Surveillance
Surveillance EQUINE DISEASE SURVEILLANCE
Findings from the National Equine Health Survey, 2013 The National Equine Health Survey (NEHS) was introduced in 2010 by the Blue Cross and British Equine Veterinary Association in response to a perceived need for some form of syndromic endemic disease surveillance in horses in the UK. Data are now collected on an annual ‘snapshot’ basis directly from horse owners. Here, Josh Slater discusses some of the findings from the survey carried out in 2013 College (3%) Dressage DISEASE prevalence data are Driving (1%) Other (8%) (7%) Competition (3%) not easy to capture outside Endurance (1%) Stud (1%) Other (23%) of reports from diagnostic Eventing (3%) Army (2%) laboratories and, as a result, Riding Hacking school (7%) there are relatively few examples (20%) RDA (1%) of comprehensive endemic disease surveillance programmes worldwide. Data can potentially Showjumping (4%) be gathered from a variety of sources including real-time reports from sentinel veterinary Non-ridden Hunting practices, data mining from companion or (2%) veterinary practice records, Livery yard Welfare (21%) retired (18%) equine insurance company (33%) Leisure (17%) records and owner-reported Polo Private yard (21%) (1%) Pony Club (3%) prevalence of disease. Each has its own merits and biases that FIG 1: Where horses are kept (n=4658). FIG 2: Main activity for which horses were used represent a balance between RDA Riding for the Disabled Association (n=5293) ease of data collection, accuracy of the data collected and how (Fig 1). Among horses’ main activities (for their horse’s health status on one day of representative the data are of the overall which some were noted in multiple categories their choosing during the survey week horse population. The National Equine giving the higher total of n=5293), 37 per cent in May 2013. The survey used a tick-box Health Surveys (NEHSs) collect data on were recorded as being used for leisure, 18 per type approach with drop-down menus a wide range of disease syndromes on an cent were retired or non-ridden companions to facilitate data entry and asked owners/ annual snapshot or census basis directly (probably reflecting the relatively large cohort keepers to report the number of horses under from horse owners as opposed to gathering of returns from equine welfare charities), 15 their care exhibiting each of 31 different diagnostic data from veterinary practices. per cent were recorded as being used mainly syndromes covering the presenting signs This article provides an update from the for equestrian disciplines and 23 per cent of for common diseases and the major body NEHS 2013 and follows an initial report horses were returned non-specified as ‘other’ systems. For the first time in 2013, the that outlined results from the NEHSs 2010 use (Fig 2). There was a broadly normal NEHS included questions on anthelmintic to 2012 (VR, April 30, 2013, vol 172, p 419). distribution of ages of horses included in the use, in particular treatment for encysted/ survey where their age was known (Fig 3). overwintering cyathostomin larvae and What was involved? Overall, 62 per cent of horses were vaccination, in particular for influenza, As in previous years, the NEHS 2013 was recorded as having one or more of the tetanus, equine herpesviruses (EHV) and conducted as an online, snapshot survey disease syndromes surveyed (Fig 4). strangles (Streptococcus equi). hosted by the Blue Cross, based on the Lameness was one of the most prevalent principle of a national census week for syndromes (18.6 per cent of horses), with What was found? the UK horse, pony, donkey and mule degenerative joint disease being the most Records for 4730 horses were submitted population, with owners/keepers reporting prevalent cause of lameness (14.8 per cent) during the NEHS 2013 by 1246 respondents, and foot lameness being recorded in a an increase of 13.5 per cent from the NEHS further 3.8 per cent of horses, which broadly 2012. The majority of horses (54 per cent) mirrored findings in previous NEHSs. for which responses were received were kept Josh Slater, BVM&S, ECEIM, PhD, MRCVS, Among other orthopaedic syndromes, either in livery yards or private yards, with 21 Royal Veterinary College, Hawkshead Lane, laminitis had a prevalence of 4.4 per per cent kept by equine welfare charities and a Hatfield, Hertfordshire AL9 7TA cent, with 25 per cent of these being first minority of returns from the competition occurrences and 75 per cent being recurrent (3 per cent) and racing (0.06 per cent) sectors e-mail: [email protected]
