Efficacy and application of a novel topical anaesthetic wound formulation for treating cattle with Foot-and-Mouth disease: A field trial in Cameroon

Use of a local anaesthetic and antiseptic wound formulation for the treatment of lambs naturally infected with Orf virus

Contagious ecthyma (CE) is a worldwide highly contagious zoonotic viral skin disease of sheep and goats. Treatment for Orf virus (ORFV) infection usually involves topical and oral antibiotics. An anaesthetic and antiseptic topical gel (Multisolfen® or Tri-Solfen®; MS®, Medical Ethics, Australia) has been documented as an efficacious therapy for lesions from mucosal and epithelial viral infections in ruminants. The present study tested a new treatment protocol of MS® for CE therapy on-farm in 150 lambs naturally infected with ORFV. Lambs were divided into three cohorts of 50 lambs each (C, D and E). Cohort C was treated with MS® 3 times with an interval of 3 days between treatments, cohort D was treated daily with hypochlorous acid, whilst cohort E served as untreated controls. The lambs were examined clinically every two days, weight measured weekly, with whole blood and sterile swabs from ORFV lesions collected for haematological analysis and specific ORFV PCR. Cohort C presented fewer lambs displaying ORFV-associated lesions than other cohorts at different times of the experiment. Further, lesions treated with MS® were milder compared with other cohorts. However, following cessation of therapy, most of the lambs again developed ORFV-associated lesions. No differences between cohorts were observed in weight, haematological and PCR results. These findings suggest that topical treatment with MS® is effective for CE in field conditions, especially in the first stages of the clinical course, although treatment with MS® may need to be extended a minimum of 4 weeks.

Use of a Local Anaesthetic/Antiseptic Formulation for the Treatment of Lambs Experimentally Infected with Orf Virus

Contagious ecthyma is a highly transmissible eruptive viral disease of the skin and mucosa of sheep and goats distributed worldwide. The treatment of orf lesions is usually based on the use of antiseptics and antibiotics for the management of presumptive secondary infections, increasing risks of antimicrobial resistance. The wound dressing formulation Tri-Solfen® (TS) containing two local anaesthetics (lignocaine and bupivacaine), adrenaline and an antiseptic (cetrimide) in a gel formulation has been demonstrated to reduce suffering and enhance recovery in cattle and buffalo with oral and skin lesions due to foot-and-mouth disease virus infection and reduced the orf viral load in lambs. In the present study, experimental infection with the orf virus was conducted in 50 newborn lambs and 25 animals were treated after the presence of the first lesions with TS and repeated three days later. Daily clinical examination, haematological, serological, biomolecular and post-mortem analyses were conducted during 34 days after treatment. Results indicated that treatment had no effect on weight gain and clinical progression of the lesions. It was determined that seroconversion after experimental infection occurs 34 days after infection and suggested that the deep basal epithelial location of the orf lesions may have prevented the therapy from having altered the clinical course.

Role of Topical Anaesthesia in Pain Management of Farm Animals, a Changing Paradigm

Field evidence indicates that livestock producers are motivated by access to products that readily deliver pain management during husbandry interventions and, more recently, viral epidermal infectious diseases, including FMD. There has been impressive adoption in Australia of a farmer-applied spray-on topical anaesthetic wound formulation (TAF; Tri-Solfen®, Medical Ethics, Australia), initially for managing pain of the breech modification ‘mulesing’ procedure that reduces susceptibility of sheep to flystrike. Over 120 million lambs have now received pain relief and cattle producers have commenced using the TAF for a range of husbandry procedures. This product has demonstrated efficacy for surgical castration and tail docking of lambs, surgical castration and dehorning of calves, surgical castration of piglets, debridement of lesions of the hoof for lame cattle and, importantly, treatment of clinical FMD lesions, including decubitus ulcerations occurring from prolonged recumbency. Multimodal use of an NSAID for improved pain management is advocated, particularly meloxicam, available by prescription from veterinarians for injection and as an oral formulation (Ilium Buccalgesic®, Troy Laboratories, Australia), with current work assessing the potential for prolonged delivery in molasses blocks. Increased use of TAF with NSAIDs significantly reduces pain and suffering in livestock, with enhanced healing of FMD lesions, reduced viral loads from Orf infections in lambs and diminished necessity of ‘antibiotic cover’, assisting antimicrobial-resistance (AMR) stewardship.

