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.
Duncan JL, McBeath DG, Preston NK.The efficacy of a fenbendazole divided dose regime against immature stages of Trichonema spp, Strongylus vulgaris and Strongylus edentatus was evaluated. A group of 8 naturally infected 30 to 36-month-old ponies was divided into 2 equal groups on the basis of previous treatment and faecal egg counts, one group being treated with 7.5 mg/kg bwt of fenbendazole daily for 5 days. This treatment regime removed 80 per cent of migrating S vulgaris larvae, 100 per cent of migrating S edentatus larvae and 95 per cent of the mucosal stages of Trichonema spp. In addition, a virtual 100 per cent eliminati...
Urch DL, Allen WR.The efficacy of orally administered fenbendazole on lung and intestinal parasitism in equids was investigated in a mixed herd of pony mares, jenny donkeys and foals. A single dose of 7.5 mg fenbendazole/kg body weight effectively removed intestinal parasites from the ponies, donkeys and foals, but higher doses and repeated treatments failed to eliminate lungworm infections in donkeys. The finding of eosinophilia proved useful in detecting lungworm infections in donkeys.
Georgi JR, Rendano VT, King JM, Bianchi DG, Theodorides VJ.Albendazole was effective in destroying Strongylus vulgaris larvae in verminous lesions of the cranial mesenteric artery when administered as a 20% suspension by stomach tube to ponies. Fifty mg/kg body weight administered twice a day for 2 days caused death and gradual disintegration of larvae over a period of 3 to 6 weeks with mild toxic signs appearing in 3 of 11 ponies. Higher total doses of albendazole (50 mg/kg twice a day for 4 days and 25 mg/kg three times a day for 5 days) lead to more rapid disintegration of the larvae but fatal toxicity was observed in 3 of 6 ponies so treated. In a...
Reinecke RK, Loots LJ, Reinecke PM.Dichlorvos in a special slow release formulation at 31 mg/kg body mass in equines was highly effective against all adult strongyles and Oxyuris equi, Parascaris equorum, Probstmayria vivipara and bots of Gasterophilus spp. It has no effect on 4th stage larvae of Trichonema ssp. nor the stomach worms Draschia megastoma and Habronema spp. Doses of dichlorovos 10 and 20 times the therapeutic dose (310 and 620 mg/kg body mass) caused transient clinical signs but these disappeared 96 hours after dosing.
Donnelly J, Joyner LP, Graham-Jones O, Ellis CP.The incidence of antibodies to Babesia equi and B. caballi in horses in the Royal Stables of His Majesty the Sultan of Oman was assessed by complement fixation (CF) and immunofluorescent antibody (IFA) tests. Two series of samples taken with a 2-year interval, mainly from animals reared in Oman, indicated a stable but high prevalence of antibodies. On the 2 occasions 94.6 and 97.7% respectively were positive to B. equi by IFA and 76.8 and 75.0% were positive by CF. For B. caballi the corresponding percentage figures were lower--67.9 and 40.9 by IFA and 30.4 and 40.9 by CF. A group of animals t...
Simpson CF, Neal FC.Four splenectomized ponies were infected with Babesia equi. Two ponies were not treated, and two were treated with 5 mg of imidocarb/kg of body weight when 20% of their erythrocytes were parasitized. The nucleus of the parasite in erythrocytes from blood smears of nontreated ponies was roundish, deep red-staining, and usually composed two-thirds of the organism. The parasite in erythrocytes from blood smears of treated ponies was swollen and vacuolated except for an area just beneath the plasma membrane where the compressed nucleus was marginated, elongated, and clumpy. Parasites in erythrocyt...
Lyons ET, Drudge JH, Tolliver SC.Critical tests were conducted in 11 naturally infected horses to evaluate the anthelmintic activity of parbendazole. Single doses at the rates of 30, 20, 10, 5, or 2.5 mg/kg of body weight were administered by stomach tube to 1, 4, 2, 2, and 2 horses, respectively. Parbendazole was active against Parascaris equorum, Oxyuris equi, Strongylus vulgaris, Strongylus edentatus, and small strongyles throughout the range of doses. Generally, small numbers of P equorum were present, but apparently a dose rate higher than 2.5 mg/kg is necessary for complete clearance. Removal of O equi was virtually 100...
Clayton HM, Duncan JL, Dargie JD.The mechanisms involved in the pathophysiological disturbances associated with the presence of mature Parascaris equorum in the small intestine were investigated with radioisotopic techniques. The results suggested that, compared with worm-free controls, infected foals had a reduction in gut motility, an increase in the body solids ratio, a lowering of the body pool of albumin and a decreased ability to incorporate dietary methionine into plasma protein.
Slocombe JO, McCraw BM.Trials were conducted in ponies to evaluate the efficacy of pyrantel pamoate (Strongid-T(R)) and two newer anthelmintics not yet commercially available, nitramisole and avermectin B(1)a, against migrating Strongylus vulgaris larvae. Ponies were removed from their mares within 24-48 hr after birth and reared in isolation, worm free. Between six and 14 weeks of age they were infected with 2000 or 2500 infective S. vulgaris larvae. Subsequently, they were monitored daily for clinical signs until the experiment terminated at 28 days postinfection. All ponies showed increased body temperature and r...
Barger IA, Lisle KA.Treatments with mebendazole, cambendazole or febantel were ineffective in reducing the faecal egg count of a group of 40 horses infected with small strongyle species. Evidence was also obtained that this apparent resistance extended to fenbendazole. In horses dosed with morantel tartrate egg counts were reduced to zero by 7 days after treatment. The development of resistance is discussed in relation to previous treatment of the horses and the mode of action of febantel.