September 20, 2014 | Veterinary Record | 271
Surveillance 1500
Number of horses
1200
900
600
300
0 25
Unknown
Age (years)
FIG 3: Age distribution (n=4690)
episodes of disease. Back problems were recorded in 5 per cent of horses. Skin disease was again frequently recorded (14.6 per cent of horses) as had been noted in previous NEHSs, with sarcoids (2.8 per cent) and melanoma (1 per cent) again being prevalent among tumours. Wounds were reported less frequently than in the NEHSs 2010 to 2012 (1.4 per cent compared to 3.6 per cent). The overall prevalence of colic was also lower in the NEHS 2013 compared with the NEHSs 2010 to 2012 (2.1 per cent compared to 5.6 per cent), although the ratio of medical to surgical colic cases was broadly similar at 6:1 in the NEHS 2013 compared with 7:1 in the NEHSs 2010 to 2012. Equine grass sickness was again reported at a low prevalence (0.1 per cent) as were myopathies (0.3 per cent). Headshaking was recorded in 1 per cent of returns and stereotypies were recorded in 800 700
Number of horses
600
500
1.2 per cent of horses, which was lower than the 4.1 per cent recorded in the NEHSs 2010 to 2012. Eye problems were more frequently recorded in the NEHS 2013 at 2.6 per cent, with an equal prevalence of uveitis and corneal disease (both at 0.3 per cent) but a higher prevalence of cataract (0.9 per cent). Respiratory diseases were relatively common, with an overall prevalence of 5 per cent, the same as in the NEHSs 2010 to 2012. Allergic respiratory disease was reported among 4.2 per cent of horses and more frequently than infectious respiratory disease (0.3 per cent). Confirmed or suspected pituitary pars intermedia dysfunction (commonly referred to as equine Cushing’s disease) was reported relatively frequently (3.3 per cent) whereas equine metabolic syndrome (EMS) was recorded less frequently (0.9 per cent). The low prevalence of EMS recorded may reflect the relatively low proportion of horses recorded as being overweight (7.8 per cent) in the NEHS 2013, with most horses (41 per cent) recorded as ideal/normal weight and 4.1 per cent recorded as being underweight. This is, however, a consistent trend in NEHSs, and is markedly different from previously published data from UK horses. This may reflect a combination of factors related to owners’ inherent underestimation of their horses’ condition score, difficulties in owners performing condition scoring accurately and differences in the sample populations contributing to these various studies. Overall, 78 per cent of horses in the NEHS 2013 were reported as being vaccinated for influenza, with most of these vaccinated
for both flu and tetanus, giving a much higher vaccine coverage estimate than those derived from vaccines sales figures, which suggest vaccination rates of only 40 to 50 per cent. While vaccination rates are not straightforward to calculate from vaccine sales, it is possible that the cohort of owners who are sufficiently motivated by equine health to take part in the NEHS are more likely to be diligent about preventive health plans, including vaccination, than some other sections of the horse-owning community. The most frequent reasons given by owners electing not to vaccinate against influenza were that their horse did not live in a yard with other animals or did not travel or mix with other horses. Use of EHV and strangles vaccines was much lower, with only 3 per cent of horses vaccinated against EHV and 2.6 per cent of horses vaccinated against strangles. The small number of donkey returns in the NEHS 2013 (n=126) make meaningful interpretation difficult; however, broadly similar trends were seen as in horses and ponies, with a greater proportion of returns in donkeys made for EMS and being overweight.
What’s next?