Effectiveness and profitability of preventive veterinary interventions in controlling infectious diseases of ruminant livestock in sub-Saharan Africa: a scoping review

Agriculture in general, and livestock production in particular, serve as a livelihood source for many people in sub-Saharan Africa (SSA). In many settings, lack of control of infectious diseases hampers livestock productivity, undermining the livelihood of rural populations. This scoping review sought to identify veterinary interventions previously evaluated as well as their relative effectiveness in controlling infectious livestock diseases. To be included, papers had to be written in English, German or French, and had to describe the effectiveness and/or profitability of preventive veterinary intervention(s) against anthrax, blackleg, bovine tuberculosis, brucellosis, contagious bovine pleuropneumonia, contagious caprine pleuropneumonia, foot-and-mouth disease, goat pox, lumpy skin disease, pasteurellosis, peste des petits ruminants, and/or sheep pox in any SSA country. Of the 2748 publications initially screened, 84 met our inclusion criteria and were analyzed. Most of the studies (n = 73, 87%) evaluated the effectiveness and/or profitability of vaccination, applied exclusively, applied jointly with, or compared to strategies like deworming, antimicrobial treatment, surveillance, feed supplementation, culling and dipping in reducing morbidity and/or mortality to livestock diseases. The effectiveness and/or profitability of antimicrobial treatment (n = 5), test and slaughter (n = 5), and use of lay animal health workers (n = 1) applied exclusively, were evaluated in the other studies. Vaccination was largely found to be both effective and with positive return on investment. Ineffective vaccination was mainly due to loss of vaccine potency under unfavorable field conditions like adverse weather events, cold chain failure, and mismatch of circulating pathogen strain and the vaccines in use.

In summary, vaccination is the most effective and profitable means of controlling infectious livestock diseases in SSA. However, to achieve effective control of these diseases, its implementation must integrate pathogen surveillance, and optimal vaccine delivery tools, to overcome the reported field challenges.

Progress With Livestock Welfare in Extensive Production Systems: Lessons From Australia

The extensive livestock production industries are vital to the national economy of Australia. Continuing improvements to extensively-raised livestock welfare is desirable, necessary and in some situations mandatory, if the social license for animal sourced food and fiber production is to continue sustainably. However, meeting increasingly high welfare standards is challenging. The changing climate in this millennium, has seen the occurrence of two of the most severe drought periods on record in Australia, resulting in complex welfare issues arising from unforeseen disease, trade and environmental catastrophes. The onset of the first drought coincided with an uncontrolled epidemic of ovine paratuberculosis. It ended just prior to a temporary ban on live export of tropical cattle to Indonesia that induced a major market failure and led to severe morbidity and mortality on some beef properties. The second drought period progressed in severity and culminated in the most extreme bushfires recorded, causing unprecedented levels of mortality, morbidity and suffering in farmed animals and wildlife. Temperature extremes have also caused periodic heat-associated or cold-induced hyopthermia losses, requiring increased vigilance and careful management to reduce both temperature-induced stress during transport and the high ovine peri-parturient losses traditionally observed in extensive sheep farming. Several issues remain controversial, including surgical mulesing of wool sheep to manage flystrike, and the continuing live export trade of sheep and cattle. However, in reviewing the increasingly complex welfare challenges for the extensive livestock population industries that are export trade dependent and remain vulnerable to welfare activism, it appears progress has been made. These include development of prescribed livestock welfare Standards and Guidelines and the introduction of the Exporter Supply Chain Assurance System (ESCAS) to address export concerns. Further, the sheep mulesing crisis led to improved producer welfare attitudes and practices, including pain management during aversive husbandry procedures that is now occurring globally. Finally, innovations in animal welfare surveillance and assessment, are additional encouraging signs that suggest improving change management of extensive farm animal welfare is occurring that provides lessons well-beyond Australian shores.

