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Topic:Infection

Infections in horses encompass a range of diseases caused by various pathogens, including bacteria, viruses, fungi, and parasites. These infections can affect different systems within the horse, such as the respiratory, gastrointestinal, and integumentary systems, leading to a variety of clinical signs depending on the pathogen and the severity of the infection. Common infectious diseases in horses include equine influenza, strangles, and equine herpesvirus. Diagnosis often involves clinical examination, laboratory testing, and sometimes imaging, to identify the causative agent and assess the extent of the disease. Treatment strategies may include antimicrobial therapy, supportive care, and preventive measures such as vaccination and biosecurity practices. This page aggregates peer-reviewed research studies and scholarly articles that explore the pathogenesis, diagnosis, treatment, and prevention of infectious diseases in equine populations.
Enhancement of equine infectious anemia virus virulence by identification and removal of suboptimal nucleotides.
Virology    September 5, 2003   Volume 313, Issue 2 588-603 doi: 10.1016/s0042-6822(03)00351-9
Cook RF, Cook SJ, Berger SL, Leroux C, Ghabrial NN, Gantz M, Bolin PS, Mousel MR, Montelaro RC, Issel CJ.Pathogenicity was reportedly restored to an avirulent molecular clone of equine infectious anemia virus (EIAV) by substitution of 3' sequences from the pathogenic variant strain (EIAV(PV)). However, the incidence of disease in horses/ponies was found to be significantly lower (P = 0.016) with the chimeric clone (EIAV(UK)) than with EIAV(PV). This was attributable to 3' rather than 5' regions of the proviral genome, where EIAV(UK) differs from the consensus EIAV(PV) sequence by having a 68-bp duplication in the 3' LTR and arginine (R(103)) rather than tryptophan (W(103)) at position 103 in the ...
Epitope specificity is critical for high and moderate avidity cytotoxic T lymphocytes associated with control of viral load and clinical disease in horses with equine infectious anemia virus.
Virology    September 5, 2003   Volume 313, Issue 2 537-552 doi: 10.1016/s0042-6822(03)00344-1
Mealey RH, Zhang B, Leib SR, Littke MH, McGuire TC.Equine infectious anemia virus (EIAV) is a lentivirus that causes persistent infections in horses. We hypothesized that high-avidity CTL specific for nonvariable epitopes might be associated with low viral load and minimal disease in EIAV-infected horses. To test this hypothesis, memory CTL (CTLm) responses were analyzed in two infected horses with high plasma viral loads and recurrent disease (progressors), and in two infected horses with low-to-undetectable viral loads and mild disease (nonprogressors). High-avidity CTLm in one progressor recognized an envelope gp90 epitope, and the data doc...
Nonulcerative keratouveitis as a manifestation of Leptospiral infection in a horse.
Veterinary ophthalmology    September 3, 2003   Volume 6, Issue 3 191-195 doi: 10.1046/j.1463-5224.2003.00288.x
Wada S, Yoshinari M, Katayama Y, Anzai T, Wada R, Akuzawa M.A 2-year-old Thoroughbred filly presented with ocular pain and epiphora of the left eye. The pupil was miotic and the cornea edematous near the ventro-temporal limbus, but did not retain any fluorescein. The topical antibiotics and atropine and diclofenac, and systemic flunixin meglumine and antibiotic therapy did not resolve the condition. A pink and fleshy infiltrate developed near the limbus indicating nonulcerative keratouveitis. The anterior uveitis deteriorated as manifested by the presence of dyscoria, hypopyon, and organized fibrin in the anterior chamber. Ocular signs were improved by...
Risk factors for fecal shedding of Salmonella from horses in a veterinary teaching hospital.
Preventive veterinary medicine    August 28, 2003   Volume 60, Issue 4 307-317 doi: 10.1016/s0167-5877(03)00143-0
Alinovi CA, Ward MP, Couëtil LL, Wu CC.Identification of risk factors for horses shedding Salmonella in their feces helps identify patients at-risk of infection and protect the overall population through heightened biosecurity. Fecal samples from 230 hospitalized horses were cultured for Salmonella spp. Historical data were collected on 21 putative risk factors and assessed for association with the risk of a horse being culture positive using forwards stepwise logistic regression. Salmonella was isolated from 13 horses--most commonly from either the first (n=5) or second (n=4) sample collected. Only presenting complaint (confounded...
