Parasites are organisms that live on or within a host, deriving nutrients at the host's expense. In horses, parasitic infections can affect various systems, including the gastrointestinal tract, skin, and respiratory system. Common equine parasites include strongyles, ascarids, tapeworms, and bots. These parasites can lead to a range of health issues, from mild discomfort to severe disease, depending on the type and burden of the infestation. This page compiles peer-reviewed research studies and scholarly articles that explore the biology, life cycle, and impact of parasites on equine health, as well as strategies for diagnosis, treatment, and prevention of parasitic infections in horses.
Reinemeyer CR, Scholl PJ, Andrews FM, Rock DW.A 3 m, video gastroscope was used to screen 47 horses suspected of being naturally infected with equine bot larvae. 17 of 47 (36.2%) candidate horses harbored Gasterophilus nasalis larvae in the proximal duodenum and 46 of 47 (97.9%) had G. intestinalis larvae in the stomach. All horses infected with G. nasalis had concurrent infections with G. intestinalis. 14 horses with dual infections were allocated randomly to two treatment groups. Seven horses in Group 1 received 2% moxidectin oral gel once at a dosage of 0.4 mg/kg bodyweight (BW), and seven horses in Group 2 were untreated controls. 14 ...
van Herwerden L, Gasser RB, Blair D.This study investigated sequence heterogeneity in the first internal transcribed spacer (ITS-1) of ribosomal DNA within and among species and strains of Echinococcus. Different ITS-1 sequence variants exist in Echinococcus granulosus and Echinococcus multilocularis, which represent at least four evolutionary lineages: (1) a sheep strain-lineage of E. granulosus, (2) a sister lineage of a cervid and camel E. granulosus ITS-1 variants, (3) a lineage including the ITS-1 variants representing horse, bovine and camel strains of E. granulosus, as well as variants from E. multilocularis, Echinococcus...
Pusterla N, Madigan JE, Chae JS, DeRock E, Johnson E, Pusterla JB.We report successful helminthic transmission of Ehrlichia risticii, the causative agent of Potomac horse fever, using trematode stages collected from Juga yrekaensis snails. The ehrlichial agent was isolated from the blood of experimentally infected horses by culture in murine monocytic cells and identified as E. risticii ultrastructurally and by characterization of three different genes.
Cogley TP, Cogley MC.A synthetic alpha-2 adrenergic agonist, detomidine hydrochloride, was used in the study of in vivo activity of Gasterophilus intestinalis (Diptera: Gasterophilidae) during migration in the tongue of the horse. Use of the drug allowed the investigator to manipulate the tongue and closely observe the movement patterns and tissue disturbance caused by burrowing first-stage larvae. Detomidine hydrochloride should be utilized in studies of drug efficacy and larval biology, whenever possible, to avoid the need to sacrifice the horse.
Baudena MA, Chapman MR, French DD, Klei TR.Cyathostome development and survival on pasture in subtropical climates of the US have yet to be completely defined and available data on seasonal transmission are minimal. In an attempt to study this phenomenon, a group of pony mares and their foals was maintained on a naturally contaminated pasture in southern Louisiana. Fecal egg counts (FEC) and numbers of infective third stage larvae (L3) kg(-1) dry herbage were recorded biweekly during two time periods, from January 1986 through December 1988, and September 1996 through October 1997. A FEC rise occurred during the late summer-early autum...
Hung GC, Chilton NB, Beveridge I, Gasser RB.In this study, molecular data sets were used to address the controversies relating to the systematics of strongyloid nematodes of equids utilising morphological data sets. DNA sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of ribosomal DNA were determined for 30 species of equine strongyles and the systematic relationships reconstructed using phenetic and phylogenetic tree-building methods. The molecular data provided support for the hypothesis that the genera with large subglobular buccal capsules are ancestral to those with small cylindrical buccal capsules,...