Efficacy and application of a novel topical anaesthetic wound formulation for treating cattle with Foot-and-Mouth disease: A field trial in Cameroon

Recently, a wound dressing formulation, (Tri-Solfen®, Medical Ethics Pty Ltd, Australia; TS) registered for use in ruminant husbandry in Australia, was registered for Foot-and-Mouth Disease (FMD) therapy in large ruminants in Laos, following clinical observations of improved welfare and healing following treatment of FMD lesions. In November 2019, an FMD outbreak in Cameroon provided an opportunity for a field trial, comparing clinical responses and recoveries to treatments on a sample of cattle (n = 36) comprising three equal groups of animals (n = 12), comparing responses to three treatments: (i) the application to lesions of TS, (ii) the administration of parenteral oxytetraycline commonly used for FMD in Cameroon; and (iii) an untreated control group (C). Appetite scores, lesion healing scores, and changes in dimensions of lesions, were recorded over a 15-day study period. Cattle treated with TS achieved both superior appetite and lesion healing scores with more rapid reduction in dimensions of lesions than other groups. Farmer observations indicated the TS treatment group had a more rapid return to eating with cessation of excessive salivation, and more rapid return of mobility (walking) with absence of overt lameness. The findings indicate that although mortality is usually low in FMD outbreaks, the disease is a debilitating and painful disorder with negative animal welfare impacts that should be addressed. All farmers expressed their desire that the product be made available for use in their region and modelling indicates that TS therapy imposes no additional financial burden on farmers, with the treatment likely to be provided at a similar or reduced cost to current treatment choices. As use of antibiotics for treatment of a viral disease potentially increases pressures for development of antimicrobial resistance and residues in the food chain, TS as an alternative non-antimicrobial therapy should be promoted for wider use in FMD outbreaks.

Effect of a Topical Formulation on Infective Viral Load in Lambs Naturally Infected with Orf Virus

Introduction

Orf is a highly contagious eruptive viral disease of the skin and mucosa of sheep and goats. Although vaccination with live or attenuated orf virus is the preferred option for disease control, the vaccine is unavailable in many countries. Treatment of orf lesions involves standard hygiene and in numerous cases, management of presumptive secondary infections with antibiotics, increasing risks of antimicrobial resistance (AMR). The wound dressing formulation Tri-Solfen^® containing two local anaesthetics (lignocaine and bupivacaine), adrenaline and an antiseptic (cetrimide) in a gel formulation was developed for pain relief in sheep undergoing surgical husbandry procedures in Australia. Recently, TS therapy was found to reduce suffering and enhance recovery in cattle and buffalo with oral and skin lesions due to foot-and-mouth disease (FMD) virus infection. It was noted that TS has a low pH and is potentially viricidal, potentially aiding disease control.

Methods

One-month-old lambs (n=14), naturally infected with orf, were recruited from a farm during a natural outbreak of the disease. The animals were selected at the early stages of the infection and randomly divided into two cohorts: Group A (n=11) treated with the topical wound gel formulation (TS); and Group B (n=3) an untreated control group. Swabs were obtained before treatment (T0) and on days one (T1), 3 (T2) and 5 (T3) post-treatment, then submitted to direct DNA extraction with real-time PCR quantification, plus incubation with primary tissue cultures from ovine skin fibroblasts (OSF) and T-immortalized goat embryonic fibroblasts (TIGEF).

Results

Although no significant differences were found in the clinical progression of the lesions and PCR quantification (p=0.722) between these small cohorts, there was a significant difference (p<0.05) in reduction in infective viral load between the groups when assessed in OSF cell cultures between T0 and T3.

Conclusion

These preliminary findings suggest that treatment of early stage lesions with this TS may reduce the infective viral load present in orf lesions.