Untangling the stranglehold through mathematical modelling of Streptococcus equi subspecies equi transmission.

Strangles, a disease caused by infection with Streptococccus equi subspecies equi (S. equi), is endemic worldwide and one of the most frequently diagnosed infectious diseases of horses. Recent work has improved our knowledge of key parameters of transmission dynamics, but important knowledge gaps remain. Our aim was to apply mathematical modelling of S. equi transmission dynamics to prioritise future research areas, and add precision to estimates of transmission parameters thereby improving understanding of S. equi epidemiology and quantifying the control effort required. A compartmental deterministic model was constructed. Parameter values were estimated from current literature wherever possible. We assessed the sensitivity of estimates for the basic reproduction number on the population scale to varying assumptions for the unknown or uncertain parameters of: (mean) duration of carriership (1∕γC), relative infectiousness of carriers (f), proportion of infections that result in carriership (p), and (mean) duration of immunity after natural infection (1∕γR). Available incidence and (sero-)prevalence data were compared to model outputs to improve point estimates and ranges for these currently unknown or uncertain transmission-related parameters. The required vaccination coverage of an ideal vaccine to prevent major outbreaks under a range of control scenarios was estimated, and compared available data on existing vaccines. The relative infectiousness of carriers (as compared to acutely ill horses) and the duration of carriership were identified as key knowledge gaps. Deterministic compartmental simulations, combined with seroprevalence data, suggest that 0.05

Chronic iron overload causing haemochromatosis and hepatopathy in 21 horses and one donkey.

BACKGROUND: Iron toxicosis is rarely reported in horses and chronic excessive oral iron intake has not been reported to cause clinical symptoms in equids. OBJECTIVES: This case series describes 21 genetically unrelated horses and one donkey with chronic iron overload causing haemochromatosis and hepatopathy. STUDY DESIGN: Case series. METHODS: All equids showing clinical signs compatible with chronic liver disease presented to Utrecht University and diagnosed with iron overload and haemochromatosis based on histopathological evaluation of liver tissue and/or blood transferrin saturation levels of >80% and proof of excess dietary iron intake due to excess iron content in drinking water were included. RESULTS: This study included 22 equids. All tested animals (n = 19) had transferrin saturation >80% and 21 of 22 had increased gamma-glutamyltransferase (γGT). Ultrasonography revealed rounded liver margins in five out of six horses and increased echogenicity in 4/6. Histological examination of liver tissue of 12 animals showed hepatitis, fibrosis and haemosiderin accumulation in macrophages and hepatocytes. Post-mortem examination also revealed haemosiderin accumulation in other organs in all seven examined animals. High iron content in drinking water was identified as the source of iron overload in all cases. All animals were housed under the same conditions for a minimum of 9 years prior to diagnosis of haemochromatosis. Of 22 animals, 13 survived until 1 January 2018, ranging from 17 to 79 months post diagnosis. MAIN LIMITATIONS: Histology of liver tissue was not available for 10 of 22 cases. CONCLUSIONS: Chronic iron overload can lead to haemochromatosis and hepatopathy in equids. Development of disease is slow and clinical signs are nonspecific. Long-term excessive iron intake in equids should be avoided. If animals drink from natural water sources, it is important to test the water for iron content. The Summary is available in Spanish - see Supporting Information.

Plasma D-dimer concentrations during experimental EHV-1 infection of horses.

BACKGROUND: Central nervous system blood vessel thrombosis is a part of the pathogenesis of equid herpesvirus-associated myeloencephalopathy (EHM). D-dimers (DD) are stable breakdown products of cross-linked fibrin, and increased DD-plasma concentrations could reflect the degree of systemic coagulation during EHV-1 infection. HYPOTHESIS: We hypothesized that blood DD concentrations will be increased during periods of EHV-1 fever and viremia, reflecting an activated coagulation cascade with fibrinolysis. ANIMALS: Twenty-eight equids were infected with EHV-1 in 3 experimental infection studies. Three (uninfected) horses were included in a separate study to evaluate methodology for DD concentration measurements. METHODS: Clinical data and quantitative viremia were evaluated, and DD concentrations were measured in blood samples on the day before the infection and during days 1-12 postchallenge. Uninfected horses were sampled every 3 hours for 48 hours. Logistic and linear regression was used to investigate the potential association between the fever and viremia with the presence or absence of DD concentrations in peripheral blood. RESULTS: DD concentrations were increased for 1-8 days in the majority of infected animals. Both viremia (odds ratio [OR] 6.3; 95% confidence interval [CI] 3.4-11.8; P = .0013) and fever (OR 4.9; CI 2.3-10.1; P = .001) were strongly associated with the likelihood of detecting DD in peripheral blood. CONCLUSIONS AND CLINICAL IMPORTANCE: EHV-1 viremia is associated with increases in DD concentration in horses and ponies. This indicates that EHV-1 viremia can lead to an activation of coagulation and fibrinolysis.