Malan FS, Reinecke RK.A single oral dose of fenbendazole (FBZ) at 10 mg/kg body mass was given to 5 donkeys. A further 5 donkeys were dosed with a medicated lick (1 mg FBZ/g lick) until the oral consumption was 10 mg/kg body mass. In both trials FBZ was highly effective against adults of the following genera: Cyathostomum, Cylicocyclus, Cylicostephanus, Cylicodontophorus, Poteriostomum, Cabellonema, Craterostomum and Triodontophorus; similarly high efficiency was obtained against the following species: Habronema majus, Habronema musca, Strongylus vulgaris and Oxyuris equi and worms identified as belonging to the su...
Callow LL, McGregor W, Rodwell BJ, Rogers RJ, Fraser GC, Mahoney DF, Robertson GM.An indirect fluorescent antibody (IFA) test for the diagnosis of Babesia equi infections was evaluated. Antigen prepared by conventional methods was of high quality in one instance and of lesser quality in a second when possible autofluorescence of the horse blood caused inconvenience in reading tests. Tests on 14 horses shown by parasitological means to be either infected (9) or uninfected (5) produced reactions at dilutions of 1/270 to 1/7290 for infected and at 1/10 to 1/90 for uninfected animals. The accuracy of the test was further demonstrated during investigations of 701 horses in 3 sta...
Clayton HM, Duncan JL, Gilbert GA.Over a period of several years the use of pyrantel embonate in the control of helminth infections on three equine establishments was monitored by the examination of faecal samples collected immediately before each anthelmintic treatment. With a monthly interval between treatments for three years the faecal egg output of the horses remained at a very low level. One one establishment this was maintained when the treatment interval was extended to one-and-a-half months after treating monthly for two years. If a treatment interval of one-and-a-half months was used continuously for a number of year...
Rendano VT, Georgi JR, White KK, Sack WO, King JM, Bianchi DG, Theodorides VJ.Albendazole was an effective larvicidal anthelmintic against the fourth stage Strongylus vulgaris larvae as late as one month post-infection. The drug was administered at a dose rate of 25 mg/kg three times daily for 5 days. Diarrhoea occurred in 3 of 4 foals treated and of these one died during belated intravenous therapy for dehydration. Arteriography allowed for an in vivo assessment of the development and regression of lesions in infected-treated foals compared to the continued development of lesions in infected-untreated foals. The arteriographic findings were confirmed at necropsy.
Rastegaev IuM.In Burjatia and Mongolia the infection of horses with rhinoestrosis and gastrophilosis accounts for 97.8-99.2% and 98.9-99.5%, respectively at the infection intensity 34 to 721 and 55 to 1473 larvae. The sheep botfly is represented by one and the horse botfly by six species; they have one generation a year. The flight of the horse botfly begins from the second decade of June and ends in the second decade of September; the flight of the sheep botfly begins in the third decade of June and ends in the first decade of September. The pupil stage lasts 20 to 61 days.
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...
Marlow CH.Horse breeding in South Africa started in 1652, shortly after the 1st European settlement in the Cape. African horsesickness posed a serious problem and after a devastating outbreak of the disease in 1719, horses were largely replaced by oxen for agricultural and transport purposes but remained important from a sporting and military point of view. Examples of the latter are the export of horses for military use to India in the mid-19th century and for use in the Crimean War in 1854, reaching a zenith in the Anglo-Boer war in which an estimated 450 000 horses succumbed. Research and disease con...
Apolinário ECF, Oliveira LLDS, Rocha RHF, Silva FVE, Santos IS, Alves CA, Dias Júnior JA, Mendes LJ, Lima WDS.The intensive use of anthelmintics has resulted in resistant parasite populations in horses. The objective of this trial was to evaluate the anthelmintic efficacies of the anthelmintics fenbendazole, ivermectin and abamectin in 24 horse farms in Northern Minas Gerais. Egg counts per gram of faeces (EPG) were performed individually in 619 animals. Animals presenting EPG counts greater than or equal to 150 were used in the tests on faecal egg count reduction (FECR), totalling 436 equines. These animals received the anthelmintics, fenbendazole, ivermectin, and abamectin. Faeces were collected 14Â...
Williams PF, Brooks SP, Cooper DR.Sir, — We wish to report the death of a foal due to a parasitic lesion caused by Parascaris equorum..P equorum is reported to cause periodic colic, enterilis, obstructive colic with occasional rupture of the small intestine. However, personal communications with other veterinarians and our experience indicate fatal cases are not as common as indictaed in the literature.
DE SALES JF, JANSEN J.Xenodiagnosis for habronemosis was 96,6% positive in 87 stud horses at Instituto Oswaldo Cuz, Rio de Janeiro, Brazil, from July-November, 1944. The A A. were unable to identify the Habronema larvae obtained from parasitider fly maggots. Measurements and drawings of the larvae are presented.
Smith MA, Carpenter AB, Nielsen MK.Essentially all grazing horses are infected with cyathostomin parasites. Adult cyathostomins reside in the large intestine of the horse and larval stages encyst within intestinal mucosa. Manual worm collection from aliquots of intestinal content is the current gold standard for retrieval and enumeration of luminal parasites, however, no research has been conducted to standardize specific parameters for processing and storage of samples. The aims of this study were (1) to evaluate the precision of current standard operating procedures for enumeration of luminal adult cyathostomin populations, (...