Field test data on small strongyles in evaluation of activity of fenbendazole given once a day for 5 consecutive days to thoroughbred yearlings on two farms in Kentucky in 2002 and 2003.
Parasitology research    August 28, 2003   Volume 91, Issue 4 312-315 doi: 10.1007/s00436-003-0959-6
Lyons ET, Tolliver SC.Fenbendazole (FBZ) suspension was administered intraorally at the dose rate of 7.0-10.3 mg/kg once a day for 5 consecutive days to 58 thoroughbred yearlings on two farms in central Kentucky in April, 2002. The average dose rates of drug given to groups of colts and fillies on each farm were 7.8-8.5 mg/kg. Only 3 of the yearlings had negative counts of strongyle eggs per gram of feces (EPGs) after treatment which was at 8.4, 8.7, or 9.4 mg/kg; the pretreatment EPG counts were low (10-30). Reduction of EPG values at the highest dose rates was 0% (at 9.5 mg/kg) and 78% (at 10.3 mg/kg). This study...
Pneumonia in horses induced by intrapulmonary inoculation of Streptococcus equi subsp. zooepidemicus.
The Journal of veterinary medical science    August 27, 2003   Volume 65, Issue 7 787-792 doi: 10.1292/jvms.65.787
Yoshikawa H, Yasu T, Ueki H, Oyamada T, Oishi H, Anzai T, Oikawa M, Yoshikawa T.To evaluate the possibility that Streptococcus equi subsp. zooepidemicus (S.z) the causative bacterial agent of equine shipping fever pneumonia (ESFP), as well as to investigate its pathogenesis, 10 horses (seven Thoroughbreds and three Anglo-Arab species, ranging from 2-4 years in age) were experimentally inoculated, via an endoscope, into bronchus of the lung lobe with a dose of 30 ml of 1-7 x 10(8) CFU/ml of S.z. After inoculation, autopsy and pathological examinations were sequentially conducted 30 min, 1, 2, 3, 4, 17, 20 hr and 2 weeks later. Pneumonia induced by the intrapulmonary inocul...
Assessing the agreement of Western blot test results for paired serum and cerebrospinal fluid samples from horses tested for antibodies to Sarcocystis neuronaf.
Veterinary parasitology    August 26, 2003   Volume 115, Issue 3 233-238 doi: 10.1016/s0304-4017(03)00224-3
Rossano MG, Kaneene JB, Schott HC, Sheline KD, Mansfield LS.Equine protozoal myeloencephalitis (EPM) is a neurological disease of equids that is caused by infection of the central nervous system with Sarcocystis neurona. Veterinarians diagnose EPM by performing a neurological examination and by ordering Western blot tests for antibodies to S. neurona in the blood and/or cerebrospinal fluid (CSF). The negative predictive value of the Western blot test is generally accepted to be high for both serum and CSF. If the agreement between serum and CSF test results is strong, serum tests could be used to substitute for CSF tests in some cases. The purpose of t...
Osteomyelitis secondary to trauma involving the proximal end of the radius in horses: five cases (1987-2001).
Journal of the American Veterinary Medical Association    August 22, 2003   Volume 223, Issue 4 486-491 doi: 10.2460/javma.2003.223.486
Swinebroad EL, Dabareiner RM, Swor TM, Carter GK, Watkins JP, Walker M, Schmitz DG, Honnas CM.To determine clinical, radiographic, and scintigraphic abnormalities in and treatment and outcome of horses with trauma-induced osteomyelitis of the proximal aspect of the radius. Methods: Retrospective study. Methods: 5 horses. Methods: Data collected from the medical records included signalment; history; horse use; degree of lameness; radiographic, ultrasonographic, and scintigraphic findings; treatment; and outcome. Results: Duration of lameness prior to referral ranged from 14 to 60 days. Mean severity of lameness was grade 3 of 5, and all horses had a single limb affected. All horses had ...
Identification of foals infected with Parascaris equorum apparently resistant to ivermectin.
Journal of the American Veterinary Medical Association    August 22, 2003   Volume 223, Issue 4 482-455 doi: 10.2460/javma.2003.223.482
Hearn FP, Peregrine AS.During September 2002, routine fecal examinations performed on 16 Thoroughbred foals residing on a farm outside Toronto, Ontario, Canada, revealed low to moderate numbers of Parascaris equorum eggs in feces from 9 of the 16. All foals were then treated with ivermectin at a dose of 220 to 280 microg/kg (100 to 127 microg/lb), p.o., and fecal egg counts were repeated 12 days later. Fecal P. equorum egg counts increased between the first and second fecal examination in 7 foals, were unchanged in 1, and decreased in 5. Fecal samples were collected 13 days after treatment from 21 additional foals t...