The NEHS continues to generate disease prevalence data from its annual snapshot of owner-reported syndromic surveillance. Lameness associated with degenerative joint disease continues to be the most frequently reported syndrome along with skin disease. Although the number of owners taking part has increased each year since the NEHS began in 2010, to maximise any benefit of the surveys to the industry it is important that all sectors of the industry support them and encourage their members to take part. The NEHS is striving to achieve its goal of gathering data from 10 per cent of the UK equine population, approximately 100,000 animals.
400 300 200 100 0
y r t r r ) ) ) ) ) ) ) ia s ic ) se m es ol ath tem itis em ea se he em ac ing MS ma he de ies ds olic al oid DT tes et de PID ve ess rgy tal tch tal ms al ae ckn l c op ys ve bl rho sea Ot robl atar hak E ano Ot iso otyp oun al c (tot Sarc (E rasi (v iso P d fe en Alle (to et i (to ble (tot isea p re W ic m e m pro in t d l a lem ep s m lip s si rgica my us s U l pro Diar s di m s C u p i r e e p a e t w l d t M t u S ble ck Sk oin b M le ad bl n pe ras Su up/ rvo er ini rst Ste ea o j Me rob tio ro Ski pro rren o e He m Hy G Liv (fi rn Fo ec pr Ba u ve La h hp Co ing N tis ep Inf ot (rec ry ati ot o o Tie ini Ey o t T is er T a n m r t i La ge sp ini De m Re La
FIG 4: Disease syndrome prevalence. EMS Equine metabolic syndrome, EDT Equine dental technician, PPID Pituitary pars intermedia dysfunction (equine Cushing’s disease)
272 | Veterinary Record | September 20, 2014
n This article originally appeared as a ‘focus article’ in the Defra/AHT/ BEVA equine disease surveillance quarterly report, a shortened version of which was published in the August 2, 2014 issue of Veterinary Record (vol 175, pp 111-114). The full report can be accessed at www.aht.org.uk/cmsdisplay/DEFRA_AHT_ BEVA_equine_reports. html doi: 10.1136/vr.g4982
Surveillance EQUINE DISEASE SURVEILLANCE
Findings from the National Equine Health Survey, 2013 The National Equine Health Survey (NEHS) was introduced in 2010 by the Blue Cross and British Equine Veterinary Association in response to a perceived need for some form of syndromic endemic disease surveillance in horses in the UK. Data are now collected on an annual ‘snapshot’ basis directly from horse owners. Here, Josh Slater discusses some of the findings from the survey carried out in 2013 College (3%) Dressage DISEASE prevalence data are Driving (1%) Other (8%) (7%) Competition (3%) not easy to capture outside Endurance (1%) Stud (1%) Other (23%) of reports from diagnostic Eventing (3%) Army (2%) laboratories and, as a result, Riding Hacking school (7%) there are relatively few examples (20%) RDA (1%) of comprehensive endemic disease surveillance programmes worldwide. Data can potentially Showjumping (4%) be gathered from a variety of sources including real-time reports from sentinel veterinary Non-ridden Hunting practices, data mining from companion or (2%) veterinary practice records, Livery yard Welfare (21%) retired (18%) equine insurance company (33%) Leisure (17%) records and owner-reported Polo Private yard (21%) (1%) Pony Club (3%) prevalence of disease. Each has its own merits and biases that FIG 1: Where horses are kept (n=4658). FIG 2: Main activity for which horses were used represent a balance between RDA Riding for the Disabled Association (n=5293) ease of data collection, accuracy of the data collected and how (Fig 1). Among horses’ main activities (for their horse’s health status on one day of representative the data are of the overall which some were noted in multiple categories their choosing during the survey week horse population. The National Equine giving the higher total of n=5293), 37 per cent in May 2013. The survey used a tick-box Health Surveys (NEHSs) collect data on were recorded as being used for leisure, 18 per type approach with drop-down menus a wide range of disease syndromes on an cent were retired or non-ridden companions to facilitate data entry and asked owners/ annual snapshot or