Physiological and behavioral responses of horses during police training.

Mounted police horses have to cope with challenging, unpredictable situations when on duty and it is essential to gain insight into how these horses handle stress to warrant their welfare. The aim of the study was to evaluate physiological and behavioral responses of 12 (six experienced and six inexperienced) police horses during police training. Horses were evaluated during four test settings at three time points over a 7-week period: outdoor track test, street track test, indoor arena test and smoke machine test. Heart rate (HR; beats/min), HR variability (HRV; root means square of successive differences; ms), behavior score (BS; scores 0 to 5) and standard police performance score (PPS; scores 1 to 0) were obtained per test. All data were statistically evaluated using a linear mixed model (Akaike's Information criterium; t > 2.00) or logistic regression (P < 0.05). HR of horses was increased at indoor arena test (98 ± 26) and smoke machine test (107 ± 25) compared with outdoor track (80 ± 12, t = 2.83 and t = 3.91, respectively) and street track tests (81 ± 14, t = 2.48 and t = 3.52, respectively). HRV of horses at the indoor arena test (42.4 ± 50.2) was significantly lower compared with street track test (85.7 ± 94.3 and t = 2.78). BS did not show significant differences between tests and HR of horses was not always correlated with the observed moderate behavioral responses. HR, HRV, PPS and BS did not differ between repetition of tests and there were no significant differences in any of the four tests between experienced and inexperienced horses. No habituation occurred during the test weeks, and experience as a police horse does not seem to be a key factor in how these horses handle stress. All horses showed only modest behavioral responses, and HR may provide complimentary information for individual evaluation and welfare assessment of these horses. Overall, little evidence of stress was observed during these police training tests. As three of these tests (excluding the indoor arena test) reflect normal police work, it is suggested that this kind of police work is not significantly stressful for horses and will have no negative impact on the horse's welfare.

[Horse milking industry in The Netherlands and Flanders]. / De paardenmelkerij in Nederland en Vlaanderen: productie en gezondheidsaspecten.

The horse milking industry is expanding in The Netherlands and Flanders. Horse milk has become popular due to its (supposed) health-enhancing properties. A horse-milking farm is not a common client for the Dutch veterinarian. When giving advice in this circumstance it should be recognised that these horses are production animals and that their milk is for human consumption. A review of the literature is given together with the results of an extensive enquiry amongst 13 horse-milking farms in The Netherlands and Flanders.

A pilot study on factors influencing the career of Dutch sport horses.

REASONS FOR PERFORMING STUDY: Welfare concerns over the reasons for interruption or termination of a sporting career in horses have been expressed. OBJECTIVES: To study the career of competition horses and factors that influence career length. METHODS: In 2004, 46,576 rider-horse combinations were registered with the Dutch National Equestrian Federation (KNHS) in dressage, show jumping, eventing and endurance. From this population, approximately 1% of horses in each discipline were selected at random and all recorded competition data from the KNHS registration system collected and supplemented by detailed rider/owner telephone enquiry, carried out in July 2009. RESULTS: A total of 520 horses were included aged 7.1 ± 3.2 years; endurance horses were on average slightly older than horses in the other 3 disciplines. A total of 334 horses (64.2%) ended their competition career with their initial rider during the study period; the mean total career time was 3.8 ± 2.8 years. Reasons for this included being sold on (51.5%), veterinary reasons (23.9%), being used for breeding (8.7%), changing to a recreational career (8.1%), rider-related issues (6.3%) and retirement (1.5%). No follow-up was available for horses sold. Orthopaedic problems accounted for the majority of the veterinary career-ending decisions (63.7%). A total of 385 horses (74.0%) had one or more career breaks; main reasons were rider-related issues (39.2%), others included temporary withdrawal from competition (21.6%), veterinary problems (21.8%), breeding (9.1%) and miscellaneous (8.3%). CONCLUSIONS: Veterinary reasons for career breaks or termination of career accounted for 21.8 and 23.9% over the period investigated. They formed the second reason (after selling) why horses stopped competing with their initial rider/owner. Veterinary reasons were the third important cause for a temporary career break. POTENTIAL RELEVANCE: Further in depth research of the reasons for interruption or termination of an equine career may be useful for the improvement of equine welfare.

The effect of a supplement containing sunflower oil, vitamins, amino acids, and peptides on the severity of symptoms in horses suffering insect bite hypersensitivity.