Clausen PH, Gebreselassie G, Abditcho S, Mehlitz D, Staak C.A field study of horses was conducted in the province of Bale, Ethiopian highlands. A rapid questionnaire analysis indicated that dourine, known as "Dirressa", is a major health problem of equines in this area. A total of 121 horses suspected of dourine were examined by use of clinical, parasitological, serological and DNA based techniques. Incoordination of hindlegs (76%), swelling of external genitalia (48.8%) and emaciation (39.7%) were the most common clinical signs observed. Using the haematocrit centrifugation technique (HCT), no trypanosomes were detected in blood, genital washes or tis...
Gianini M, Sutter O, Burger D, Bracher V.Gastrointestinal function was assessed in normal foals before, during and after the onset of 'foal heat diarrhoea' by haematological, biochemical, microbiological and parasitological methods, and by a combined lactose tolerance-breath hydrogen excretion test. Warmblood mares (n=11) and their foals were used. The foals were assessed according to a standard protocol after birth and at regular intervals thereafter. All except one of the foals suffered from diarrhoea that started between day 8 and day 12 after birth, which lasted for 1-4 days. Rotavirus was detected in the faeces of five foals, bu...
Majewska AC, Werner A, Sulima P, Luty T.The present study was undertaken to investigate the prevalence of Cryptosporidium infection in horses used for recreational riding as well as in humans. A total of 106 faecal specimens from horses raised in 4 localities of western Poland and 6 stool samples from 3 persons who had constant or sporadic contact with horses were screened microscopically for oocysts using modified Ziehl-Neelsen staining. Enzyme immunoassay (EIA) was additionally used for the detection of coproantigen in human stool samples as well as in 43 randomly selected horse faecal samples. The overall infection rate of horses...
Sandin A, Skidell J, Häggström J, Girma K, Nilsson G.Necropsy records from 702 horses, less than one year old, that were subjected to necropsy between 1924 and 1996 were used to estimate the prevalence of gastric ulceration in younger horses and to evaluate some potential risk factors that may contribute to the development of gastric ulceration. Information concerning breed, gender, age, season of death, clinical signs of colic, medical treatment, parasitism and documentation of diseases in different organs were recorded, as well as size, number and anatomical distribution of ulcers. Gastric ulcers were found in 96 of 702 young horses (14%) and ...
Silvina Fernández A, Henningsen E, Larsen M, Nansen P, Grønvold J, Søndergaard J.An experiment was carried out in 1997 to test the efficacy of an isolate of the microfungus Duddingtonia flagrans against free-living stages of horse strongyles under conditions in the field and to assess the eventual effect of the fungus on the normal degradation of faeces. Faecal pats were made from faeces of a naturally strongyle infected horse, which had been fed fungal material at a dose level of 106 fungal unit/kg bwt. Control pats without fungi were made from faeces collected from the same animal just before being fed fungi. Faecal cultures set up for both groups of faeces to monitor th...
Hutchens DE, Paul AJ, DiPietro JA.Routine anthelmintic treatments are one of the most important components of an equine wellness program used by horse owners and veterinarians today. Thirteen different compounds are available in the United States in the treatment of gastrointestinal parasites, most of which are available over the counter. As a result, there is a decreased reliance on the veterinarian to perform routine tube dewormings. Therefore, the future of the veterinarian's role in the management of gastrointestinal parasites is likely to be in the consultation and design of parasite control programs. With this in mind, t...
Murphy AJ, Mansfield LS.Sarcocystis neurona is a protozoan parasite that causes a neurological disease in horses called equine protozoal myeloencephalitis. The route of transmission is speculated to be by fecal-oral transfer of sporocysts shed from opossums. Controversy exists regarding both the natural life cycle for this parasite as well as the species identity of opossum Sarcocystis. To provide stage-specific material for species comparison, 27 opossums from southern Michigan were screened for Sarcocystis spp. sporocysts. Seven opossums were positive for Sarcocystis sporocysts by fecal flotation. A simplified, eff...
