First reported case in an Irish flock of MCF- like systemic necrotizing vasculitis in sheep associated with ovine herpesvirus 2.

BACKGROUND: Ovine gammaherpesvirus 2 (OvHV-2) is the causative agent of sheep associated malignant catarrhal fever (MCF). As sheep are the adapted host for OvHV-2, it is generally presumed that infection is not associated with disease in this species. However, a recent case review combined in-situ hybridisation, PCR and histopathology and correlated the viral distribution with systemic necrotizing vasculitis and concluded OvHV-2 was the likely agent responsible for sporadic, MCF-like vascular disease in sheep. CASE PRESENTATION: Using similar methods this case study reports on the findings of the first reported cases in an Irish Flock of MCF- like systemic necrotizing vasculitis in sheep associated with OvHV-2. Sheep A, a 16-month-old Texel-cross hogget displayed signs of ill- thrift, Sheep B, a nine-month-old Belclare-cross lamb, was found dead having displayed no obvious symptoms. Both cases occurred on the same farm, however the animals were not related. Lymphohistiocytic vasculitis of various tissues was the predominant histopathological finding in both animals. CONCLUSION: By combining histopathology, PCR and in-situ hybridisation results, MCF- like systemic necrotizing vasculitis associated with OvHV-2 has been diagnosed for the first time in an Irish flock.

Irish farmers' interactions with regional veterinary laboratories- reasons, results, reactions: a survey.

BACKGROUND: Animal health surveillance is important in ensuring optimal animal health and welfare. Monitoring of diagnostic submissions, including post-mortem examination of carcasses, at the Department of Agriculture Food and the Marine laboratories, provides the basis for this type of passive surveillance in Ireland. The process requires engagement from veterinarians and farmers from all sectors of the agricultural spectrum. This study aims to identify the reasons why farmers engaged in dairy, beef, sheep, and mixed farming enterprises submit carcasses or not to the Regional Veterinary Laboratories. RESULTS: Surveys were distributed in hard copy format at Regional Veterinary Laboratories, and fifty Teagasc facilitated farmer discussion groups. There were 1179 responses collected in 54 locations. The top reasons participants submitted to the laboratories were 1) to guide treatment/ vaccination, 2) fear of a contagious disease, and 3) if their veterinarian advised them to. The top reasons for not submitting were 1) the vet making a diagnosis on the farm, 2) the distance from the laboratory, and 3) lack of time and labour. Implementation of vaccination protocols was the main change implemented based on results, followed by management changes and the use of different treatments, e.g., switching from antibiotic to parasite treatment. Sheep enterprises were more likely than dairy to choose distance and cost as a reason not to submit. Dairying enterprises were more likely than other enterprise types to submit if they feared a contagious or zoonotic disease. CONCLUSION: Positively, this survey shows the desire of participants to submit to the laboratories to guide treatment and vaccination protocols, potentially indicating that positive engagement between stakeholders and the RVLs will help promote optimal animal health and promote responsible antimicrobial use. Results also show the critical role of veterinarians in continued disease surveillance on farms. Maintaining engagement with all farming sectors will be essential in promoting successful animal health surveillance.

Suspected cyanide toxicity in cattle associated with ingestion of laurel - a case report.

BACKGROUND: Cyanide is one of the most rapidly acting toxins affecting cattle, with poisoning typically occurring following ingestion of cyanogenic plants. Laurel (Prunus laurocerasus), is one such potentially toxic cyanogenic plant. This case report details fatalities in an Irish herd following the ingestion of laurel and aims to raise awareness of the potential risk that access to laurel hedges poses to farm animals. CASE PRESENTATION: Over a twelve-day period, the death occurred of 36 dairy-cross weanlings; the majority (22 weanlings) died over a two-day period. Two days following entry to a field bounded by a laurel hedge, the weanlings displayed signs of lethargy and profuse green diarrhoea. In the majority of animals there was a limited response to treatment with antimicrobials, vitamin B complex and fluid therapy. Recumbency and death ensued. Cyanosis was noted terminally. Two weanlings were submitted for post mortem examination. Laurel leaves were identified in the rumen contents of one weanling. Post mortem findings and additional test results on cohort animals suggested a number of pathological processes may have been involved in the animals, possibly complicating/exacerbating the effects of laurel ingestion. However, cyanide was considered a factor in a least some of the casualties and arrangements were made to test for cyanide on blood samples from a random selection of seven cohort animals. Although collected one week after exposure to the laurel hedge, toxic cyanide levels were recorded in a sample from one animal, which subsequently died. CONCLUSIONS: The large fatality rate serves as a timely reminder to include plant poisoning as a differential diagnosis when dealing with large numbers of rapid fatalities. Failure to thoroughly examine rumen contents and collect a detailed history in this case, could easily have allowed death to be attributed to other causes and the involvement of cyanide toxicity to be missed. In cases of individual or group fatalities, history is invaluable and recent entry to new grazing areas or any potential diet change or access to garden plants should be thoroughly investigated.