census basis directly (probably reflecting the relatively large cohort keepers to report the number of horses under from horse owners as opposed to gathering of returns from equine welfare charities), 15 their care exhibiting each of 31 different diagnostic data from veterinary practices. per cent were recorded as being used mainly syndromes covering the presenting signs This article provides an update from the for equestrian disciplines and 23 per cent of for common diseases and the major body NEHS 2013 and follows an initial report horses were returned non-specified as ‘other’ systems. For the first time in 2013, the that outlined results from the NEHSs 2010 use (Fig 2). There was a broadly normal NEHS included questions on anthelmintic to 2012 (VR, April 30, 2013, vol 172, p 419). distribution of ages of horses included in the use, in particular treatment for encysted/ survey where their age was known (Fig 3). overwintering cyathostomin larvae and What was involved? Overall, 62 per cent of horses were vaccination, in particular for influenza, As in previous years, the NEHS 2013 was recorded as having one or more of the tetanus, equine herpesviruses (EHV) and conducted as an online, snapshot survey disease syndromes surveyed (Fig 4). strangles (Streptococcus equi). hosted by the Blue Cross, based on the Lameness was one of the most prevalent principle of a national census week for syndromes (18.6 per cent of horses), with What was found? the UK horse, pony, donkey and mule degenerative joint disease being the most Records for 4730 horses were submitted population, with owners/keepers reporting prevalent cause of lameness (14.8 per cent) during the NEHS 2013 by 1246 respondents, and foot lameness being recorded in a an increase of 13.5 per cent from the NEHS further 3.8 per cent of horses, which broadly 2012. The majority of horses (54 per cent) mirrored findings in previous NEHSs. for which responses were received were kept Josh Slater, BVM&S, ECEIM, PhD, MRCVS, Among other orthopaedic syndromes, either in livery yards or private yards, with 21 Royal Veterinary College, Hawkshead Lane, laminitis had a prevalence of 4.4 per per cent kept by equine welfare charities and a Hatfield, Hertfordshire AL9 7TA cent, with 25 per cent of these being first minority of returns from the competition occurrences and 75 per cent being recurrent (3 per cent) and racing (0.06 per cent) sectors e-mail: [email protected]
September 20, 2014 | Veterinary Record | 271
Surveillance 1500
Number of horses
1200
900
600
300
0 25
Unknown
Age (years)
FIG 3: Age distribution (n=4690)
episodes of disease. Back problems were recorded in 5 per cent of horses. Skin disease was again frequently recorded (14.6 per cent of horses) as had been noted in previous NEHSs, with sarcoids (2.8 per cent) and melanoma (1 per cent) again being prevalent among tumours. Wounds were reported less frequently than in the NEHSs 2010 to 2012 (1.4 per cent compared to 3.6 per cent). The overall prevalence of colic was also lower in the NEHS 2013 compared with the NEHSs 2010 to 2012 (2.1 per cent compared to 5.6 per cent), although the ratio of medical to surgical colic cases was broadly similar at 6:1 in the NEHS 2013 compared with 7:1 in the NEHSs 2010 to 2012. Equine grass sickness was again reported at a low prevalence (0.1 per cent) as were myopathies (0.3 per cent). Headshaking was recorded in 1 per cent of returns and stereotypies were recorded in 800 700
Number of horses
600
500