Insect bite hypersensitivity (IBH) is most often caused by Culicoides spp., although other insect species are also thought to play a role in causing this disease. The disease has been reported to occur in most countries, with a prevalence of up to 28% in some countries in some breeds. The only truly effective therapy currently available is to prevent horses from coming into contact with Culicoides midges, which can be achieved by stabling horses during certain times of the day or by covering them with insect blankets. The effect of a new dietary supplement containing vitamins, polypeptides, and amino acids on IBH severity was tested at the start of the Culicoides season (April 2009). Fifty horses participated in this placebo-controlled, double-blinded study: 25 horses received the supplement and 25 received placebo for 30 days; thereafter all horses received the supplement for a further 30 days. The investigators scored the severity of IBH in all horses, based on clinical evaluation and digital photographs taken before and after the first 30 days of the trial. The owners were asked to assess the severity of the signs prior to the investigation and after the first and second 30-day periods. For each period, IBH clinical symptoms were classified as increased, decreased, or the same. Results showed that investigator-assessed symptoms became worse in more horses receiving placebo than in horses receiving supplement, indicating a positive effect of the supplement. However, there were no treatment-group differences when symptom severity was scored by the horse owners. No side-effects were observed.

Methicillin-resistant Staphylococcus aureus in horses and horse personnel: an investigation of several outbreaks.

At the Veterinary Microbiological Diagnostic Center, the Netherlands, the percentage of methicillin-resistant Staphylococcus aureus (MRSA) isolates found in equine clinical samples increased from 0% in 2002 to 37% in 2008. MRSA of spa-type t064, belonging to MLST ST8 and spa-types t011 and t2123, both belonging to the livestock-associated MLST ST398, predominated. During an outbreak of post-surgical MRSA infections in horses at a veterinary teaching hospital in 2006/2007, MRSA isolates of spa-type t2123 were cultured from 7 horses and 4/61 personnel which indicated zoonotic transmission. After intervention the outbreak stopped. However, another outbreak occurred in 2008, where 17 equine MRSA isolates of spa-type t011 (n=12), t2123 (n=4), and t064 (n=1) were found. This time, 16/170 personnel were positive for MRSA with spa-type t011 (n=11) and t2123 (n=5). Personnel in close contact with horses were more often MRSA-positive (15/106) than those without (1/64). Screening of horses upon admission showed that 9.3% were MRSA-positive predominantly with spa-type t011. Weekly cross-sectional sampling of all hospitalized horses for 5 weeks showed that 42% of the horses were MRSA-positive at least once, again predominantly with spa-type t011, which suggests that nosocomial transmission took place. Fifty-three percent of the environmental samples were MRSA-positive, including samples from students' and staff members' rooms, and all were spa-type t011. This indicates that humans contribute to spreading the organism. Culturing of samples employing high-salt pre-enrichment performed better than a comparable method without pre-enrichment. Our results show that nosocomial transmission occurs in equine clinics and suggests that personnel play a role in the transmission.

Measuring the height at the withers of ponies at a competition and at home using a laser device.

Measuring the height of ponies at the withers is currently a prerequisite at Fédération Equestre Internationale (FEI) competitions. A pony measured at a competition site must not measure more than 151 cm with, or 150 cm without horse shoes. When a pony exceeds the regulated height, it is excluded from participation in the competition. Moreover, the sale value of a pony can decrease dramatically if by height measurement it is designated as a 'horse'. The aim of this study was firstly to determine whether measuring ponies at the withers with a laser device is repeatable; secondly, to evaluate whether laser measurements are more accurate than use of a conventional measuring stick, and, thirdly, to evaluate the difference in height at the withers between ponies at home and the height of the same ponies at a competition. Fifteen clinically healthy horses and 38 healthy ponies were used in the study. A statistical evaluation was performed to determine whether there was a correlation or a significant difference between measurements (P<0.01). The repeatability of the laser measurements, the comparison of the use of the laser versus the measuring stick, and of the measurements done at home compared to the competition site were all very high (0.999, 0.0997 and 0.992, respectively; P<0.01). The mean height measured at a competition was 141.9+/-9.0 cm and of the same ponies at home was 142.4+/-9.1 cm. This difference was not significantly different, although there was a tendency for ponies measured at home to have a higher height at the withers compared to the same ponies at a competition.

Generalized sarcoidosis in two horses.

Equine sarcoidosis is a rare disorder usually characterized by exfoliative dermatitis, moderate to severe wasting, and sarcoidal granulomatous inflammation of multiple organ systems. It has an unknown aetiopathogenesis. The condition is not related to equine sarcoid. This case report describes generalized cutaneous and systemic sarcoidosis in an 11-year-old Trakehner mare (case A) and in a 7-year-old Dutch Warmblood gelding (case B). Case A was presented with cutaneous sarcoidosis on the head and body and was diagnosed on the basis of histological examination of skin. Case B presented with multiple subcutaneous nodules (2-15 cm in diameter) and the diagnosis was established at postmortem examination. Both horses showed distinctive histology of the skin with extensive lymphohistiocytic infiltration and Langhans-type multinucleated giant cells. Haematology and biochemistry revealed a normal total white blood cell count with a right shift in both horses. Case B was anaemic and had a slightly elevated total protein concentration with hyperglobulinaemia. Both horses were unresponsive to corticosteroids and were euthanized.