Identification of variations in SzP proteins of Streptococcus equi subspecies zooepidemicus and the relationship between protein variants and clinical signs of infection in horses.
American journal of veterinary research    August 21, 2003   Volume 64, Issue 8 976-981 doi: 10.2460/ajvr.2003.64.976
Walker RL, Runyan CA.To determine whether previously unidentified variations of the SzP protein of Streptococcus equi subsp zooepidemicus were present in horses with various clinical signs of infection and whether any relationship could be identified between SzP protein variants and naturally occurring clinical conditions. Methods: 23 isolates of S equi subsp zooepidemicus were recovered from specimens of horses with various clinical conditions and used as a representative population of isolates for evaluation of different SzP protein variants. Methods: Genetic heterogeneity of the isolates was demonstrated by rep...
Evaluation of treatment of colostrum-deprived kittens with equine IgG.
American journal of veterinary research    August 21, 2003   Volume 64, Issue 8 969-975 doi: 10.2460/ajvr.2003.64.969
Crawford PC, Hanel RM, Levy JK.To evaluate equine IgG as a treatment for kittens with failure of passive transfer of immunity (FPT). Methods: 13 specific pathogen-free queens and their 77 kittens. Methods: Kittens were randomized at birth into 9 treatment groups. One group contained colostrum-fed (nursing) kittens; the other groups contained colostrum-deprived kittens that were administered supplemental feline or equine IgG PO or SC during the first 12 hours after birth. Blood samples were collected at serial time points from birth to 56 days of age for determination of serum IgG concentrations. The capacity of equine IgG t...
Association between the MHC gene region and variation of serum IgE levels against specific mould allergens in the horse.
Genetics, selection, evolution : GSE    August 21, 2003   Volume 35 Suppl 1, Issue Suppl 1 S177-S190 doi: 10.1186/1297-9686-35-S1-S177
Curik I, Fraser D, Eder C, Achmann R, Swinburne J, Crameri R, Brem G, Sölkner J, Marti E.To investigate whether the equine major histocompatibility complex (MHC) gene region influences the production of mould-specific immunoglobulin E antibodies (IgE), alleles of the equine leukocyte antigen (ELA-A) locus and three microsatellite markers (UM-011, HTG-05 and HMS-42) located on the same chromosome as the equine MHC were determined in 448 Lipizzan horses. Statistical analyses based on composite models, showed significant associations of the ELA-A and UM-011 loci with IgE titres against the recombinant Aspergillus fumigatus 7 antigen (rAsp f 7). UM-011 was also significantly associate...
Analysis of anamnestic immune responses in adult horses and priming in neonates induced by a DNA vaccine expressing the vapA gene of Rhodococcus equi.
Vaccine    August 19, 2003   Volume 21, Issue 25-26 3815-3825 doi: 10.1016/s0264-410x(03)00329-3
Lopez AM, Hines MT, Palmer GH, Knowles DP, Alperin DC, Hines SA.Rhodococcus equi remains one of the most important pathogens of early life in horses, yet conventional vaccines to prevent rhodococcal pneumonia have not been successful. DNA vaccination offers an alternative to conventional vaccines with specific advantages for immunization of neonates. We developed a DNA vaccine expressing the vapA gene (pVR1055vapA) that induced an anamnestic response characterized by virulence associated protein A (VapA)-specific IgG antibodies in sera and bronchoalveolar lavage fluid (BALF) as well as VapA-specific proliferation of pulmonary lymphocytes when tested in adu...
Model of the equine rhinitis A virus capsid: identification of a major neutralizing immunogenic site.
The Journal of general virology    August 15, 2003   Volume 84, Issue Pt 9 2365-2373 doi: 10.1099/vir.0.19232-0
Kriegshäuser G, Wutz G, Lea S, Stuart D, Skern T, Kuechler E.Mouse monoclonal antibodies (mAbs) were employed to select neutralization escape mutants of equine rhinitis A virus (ERAV). Amino acid changes in the ERAV mutants resulting in resistance to neutralization were identified in capsid protein VP1 at Lys-114, Pro-240 and Thr-241. Although the changes were located in different parts of the polypeptide chain, these mutants exhibited cross-resistance against all four mAbs employed, indicating that these residues contribute to a single immunogenic site. To explain this result, we constructed a model of the three-dimensional structure of the ERAV capsid...
