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.
Pandey VS.Between August 1978 and July 1979 the anterior mesenteric artery and its branches were collected regularly from adult horses and examined for Strongylus vulgaris larvae. The incidence of infection varied from 55 to 100% (annual mean 80%). The mean monthly number of larvae ranged form 3 to 22 with an annual overall mean of 13. The arterial infection was at its minimum in December to January, rose gradually to attain the peak in June and declined thereafter. These observations indicated that S. vulgaris is an annual species in Morocco, infection occurring during the rainy season (November-April)...
Austin RJ, Dies KH.The protozoan, Klossiella equi was found in the kidneys of an aged Shetland mare raised in the Fredericton area of New Brunswick. This is the first published report of K. equi in a horse in Canada. The microscopic appearance of the parasite in the kidney is described. A brief discussion of other conditions seen in the horse is also presented.
Webster JH, Baird JD, Gunawan M, Martin IC, Kelly JD.The susceptibility of a known thiabendazole-resistant population of small strongyles to anthelmintics of both benzimidazole and non-benzimidazole groups, was determined. In the first study, 42 horses infected with thiabendazole-resistant small strongyles were allocated to 6 groups. Treatment groups received one of the following anthelmintics: mebendazole, febantel, febantel plus trichlorphon, morantel tartrate, or a combination of thiabendazole, piperazine and trichlorphon. Morantel tartrate and the thiabendazole/piperazine/trichlorphon combination produced highly significant (p less than 0.00...
Kelly JD, Webster JH, Griffin DL, Whitlock HV, Martin IC, Gunawan M.A survey was conducted to determine whether benzimidazole resistant populations of equine strongyles are present in New South Wales and north central Victoria; what is their frequency and geographical distribution; which species are involved; and whether different methods of parasite control could be related to the occurrence and frequency of anthelmintic resistant populations. Resistant populations of strongyles were found over wide areas of New South Wales and in north central Victoria. There was no relationship between geographical location and the occurrence of benzimidazole resistance. Th...
Baker JR, Ellis CE.The causes of death recorded in 480 consecutive post mortem examinations of horses performed at the department of pathology, Veterinary Field Station, University of Liverpool, between February 1958 and February 1980, are reported. The alimentary, locomotor and nervous systems were those most frequently diseased. The most common specific entities were those associated with grass sickness, fractures and endoparasitism.
Erber M, Geisel O.The prevalence of Sarcocystis spp. in horses was investigated in a survey at the Munich abattoir during 1978/79. Muscle specimens (oesophagus, diaphragm, sublingual muscle, myocardium) were examined using tryptic digestion. Out of 200 horses 31 (15.5%) were found to be carriers of sarcocysts. No parasites were found in the myocardium. In three animals sarcocysts could be isolated and differentiated in fresh preparations. Cysts with 5 to 11 microns by less than 0.5 microns hairlike, unstable protrusions were classified as Sarcocystis equicanis, whereas those with 2.5 to 4.5 microns by 0.8 to 1....
Cranley JJ, McCullagh KG.The hearts and aortas of 2076 unselected horses of all ages were examined immediately after slaughter. Focal zones of fibrosis, observed in the myocardium of 14.3 per cent of hearts examined, were found in both atria and ventricles and were unrelated to age. Microscopically the majority of lesions involved myocardial fibre lysis and replacement fibrosis, although acute infarction was present in some cases. Intramyocardial arterioles in or adjacent to the lesions exhibited occlusive arteriosclerotic changes whereas those elsewhere remained patent. The evidence strongly suggests that the myocard...
Pecheur M.A number of good anthelmintic drugs are currently available which eliminate gastrointestinal nematodes of equids with over 90% success. This is shown by comparing results of critical tests conducted with 9 anthelmintic agents on ponies using the following dosages: 19 mg/kg for Pyrantel embonate, 10 mg/kg for Oxfendazole, 10 mg/kg for Mebendazole, 5 mg/kg for Albendazole, 40 mg/kg for Dichlorvos, 44 mg/kg for Thiabendazole, 7.5 mg/kg, for Fenbendazole, 20 mg/kg for Cambendazole and 7 mg/kg for Parbendazole. From 6 to 9 ponies were treated with each of these anthelmintic agents. Based on total a...