Pozio E, Paterlini F, Pedarra C, Sacchi L, Bugarini R, Goffredo E, Boni P.A total of 120 muscle tissues from three horses naturally infected with Trichinella spiralis were examined. The head was the most infected site. In particular, the muscles harbouring the highest number of larvae were: musculus buccinator (12, 411 and 1183 larvae g-1), the tongue (11, 615 and 1749 larvae g-1), m. levator labii maxillaris (17,582 and 1676 larvae g-1), and the masseter (4.9, 289 and 821 larvae g-1). Compared with the diaphragm, the number of larvae per gram was from 3.5 to 6.8 times higher in the tongue, from 3.5 to 6.5 higher in m. levator labii maxillaris, and from 2.5 to 4.6 h...
Dubey JP, Mattson DE, Speer CA, Baker RJ, Mulrooney DM, Tornquist SJ, Hamir AN, Gerros TC.An isolate of Sarcocystis neurona (SN6) was obtained from the spinal cord of a horse from Oregon with neurologic signs. The parasite was isolated in cultures of bovine monocytes and equine spleen cells. The parasite divided by endopolygeny and completed at least one asexual cycle in cell cultures in three days. Two gamma interferon knockout mice inoculated with cell culture-derived merozoites became ill 35 d later and S. neurona schizonts and merozoites were found in encephalitic lesions. The parasite in tissue sections of mice reacted with S. neurona-specific antibodies and S. neurona was rei...
Chapman MR, Kearney MT, Klei TR.With the increased interest in equine cyathostomes it has become apparent that some evaluations of methods currently used to count the various larval stages which occur in the mucosa would be beneficial. Experiments were conducted to investigate the effects of fixation and storage of mucosal tissues at -20 C on the accuracy of counting these larvae. The accuracy of counting developing larvae within the mucosa by transmural illumination (TMI) and by artificial digestion (DIG) of the mucosa was also compared. The data indicate that fixation of digested mucosa in PBS-buffered 5% or 10% formalin d...
Cogley TP, Cogley MC.The degree of penetration into the stomach and duodenum of the horse by bot fly larvae, Gasterophilus intestinalis (De Geer) and G. nasalis (Linnaeus) (Diptera : Gasterophilidae) was evaluated. Evidence of larval perforation of the stomach or duodenum was not found on gross inspection. Palpation of the intact stomach and duodenum was not effective in establishing the existence of Gasterophilus larvae within the organs. Findings suggest that larvae of both species produce an ulcer of similar depth within the gastrointestinal wall. The ulcer depth produced by larvae did not correlate with the no...
Dubey JP, Venturini MC, Venturini L, McKinney J, Pecoraro M.Sera from 76 horses from Argentina were examined for antibodies to Sarcocystis neurona, Toxoplasma gondii and Neospora caninum. Antibodies to S. neurona were found in 27 (35.5%) of 76 horses using immunoblots with culture derived merozoites as antigen. Antibodies to T. gondii were found in 10 (13.1%) of 76 horses by using the modified agglutination test with formalin-fixed tachyzoites and mercaptoethanol; titers were 1:25 (two horses), 1:50 (six horses), 1:100 (two horses), and 1:200 (one horse). Antibodies to N. caninum were not found in any of the 76 horses by the use of N. caninum agglutina...
Ambawat HK, Malhotra DV, Kumar S, Dhar S.Equine babesiosis, caused by Babesia equi and transmitted by ticks is of major economic importance in India. The adverse effects which B. equi organism and its metabolites inflict on red blood cells have not been reported. Erythrocytes were analysed for red cell membrane phospholipids, proteins and haemoglobin (Hb) concentration and plasma for malondialdehyde (MDA) in B. equi carrier donkeys before splenectomy (50% parasitaemia. Before splenectomy the mean values of membrane protein, phospholipids, plasma MDA and Hb were found to be 1.63 +/- 0.12 mg/ml PCV, 2.28 +/- 0.9 mg/ml PCV, 3.63 +/- 0.3...
Silva AV, Costa HM, Santos HA, Carvalho RO.Thirty six horses from nine Brazilian states (Goiás, Minas Gerais, Pará, Maranhão, Piauí, Paraíba, Pernambuco, Rio Grande do Norte, and Ceará) were examined for infections by small strongyles. The following species were identified: Cylicocyclus nassatus, C. insigne, C. brevicapsulatus, C. leptostomum, C. radiatus, C. ultrajectinus, C. ashworthi, Cylicostephanus goldi, C. calicatus, C. minutus, C. longibursatus, Petrovinema poculatum, Coronocyclus coronatus, C. labiatus, C. labratus, Cyathostomum catinatum, C. pateratum, C. alveatum, Parapoteriostomum euproctus, Cylicodontophorus bicorona...
