Abstract
AIM: To examine the on-farm biosecurity practices of a group of commercial Thoroughbred stud farms in the North Island of New Zealand, in the absence of an exotic disease outbreak.
METHODS: A cross-sectional survey of biosecurity practices was conducted during the 2006/2007 Thoroughbred breeding season, and consisted of data from commercial Thoroughbred farms in the North Island of New Zealand standing a stallion. Data were collected on-farm by a single interviewer, using 17 open, closed and multiple-choice questions examining general farm/operation size and features, general animal health and biosecurity practices, biosecurity practices in relation to breeding stock, and opinions about the application of on-farm quarantine measures. Data were examined for differences in biosecurity practice between farms with and without shuttle stallions, and differing in size.
RESULTS: Data were collected from 28/34 selected farms during the 2006/2007 breeding season. Thirteen farms were classified as small, 10 medium, and five large; shuttle stallions were present on 12 farms. Commercial transporters were responsible for the delivery of 79% (3,116/3,945) of the mares. On arrival non-resident mares were rarely isolated though they were screened for cough (25/28; 89%) or nasal discharge (28/28; 100%); constraints on implementing arrival quarantine protocols for such mares were time (5/28; 18%), space (11/28; 39%), and staff workload (4/28; 14%).
In the absence of disease, few farms (3/28; 11%) implemented protocols between cohorts of horses. However, focal points of high interaction between horses, such as foaling paddocks, isolation yards and crushes, were regularly cleaned and/or disinfected. In the presence of disease, the vast majority of farms (92–100%) implemented control measures such as changing clothes and washing hands between cohorts.
Stallions were rarely quarantined on arrival. If the stallion was imported many considered pre-importation quarantine to be sufficient. Farms with shuttle stallions were more likely to have an arrival protocol in place than those that did not (92% vs 50%; p<0.05).
CONCLUSIONS AND CLINICAL RELEVANCE: Most stud managers were aware of the need for on-farm biosecurity; management constraints meant that protocols might not always be followed. The absence of an exotic disease outbreak and the overwhelming confidence of stud managers in the Ministry of Agriculture and Forestry (MAF) in preventing an exotic disease incursion were reasons for a lack of implementation of on-farm biosecurity protocols.
| MAF | = |
Ministry of Agriculture and Forestry |
Introduction
Thoroughbred breeding is a major economic enterprise in New Zealand, with approximately 40% of the annual foal crop being exported either as yearlings or as young racehorses. In order to meet the demands of the export market, there is a constant importation of breeding stock into New Zealand. During the 2006/2007 breeding season 25 shuttle stallions, i.e. stallions covering mares in breeding seasons in a given year in both the Northern and Southern Hemispheres, were imported for stud duties. The majority originated from England and Ireland (n=15), four from the United States of America, three from Japan, and three from continental Europe; all from countries endemic for equine influenza (Anonymous 2008). The increasing globalisation of the breeding industry provides breeders in New Zealand with the opportunity to access internationally recognised bloodstock.
The movement of mares and stallions across international borders poses a considerable biosecurity risk, as was demonstrated by the recent outbreak of equine influenza in Australia. Presently, New Zealand is one of only three countries recognised to be free of equine influenza, with Australia officially declared free of the disease on 25 December 2008 (Cowled et al. Citation2009). The introduction of equine influenza into a naïve population would have major effects on the entire equine industry. The potential economic and social cost of an outbreak of equine influenza highlights the need to understand the on-farm animal health practice and biosecurity measures used in this industry.
The Thoroughbred breeding industry is the largest of the equine breeding industries in New Zealand. Furthermore, the requirement for natural service by Thoroughbred registries means that during the breeding season there are significant movements of mares between farms, to foal and be served, as well as ‘walk-in’ mares transported to the farm to be served and sent home on the same day. This movement of mares during the season could potentially facilitate the spread of an exotic disease between premises should such a disease incursion occur. Movement of horses between farms also facilitates the spread of endemic infectious diseases, such as strangles (Streptococcus equi subsp. equi). In order to design control programmes in the face of an exotic disease incursion, or for the control of endemic diseases, it is important to understand the biosecurity practices currently in place.
