 15 showed a viral load up to 1.4 copies per cell. In stark contrast, all equids (22/22) bearing rapidly growing and/or multiple aggressive sarcoids had a viral load between 3 and 569 copies per cell. Consistent results were obtained with qPCR against E5, L1 and L2. Conclusions: While tumours of the same clinical type carried variable virus load, confirming that viral titre does not determine clinical appearance, we identified a highly significant correlation between intralesional viral load and disease severity. Potential relevance: The rapid determination of BPV viral load will give a reliable marker for disease severity and may also be considered when establishing a therapeutic strategy.     

A pilot study on the use of ultra-deformable liposomes containing bleomycin in the treatment of equine sarcoid

The efficacy of a novel topical liposome-encapsulated preparation of bleomycin (Bleosome) was studied in 118 clinical cases of equine sarcoid and efficacy was compared with two other standard conventional treatments, tazarotene and 5-fluorouracil (5-FU) as well as with the Bleosome in combination with each of these two conventional treatments. Treatments were arbitrarily assigned. Fifty-two of the 118 sarcoids (44%) were resolved after 12 months but there were significant differences between treatment groups with the combinations of either 5-FU and bleomycin, or tazarotene and bleomycin resulting in significantly superior resolution of 77 and 78% of the lesions, respectively. The preliminary results suggest that bleomycin in a liposomal carrier may be a useful treatment modality for superficial, diffuse and verrucose sarcoids. The treatment process was simple, and outcomes were functionally and cosmetically excellent. Liposome-encapsulated bleomycin is economic compared to radiation and other treatment options and can be applied effectively by the owner under guidance. Further studies with different administration protocols and higher concentrations of bleomycin are warranted.     

A review of equine mucocutaneous squamous cell carcinoma

Squamous cell carcinoma (SCC) accounts for approximately 20% of all equine mucocutaneous (MC) tumours and continues to present a therapeutic challenge to practitioners. Most MC‐SCC are locally invasive and slow to metastasise, but metastasis to local lymph nodes is not uncommon. The most common location for MC‐SCC is the periorbital region, with the eyelid most commonly affected. Although only 13% of MC‐SCC involves the external genitalia, MC‐SCC is the most common neoplasm of male genitalia. Equine caballus papillomavirus‐2 has recently been linked to MC‐SCC and may prove to be necessary for tumour development. Risk factors may include chronic exposure to ultraviolet light and chronic skin irritation. Horses developing genital MC‐SCC tend to be older compared to those with periorbital MC‐SCC. Histopathology is required for definitive diagnosis of MC‐SCC, although horse phenotype and lesion location may suggest MC‐SCC. Several treatment modalities have been successful in eliminating or managing MC‐SCC, with surgical excision and intratumoural chemotherapy yielding the best results. Other treatment options including cryotherapy, hyperthermia, radiotherapy and photodynamic therapy are often used as adjunctive therapies. Early recognition of tumours and prompt intervention are associated with a positive outcome.     

Periocular sarcoid in a horse

A periocular nodular sarcoid of the right upper and lower eyelids was diagnosed in an 11-year-old Thoroughbred mare. Computed tomography scan revealed the extent of the tumor. The mass was surgically debulked under general anesthesia, and the affected periocular region was injected intralesionally with Bacillus of Calmette and Guerin (BCG). An emulsion of cell wall fractions was used, which has been modified to reduce the toxic and allergic effect, but retain the antitumor activity. In total, five injections were performed at 2-week intervals. At follow-up 7 months after the last BCG injection, the tumor was completely resolved. Two years after the last treatment, the horse remains tumor-free.     

Equine sarcoid of the glans penis with bovine papillomavirus type 1 in a miniature horse (Falabella)

A 23-year-old Falabella gelding kept in Tochigi, Japan, for more than 20 years presented with a recurrent mass of the glans penis that was first noticed about a year earlier. Partial phallectomy was performed with no adjunctive therapy for local regrowth of the mass. The horse was euthanized 3 months after surgery for urinary retention due to suspected regrowth. The resected mass affected the genital and urethral mucosa of the glans penis, and was diagnosed as equine sarcoid by histopathology and identification of bovine papillomavirus (BPV) DNA. Phylogenetic analysis of the BPV genome of the sarcoid showed high sequence homology to BPV type 1 (BPV-1) from Hokkaido, Japan, suggesting a geographical relationship for BPV-1 in Japan.     

