Physiological and behavioural effects of intradermal injection of sodium lauryl sulfate as an alternative to mulesing in lambs

Traumatic sheep myiasis: A review of the current understanding

Myiasis, or the infestation of live humans and vertebrate animals by dipterous larvae, is a health issue worldwide. The economic impact and potential threat to animal health and wellbeing of this disease under the animal husbandry sector is considerable. Sheep are a highly vulnerable livestock category exposed to myiasis (sheep strike), due to several unique predisposing factors that attract flies. The successful mitigation of this disease relies on a thorough understanding of fly population dynamics associated with the change in weather patterns and the evaluation of this disease through different branches of science such as chemistry, molecular biology, and microbiology. The present review provides a summary of the existing knowledge of strike in sheep, discussed in relation to the application of volatile organic compounds, metagenomics, and molecular biology, and their use regarding implementing fly control strategies such as traps, and to increase the resilience of sheep to this disease through improving their health and wellbeing.

Analgesia for Sheep in Commercial Production: Where to Next?

Simple Summary

Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on industry to alleviate pain associated with husbandry practices, injury and illness. Although a number of analgesic solutions are now available for sheep, providing some amelioration of the acute pain responses, this review has highlighted a number of potential areas for further research.

Abstract

Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on livestock production industries to alleviate pain associated with husbandry practices, injury and illness. Over the past 15–20 years, there has been considerable research effort to understand and develop mitigation strategies for painful husbandry procedures in sheep, leading to the successful launch of analgesic approaches specific to sheep in a number of countries. However, even with multi-modal approaches to analgesia, using both local anaesthetic and non-steroidal anti-inflammatory drugs (NSAID), pain is not obliterated, and the challenge of pain mitigation and phasing out of painful husbandry practices remains. It is timely to review and reflect on progress to date in order to strategically focus on the most important challenges, and the avenues which offer the greatest potential to be incorporated into industry practice in a process of continuous improvement. A structured, systematic literature search was carried out, incorporating peer-reviewed scientific literature in the period 2000–2019. An enormous volume of research is underway, testament to the fact that we have not solved the pain and analgesia challenge for any species, including our own. This review has highlighted a number of potential areas for further research.

Efficacy of precisely injected single local bolus of lignocaine for alleviation of behavioural responses to pain during tail docking and castration of lambs with rubber rings

Delivery of local anaesthetic at the time of castration and tail docking (marking) could improve welfare outcomes in lambs. This study examined pain responses in lambs marked using rubber rings, with or without local anaesthetic precision injected using the Numnuts® instrument. On each of two commercial farms, 150 prime lambs aged 4 to 10 weeks, balanced for sex, were randomly allocated to 3 treatments: handled in a lambing cradle (Sham), handled and marked with rubber rings (Ring) or handled and marked with rubber rings and treated with 30 mg lignocaine using the Numnuts® instrument (NNLA). Time to mother up (one trial site only), acute pain related behaviours at 5, 20, 35 and 50 min, and postures at 10 min intervals from 60 to 180 min were recorded. NNLA lambs tended to mother up more quickly than Ring lambs (P = 0.09), and more slowly (P = 0.07) than Sham lambs. Acute pain behaviours were significantly more frequent in Ring and NNLA than Sham (P < 0.001) from 5 to 50 min. NNLA was significantly lower than Ring at 5 min (P < 0.001) and 20 min (P = 0.001). Ring and NNLA did not differ at 35 or 50 min. Abnormal postures were higher in Ring and NNLA than Sham at 60, 70, 80, 90 and 150 min (P < 0.048). Ring and NNLA did not differ at any time point between 60 and 180 min. Delivery of lignocaine with the Numnuts® instrument improved welfare outcome of lambs during the acute pain response caused by castration and tail docking with rubber rings.

Acute phase biomarkers of diseases in small ruminants: an overview

Acute phase proteins (APPs) are a large group of proteins synthesised mainly by the liver. Their production is stimulated in response to disturbances in the systemic homeostasis. It is known that each species has a specific set of APPs. Serum amyloid A and haptoglobin are the main APPs in small ruminants and their plasma concentration is changed most significantly in comparison with minor APPs such as ceruloplasmin. In general, APPs could provide valuable information on the general condition of the organism but cannot point at the exact disease. Therefore, APPs should be included as an additional indicator in clinical diagnosis. Knowledge of APPs behaviour in disease states has a remarkable potential for detecting animals with subclinical infections, determining the prognosis of clinical infection, differentiation between viral and bacterial disease, treatment monitoring, vaccine effectiveness and stress conditions. The aim of this review is to present data on APPs behaviour during some parasitic and infectious diseases as well as pathological conditions leading to aseptic inflammation and stress in sheep and goats.

A pen study evaluation of buccal meloxicam and topical anaesthetic at improving welfare of lambs undergoing surgical mulesing and hot knife tail docking