Equine arteritis virus non-structural protein 1, an essential factor for viral subgenomic mRNA synthesis, interacts with the cellular transcription co-factor p100.
The Journal of general virology    August 15, 2003   Volume 84, Issue Pt 9 2317-2322 doi: 10.1099/vir.0.19297-0
Tijms MA, Snijder EJ.Non-structural protein 1 (nsp1), the N-terminal subunit of the replicase polyprotein of the arterivirus Equine arteritis virus (EAV), is essential for viral subgenomic mRNA synthesis, but fully dispensable for genome replication. However, at the molecular level, the role of nsp1 in EAV subgenomic mRNA synthesis is poorly understood. A yeast two-hybrid screen did not reveal interactions between EAV nsp1 and other viral non-structural proteins or the nucleocapsid protein, although both nsp1 and the nucleocapsid protein were found to form homomers. Subsequently, a yeast two-hybrid screen of a HeL...
Thyroid function in mature horses ingesting endophyte-infected fescue seed.
Journal of the American Veterinary Medical Association    August 9, 2003   Volume 223, Issue 3 340-345 doi: 10.2460/javma.2003.223.340
Breuhaus BA.To determine whether ingestion of fescue seed infected with the endophyte Neotyphodium coenophialum would alter thyroid function in adult horses. Methods: Original study. Methods: 4 adult mares that were not pregnant and 6 adult geldings. Methods: Thyrotropin releasing hormone stimulation tests were performed while horses received a standard diet and after infected seed (2.3 kg/d [5 lb/d]) had been fed for 1 and 2 months. Serum prolactin concentrations were measured to verify endophyte absorption. Results: Serum prolactin concentrations indicated that at least 8 of 10 horses absorbed the endop...
A case control study of factors and infections associated with clinically apparent respiratory disease in UK Thoroughbred racehorses.
Preventive veterinary medicine    August 6, 2003   Volume 60, Issue 1 107-132 doi: 10.1016/s0167-5877(03)00085-0
Newton JR, Wood JL, Chanter N.A matched case control study was used to determine infections and other factors associated with clinically apparent respiratory disease in young racehorses in training in the UK. A total of 170 cases, defined as horses with sudden onset coughing, nasal discharge or pyrexia, were identified and matched to 632 non-affected controls by trainer and time period. Factors examined included age, sex, time since entry into the training yard, time since last race and different infections including tracheal and nasopharyngeal (NP) bacteria and viruses. Multivariable conditional logistic regression (CLR) ...
Embryogenesis and the first-stage larva of Thelazia lacrymalis.
Journal of helminthology    August 5, 2003   Volume 77, Issue 3 227-233 doi: 10.1079/JOH2003167
Dongus H, Beelitz P, Schöl H.The female reproductive system of Thelazia lacrymalis (Nematoda: Thelaziidae) was investigated by light and scanning electron microscopy (SEM) with regard to the developmental stages and the stage deposited by the gravid nematode. Female T. lacrymalis have a didelphic and opisthodelphic type of reproductive system with paired ovaries, oviducts and uteri and a single vagina and vulva. Round and spindle-shaped primary oocytes are documented within the ovaries and oviducts, respectively. The distal part of each uterus provides a fertilization chamber filled with spermatozoa, followed by a sphinct...
Suppurative cholangiohepatitis and enteritis in adult horses.
Journal of veterinary internal medicine    August 2, 2003   Volume 17, Issue 4 583-587 
Davis JL, Jones SL.No abstract available
Clinical efficacy of trimethoprim/sulfadiazine and procaine penicillin G in a Streptococcus equi subsp. zooepidemicus infection model in ponies.
Journal of veterinary pharmacology and therapeutics    July 31, 2003   Volume 26, Issue 4 247-252 doi: 10.1046/j.1365-2885.2003.00483.x
Ensink JM, Smit JA, van Duijkeren E.Tissue chambers, implanted subcutaneously on both sides of the neck in eight ponies, were inoculated with Streptococcus equi subsp. zooepidemicus in order to compare the clinical efficacy of trimethoprim/sulfadiazine (TMP/SDZ) and penicillin G treatment in a purulent infection. The TMP/SDZ treatment consisted of one intravenous (i.v.) injection of 5 mg/kg TMP and 25 mg/kg SDZ and the same dose of TMP/SDZ per os (p.o.), both given 20 h after inoculation. The oral dose was then repeated every 12 h for 21 days. The penicillin treatment consisted of one i.v. injection of 20 000 IU/kg sodium penici...