Sangster NC.Anthelmintic-resistance has emerged as a problem in several animal industries. In the horse, cyathostome resistance to all available treatments except for the avermectin/milbemycins means that these drugs provide the cornerstone of control. Ivermectin has been available for several years; the related compound moxidectin is more recent. Although we do not know for sure, aspects of moxidectin such as its persistent action and its efficacy against mucosal stages of cyathostomes, may enhance the rate of development of resistance. On the other hand, selection pressure would be reduced if the persis...
Love S, Murphy D, Mellor D.Cyathostomes are now the principle parasitic pathogen of the horse: a remarkable transformation during the last 25 years from virtual obscurity to focus of attention in equine parasitology. This rise to prominence coincides with the marked decrease in prevalence of large strongyle infections as a result of widespread use of modern anthelmintic compounds. On the basis that strongyle-associated diseases continue to commonly occur in the absence of these large strongyle species, clinical attention has turned to the pathogenicity of cyathostomes. Although many horses harbour burdens of tens of tho...
Craig TM.Internal parasites of horses are ubiquitous but that does not suppose that the level of infection does not vary with climatic conditions. Climate determines the limits of where a parasite species can survive the external environment and weather determines the transmission pattern within the climatic bounds [Levine, N.D., 1963. Adv. Vet. Sci. 8, 215-261]. Arid areas have a more limited exposure potential to important parasites but the level of exposure can nonetheless lead to disease. It must be remembered that, even in arid areas, it does rain and irrigation, overflow from water troughs, dew d...
Young KE, Garza V, Snowden K, Dobson RJ, Powell D, Craig TM.Diversity of parasite populations was compared between two herds of horses, one a regularly treated herd the other a feral herd which has bad no anthelmintic treatment for at least 25 years. Eggs obtained from fecal samples of both herds were tested for anthelmintic resistance by use of an in-vitro larval hatch/development assay (LDA), DrenchRite. A fecal egg reduction test was also performed with the domesticated herd using fenbendazole, pyrantel pamoate and ivermectin. Cyathostomes were the predominant group of worms present in both herds. Trichostrongylus axei was seen in both herds, but St...
Courtney CH.Few studies investigating the seasonal transmission of equine cyathostomes have been done in warm climates. Two Australian studies used experimentally-infected plots to determine hatching, development and survival of free living stages of equine cyathostomes. Four studies in the southern United States used pasture larval counts, and in some instances tracer animals, to determine seasonal availability of infective cyathostome larvae on naturally-infected pastures. With the exception of the dry Australian tropics, a general pattern of peak transmission of cyathostomes during the cooler seasons o...
Lyons ET, Tolliver SC, Drudge JH.Small strongyles are highly prevalent in horses and can be found worldwide. Even though over 50 species of these parasites have been described, about 10 species comprise the bulk of the total number present in horses. Efforts to control small strongyles and other equine internal parasites have been undertaken for many years. Some of the early medications and control measures provided questionable activity against endoparasites; whether effective or not, they could be detrimental to the horse. Beginning in the early 1900s, scientific effort was used to evaluate activity of antiparasitic compoun...
Duncan JL, Arundel JH, Drudge JH, Malczewski A, Slocombe JO.These guidelines have been designed to assist in the planning, operation and interpretation of studies which would serve to assess the efficacy of drugs against internal parasites of horses. Although the term anthelmintic is used in the title and text, these guidelines include studies on drug efficacy against larvae of horse bot flies, Gasterophilus spp, which are non-helminth parasites commonly occurring in the stomach of horses. The advantages, disadvantages and application of critical and controlled tests are presented. Information is also provided on selection of animals, housing, feed, do...