Louw JP, Meyer S, Schröder J.The anthelmintic efficacy of a 44.5% paste formulation of cambendazole was evaluated in a critical trial performed on 5 horses and a donkey. A dosage of 20 mg/kg showed reduction of mean parasite burdens as follows: Strongylinae greater than 99%; Cyathostominae 94%; immature and adult Oxyuris equi 89 and greater than 99%; Probstmayria vivipara greater than 99% and Habronema muscae 97%. Parascaris equorum and Anoplocephala perfoliata were present in small numbers in individual animals only, and while all were removed by treatment, the small numbers did not justify calculation of a percentage ef...
Malan FS, Reinecke RK.A single oral dose of fenbendazole (FBZ) at 10mg/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 10mg/kg body mass. In both trials FBZ was highly effective against adults of the following genera: Cyathostomum, Cylicocyelus, 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 subf...
Klei TR, Torbert BJ.The controlled test method was used to evaluate the antiparasitic efficacy of IM inoculated 22,23-dihydroavermectin B1 (ivermectin) against gastrointestinal parasites of horses (ponies). Parasite infections were naturally acquired in southern Louisiana. Dose levels of the drug tested were 0.2 mg/kg, 0.3 mg/kg, and 0.5 mg/kg. Ivermectin at all dose levels tested had an efficacy greater than 97% (P less than 0.05) against Gasterophilus intestinalis larvae, Trichostrongylus axei, Oxyuris equi larvae, Strongylus vulgaris, S edentatus, 15 species of small strongyles, and small strongyle larvae. Pon...
Pandey VS.The lungs and livers of 429 adult donkeys from different parts of Morocco were examined for hydatid cysts; 4·2% of lungs were infected and 2·1% of livers. Most of the cysts were small and had very hard thick walls; 61% of the donkeys had only one hydatid cyst; 78·5% of them were sterile and 29% caseated or calcified.
Al-Khalidi NW, Weisbrode SE, Dubey JP.Nine ponies were fed 100,000 infective Toxoplasma gondii oocysts and were given corticosteroid injections before and after feeding the T gondii oocysts. Titers to the Sabin-Feldman dye tests (1:2 to 1:16,384) developed within postinoculation days (PID) 7 to 21 and antibodies persisted to PID 133. Toxoplasma organisms were isolated from the tissues of 4 ponies (heart of 4, brain of 2, spinal cord of 3, diaphragm of 1, skeletal muscle of 1, liver of 1, kidneys of 1) killed between PID 36 and 63, but not from 5 ponies killed between PID 117 and 150. Seemingly, ponies are one of the more resistant...
Drudge JH, Lyons ET, Tolliver SC.The basic-dose confirmation tests of tioxidazole for removal of susceptible populations of gastrointestinal parasites of the horse were made in 10 naturally infected horses, using the critical test method (experiment A). A single dose of toxidazole, given at the rate of 11 mg/kg of body weight, was administered to 5 horses by stomach tube and to 5 horses by mixing the drug with the daily grain ration. In the 5 horses given the drug by stomach tube, aggregate average removals were 90% or more for 5 horses infected with Stronglyus vulgaris, 5 infected with S edentatus, 5 infected with small stro...
Simpson CF, Taylor WJ, Kitchen H.Four splenectomized Welsh ponies were infected with Babesia equi. Two ponies were treated with imidocarb dipropionate, and two were not treated. By light microscopic examination, 1% to 2% of the parasitized erythrocytes of treated ponies contained crystalline inclusions. The crystals were rectangular, diamond, or burr shaped. They occupied most of the erythrocytic cytoplasm, and, as a result, the remainder of the pale staining cytoplasm was inconspicuous in Wright-Giemsa-stained blood smears. The size and shape of intraerythrocytic inclusions varied when examined by electron microscopy, but in...
Rao UR, Chapman MR, Singh RN, Mehta K, Klei TR.Transglutaminases (E.C. 2.3.3.13) are a family of Ca(2+)-dependent enzymes that stabilize protein structure by catalyzing the formation of isopeptide bonds. A novel form of transglutaminase has been identified and characterized that seem to play an important role in growth, development, and molting in adult and larval stages of filarial nematodes. The aim of this study was to identify the ubiquitous nature of this enzyme in other nematodes and to measure its significance to larval growth, molting, and development. For this purpose, equine Strongylus spp. were used. Activity of this enzyme was ...