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Topic:Epidemiology
Epidemiology in horses involves the study of the distribution and determinants of health-related states and events in equine populations. It encompasses the investigation of patterns, causes, and effects of diseases and health conditions within horse populations. This field of study aims to identify risk factors for disease and targets for preventive healthcare. Key components of equine epidemiology include disease surveillance, outbreak investigation, and the study of disease dynamics within herds or regions. Research in this area often focuses on infectious diseases, zoonotic diseases, and the impact of environmental factors on equine health. This page compiles peer-reviewed research studies and scholarly articles that explore various aspects of epidemiology in horses, including disease prevalence, transmission pathways, and strategies for disease prevention and control.
Eyeworms (Thelazia lacrymalis) in one- to four-year-old Thoroughbreds at necropsy in Kentucky (1984 to 1985). From Mar 1, 1984, to Feb 28, 1985, both eyes from 189 one- to four-year-old Thoroughbreds (88 males, 90 females, and 11 geldings) in Kentucky were examined at necropsy for eyeworms. Thelazia lacrymalis was recovered from 45% of 1-year-old horses, 26% of 2-year-old horses, 45% of 3-year-old horses, and 50% of 4-year-old horses; overall, 43% of 1- to 4-year old horses were infected. Prevalence of eyeworms in horses in the present study was comparable with that in horses of similar ages examined at necropsy in Kentucky in 2 previous studies (1975 to 1976 and in 1979), except for the lower percent...
Salmonellosis in hospitalized horses: seasonality and case fatality rates. Salmonellosis was studied during an 11-year period (July 1971 through June 1982) in 245 hospitalized horses. Ten years' data (207 cases) were analyzed in a time series study. Peak seasonality of the disease was from June through September. The cycle curve revealed 3 major outbreaks, with no apparent periodicity. Eighteen Salmonella serotypes caused clinical salmonellosis in horses, but 84% of the cases and 90% of the deaths were caused by 5 serotypes: Salmonella typhimurium, S typhimurium var copenhagen, S anatum, S kottbus, and S saint-paul. Overall, the case fatality rate was 44.9%. Excludin...
Risk factors for salmonellosis in hospitalized horses. A case-control study to identify risk factors associated with isolation of Salmonella was accomplished, using data from records of horses hospitalized in the period July 1971 through June 1982. Horses in which nasogastric tubes were passed were at 2.9 times greater risk of having Salmonella isolated, compared with horses that did not undergo this procedure. Horses treated with antibiotics parenterally were at 6.4 times greater risk, and those treated with antibiotics orally and parenterally were at 40.4 times greater risk of developing salmonellosis, compared with horses not receiving such tre...
An outbreak of suspected equine infectious anaemia in Guyana. An outbreak of suspected equine infectious anaemia (EIA) among a population of 678 horses from 16 farms occurred in the Rupununi Savannahs of Guyana. Clinical signs of EIA were detected in 110 horses. Agar gel immunodiffusion (AGID) tests on 92 sera examined showed positive serological evidence of EIA in 67 (72·8%). The mean packed cell volume of 50 horses studied was 0·178
and the mean red blood cell count was 3·7 × 1012/l with the mean white blood cell count 4·1 × 109/l.
The morbidity rate of the disease was 14·0% and the mortality rate 11·1%. The majority (78%) of all seroposi...
Foetal and neonatal foal losses on equine herpesvirus type 1(EHV-1) infected farms before and after EHV-1 vaccination was introduced. On 6 farms with a history of EHV-1 abortions the overall prevalence of losses due to abortion, stillbirth and neonatal foal mortality during 5 foaling seasons preceding the introduction of vaccination against EHV-1 were compared with corresponding data for 8 subsequent seasons in which all horses were immunized with a modified live EHV-1 vaccine. Although both sporadic and epizootic EHV-1 abortions occurred in immunized mares, the numbers of foetal and neonatal foal losses decreased significantly (chi 2 = 15.75; p less than 0.001) from 11.8% (343 of 2897 pregnancies) during the seasons 1969-19...
Antistreptolysin O titer in horses. Antistreptolysin O (ASO) titers were determined in the sera of 532 horses from stud farms and 436 working horses from small farms. A statistically significant correlation was seen between the ASO titer and the age of the horses. There was a significant difference between mean ASO titer in horses 0-2 years and horses 2-10 years In horses older than 10 years the titer was significantly higher than mean ASO titer for the group. Twenty four of 30 horses in which ASO titer was higher or equal to 80 I.U. had histories which suggested that streptococcal infection had occurred. Clinical and bacteriolo...