Grubbs ST, Amodie D, Rulli D, Wulster-Radcliffe M, Reinemeyer C, Yazwinski T, Tucker C, Hutchens D, Smith L, Patterson D.The safety and efficacy of 2% moxidectin/12.5% praziquantel oral gel administered at a rate of 0.4 mg moxidectin and 2.5 mg praziquantel/kg was studied in client-owned horses under field use conditions. Four hundred horses (300 treated with moxidectin/praziquantel oral gel and 100 treated with vehicle) were enrolled, feces were collected, and eggs were counted. Investigators as well as horse owners were masked to treatment assignment. No adverse reactions to treatment were observed in any horses. Moxidectin/praziquantel gel reduced Anoplocephala spp by more than 99% and provided a significant ...
Blaga R, Cretu CM, Gherman C, Draghici A, Pozio E, Noeckler K, Kapel CM, Dida I, Cozma V, Boireau P.Herbivorous animals are usually, by virtue of their diet, outside the major transmission cycles of Trichinella spp. However, since 1975, the year of the first report of human trichinellosis caused by the consumption of infected horse meat, the domestic horse has appeared as a novel vector of Trichinella spp. infection to humans, with 15 outbreaks documented in France and Italy. Romania, one of the main countries exporting horses into the European Union (EU), experienced a dramatic increase of Trichinella spp. infection in both domestic pigs and humans in the 1990s. Some Trichinella spiralis-in...
Fayer R, Dubey JP.Eight ponies and a horse were inoculated orally with sporocysts of Sarcocystis fayeri from dogs. They were examined for clinical signs of infection and killed 10, 15, 20, 25, 30, 50 (horse), 77, 101, and 156 days after inoculation (DAI). Elevated temperature was observed in three ponies 20 and 26 DAI and anemia was observed in three ponies and the horse 15 to 69 DAI. Schizonts were found in or near cells lining capillaries or arteries of the heart, brain, and kidney 10, 20, and 25 DAI. Immature cysts containing only metrocytes were first found in muscles 50 DAI. Mature intramuscular cysts cont...
Zouiten H, Berrag B, Oukessou M, Sadak A, Cabaret J.Sport and leisure horses in Morocco are treated with several anthelmintics, organophosphates (dichlorvos), benzimidazoles (mostly thiabendazole) or tetrahydropyrimidines (mostly pyrantel pamoate) against nematodes. We studied three horse stables in Rabat, one in Meknes and one in Bouznika. Two of the Rabat and Bouznika stables had introduced a large number of horses from countries (Argentina or Europe) where resistance to benzimidazoles is frequent, whereas the Meknes stud farm remained without foreign introduction. The number of treatments was not very frequent (twice a year in adult horses) ...
Borgsteede FH, Dvojnos GM, Kharchenko VA.The efficacy of treatment with cambendazole was tested in 1-year-old horses on a farm in Dubrovka, Ukraine. Thirty-five horses were treated. Their egg output was compared on the day of treatment and 14 days later with that of 33 untreated horses. Before treatment the mean number of eggs g-1 faeces was 614 in the controls and 766 in horses that had been treated. After 14 days the mean egg output in the controls was 580 and in the treated horses 369. This means a reduction of 54.5%. Only cyathostome larvae could be cultured from faeces collected after treatment. It can be concluded that benzimid...
Slocombe JO, Cote JF, McMillan I.Twenty-eight horses with a residual burden of strongyle eggs in the faces after treatment with mebendazole (MBZ) paste were treated with a suspension of either MBZ or oxibendazole (OBZ). Fecal samples were collected before and 14 days after these treatments. The number of strongyle eggs/g (epg) of feces for each horse was estimated using the Cornell-McMaster dilution and the Cornell-Wisconsin double centrifugation procedures. The epg for each horse was transformed using log (x + 1) and in an analysis of variance of the reduction in egg count for each horse on the logarithmic scale, there was a...
Greatorex JC.The clinical manifestations, diagnosis and differential diagnosis of "verminous aneurysm" formation at the root of the cranial mesenteric artery and coeliac artery resulting from Strongylus vulgaris larvae migration are described. Forty-nine of 57 cases were successfully treated with low molecular weight dextran (dextran 70).