Despite the economic importance of the Thoroughbred breeding industry, data quantifying the production process are relatively limited (Morel et al. Citation2007; Rogers et al. Citation2007, Citation2009; Stowers et al. Citation2009), and to date nothing has been published examining on-farm animal health and biosecurity practices. The aim of this study was to examine the biosecurity practices on commercial Thoroughbred breeding farms in the North Island of New Zealand, in the absence of an exotic disease incursion.
Materials and methods
Sample
Farms were selected from the list of farms-by-region published in the 2006 Register of Thoroughbred Stallions of New Zealand (Anonymous Citation2006). The target farms in the south Auckland, Waikato and Central Districts regions of the North Island represented 34/49 of all farms in New Zealand on the register. Contact details were obtained from the New Zealand Thoroughbred Stallion Register, and the stud managers were contacted via phone, to arrange a suitable time and date for an interview. If there was no response after three phone attempts, the studs were not included in the survey sample.
Design of the questionnaire, and collection of data
The questionnaire consisted of a combination of 17 open, closed and multiple-choice questions. The questions covered general farm/operation size and features, general animal health and biosecurity practices, biosecurity practices in relation to breeding stock, and opinions about the application of on-farm quarantine measures (see Supplementary Table 1). The questionnaire was administered in a face-to-face format by one interviewer that was familiar with the equine industry, during November 2006. During the interview, the stud manager's responses were recorded on a pro-forma recording sheet created specifically for the questionnaire. If requested, the survey was sent to the stud manager prior to collection of data. Data were entered into MS Excel 2003 (Microsoft Corporation, Redmond WA, USA).
Classification of breeding farms
Breeding farms were divided into three categories depending on the total number of mares on the farm during the 2006/2007 breeding season (01 September–31 December). The categories were small (≤90 mares), medium (91–199 mares), and large (≥200 mares) farms.
Statistical analysis
The data were stratified by either size of the farm, or according to the presence or absence of a shuttle stallion. A Fisher's exact test was used to determine if the variables of interest differed between the categories of farm size, or due to the presence or absence of a shuttle stallion. All data were analysed using SAS v9.1 (SAS Institute Inc, Cary NC, USA), with significance set at p<0.05. Data are presented as counts and percentages.
Results
Features of the breeding farm
Completed questionnaires were obtained from 28 farms, of which 13 were classified small, 10 medium, and five large. A shuttle stallion was present on 12 farms, and absent on 16 farms.
The majority of stallions on a farm were owned (48/85; 57%) rather than leased (12/85; 14%), or were shuttle stallions (25/85; 29%). No large farms leased stallions, whilst 5/23 (22%) and 7/34 (21%) stallions on small and medium farms were leased, respectively.
The farms sampled managed 3,945 broodmares, approximately 60% of the 6,623 Thoroughbred broodmares bred by a stallion standing in New Zealand during the 2006/2007 breeding season. On large and medium farms 41% (812/1,980) and 48% (614/1,280) of mares were walk-in mares compared with 37% (253/685) of mares on small farms. A foaling service to non-resident mares was provided for 2% (39/1,980), 15% (192/1,280), and 12% (82/685) of mares on large, medium, and small farms, respectively. The vast majority of non-resident mares that were brought on-farm were transported by commercial horse floats (3,116/3,945; 79%) rather than transport provided by the farm (158/3,945; 4%) or the owner of the mare (670/3,945; 17%). Small farms were more likely to transport mares using their own transport (62/685; 9%) than were medium farms, which did not use their own transport, or large farms (p=0.001), of which only one provided their own transport. However, the large farm only transported 2.5% of non-resident mares visiting that farm
General precautions against disease spread
General precautions used to prevent the spread of disease in the absence and presence of illness are show in Table . In the absence of disease, few stud managers reported washing their hands, cleaning footwear, or changing clothes. However, in the presence of disease, on most farms it was noted that people washed hands or changed footwear and clothes. Washing of hands predominantly referred to rinsing hands under running water, although one stud manager used soap and actually washed their hands. In the absence of disease, the mucking-out of foaling paddocks (19/28; 68%), and cleaning (27/28; 96%) and disinfecting of crushes (26/28; 93%) was common.