Mulesing is a painful husbandry procedure commonly used to reduce the risk of breech strike in sheep. This study assessed the behavioural (over 6 h), cortisol, haptoglobin and haematology responses to surgical mulesing plus tail hot knife docking (mulesing); modulated by a buccal meloxicam formulation (Buccalgesic), a topical local anaesthetic wound dressing (Tri-Solfen) or both agents. 24 lambs were allocated to each of: 1) Placebo and sham handled (Sham); 2) Placebo and mulesing (Mules); 3) Buccalgesic and mulesing (Mules + B); 4) Tri-Solfen and mulesing (Mules + T); 5) Placebo, Tri-Solfen and mulesing (Mules + T + P); 6) Buccalgesic, Tri-Solfen and mulesing (Mules + T + B). Compared with Mules, Mules + T had a lower cortisol response (72.5 ± 8.7 nmol/L v 122.9 ± 8.7 nmol/L) at 30 min, reduced statue standing at 2 h (3.9% v 11.4%) and increased lying (20.9-25.0% v 7.3-12.5%). Mules + B had reduced cortisol response at 6 h (48.1 ± 8.5 nmol/L), reduced Neutrophil:Lymphocyte ratio at 6 h (Mules + B: 1.25; Mules: 2.44), reduced statue standing at 2 h and 4-6 h (4.1-8.3%), and increased lying at 5 h (27.4%). Mules + B + T had lower cortisol concentrations at 30 mins (86.51 ± 8.71 nmol/L), TWCC not significantly different from Sham at 6 h (9.07 vs 8.09) and 24 h (9.05 vs 8.38). Mules + T + B had significantly lower TWCC than Mules at 12 h (9.56 vs 11.05) and 24 h (9.05 vs 10.42). Mules + T + B did not.

Evaluation of Animal-Based Indicators to Be Used in a Welfare Assessment Protocol for Sheep

Sheep are managed under a variety of different environments (continually outdoors, partially outdoors with seasonal or diurnal variation, continuously indoors) and for different purposes, which makes assessing welfare challenging. This diversity means that resource-based indicators are not particularly useful and, thus, a welfare assessment scheme for sheep, focusing on animal-based indicators, was developed. We focus specifically on ewes, as the most numerous group of sheep present on farm, although many of the indicators may also have relevance to adult male sheep. Using the Welfare Quality^® framework of four Principles and 12 Criteria, we considered the validity, reliability, and feasibility of 46 putative animal-based indicators derived from the literature for these criteria. Where animal-based indicators were potentially unreliably or were not considered feasible, we also considered the resource-based indicators of access to water, stocking density, and floor slipperiness. With the exception of the criteria “Absence of prolonged thirst,” we suggest at least one animal-based indicator for each welfare criterion. As a minimum, face validity was available for all indicators; however, for many, we found evidence of convergent validity and discriminant validity (e.g., lameness as measured by gait score, body condition score). The reliability of most of the physical and health measures has been tested in the field and found to be appropriate for use in welfare assessment. However, for the majority of the proposed behavioral indicators (lying synchrony, social withdrawal, postures associated with pain, vocalizations, stereotypy, vigilance, response to surprise, and human approach test), this still needs to be tested. In conclusion, the comprehensive assessment of sheep welfare through largely animal-based measures is supported by the literature through the use of indicators focusing on specific aspects of sheep biology. Further work is required for some indicators to ensure that measures are reliable when used in commercial settings.

Electro-analgesia for sheep husbandry practices: a review

Several sheep-husbandry practices such as mulesing, castration, ear-tagging and tail-docking are currently performed with no, or little, anaesthesia or analgesia. The potential for using electrotherapies to provide analgesia during and after these operations is examined in this review. The most common electrotherapy is transcutaneous electrical nerve stimulation (TENS). TENS is the application of an electrical current from electrodes placed on the skin. Analysis of a large number of trials in humans and in animal models indicates that TENS provides effective relief from acute and chronic pain, including pain associated with surgery. There is strong evidence now that TENS analgesia operates at the levels of the periphery, the spinal cord and in the brain. The mechanisms involve the autonomic nervous system, the opioid pathways and neurotransmitters involved in descending inhibitory pathways from the brain. Centrally operating pathways mean the current does not have to be applied near the injured site and there is evidence of sustained pain relief lasting hours, days or even weeks post-treatment, particularly after very high-frequency, randomly variable current applications. Treatment of sheep during painful operations with such a current has the potential to provide immediate and possibly sustained pain relief. Combining such a treatment with electro-immobilisation of the animal would be advantageous for sheep-husbandry operations, but there is considerable evidence that high-intensity currents producing tetanic contractions are aversive and probably painful for sheep. Investigations of the application and efficacy of electrotherapies for painful sheep operations should be undertaken.

Prevalence of breech-strike in mulesed, clipped and unmulesed Merino hoggets in south-eastern Australia

OBJECTIVE

To compare the prevalence of breech flystrike ('breech-strike') on 12-20-month-old Merino hoggets that were mulesed, had breech and tail clips applied ('clipped') or were left unmulesed but treated strategically with long-acting insecticide.

DESIGN

A cohort study on three farms in southern Victoria.

METHODS

Three treatment groups were established at lamb marking on each farm. The unmulesed group was treated with dicyclanil when 12 months old in September or October ('early-season treatment'). The prevalence of breech-strike and key risk factors, including soiling of the breech with faeces ('dag') and urine ('stain'), and breech wrinkle, were compared between the groups.

RESULTS

Over all the farms, breech-strike occurred on 1.1% of mulesed sheep and 7.7% of clipped sheep. Clipped sheep had a relative risk of breech-strike of 18.2-, 16.8- and 3.0-fold that of mulesed sheep on the three farms. Unmulesed sheep treated with dicyclanil had a similar prevalence of breech-strike to that of mulesed sheep (overall 0.9%, range 0-2.5%), but had significantly more dag, stain and wrinkle.

CONCLUSION

Early-season treatment of unmulesed sheep prevented most breech-strikes during the spring and early summer, and offers a short- to medium-term option for the control of breech-strike in south-eastern Australia. There were some benefits associated with using clips, namely less dag and stain, and a shorter time spent crutching. However, to control breech-strike the clipped sheep should be treated the same as unmulesed sheep. Reducing the prevalence and severity of dag will be a major component of strategies to control breech-strike of Merinos in this region.