1.2 per cent of horses, which was lower than the 4.1 per cent recorded in the NEHSs 2010 to 2012. Eye problems were more frequently recorded in the NEHS 2013 at 2.6 per cent, with an equal prevalence of uveitis and corneal disease (both at 0.3 per cent) but a higher prevalence of cataract (0.9 per cent). Respiratory diseases were relatively common, with an overall prevalence of 5 per cent, the same as in the NEHSs 2010 to 2012. Allergic respiratory disease was reported among 4.2 per cent of horses and more frequently than infectious respiratory disease (0.3 per cent). Confirmed or suspected pituitary pars intermedia dysfunction (commonly referred to as equine Cushing’s disease) was reported relatively frequently (3.3 per cent) whereas equine metabolic syndrome (EMS) was recorded less frequently (0.9 per cent). The low prevalence of EMS recorded may reflect the relatively low proportion of horses recorded as being overweight (7.8 per cent) in the NEHS 2013, with most horses (41 per cent) recorded as ideal/normal weight and 4.1 per cent recorded as being underweight. This is, however, a consistent trend in NEHSs, and is markedly different from previously published data from UK horses. This may reflect a combination of factors related to owners’ inherent underestimation of their horses’ condition score, difficulties in owners performing condition scoring accurately and differences in the sample populations contributing to these various studies. Overall, 78 per cent of horses in the NEHS 2013 were reported as being vaccinated for influenza, with most of these vaccinated
for both flu and tetanus, giving a much higher vaccine coverage estimate than those derived from vaccines sales figures, which suggest vaccination rates of only 40 to 50 per cent. While vaccination rates are not straightforward to calculate from vaccine sales, it is possible that the cohort of owners who are sufficiently motivated by equine health to take part in the NEHS are more likely to be diligent about preventive health plans, including vaccination, than some other sections of the horse-owning community. The most frequent reasons given by owners electing not to vaccinate against influenza were that their horse did not live in a yard with other animals or did not travel or mix with other horses. Use of EHV and strangles vaccines was much lower, with only 3 per cent of horses vaccinated against EHV and 2.6 per cent of horses vaccinated against strangles. The small number of donkey returns in the NEHS 2013 (n=126) make meaningful interpretation difficult; however, broadly similar trends were seen as in horses and ponies, with a greater proportion of returns in donkeys made for EMS and being overweight.
What’s next?
The NEHS continues to generate disease prevalence data from its annual snapshot of owner-reported syndromic surveillance. Lameness associated with degenerative joint disease continues to be the most frequently reported syndrome along with skin disease. Although the number of owners taking part has increased each year since the NEHS began in 2010, to maximise any benefit of the surveys to the industry it is important that all sectors of the industry support them and encourage their members to take part. The NEHS is striving to achieve its goal of gathering data from 10 per cent of the UK equine population, approximately 100,000 animals.
400 300 200 100 0
y r t r r ) ) ) ) ) ) ) ia s ic ) se m es ol ath tem itis em ea se he em ac ing MS ma he de ies ds olic al oid DT tes et de PID ve ess rgy tal tch tal ms al ae ckn l c op ys ve bl rho sea Ot robl atar hak E ano Ot iso otyp oun al c (tot Sarc (E rasi (v iso P d fe en Alle (to et i (to ble (tot isea p re W ic m e m pro in t d l a lem ep s m lip s si rgica my us s U l pro Diar s di m s C u p i r e e p a e t w l d t M t u S ble ck Sk oin b M le ad bl n pe ras Su up/ rvo er ini rst Ste ea o j Me rob tio ro Ski pro rren o e He m Hy G Liv (fi rn Fo ec pr Ba u ve La h hp Co ing N tis ep Inf ot (rec ry ati ot o o Tie ini Ey o t T is er T a n m r t i La ge sp ini De m Re La
FIG 4: Disease syndrome prevalence. EMS Equine metabolic syndrome, EDT Equine dental technician, PPID Pituitary pars intermedia dysfunction (equine Cushing’s disease)
272 | Veterinary Record | September 20, 2014
n This article originally appeared as a ‘focus article’ in the Defra/AHT/ BEVA equine disease surveillance quarterly report, a shortened version of which was published in the August 2, 2014 issue of Veterinary Record (vol 175, pp 111-114). The full report can be accessed at www.aht.org.uk/cmsdisplay/DEFRA_AHT_ BEVA_equine_reports. html doi: 10.1136/vr.g4982