Lyons ET, Tolliver SC.Macrocyclic lactones (MLs) revolutionized parasite control in horses and other animals. They are unique in that they are effective against arthropods and nematodes. The first of the widely used avermectins was ivermectin. In 1983, it was marketed for use in horses as an injectable formulation but was withdrawn in 1984 after about a year and half on the market because of adverse problems. It was replaced by a paste formulation and an oral/stomach tube liquid formulation. Ivermectin is highly active on bots, ascarids, large and small strongyles, pinworms, strongyloides, stomach worms, and some o...
Lyons ET, Tolliver SC, Stamper S, Drudge JH, Granstrom DE, Collins SS.Praziquantel injectable formulation was administered at 0.5 mg k-1 per os to 24 equids naturally infected with 1-183 (average 40) Anoplocephala perfoliata. Drug activity was evaluated by a modified critical test method with necropsy 24 h after treatment. There was variable efficacy of 0-100% (aggregate average 85%); for 18 equids, 93-100%, for three equids, 70-85%, and for three equids, 0-20%.
Herd RP, Stinner BR, Purrington FF.Environmental consequences of treating horses with recommended dosages of ivermectin paste were studied in two controlled experiments with 29 horses in Ohio. In 1988, dung dispersal rates were measured by changes in dry weight over time of 48 copromes (300 g) formed from feces taken from four treatment and four control horses 3 days post ivermectin treatment. There was delayed dispersal of copromes from horses treated with ivermectin in June, resulting in significantly heavier ivermectin copromes compared with those of control horses by September. There was no difference in ivermectin or contr...
Dávila AM, Souza SS, Campos C, Silva RA.Since little information is available on the epizootiological status of Trypanosoma evansi in South America and particularly Brazil, we evaluated equine serum samples collected in 1993, 1994, 1995 and 1997 for the presence of antibodies against this trypanosome species. Our study shows corroborative evidence about the correlation among high T. evansi seroprevalence and the rainy season in the Pantanal, Brazil. The higher seroprevalence was 79.2% in horses from a ranch located in the Nhecolândia sub-region in 1994 and the lower 5.8% in animals from the same ranch in 1997. No seroprevalence was...
Hatch C, McCaughey WJ, O'Brien JJ.During the months October-May inclusive 90-8% of horses slaughtered at an abattoir near Dublin and 66-9% of those at an abattoir near Belfast were infected with Gasterophilus intestinalis; 28-6% of horses at the former abattoir harboured G nasalis while none of the horses examined at the latter abattoir was found to be infected with this species.
MacKay RJ, Urquhart KA.Eight mature horses which had been affected with a moist cough for six weeks were found to have large numbers of eosinophils in tracheal mucus samples taken by transtracheal washing. These horses were kept on irrigated pasture and fed a hay-free diet. A companion yearling donkey was found to be passing Dictyocaulus arnfieldi larvae in its faeces. Two oral treatments with a dose of thiabendazole (440 mg/kg) resulted in the resolution of the clinical signs and the disappearance of eosinophils from transtracheal washings. The eosinophilic bronchitis seen in these horses was presumed to be a manif...
Brown CM, Slocombe RF, Derksen FJ.A method of fiberoptic gastroduodenoscopy and biopsy was developed for use in large horses. A 275 cm X 13.5 mm fiberendoscope was used to examine the stomach and proximal portion of the duodenum. Food was withheld for 24 to 48 hours before examination. In more than 50 horses, gastric and duodenal structures were easily visualized. A variety of lesions was detected, including parasitic lesions, gastric ulcers, gastric neoplasia, and pyloric stenosis. Mucosal biopsy specimens were obtained in selected cases.
Uhlinger CA.This article focuses on what has been established concerning the interaction of equine parasites and their hosts, highlighting those issues for which convincing data are still lacking. There is a compelling need for the participation of the veterinarian in the design of appropriate anthelmintic treatments and prevention strategies.