Analysis of the beta-tubulin codon 200 genotype distribution in a benzimidazole-susceptible and -resistant cyathostome population.
Parasitology    July 30, 2003   Volume 127, Issue Pt 1 53-59 doi: 10.1017/s0031182003003317
Pape M, Posedi J, Failing K, Schnieder T, von Samson-Himmelstjerna G.To study the prevalence of the polymorphism in position 200 of the beta-tubulin gene in the mechanism of benzimidazole (BZ) resistance in cyathostomes of horses, an allele-specific PCR was used to detect the genotype of individuals of BZ-susceptible and BZ-resistant populations. The molecular analysis of 100 adults recovered from an anthelmintic-naïve horse revealed 80% homozygous TTC/TTC individuals, 17% heterozygous TTC/TAC and 3% homozygous TAC/TAC. A naturally infected horse was treated with increasing fenbendazole (FBZ) dosages to select a BZ-resistant population of cyathostomes. The PCR...
Clotrimazole, ketoconazole, and clodinafop-propargyl as potent growth inhibitors of equine Babesia parasites during in vitro culture.
The Journal of parasitology    July 26, 2003   Volume 89, Issue 3 604-606 doi: 10.1645/0022-3395(2003)089[0604:CKACAP]2.0.CO;2
Bork S, Yokoyama N, Matsuo T, Claveria FG, Fujisaki K, Igarashi I.The antifungal agents clotrimazole (CLT) and ketoconazole (KC) and the herbicide clodinafop-propargyl (CP) inhibit growth of Plasmodium sp., Toxoplasma sp., and Trypanosoma sp. In the present study, we evaluated these drugs against the in vitro growth of the equine protozoan parasites Babesia equi and B. caballi. Clotrimazole (IC50: 2 and 17 microM), KC (IC50: 6 and 22 microM), and CP (IC50: 450 and 354 microM) were effective growth inhibitors. Interestingly, intraerythrocytic KC-treated Babesia sp. were observed to be in immediate contact with the plasma fraction of the blood in electron micr...
Pathogenicity of a Venezuelan equine encephalomyelitis serotype IE virus isolate for ponies.
The American journal of tropical medicine and hygiene    July 24, 2003   Volume 68, Issue 4 485-494 
Sahu SP, Pedersen DD, Jenny AL, Schmitt BJ, Alstad AD.The enzootic or endemic strains of Venezuelan equine encephalomyelitis (VEE) virus (ID, IE, IF, and II-VI) are considered avirulent. In 1993 and 1996, outbreaks of encephalitis occurred in the horse populations in the Chiapas and Oaxaca provinces of Mexico, respectively. In both instances, enzootic VEE virus subserotype IE was isolated from brain tissues of dead horses. The present study investigated the pathogenicity of the Chiapas viral isolate (NVSL VEE IE 93-42124) in ponies. Three ponies were inoculated intradermally with 4, 5, and 6 logs, respectively, of the NVSL VEE IE 93-42124 viral i...
Neonatal neutropenia in an Arabian foal.
Equine veterinary journal    July 24, 2003   Volume 35, Issue 5 517-520 doi: 10.2746/042516403775600497
Davis EG, Rush B, Bain F, Clark-Price S, Wilkerson MJ.No abstract available
Preliminary evidence for dormant clostridial spores in equine skeletal muscle.
Equine veterinary journal    July 24, 2003   Volume 35, Issue 5 514-516 doi: 10.2746/042516403775600569
Vengust M, Arroyo LG, Weese JS, Baird JD.Clostridial myonecrosis is caused by histotoxic or tissue- destroying clostridia (Allen et al. 1999). Clostridium perfringens and C. septicum are the most common isolates in horses, followed by C. chauvoei, C. novyi and C. fallax (McLaughlin et al. 1979; Westman et al. 1979; Hagemoser et al. 1980; Murphy 1980; Van Heerden and Botha 1982; Coloe et al. 1983; Valberg and McKinnon 1984; Rebhun et al. 1985; Perdrizet et al. 1987). The disease is characterised by a rapid spread of tissue necrosis combined with a lack of leucocyte infiltration at the site of infection (Stevens et al. 1987). ...