Flock health survey of Irish Texel society breeders and larynx examination in Texel sheep.

BACKGROUND: Laryngeal chondritis is a disease of undetermined aetiology, characterised by oedema, ulceration, abscessation and necrosis of the laryngeal mucosa and cartilage. The initial aim of the study was to document flock health issues identified by Irish pedigree Texel breeders using a questionnaire survey. Additionally, given the reports of breed predisposition for laryngeal chondritis in Texels, a further aim was to identify if laryngeal problems were perceived as an issue. Work was then conducted to identify if pre-clinical laryngeal mucosal pathology was identifiable in Texel sheep showing no overt clinical signs of respiratory disease and if associations existed between laryngeal measurements and laryngeal pathology.Thirty one larynges were collected from a Texel flock that previously had laryngeal chondritis diagnosed in fallen stock. Gross visual inspection was performed to identify and grade (0-5) laryngeal pathology. A series of measurements were then performed on larynges that had been formalin fixed. Associations between independent variables (larynx measurements) and the dependent variable (laryngeal pathology score) were examined. RESULTS: Respiratory disease was the most frequently identified health issue. Farmer-diagnosed 'throat problems' were reported by over 80% of respondents.Laryngeal pathology was noted in Texels showing no overt clinical signs of respiratory disease. Associations between laryngeal measurements and laryngeal pathology were identified relating to the angle between the cranial point of the cricoid cartilage and the vocal process of the arytenoid cartilage. CONCLUSIONS: Mild laryngeal pathology was noted in animals with no overt clinical signs of respiratory disease. Future research should examine whether significant associations between laryngeal measurements and laryngeal pathology identified in the current study can be measured ante mortem, and whether such ante mortem measurements will allow early identification of sheep at risk of developing laryngeal chondritis.

Descriptive analysis of ovine mortality in sentinel sheep flocks in Ireland.

BACKGROUND: Studies of sheep mortality or cause-specific mortality, in Ireland or internationally, are relatively scarce but are important in presenting baseline levels and changing trends of endemic disease. This study assessed sheep mortality and cause-specific mortality in 33 sentinel sheep flocks in Ireland. METHODS: Sentinel flocks were requested to submit carcases of all sheep that died to the regional veterinary laboratories (RVLs) of the Department of Agriculture, Food and Marine during a calendar year (2016). Postmortem examinations were performed on 1247 submissions to Athlone, Kilkenny and Sligo RVLs. RESULTS: The median overall submission rate was 13.8 per cent (range 2.5 per cent-35.8 per cent) per adult female sheep in the flock in January 2016. The median fetal, perinatal, lamb and adult submissions per adult female sheep in the flock in January 2016 were 2.1 per cent (0.0 per cent-15.2 per cent), 3.5 per cent (0.0 per cent-20.0 per cent), 3.0 per cent (0.0 per cent-12.4 per cent) and 2.8 per cent (0.8 per cent-7.1 per cent), respectively. The frequency of detection of categories of postmortem diagnoses in fetuses, perinates, lambs and adults are presented. CONCLUSIONS: Comparisons with existing passive surveillance findings reflect some differences in the relative frequency of detection of certain categories of disease suggesting that sentinel flock surveillance could usefully supplement existing passive animal disease surveillance activities for ovine disease.

Ivermectin treatment failure on four Irish dairy farms.