Treatment of clinically diagnosed equine sarcoid with a mistletoe extract (Viscum album austriacus)

Background: Equine sarcoids (ES) are common, difficult to treat, and have high recurrence rates. Viscum album extracts (VAE) are used in human cancer treatment. Hypothesis: That therapy with VAE (Iscador P) is effective in the treatment of ES. Animals: Fifty‐three horses (444 ES); 42 were treated with VAE or placebo as monotherapy; 11 were treated with VAE or placebo after selective excision of ES. Methods: Prospective, randomised, blinded, clinical trial. Horses were randomly assigned to treatment (VAE; n = 32) or control group (Placebo; n = 21). One milliliter of VAE (Iscador P) in increasing concentrations from 0.1 to 20 mg/mL or physiological NaCl solution was given SC 3 times a week over 105 days. Number, localization, and type of the ES were documented over 12 months. A subset of 163 clinically diagnosed equine sarcoid (CDES) lesions (95 VAE, 68 Placebo) was evaluated in detail, considering clinical findings and tumor volume. Results: No undesired adverse effects were observed except for mild edema at the injection site in 5 of 32 horses (16%). Complete or partial regression was observed in 13 horses of the VAE group (41%) and in 3 of the control horses (14%; P < .05). After VAE treatment, 48 of 95 CDES (67%) showed an improvement compared with 17 of 68 CDES in the control group (40%; P < .01). Twenty‐seven CDES had disappeared completely in the VAE group (38%) compared with 9 CDES in the control group (13% NS). Conclusions and Clinical Importance: VAE (Iscador P) represents a safe and effective treatment for CDES.     

A review of equine sepsis

Sepsis is defined as an exaggerated, systemic inflammatory response to infection and is a common condition in horses. Systemic inflammatory response syndrome (SIRS) associated with bacterial infection is a hallmark of sepsis. Sepsis in neonatal foals is a common sequela of failure of passive transfer and, in addition to development of SIRS, may be characterised by bacteraemia, pneumonia, enterocolitis, omphalophlebitis, meningoencephalitis or arthritis. Sepsis in mature horses is most commonly observed secondary to gastrointestinal lesions that result in disrupted mucosa and bacterial translocation into circulation (endotoxaemia). Pleuropneumonia and metritis may also cause sepsis in mature horses. Diagnosis of sepsis is based on SIRS criteria as well as suspected or confirmed infection. Due to the relatively low sensitivity of microbial culture and the subjectivity of sepsis scoring, many sepsis biomarkers are being studied for their usefulness in diagnosis and prognostication of sepsis in horses. Treatment of sepsis requires an intensive care approach that includes antimicrobial drug administration, fluid resuscitation and pressure support, and treatment for inflammation, endotoxaemia and coagulopathy. Early recognition of sepsis and prompt antimicrobial drug treatment are critical for a successful outcome. Multiple organ dysfunction syndrome may occur in severe cases of sepsis, with common manifestations including laminitis and coagulopathies. Although prognosis for septic mature horses depends highly on the primary disease process, the overall survival rate in septic neonatal foals ranges from 26 to 86%, with most studies indicating a survival rate of 45–60%.     

Electronic brachytherapy used for the successful treatment of three different types of equine tumours

An electronic form of interstitial brachytherapy was used to treat tumours on 3 different horses. One horse was treated for an ocular lymphoma, the second for a sarcoid, and the third for melanoma. This form of brachytherapy contains inherent advantages over previously used forms of brachytherapy and provides another treatment option for equine tumours that cannot be treated with, or do not respond to, conventional tumour therapies.     

A review of equine laryngoplasty complications

Prosthetic laryngoplasty is a common treatment for equine recurrent laryngeal neuropathy (RLN). Complications of this surgery include immediate post operative problems, such as dysphagia, seroma formation, wound infection and sudden loss of arytenoid abduction. Longer term complications include gradual loss of arytenoid abduction, chronic coughing, arytenoid granulomas and dynamic upper airway collapse unrelated to RLN such as palatal dysfunction, and aryepiglottic fold or vocal fold collapse. However, the benefit of this procedure greatly outweighs these potential post operative complications, especially if appropriate surgical and post operative management practices are employed.     