Detection of EHV-1 and EHV-4 in placental sections of naturally occurring EHV-1- and EHV-4-related abortions in the UK: use of the placenta in diagnosis.
Equine veterinary journal    July 24, 2003   Volume 35, Issue 5 430-433 doi: 10.2746/042516403775600451
Gerst S, Borchers K, Gower SM, Smith KC.EHV-1 and EHV-4 abortion diagnosis is based upon detailed examination of the aborted fetus. However, in some cases, only the placenta is available for examination. Furthermore, the contribution of lesions in the placenta to pathogenesis and diagnosis of EHV-1 and EHV-4 abortion has been neglected. Objective: To assess the utility of placental examination in equine herpesvirus-1 (EHV-1) and EHV-4 abortion diagnosis. Methods: Sections of allantochorion from 49 herpesvirus abortions were analysed by PCR, in situ hybridisation and immunostaining. Results: Virus-specific nested PCR confirmed the pr...
Clostridium difficile: prevalence in horses and environment, and antimicrobial susceptibility.
Equine veterinary journal    July 24, 2003   Volume 35, Issue 5 465-471 doi: 10.2746/042516403775600505
Båverud V, Gustafsson A, Franklin A, Aspán A, Gunnarsson A.Clostridium difficile has been associated with acute colitis in mature horses. Objective: To survey C. difficile colonisation of the alimentary tract with age, occurrence of diarrhoea and history of antibiotic therapy; and to study the occurrence and survival of C. difficile in the environment and antimicrobial susceptibility of isolated strains. Methods: A total of 777 horses of different breeds, age and sex were studied. Further, 598 soil samples and 434 indoor surface samples were examined. Antimicrobial susceptibility of 52 strains was investigated by Etest for 10 antibiotics. Results: In ...
Lysosomal storage disease in Sida carpinifolia toxicosis: an induced mannosidosis in horses.
Equine veterinary journal    July 24, 2003   Volume 35, Issue 5 434-438 doi: 10.2746/042516403775600523
Loretti AP, Colodel EM, Gimeno EJ, Driemeier D.This study reports a neurological disease unrecognised until now in ponies in southern Brazil. Objective: Epidemiological data strongly suggests that the ingestion of Sida carpinifolia is involved in the aetiology. We tested the hypothesis that it is an acquired lyosomal storage disease. Methods: Following the death of 3 ponies, all ponies from the premises were closely monitored; epidemiological data and clinical findings carefully recorded. Fragments of several organs, including CNS, were fixed in neutral formalin and embedded in paraffin-wax. Sections were stained with haematoxylin and eosi...
A survey of equine abortion, stillbirth and neonatal death in the UK from 1988 to 1997.
Equine veterinary journal    July 24, 2003   Volume 35, Issue 5 496-501 doi: 10.2746/042516403775600578
Smith KC, Blunden AS, Whitwell KE, Dunn KA, Wales AD.A detailed review of laboratory records for equine abortion is fundamental in establishing current disease trends and suggesting problems important for further research. Objective: To review the causes of abortion and neonatal death in equine diagnostic submissions to the Animal Health Trust over a 10 year period. Methods: The diagnoses in 1252 equine fetuses and neonatal foals were reviewed and analysed into categories. Results: Problems associated with the umbilical cord, comprising umbilical cord torsion and the long cord/cervical pole ischaemia disorder, were the most common diagnoses (38....
Comparison of in vitro methods and faecal egg count reduction test for the detection of benzimidazole resistance in small strongyles of horses.
Veterinary research communications    July 23, 2003   Volume 27, Issue 4 281-288 doi: 10.1023/a:1024079907895
Königová A, Várady M, Corba J.The objective of the study was to compare the in vitro egg hatch test (EHT), larval development test (LDT) and in vivo faecal egg count reduction test (FECR test) for the detection of benzimidazole resistance in equine strongyles. The presence of resistant or susceptible strongyle populations was determined in 25 stud farms using the in vivo FECR test and in vitro EHT. On the basis of the FECR values, resistance to fenbendazole was detected on 15 of the 25 farms (60%). The ED50 value (anthelmintic concentration producing 50% inhibition of hatching) for suspected resistant populations varied fr...