We report on the use of the faecal egg count reduction test to evaluate the performance of ivermectin in treating gastrointestinal nematode infections in first grazing season (FGS) calves on four dairy farms in Co. Kilkenny, Ireland. On each farm, FGS calves were injected subcutaneously with ivermectin in accordance with their live weight (day 0). Calves were individually faecal sampled on both day 0 and day 14. Faecal egg counts were determined using the Mini-FLOTAC technique. Composite faecal cultures for each farm were performed on each sampling occasion. The faecal egg count reductions (mode) ranged from 17.3-80.2% with the lower 95% confidence limit ranging from 3.1-72.3% on the four farms, respectively. Ivermectin-resistant nematodes were detected on all farms, with evidence of Ostertagia resistance on one farm. This study highlights the urgent need for Irish producers to reappraise their parasite control practices.

A nationwide survey of anthelmintic treatment failure on sheep farms in Ireland.

BACKGROUND: Between 2013 and 2015 the Department of Agriculture, Food and the Marine (DAFM) administered a sheep technology adoption programme (STAP), with the aim of increasing profitability on Irish sheep farms by encouraging the adoption of best management practices. One of the options available to STAP participants was to test the efficacy of the anthelmintic treatment (benzimadazole, levamisole or macrocyclic lactone) used in their flocks by means of a drench test, which is a modification of the faecal egg count reduction test; individual faecal samples were collected from the same group of lambs before and after anthelmintic treatment, the number of eggs present pre and post treatment was subsequently determined from a pooled sample. RESULTS: In total, 4211 drench tests were undertaken by farmers during the 3 years of the programme. Information on the anthelmintic product used was available for 3771 of these tests; anthelmintics from the classes benzimidazole (BZ), levamisole (LV) and macrocyclic lactone (ML) (avermectins (AVM) plus moxidectin (MOX)) were used in 42.0%, 23.4% and 32.5% of tests, respectively. The remaining 2.1% of tests involved an inappropriate product. The efficacy of treatment against 'other trichostrongyles' (excluding Nematodirus spp and Strongyloides papillosus.) could be established for 1446 tests, and 51% of these tests were considered effective (i.e. a reduction of faecal egg count (FEC) ≥ 95%). There was a significant difference among the drug groups in efficacy; 31.5%, 51.9%, 62.5% and 84% of treatments were considered effective for BZ, LV, AVM, MOX, respectively. The efficacy of treatment against Nematodirus spp. could be established for 338 tests and the overall efficacy was 96%. CONCLUSIONS: Due to the significant difference among the anthelmintic classes for efficacy against 'other trichostrongyles' along with the high level of efficacy against Nematodirus spp., a genus for which anthelmintic resistance is rarely reported, it is concluded that anthelmintic resistance was responsible for the majority of the anthelmintic treatment failures observed.

Bovine and ovine rumen fluke in Ireland-Prevalence, risk factors and species identity based on passive veterinary surveillance and abattoir findings.

The prevalence of rumen fluke, the incidence of clinical paramphistomosis and the trematode's species identity were studied in cattle and sheep in the Republic of Ireland using passive veterinary surveillance (faecal examination and necropsy results; 2010-2013) and abattoir data. Based on faecal examination, the prevalence of rumen fluke was higher in cattle than in sheep. Rumen fluke prevalence in cattle and sheep fluctuated over the year and in most years (2011-2013), prevalence was higher in winter (December-February) than in summer (June-August). For 3 of 4 years studied, there was no correlation between monthly prevalence of rumen fluke and prevalence of liver fluke as estimated by faecal examination. At sample level, joint occurrence of rumen fluke and liver fluke was 1.1-2.0 times more common than would be expected under the assumption of independence. Based on necropsy data, a spike in deaths attributed to paramphistomosis was observed in 2012, when rainfall was unusually high. This spike in mortality was not accompanied by a spike in faecal prevalence, emphasizing that the incidence of disease, which is due to high burdens of juvenile rumen fluke in the gut, is not correlated with prevalence of infection, which is measured by faecal examination and reflects presence of adult fluke in the rumen. At slaughter, 52% of 518 cattle from 101 herds were positive for rumen fluke, compared to 14% of 158 sheep. Prevalence in cattle was higher than reported in most studies from mainland Europe and varied by animal category, age, sex, abattoir visit and location (county) of farm from which the animal was submitted for slaughter, but in multivariate analysis, only sampling month and county were significantly associated with detection of rumen fluke. The identity of rumen fluke in cattle and sheep was confirmed as Calicophoron daubneyi. Although C. daubneyi is thought to share an intermediate host snail with Fasciola hepatica, the differences in prevalence between host species and over time suggest that the epidemiology of C. daubneyi is distinct from that of F. hepatica. Further studies of the C. daubneyi life-cycle in ruminant hosts, intermediate snail hosts and the environment will be needed to gain a better understanding of modes of transmission and options for control of rumen fluke infection and disease.