Machtinger ET, Geden CJ.House flies (Musca domestica L.) and stable flies (Stomoxys calcitrans (L.)) (Diptera: Muscidae) are common pests in equine and cattle facilities. Pupal parasitoids, primarily in the genera Spalangia and Muscidifurax (Hymenoptera: Pteromalidae), can be purchased for biological control of these flies. However, little is known about the host-habitat preferences associated with host-seeking by these parasitoids. The preferences of two Spalangia and two Muscidifurax species to odors associated with house fly hosts in equine and bovine manure were investigated in the laboratory using a Y-tube olfac...
Horak IG, Knight MM, de Vos V.The arthropod parasite burdens of 14 Cape mountain zebra (Equus zebra zebra), shot for survey purposes in the Mountain Zebra National Park in the eastern Cape Province, were determined. Three species of Gasterophilus larvae and 9 ixodid tick species were recovered. Larvae of Gasterophilus pecorum were the most numerous of the fly larvae recovered and Margaropus winthemi was the most abundant tick. Two horses examined in the park were infested with 3 species of Gasterophilus larvae and 7 species of ixodid ticks.
Zhang K, Zhou R, Huang H, Ma W, Qi Y, Li B, Zhang D, Li K, Chu H.The aim of this study was to identify the aggregation sites and transmission characteristics of Gasterophilus pecorum, the dominant pathogen of endangered equines in desert steppe. Therefore, we tested with a four-arm olfactometer the olfactory response of the G. pecorum adults to the odors that have a great impact on their life cycle, and also investigated the occurrence sites of the adults in the area where the Przewalski's horse (Equus przewalskii) roam frequently during the peak period of G. pecorum infection. The results of four-directional olfactory test showed that the fresh horse feces...
Deprez P, Vercruysse J.The results of the treatment with moxidectin or ivermectin of 20 horses with clinical cyathostominosis were studied during a 3-week observation period. Both treatments were effective in completely eliminating larvae from the faeces within 1 or 2 weeks, but no significant improvement in body weight or clinical parameters could be demonstrated over the observation period. The poor short time results of the treatment support the need for an adequate prevention of cyathostominosis in horses.
Aromaa M, Hautala K, Oksanen A, Sukura A, Näreaho A.One-hundred-and-thirty-nine fecal samples were examined to assess the prevalence of Parascaris spp. and strongyle infections in two-year-old or younger horses in Finland. The owners of the horses were asked to answer an online questionnaire about the horses' environment and the management practices of the stable. The results of fecal examination and the survey were analyzed to evaluate the effect of different risk factors as ascertained by the survey on parasite prevalence. The prevalence of Parascaris spp. infections at 11.5% was lower than expected based on previous research and the strongyl...
Javanshir A, Tavassoli M, Esmaeilnejad B.Trypanosoma evansi, the causative agent of "surra" is enzootic in Iran. The current study aimed to detect T. evansi in horses from different regions of Iran using morphological, serological, and molecular methods. In 2021, 400 blood samples were collected from horses in eight regions. Eighty horses showed clinical signs such as cachexia (n = 64), fever (n = 36), foot edema (n = 40), and abdominal edema (n = 32), and 320 horses appeared healthy. All samples from the studied regions were evaluated for the presence of trypanosomes using direct analysis of blood smears, mercuric chloride, and PCR-...
Klei TR, Turk MA, McClure JR, Holmes RA, Dennis VA, Chapman MR.Eight of 10 pony foals reared under helminth-free conditions were inoculated PO with 50 Strongylus vulgaris infective larvae/week for 4 weeks, at which time 1 foal died of acute verminous arteritis. Inoculation of 7 remaining foals continued at 2-week intervals for 20 weeks. Of the 7 foals, 3 were treated with ivermectin (0.2 mg/kg of body weight) in an oral paste formulation at experiment weeks 8, 16, 24; 4 foals were not treated. Two foals were not inoculated or treated and served as controls. After the first ivermectin treatment, ivermectin-treated foals had fewer days (12 +/- 2.9) with rec...
