Gasterophilus species, commonly known as horse botflies, are parasitic insects that affect horses. These flies lay their eggs on the horse’s body, and the larvae, upon hatching, migrate to the mouth and gastrointestinal tract. The presence of Gasterophilus larvae can cause irritation and potential damage to the oral and gastric mucosa. The lifecycle of these parasites involves several stages, including egg laying, larval development, and eventual passage through the digestive system. Understanding the biology and impact of Gasterophilus species is important for managing their effects on equine health and welfare. This page compiles peer-reviewed research studies and scholarly articles that explore the lifecycle, epidemiology, and control measures of Gasterophilus species in horses.
Two closed horse herds (Old Lot 4 and Field 24), infected since 1966 with Population B small strongyles resistant to thiabendazole (TBZ) and phenothiazine (PTZ), were terminated in February, March, and May, 2005. At necropsy, only the large endoparasites were identified and counted. The number of horses on pasture was 14 (239 days of age to 23 years old) for Old Lot 4 and two (3 to 20 years old) for Field 24. The time of the last antiparasitic treatment, relative to the year (2005) of necropsy, was 26 years for Old Lot 4 and 9 years for Field 24 horses. Gasterophilus intestinalis third instars...
Lyons ET, Drudge JH, Tolliver SC.Critical tests of the activity on large strongyles, ascarids, mature pinworms, and bots were carried out in 11 horses intraorally treated with a paste formulation of thiabendazole. The dose level of 44 mg/kg was administered to 3 horses, and the dose level of 88 mg/kg to 8 horses. Removals of Strongylus vulgaris and mature Oxyuris equi were 100% at the 2 dose levels, and efficacy against Strongylus edentatus varied from 95 to 99% and 89 to 100% for the 44- and the 88-mg/kg dose levels, respectively. Strongylus equinus was completely removed from the 1 infected horse treated at the dose level o...
Bauer C, Bürger HJ.A paste formulation containing 14.3 per cent of oxibendazole and 44 per cent of trichlorfon was administered to 33 ponies and horses. The dose rate used was equivalent to 10 mg and 30 mg/kg bodyweight, of oxibendazole and trichlorfon respectively. After treatment 25 animals passed between one and 82 third stage larvae of Gasterophilus intestinalis in their faeces. Dosing with 0.2 mg ivermectin/kg bodyweight three weeks later resulted in six animals expelling between one and four bots. The efficacy of the oxibendazole-trichlorfon paste was on average 96.2 per cent. This drug combination given t...
Roelfstra L, Vlimant M, Betschart B, Pfister K, Diehl PA.A morphological study of the midgut and salivary glands of second and third instars of Gasterophilus intestinalis (De Geer) (Diptera: Oestridae) was conducted by light, scanning and transmission electron microscopy. The midgut is anteriorly delimited by a proventriculus, without caeca, and is composed of posterior foregut and anterior midgut tissue from which a double-layered peritrophic matrix is produced. The midgut can be divided into anterior, median and posterior regions on the basis of the structural and physiological variations of the columnar cells which occur along its length. Two oth...
Kingsbury PA, Reid JF.Oxfendazole was administered in paste or drench formulations to groups of five horses carrying naturally acquired worm burdens. At a dose rate of 10 mg/kg the efficacy of either formulation appeared similar. One hundred per cent of the adult populations of the following genera was removed: Parascaris, Oxyuris, Strongylus (S edentatus, S vulgaris), Triodontophorus and Trichostrongylus axei. Efficacy against adult small strongyles, adult Habronema microstoma and immature Oxyuris equi was in the region of 96 to 99 per cent. The level of efficacy against immature small strongyles was at least 74 t...
Brocard P, Pfister K.The combined drug Mebendazole plus Trichlorfon (Telmin plus Trichlorfon, Janssen Pharmaceutica, Beerse/Belgium) has been tested in a field trial against naturally acquired Gasterophilus spp. infestations in horses. 44 foals (1 to 1.5 years old, 350-450 kg body-weight) originating from different endemic areas of Switzerland, have been randomly allocated to two groups as follows: 28 foals were treated with Mebendazole plus Trichlorfon, 16 animals served as untreated controls. The drug (paste) was administered and dosed according to the user's instruction. Macroscopic examinations of the digestiv...
Gawor JJ.The digestive tracts of 50 working horses from private farms in Poland were examined. Thirty-seven nematode species, two tapeworm species and one species of botfly were recovered. The most prevalent small strongyle species were Cyathostomum catinatum, Cylicocyclus nassatus, Cylicostephanus goldi, Cylicostephanus longibursatus, Cyathostomum coronatum, Cylicostephanus calicatus, Cylicocyclus leptostomus and Cylicostephanus minutus. Thirteen cyathostome species showed a site preference in the ventral colon, five in the dorsal colon and three in the caecum. One species, Cylicocyclus triramosus, wa...
Al-Mokaddem AK, Ahmed KA, Doghaim RE.Donkeys (Equus africanus asinus) are important working animals, particularly in countries where the majority of the population lives below the poverty line. Gastric ulceration has been shown to be common in British donkeys but donkeys from other parts of the world have not been as extensively researched. Objective: This study was performed as a preliminary overview of the severity and distribution of gastric lesions in mature donkeys and to document which parasites were present. Methods: Descriptive study of pathological findings. Methods: Stomachs of 35 mature draught donkeys were examined gr...