Bilateral salpingitis, hydrosalpinx and oophoritis in a mare. Bilateral salpingitis, hydrosalpinx and oophoritis were diagnosed in a mare with concurrent lymphosarcoma. Salpingitis, hydrosalpinx and oophoritis are rare in the mare (1,2,3,5,8,9,11-13). Bilateral salpingitis is an important cause of infertility in all species and is most often due to ascending infection (3-5,10,11). The source of salpingitis in this mare probably was ascending infection from the uterus after parturition. The apparent infertility of the mare was attributed to debilitation from the lymphosarcoma and multiplicity of genital pathoses.
Polymorphic restriction sites in the horse beta-globin gene cluster. Horse DNA samples digested with PstI and probed with the rabbit beta 1 globin gene show three phenotypes determined by one fragment of variable length (about 5.1 or 3.3 kb). Family data demonstrate that these fragments segregate as Mendelian alleles. The frequencies of the two alleles are 0.66 for the 3.3-kb fragment and 0.34 for the 5.1-kb one. Another polymorphism has been detected with BamHI. Again three phenotypes determined by two alleles (fragments of 7.5 and 3.8 kb) have been observed. Allelic frequencies of the 7.5- and 3.8-kb fragments are 0.24 and 0.76 respectively. The two polymorph...
Control of strongylosis in horses by alternate grazing of horses and sheep and some other aspects of the epidemiology of Strongylidae infections. Alternate grazing of horses and sheep as a control measure for gastrointestinal helminthiasis was studied in three grazing experiments in 1981, 1982 and 1983. Each year a group of three mare yearling Shetland ponies, which were kept on a small pasture from spring to autumn, were compared with a similar group which grazed a similar or the same pasture until July and were subsequently removed to a similar pasture which had been grazed by sheep from April to July. In addition both groups were treated with an anthelmintic when the latter group was removed to the sheep pasture. Pasture larval count...
[Chaetotaxy of Gastrodiscus aegyptiacus cercaria (Trematoda, Paramphistomoidea) a horse parasite]. Cercarial chaetotaxy of Gastrodiscus aegyptiacus (Paramphistomoidea), parasite of the Horse, is described. Cercariae were shed by experimentally infected Bulinus forskalii. This description is the first one of a Gastrodiscidae. The cercarial chaetotaxy of the Gastrodiscidae is quite different from those of Paramphistomoidea and Diplodiscidae.
Studies on the sequence of variable antigen types in ponies infected with a clone of Trypanosoma evansi. The sequential appearance of variable antigen types (VATs) of a clone of Trypanosoma evansi was studied in four ponies. Using luminol-dependent chemiluminescence, VAT populations which had been isolated from parasitemic peaks of single ponies, were tested for specificity with serum samples collected from other ponies. When antibody activity was demonstrated in a combination of trypanosomes and serum, it was concluded that a major VAT appeared in common. In the serum of all animals antibody activity was demonstrated to all VAT populations isolated from the other ponies during the first 4 weeks ...
Equine leukocyte antigens: relationships with sarcoid tumors and laminitis in two pure breeds. Frequencies of equine leukocyte antigen distribution were determined by complement-mediated cytotoxicity testing among populations of Thoroughbred and Standardbred horses, including animals affected with equine sarcoid and laminitis. A highly significant association is described between the presence or history of sarcoid lesions in Thoroughbreds and the expression of the major histocompatibility complex (MHC)-encoded antigens, W3 and B1. No association was found between antigenic expression frequencies and laminitis in either breed. These findings suggest that a strong relationship exists betw...
Salmonella serotypes from animals in New York State, 1978-1983. The salmonella serotypes isolated during 1978 to 1983 at the diagnostic and clinical laboratories of the New York State College of Veterinary Medicine from animal sources in New York state were reviewed and compared to earlier data from New York state animals and to national data for both human and animal sources. A total of 255 salmonella strains were studied from the six year period and included 33 serotypes. Salmonella enteritidis ser Typhimurium continued to be the most commonly reported serotype followed by serotype Anatum. Generally serotypes from New York state animals reflected nationa...
Equine herpesvirus type 1 (EHV-1) induced abortions and paralysis in a Lipizzaner stud: a contribution to the classification of equine herpesviruses. Out of 30 cases of abortion and perinatal deaths in a Lipizzaner stud in Austria 10 mares died after having shown central nervous system disturbances, ataxias and paralysis. The etiological agent of this "abortion storm" was equine herpesvirus type 1 (EHV-1). The restriction enzyme pattern of the DNA from 5 isolates recovered from fetuses has been analyzed and compared with the known reference strains of EHV-1, -2, -4 and an Austrian vaccine strain. The DNA restriction profiles of the Lipizzaner isolates as well as of the vaccine strain could be identified as being typical of abortigenic strai...