Table 1. Number and percentage of Thoroughbred stud farms in New Zealand where precautions were taken to prevent the spread of disease in the absence or presence of disease, by size of the breeding farm. Farm categories were small (≤90), medium (91–199), and large (≥200) numbers of mares on-farm during the 2006/2007 breeding season.
Forty-three percent of farms had no entry protocol when a veterinarian entered the premises. Fewer small farms had entry protocols (6/13; 46%) than medium (6/10; 60%) and large (4/5; 80%) farms. However, there were no significant differences between the categories of farm size. Of those farms that had entry protocols the protocols ranged from changing clothing to cleaning or changing shoes (Table ). Some farms required the veterinarian to change their clothes and clean or change their shoes. One large farm required veterinarians to wash hands, clean shoes and equipment, change clothes, and use the stud's equipment.
Precautions relating to breeding stock
Breeding farms with shuttle stallions were more likely than farms without shuttle stallions to have some precautions in place when a stallion arrived on the premises (Table ). On most farms stallions were not routinely isolated on arrival (19/28; 68%), however 25% of managers reported sometimes isolating stallions. There was a tendency for the isolation policy for stallions to be influenced by the presence of shuttle stallions on the farm (p=0.08). The majority of stud managers on farms that had shuttle stallions viewed the quarantine upon arrival to New Zealand as a reason for not isolating stallions. In contrast, only 1/16 stud managers on farms that had no shuttle stallions mentioned previous quarantine as a reason not to isolate horses. Stallions were significantly more likely to have a physical examination or be tested for infectious or sexually transmitted diseases when entering a farm that had shuttle stallions (11/12; 92%) than farms that did not have shuttle stallions (9/16; 56%; p<0.05).
Table 2. Number and percentage of Thoroughbred stud farms in New Zealand with protocols for the entry of veterinarians onto their farms, by size of the breeding farm. Farm categories were small (≤90), medium (91–199), and large (≥200) numbers of mares on-farm during the 2006/2007 breeding season.
Table 3. Number and percentage of Thoroughbred stud farms in New Zealand with procedures in place when a stallion entered the farm, by whether a shuttle stallion was present on the breeding farm.
Upon arrival non-resident mares were rarely examined physically (Table ). However, the vaccination and drench history of the mare was checked by 22/28 (79%) and 27/28 (96%) mangers, respectively. Managers of small and medium farms were more likely to check the mare's history of recent illness than managers of large farms (Table ). On most farms horses were observed for the presence of a cough (25/28; 89%) or nasal discharge (28/28; 100%).
A total of five managers, four from small and one from a large farm, reported having isolated a mare in the week prior to being surveyed; the length of isolation ranged from 3 to 7 days, and the main reasons given for isolation were that the farm of origin was unknown or the mare was underweight (low body condition score). One farm identified nasal discharge and unknown farm of origin as their basis for isolating a mare.
When asked if they had ever isolated mares, most managers (25/28; 89%) had done so in the past. The duration of isolation ranged from 1 to 90 days but most often mares were isolated for ≤1 week (56%). The reasons given for isolating a mare are shown in Table . For small and medium farms poor condition or illness were the most common reasons given for isolating a mare. When mares were placed in isolation they were often given a clinical examination (Table ). When a mare was isolated, walk-in mares were commonly drenched, and housed separately. The use of disinfectants in quarantine yards increased as the size of the farm increased, from 2/13 (15%) on small to 2/5 (40%) on large farms. Managers commonly reported restricting visual and tactile contact between resident mares (22/28; 79%), although they less commonly restricted such contact between the isolated mare and walk-in mares (17/28; 61%). The changing or cleaning of shoes and clothes appeared to be more common for large than small or medium farms (Table ).