Safety and immunogenicity of BPV-1 L1 virus-like particles in a dose-escalation vaccination trial in horses

Reasons for performing study: Infection with bovine papillomaviruses types 1 and 2 (BPV‐1, BPV‐2) can lead to the development of therapy‐resistant skin tumours termed sarcoids and possibly other skin diseases in equids. Although sarcoids seriously compromise the welfare of affected animals and cause considerable economic losses, no prophylactic vaccine is available to prevent this common disease. In several animal species and man, immunisation with papillomavirus‐like particles (VLP) has been shown to protect efficiently from papillomaviral infection. Hypothesis: BPV‐1 L1 VLPs may constitute a safe and highly immunogenic vaccine candidate for protection of horses against BPV‐1/‐2‐induced disease. Methods: Three groups of 4 horses each received 50, 100 or 150 µg of BPV‐1 L1 VLPs, respectively, on Days 0, 28 and 168. Three control horses received adjuvant only. Horses were monitored on a daily basis for one week after each immunisation and then in 2 week intervals. Sera were collected immediately before, 2 weeks after each vaccination and one and 2 years after the final boost and analysed by pseudovirion neutralisation assay. Results: None of the horses showed adverse reactions upon vaccination apart from mild and transient swelling in 2 individuals. Irrespective of the VLP dose, all VLP‐immunised horses had developed a BPV‐1‐neutralising antibody titre of ≥1600 plaque forming units (pfu)/ml 2 weeks after the third vaccination. Eight of 10 trial horses still available for follow‐up had neutralising antibody titres ≥1600 pfu/ml one year and ≥800 pfu/ml 2 years after the last immunisation. Conclusion: Intramuscular BPV‐1 L1 VLP vaccination in horses is safe and results in a long‐lasting antibody response against BPV‐1. Neutralisation titres were induced at levels that correlate with protection in experimental animals and man. Potential relevance: BPV‐1 L1 VLPs constitute a promising vaccine candidate for prevention of BPV‐1/‐2‐induced disease in equids.     

Differential expression of microRNAs in bovine papillomavirus type 1 transformed equine cells

Bovine papillomavirus (BPV) types 1 and 2 play an important role in the pathogenesis of equine sarcoids (ES), the most common cutaneous tumour affecting horses. MicroRNAs (miRNAs), small non‐coding RNAs that regulate essential biological and cellular processes, have been found dysregulated in a wide range of tumours. The aim of this study was to identify miRNAs associated with ES. Differential expression of miRNAs was assessed in control equine fibroblasts (EqPalFs) and EqPalFs transformed with the BPV‐1 genome (S6‐2 cells). Using a commercially available miRNA microarray, 492 mature miRNAs were interrogated. In total, 206 mature miRNAs were differentially expressed in EqPalFs compared with S6‐2 cells. Aberrant expression of these miRNAs in S6‐2 cells can be attributed to the presence of BPV‐1 genomes. Furthermore, we confirm the presence of 124 miRNAs previously computationally predicted in the horse. Our data supports the involvement of miRNAs in the pathogenesis of ES.     

A review of approaches to assessing equine welfare

Veterinary surgeons are required to assess an animal's welfare in a range of different circumstances in the course of their daily work. These assessments may relate to the long‐term welfare of an individual animal under their care, or the current welfare of a population of animals that are unfamiliar to them as individuals. The welfare assessment made may subsequently have implications for the treatment that an animal receives or for the decision of whether or not an animal should remain in its current home. Yet welfare assessment is not straightforward. Here we review the challenges that welfare assessment presents and review the tools currently available to meet them. Lastly, we look towards the future of equine welfare assessment, with examples of current research to develop tools and optimise welfare assessment.     

A review of equine rectal tears and current methods of treatment

Rectal tears are a risk of rectal palpation during equine clinical examination and can be life‐threatening; prompt medical and surgical intervention is required to improve patient outcome. Depending on the degree of the tear, conservative treatment or surgical management may be warranted. Surgical management involves either direct suturing or faecal diversion techniques, such as colostomy or a temporary indwelling rectal liner. The prognosis for a horse with a rectal tear depends on size of the tear, grade and location of the tear, and time between occurrence and first aid measures.     

The use of progestins in equine medicine: A review

Progesterone is in constant fluctuation throughout the lifespan of the horse. As a key regulator of the hypothalamic–pituitary–gonadal axis, progesterone is involved in numerous aspects of reproduction. Synthetic analogs of progesterone, deemed progestins, are widely available to industry to act as progestogenic within the reproductive tract, although few are bioactive in the horse. Utilised to suppress oestrous, delay ovulation, maintain pregnancy, and for behavioural modifications, progestins are a commonly administered class of pharmaceuticals in veterinary medicine. In this review, we discuss the progestins available to equine industry, in addition to assessing efficacy, pharmacokinetics, and potential side effects following administration of each.