Prevalence of benzimidazole-resistant small strongyles in horses in a southeastern Pennsylvania practice. A survey was conducted to determine the prevalence of benzimidazole (BZ)-resistant small strongyles in horses in a southeastern Pennsylvania practice. Resistant parasites were found in 291 of 342 horses surveyed. Anthelmintic practices and pasture management factors in use for 3 to 6 years did not correlate with the presence of resistant small strongyles. Benzimidazole-resistant small strongyles were recovered in horses that had been treated alternately with BZ and non-BZ products and in horses receiving BZ products as infrequently as twice a year. However, inasmuch as the horses may have been...
Sudden death in training and racing Thoroughbred horses. We reviewed case records, necropsy reports, and histologic sections from 25 Thoroughbred racehorses that died suddenly at 3 Chicago racetracks. These were young horses ranging in age from 2 to 5 years. There were more females (n = 16) than males (n = 9), and the incidence of death increased slightly in the spring and summer. Twenty-one of the 25 horses died while racing or training. Only 8 of the 25 horses (32%) had lesions sufficient to account for the death. In 6 of those 8 cases, death was caused by massive thoracic or abdominal hemorrhage. The site or nature of the vascular defect in these...
A retrospective study of equine infectious anemia based on the canadian control program. Equine infectious anemia in Canada was reviewed for the period January 1976 to December 1981. The human and ecological factors prevailing in Canada are deemed instrumental with respect to the evolution of the disease. The natural spread of the disease on a large scale has not been influenced by the Federal program. Reactors with signs of the disease are important for it's propagation. The author underlines the necessity of cooperation with private practising veterinarians to control it.
Bacterial isolates from tracheobronchial aspirates of healthy horses. Of tracheobronchial aspirates from 50 clinically healthy Thoroughbred racehorses, 4 (8%) had aerobic bacteria with recognized pathogenicity, 12 (24%) contained transient bacterial isolates, and 37 (74%) had no bacterial growth. Of tracheobronchial aspirates from 36 pastured, nonracing racehorses, 3 (8%) had bacteria with recognized pathogenicity, 23 (64%) contained transient bacteria, and 10 (28%) had no bacterial growth. Anaerobes were not isolated from 12 of 12 pastured horses. Transient bacteria were isolated more often in the pastured horses.
Ticks on livestock in St. Lucia. Cattle, sheep, goats and horses were examined for ticks. Over 95% of Holstein cross-breeds, 28% of sheep (local mixed breeds) and 18% of goats (local mixed breeds) examined from 18 August to 4 September 1983 were infested with the southern cattle tick, Boophilus microplus Canestrini. About 90 and 17% of the horses examined were infested with the tropical horse tick, Anocentor nitens Neumann, and the tropical bont tick, Amblyomma variegatum Fabricius, respectively. The tropical bont tick was found infesting 10% of cattle in the Gros Islet area of St. Lucia. The tropical bont tick was also found...
Antibodies to Borrelia burgdorferi in New England horses: serologic survey. Twelve of 50 randomly selected horses from areas endemic for Borrelia burgdorferi had indirect fluorescent antibody titers of 1:8 to 1:2,048 against B burgdorferi. One of 50 horses from nonendemic areas had a titer of 1:8. This difference in the number of horses seropositive for B burgdorferi (P less than 0.002) and our finding that seropositive horses did not have agglutinating antibodies against potentially cross-reacting Leptospira spp indicated that horses in endemic areas were exposed to B burgdorferi and that the spirochete induced an antibody response in the horses.
Use of oxibendazole for control of cambendazole-resistant small strongyles in a band of ponies: a six-year study. Oxibendazole (OBZ; 10 mg/kg of body weight) was administered to ponies at 8-week intervals to control strongylosis in a breeding band of Shetland-type ponies (n = 29 to 50) from October 1978 through September 1984. A similar use of cambendazole (CBZ; 20 mg/kg of body weight) in this band of ponies during the preceding 4-year period resulted in the survival of a CBZ-resistant population (S) of small strongyles. Effectiveness of OBZ treatments was monitored by pre- and posttreatment counts of the number of strongyle eggs per gram of feces (epg) and of the number of strongyle larvae per gram of f...