Table 4. Number and percentage of Thoroughbred stud farms in New Zealand with procedures in place when a mare entered the farm, by size of the breeding farm. Farm categories were small (≤90), medium (91–199), and large (≥200) numbers of mares on-farm during the 2006/2007 breeding season.
Table 5. Number and percentage of Thoroughbred stud farms in New Zealand with the reasons that a mare would be isolated on arrival at the farm, by size of the breeding farm. Farm categories were small (≤90), medium (91–199), and large (≥200) numbers of mares on-farm during the 2006/2007 breeding season.
Ta ble 6. Number and percentage of Thoroughbred stud farms in New Zealand with the action taken when a mare was isolated on the farm, by size of the breeding farm. Farm categories were small (≤90), medium (91–199), and large (≥200) numbers of mares on-farm during the 2006/2007 breeding season.
The majority of stud mangers believed that they implemented the stud's quarantine protocol for walk-in mares (21/28; 75%). The main reasons reported for failure of implementation of the quarantine procedure were limitations of time (5/28; 18%) and space (11/28; 39%), staff workload (4/28; 14%), and communication between staff (5/28; 18%). Of the eight managers that did not implement their quarantine protocols, five cited New Zealand's disease-free status as one reason for not isolating mares, and three indicated that they did not believe that it was important.
Discussion
The Thoroughbred stud farms in this study were sampled using non-random methods, and a number of the selected stud mangers did not participate. While random sampling from all Thoroughbred breeding farms in New Zealand may have resulted in a more representative sample this was considered to be impractical, and likely to have resulted in a low response rate and logistical difficulties. The farms sampled managed approximately 60% of the 6,623 broodmares bred by a stallion standing in New Zealand during the 2006/2007 breeding season. Therefore, the results likely represent the common practices on breeding farms in the country at the time of the survey. However, the survey was conducted in 2006, prior to the equine influenza outbreak in Australia. As such, respondents in New Zealand were operating complacently in which there was little risk of disease, as highlighted by five respondents noting that there was no need to quarantine mares because diseases were stopped at the border. It is possible that should this study be repeated today the results, in particular those relating to the quarantine of mares and stallions, may be different.
It is unlikely that the results of this survey would not have been affected by recall bias as data about breeding practices were collected during the breeding season. It is possible that stud mangers gave the answers that they believed we wanted, but this was considered unlikely as a number of them actually indicated that they had limited or no protocols in place to prevent the spread of disease.
The size of the breeding farm had an impact on commercial activities and disease-risk profile. The large and medium farms were more likely to have mares arriving for service only than small farms. Smaller- and medium-sized farms were more likely to provided a foaling service to non-resident mares than large farms, possibly providing an additional revenue stream. Consequently, medium farms had a higher frequency of short-duration visits by mares than large and small farms. When compared with large and small farms, medium farms were likely to have a higher number of mare-to-mare interactions, and more visits from horse transporters. Therefore, medium farms were likely to be a higher risk for the introduction and spread of disease than small and large farms. The foaling-down of non-resident mares for clients also meant that the small and medium farms provided a direct interface/ interaction between the racing and sport-horse industries. The interaction between industry groups is of major importance when considering efficient biosecurity control measures, as highlighted by the recent equine influenza outbreak in Australia.
New Zealand's Thoroughbred industry has historically sourced stallion prospects from overseas, and this has meant that, irrespective of the size of the farm, stud managers have an interaction with importation quarantine and MAF Biosecurity New Zealand. Additional isolation procedures were initiated on very few farms upon arrival of the stallion on the breeding farm. If shuttle stallions were hosted they were more likely to have some biosecurity protocols in place to quantify the health status of the stallion on arrival. Whilst the overwhelming confidence of the stud managers in New Zealand's border security is pleasing, it does mean that certain on-farm quarantine or biosecurity practices are not implemented, and this could leave the farm, or the breeding industry, in a vulnerable position should a breach of national biosecurity occur. Lack of good biosecurity practices is also of concern as it leaves farms open to endemic diseases such as strangles. However, it is likely that stud managers are now more conscious of the risk of a biosecurity breach, and have accordingly modified management practices relating to the arrival of a new stallion on the property.