Ural K, Ulutas B, Kar S.The purpose of this prospective, double-blinded, placebo-controlled clinical trial was to investigate the efficacy of topical eprinomectin for the treatment of psoroptic mange infestation in horses. 24 privately owned hunter/jumper and dressage horses were diagnosed with psoroptic mange infestation based on physical findings and skin scraping results were enrolled and randomly assigned to either topical eprinomectin pour-on solution (at a dose of 500microg/kg body weight weekly once for four applications) treatment group or a placebo group (purified water). Clinical evaluations and skin scrapi...
Bonneau S, Maynard L, Tomczuk K, Kok D, Eun HM.In this blinded randomized and controlled study, the anthelmintic efficacy of a tablet formula of ivermectin-praziquantel was evaluated in horses experimentally infected with three species of Strongylus larvae. Eighteen previously dewormed horses were inoculated on study day 0 with third-stage larvae of Strongylus vulgaris, Strongylus equinus, and Strongylus edentatus. The horses were randomly allocated to three groups (n = 6): test-drug (tablet formula), positive-control (reference gel), and negative-control (placebo tablet). On day 56, the horses were treated once with the respective drugs. ...
Vibe-Petersen G, Nielsen K.Based upon case reports from 36 cases of verminous thrombosis of arteria mesenterica cranialis--all of which were verified at necropsy--clinical symptoms, course and pathological lesions are described. Seventy five per cent of the patients were under 3 years old, and 73% of the cases showed initial signs during the period July-December. Salient clinical findings were, unthrifty appearance and emaciation, diarrhoea--observed in two thirds of the patients--and colic--observed in 50 per cent of the cases. Haematological and biochemical findings were inconclusive, yet, hypoproteinaemia was a rathe...
Lyons ET, Dorton AR, Tolliver SC.Activity of fenbendazole (FBZ), oxibendazole (OBZ), piperazine (PIP) and pyrantel pamoate (PRT) alone and combinations of OBZ and PIP and of OBZ and PRT was evaluated against parascarids, strongyles and strongyloides in horse foals (n=281).This was on two farms - Farm A - mixed light-horses (n=26) and Farm B-Thoroughbreds (n=255) - in Central Kentucky in field tests in 2014 and 2015. Foals on both farms were treated one to three times each; an exception was that seven foals on Farm A were nontreated controls. Before treatment, the foals on Farm A were all weighed on scales but weights for Farm...
Slocombe JO, McCraw BM.Four pony foals were inoculated with Strongylus edentatus infective larvae and on days 3 and 4 postinfection two of the ponies were treated with thiabendazole, each at the rate of 440 mg/kg of body weight. Total circulating eosinophil counts in untreated ponies increased to over 1700 per cu mm after the second week postinfection. In the treated ponies as well as in an uninfected untreated pony eosinophil counts did not increase beyond 100 per cu mm. At necropsy on day 35 postinfection the cecum, colon and omentum of treated ponies were normal and few tracks were present on the surface of the l...
Eysker M, van Doorn DC, Lems SN, Weteling A, Ploeger HW.Due to excessive and inappropriate use of dewormers anthelmintic resistance has developed as a significant problem in horse parasites in the Netherlands. Since it is unlikely that new classes of anthelmintics against horse nematodes will be introduced in the near future, it is important to use the present drugs wisely. Veterinarians should advice horse owners about worm control programs with a more targeted approach. The number of anthelmintic treatments should be reduced and, through selective anthelmintic treatments, further development of anthelmintic resistance should be delayed. Preferabl...
Maldonado-Cabrera B, Sánchez-Machado DI, López-Cervantes J, Osuna-Chávez RF, Ibarra-Zazueta C, Robles-Zepeda RE.Consultation was requested for a 7-year-old Gypsy Vanner male horse with a 2-year history of foreskin injury. Upon revision, an ulcer, 153 cm2 in size, with yellowish granules was observed; a RESVECH 2.0 evaluation revealed a score of 32/35 points. Medical history confirmed multiple failed deworming, anti-inflammatory, and antibiotic treatments with different topical therapies and recurrence in summer. Laboratory results confirmed elevated total proteins (8.8 g/dL) and globulins (5.5 g/dL), negative bacterial and fungal cultures, as well as negative coproparasitoscopic findings, and finally, i...