Costa AJ, Barbosa OF, Moraes FR, Acuña AH, Rocha UF, Soares VE, Paullilo AC, Sanches A.A total of 24 male and female equines of mixed breed, 10-20 months of age and naturally infected with internal parasites was utilized in a controlled test to evaluate the efficacy of a moxidectin 2% gel formulation at the dosage of 0.4 mg moxidectin per kg of live weight and an ivermectin 1.87% commercial paste formulation at the dosage 0.2 mg ivermectin per kg applied orally. Animals were allocated into three groups of eight horses each based on pre-treatment eggs per gram (EPG) counts and treatments were randomized among the groups. One group was kept as untreated controls. One animal in the...
Presson BL, Hamm D, Yazwinski TA, Pote LM.Critical tests were performed on 6 horses to evaluate the antiparasitic effectiveness of oxfendazole given in combination with trichlorfon in a paste formulation. Treatments were given orally as a single dose. The rates of active ingredient administration were 2.5 and 40 mg/kg of body weight for oxfendazole and trichlorfon, respectively. The combined activities of the 2 antiparasitic compounds proved 100% efficacious in the removal of adult Strongylus vulgaris, S edentatus, Oxyuris equi, and Parascaris equorum. Fourth stage O equi, and 2nd and 3rd instars of Gasterophilus nasalis also were com...
Two closed horse herds (Old Lot 4 and Field 24), infected since 1966 with Population B small strongyles resistant to thiabendazole (TBZ) and phenothiazine (PTZ), were terminated in February, March, and May, 2005. At necropsy, only the large endoparasites were identified and counted. The number of horses on pasture was 14 (239 days of age to 23 years old) for Old Lot 4 and two (3 to 20 years old) for Field 24. The time of the last antiparasitic treatment, relative to the year (2005) of necropsy, was 26 years for Old Lot 4 and 9 years for Field 24 horses. Gasterophilus intestinalis third instars...
Ribbeck R, Ilchmann G, Hiepe T.Research into the immunological diagnosis of gasterophilosis. So far there have been no reliable methods of diagnosing equine gasterophilosis intra vitam. Horses from the G.D.R. and the M.P.R. spontaneously infected with Gasterophilus spp. were tested for antibodies by the immunotechniques of counterimmunoelectrophoresis after Pesendorfer, passive haemagglutination and the intradermal test using antigen made from larvae of all 6 Gasterophilus spp. present in the palaearctis. All 3 techniques produced positive results. The intradermal injection produced an immediate reaction. A correlation betw...
Kraouchi DE, Meradi S, Bentounsi B.The composition, prevalence, and seasonal dynamic of species were studied at the slaughterhouse of Constantine region (East Algeria) in 128 horses over an 18 months period. Our survey revealed that 124 (96.9%) horses were infected with a mean intensity of 161 larvae of spp. Four species of were identified; and were by far the predominant species with 95.3% and 77.3% respectively, followed by (14.0%) and (10.1%). The age, sex, and breed of horses did not affect the distribution of the infection. Second-stage larvae (L2) of were absent between April and July and present in higher numbers...
Drudge JH, Lyons ET, Tolliver SC.Critical tests were carried out in 10 horses to evaluate the antiparasitic activity of febantel given alone or with trichlorfon. Paste formulations were administered intraorally at dose levels of 6 mg of febantel (active ingredient)/kg and 35 mg of trichlorfon (active ingredient)/kg. In 5 tests with febantel alone, removal of 100% was recorded for mature or immature Parascaris equorum from 2 infected horses. Strongylus vulgaris from 4 infected horses, S edentatus from 5 infected horses, and mature Oxyuris equi from 1 infected horse; and removal of 96% was recorded for small strogyles from 1 ho...
Lyons ET, Bolin DC, Bryant UK, Cassone LM, Jackson CB, Janes JG, Kennedy LA, Loynachan AT, Boll KR, Burkhardt AS, Langlois EL, Minnis SM, Welsh SC....Parasite infections are more quantifiable postmortem than antemortem in horses. Thus a study was carried out examining dead horses for specific parasite species. Most of the weanling and older horses submitted to the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) for postmortem examination between November 22, 2016 and March 23, 2017 were examined for certain species of internal parasites. The stomach and duodenum from 69 horses were examined for bots (Gasterophilus spp.). Combined data for both Thoroughbred and non-Thoroughbred (16 other than Thoroughbred breeds/mixed breeds)...
Rabei ȘO, Cârstolovean AS, Culda CA, Mihalca AD.This is the first study that targets the epidemiology of Gasterophilus spp. in slaughtered horses from Romania. Previously to our research, there were five recorded species: Gasterophilus haemorrhoidalis, Gasterophilus inermis, Gasterophilus intestinalis, Gasterophilus nasalis, and Gasterophilus pecorum with a dispersed distribution throughout the country, the data being recorded more than 73 years ago. The collection of Gasterophilus larvae was carried out from the digestive system (stomach, duodenum, and rectum) of horses in three abattoirs, monthly between January 2023 and December 2023. Fo...