Without a disease outbreak on-farm precautions were scant, as would be expected in a relatively disease-free environment. Low-level protocols, such as washing hands or cleaning general equipment between groups of horses, were implemented on few farms. High-risk areas for spread of disease, such as foaling paddocks, and particularly the crush facility, were cleaned regularly, and in the case of the crush, disinfected regularly, indicating an awareness of the potential for these areas to become foci of disease transmission.
In the absence of risk of an exotic disease, limited protocols were in place on small and medium farms for the visiting veterinarian. Within these farms, the most common requirement was for the veterinarian to change clothes (overalls). In contrast, there was a greater emphasis on large farms of ensuring a change of clothes and shoes, and in one case ensuring use of the stud's own equipment, to reduce the risk of the veterinarian inadvertently being a disease vector. The opportunity for staff (and veterinarians) to be vectors has historically been underestimated. The role veterinarians can play in disease transmission is highlighted by the recent equine influenza outbreak in Australia, in which a number of people, including veterinarians, reported not showering upon leaving the quarantine station (Callinan Citation2008). The possible role of humans in the spread of equine influenza in the United Kingdom has also been highlighted (Christley and French Citation2003).
The nature of the Thoroughbred breeding industry, with the requirement for natural service, provides signiflcant stock-management issues for managers of the breeding farm. During the breeding season there is a large influx of mares to foal-down and be bred as early in the season as possible. In addition, on the medium and large farms there were walk-in mares that arrived for 1–2 days to be covered by the stallion before returning to their host farm. The large influx of mares, at sometimes irregular intervals, from multiple points of origin provides a logistical nightmare for consistent implementation of a biosecurity and isolation policy of mares upon their arrival. A compounding factor for this is the large number of mares delivered by commercial transport, in some cases from multiple points of origin. The equine influenza outbreak in South Africa highlighted how the use of commercial transporters and movement of breeding stock could provide an ideal mechanism for the rapid dissemination of infection (Guthrie et al. Citation1999). In New Zealand's favour, telephone follow-up by one of the authors identifled adequate biosecurity practices, e.g. mucking-out after each horse and washing/disinfecting the truck at the end of the day, were implemented by most commercial horse transporters. The industry is also a relatively small and tightly knit group; when screening the mare on arrival many stud managers operated on trust if they knew the point of origin of the mare. Many stud managers, particularly on the larger farms, responded that irrespective of the point of origin they still checked the vaccination and drench history of the mares but the ability to effectively do this during the height of the season for all mares and follow standard arrival protocol was doubtful. It was apparent that on many farms clinical signs such as nasal discharge and coughing were used as primary screening procedures.
Nasal discharge, coughing, and mares from an unknown source were the primary reasons for isolation. Interestingly, some stud mangers indicated that, even prior to the outbreak of equine influenza in Australia, they were more likely to quarantine a mare if it had come from that country. Therefore, the number of stud mangers currently isolating mares from Australia may have increased. One would expect this practice to still be common, even though Australia has regained its disease-free status and does not currently pose a risk for equine influenza.
Most managers reported having isolated a mare. However, observations on-farm raised issues about the effectiveness of isolation. For example, there was often an inability to separate isolated horses and walk-in mares due to issues of space. The inability to separate horses is likely to be greatest during the height of the breeding season.
This study identifled that most stud managers were aware of the need for on-farm biosecurity. However, the management pressures during the breeding season, the absence of an equine exotic disease outbreak in Australasia, and the stud manager's confldence in the ability of MAF Biosecurity New Zealand to prevent an exotic disease incursion often meant that on-farm biosecurity measures were lacking, leaving the industry vulnerable to a possible exotic disease outbreak. It would be of interest to examine the changes in implementation of biosecurity protocols within the industry since the equine influenza outbreak in Australia, as this will have invariably altered the perception of disease risk and on-farm management practices.
65087supplementarytable1.pdf
Download PDF (122.2 KB)Acknowledgements
The authors would like to thank the stud managers for their generous assistance during the height of the breeding season, and fleur Bessems for the collection and collation of data.
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