High level of treatment failure with commonly used anthelmintics on Irish sheep farms.

BACKGROUND: In 2013 a Technology Adoption Program for sheep farmers was established to encourage the implementation of best management practices on sheep farms in Ireland. There were 4,500 participants in this programme in 2013. As part of this programme, farmers had the option to carry out a drench test to establish the efficacy of their anthelmintic treatment. RESULTS: Flock faecal samples were collected before and after treatment administration and gastrointestinal nematode eggs enumerated. In total there were 1,893 participants in the task, however only 1,585 included both a pre- and post-treatment faecal sample. Of those, 1,308 provided information on the anthelmintic product that they used with 46%, 23% and 28% using a benzimidazole (BZ), levamisole (LEV) and macrocyclic lactone (ML) product respectively. The remaining farmers used a product inapplicable for inclusion in the task such as a flukicide or BZ/LEV combination product. Samples were included for analysis of drench efficacy if the pre-treatment flock egg count was ≥200 eggs per gram and the interval post-sampling was 10-14 days for BZ products, 4-7 days for LEV products and 14-18 days for ML products. These criteria reduced the number of valid tests to 369, 19.5% of all tests conducted. If the reduction post-treatment was ≥95% the treatment was considered effective. Only 51% of treatments were considered effective using this criterion. There was a significant difference in efficacy between the anthelmintic drug classes with BZ effective in only 30% of treatments, LEV effective in 52% of cases and ML effective in 76% of cases. CONCLUSIONS: Gastrointestinal nematode anthelmintic treatments, as practiced on Irish farms, have a high failure rate. There was a significant difference between the efficacies of the anthelmintic classes with BZ the least effective and ML the most effective.

An aetiopathological study of chronic bronchopneumonia in lambs in Ireland.

Chronic bronchopneumonia in lambs, also known as 'atypical' or 'chronic, non-progressive' pneumonia is a common, frequently sub-clinical disease affecting animals under 12-months-old in intensive production systems. Infection with both Mycoplasma ovipneumoniae and Mannheimia haemolytica have been implicated in the aetiology of this condition and a variety of pulmonary lesions can result. In this study, detailed laboratory examination of 30 abattoir-derived lungs with the characteristic gross features of atypical pneumonia (AP) was carried out with a view to refining and correlating the histopathological and microbiological criteria required for the diagnosis of this disease. For the first time a broad range of laboratory detection techniques including bacterial and virus isolation, fluorescent antibody tests and immunohistochemistry were used in parallel to identify potential causative pathogens such as M. ovipneumoniae, M. haemolytica, parainfluenza type-3 (PI3) virus and respiratory syncytial virus (RSV) in AP lesions. The most consistent finding was the association of gross AP lesions with M. ovipneumoniae, identified by either culture or immunohistochemistry in 27 (90%) of the 30 cases. However the presence M. ovipneumoniae organisms or antigen did not consistently correlate with particular histopathological changes. Furthermore, peri-airway lymphoid hyperplasia, intra-alveolar exudation and nodular 'hyaline scars', which are all previously reported microscopic lesions of AP, were not identified in 12 (40%) of the cases and isolation of M. haemolytica was over-represented in lungs exhibiting suppurative lesions. These findings illustrate the complex aetiopathogenesis of this disease and highlight the requirement to use a combination of diagnostic criteria in its laboratory diagnosis.