Topic:Parasites
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.
Parasites in Kentucky Thoroughbreds at necropsy: emphasis on stomach worms and tapeworms. A total of 363 Thoroughbreds (62 males, 292 females, and 9 geldings), 1 to 26 years of age, were examined at necropsy for internal parasites for about a 12-month period from February 1981 through February 1982. Emphasis was on examining the stomach for nematodes and the small intestine and cecum for tapeworms. Parasites recovered from the stomach and infection rates were: Habronema spp--immature (24%), H muscae--adult (38%), Draschia megastoma--immature (13%), D megastoma--adult (62%), and Trichostrongylus axei--adult (4%); lesions caused by D megastoma were found upon gross observation in 58%...
Antibody responses of ponies to initial and challenge infections of Strongylus vulgaris. An indirect fluorescent antibody assay (IFA) was developed using Strongylus vulgaris third stage larvae (L3) as antigens. Observations using the IFA indicate that a species-specific antibody response to S. vulgaris L3 develops in S. vulgaris-infected ponies and that some surface L3 antigens are shared by adult worms. Sequential antibody levels against S. vulgaris were measured in strongyle-naive and in immune ponies following initial and challenge infections using the IFA and an indirect hemagglutination assay (IHA). Antibody levels measured by IFA increased faster following initial infections...
Efficacy of ivermectin in controlling Strongyloides westeri infections in foals. Twenty-eight foals whose dams were treated IM with ivermectin (200 micrograms/kg of body weight) on the day of parturition were compared with 35 foals whose dams were administered only the vehicle. The effect of ivermectin on the vertical transmission of Strongyloides westeri and foal heat diarrhea was determined by a comparison of results obtained in the 2 groups. Foals from treated mares had significantly fewer S westeri eggs per gram of feces from 17 to 28 days postpartum. There were no differences observed in the frequencies of severity of foal heat diarrhea between the treated and control...
The activity of closantel as an equine antiparasitic agent. Eighteen pony foals were experimentally infected with 500 third stage larvae of Strongylus vulgaris at 2 weeks, and at 2, 4, 6 and 8 months after birth. For the duration of the study, all foals were kept in the same pasture with their mothers to allow natural infection with other parasites by exposure to a contaminated environment. Twelve of the foals were utilized in groups of 3 and treated orally five times at two month intervals starting at one month of age with closantel at doses of 5, 10, 20 or 40 mg kg-1. Ten months after birth the foals were necropsied to determine the parasitic burdens...
Studies on the strongyle egg output of horses after treatment with oxfendazole (Synanthic vet. Syntex). The effect of oxfendazole (Synanthic vet. Syntex) on the strongyle egg output of naturally infected horses was evaluated. It was demonstrated that the compound, administered orally as an 18,5% paste or as 6,48% pellets mixed in feed (46.3 grams per 300 kg bodyweight) at a dose-rate of 10 mg per kg bodyweight, markedly reduced the strongyle egg output over a 10 week period. As this period to egg reappearance is considerably longer than for most other anthelmintics at recommended dose levels, oxfendazole may be considered a valuable compound for the control of strongylosis in horses.
[Contribution to the parasitic fauna of the GDR (German Democratic Republic). 7. Occurrence of Gasterophilus larvae (Diptera: Gasterophilidae) in horses]. Observations were carried out from May 1977 to May 1980 on occurrence, fauna, and seasonal dynamics of Gasterophilus spp. in 2,539 horses for butchering from all districts of the German Democratic Republic and also in 79 horses after control against gasterophilosis. 99.98% of the 13,742 second and third instar larvae of horses for butchering were Gasterophilus intestinalis, only 0.02% Gasterophilus nasalis. Out of 7,765 larvae passed after control measures Gasterophilus intestinalis dominated with more than 96%. Only in four districts of the German Democratic Republic Gasterophilus nasalis was...
Critical tests in equids with fenbendazole alone or combined with piperazine: particular reference to activity on benzimidazole-resistant small strongyles. Seven critical tests in equids were conducted with single doses of fenbendazole (5 mg kg-1) alone (Panacur--American Hoechst, Somerville, NJ); (2 tests with paste and 1 with suspension formulation) or in combination with piperazine (American Hoechst); (40 mg base kg-1); (4 tests with paste formulation). The main purpose of the tests was evaluation of activity against benzimidazole-resistant small strongyles (Cyathostomum catinatum, Cyathostomum coronatum, Cylicocyclus nassatus, Cylicostephanus goldi, and Cylicostephanus longibursatus). Natural infections of 2 populations of benzimidazole-resis...
Equine complement activation as a mechanism for equine neutrophil migration in Onchocerca cervicalis infections. Extracts of Onchocerca cervicalis, an equine parasite, were incubated with radiolabeled equine neutrophils and neutrophil migration was assessed for factors derived from the parasite itself or for host-derived factors after incubation of these same parasite extracts with equine serum. No stimulus for cell migration was observed in saline extracts of adult worms, uterine microfilariae, or skin microfilariae at any dosage tested. However, after incubation of saline extracts with fresh normal equine sera a marked stimulus for neutrophil migration was observed. Ablation of this biologic activity w...
Fine structure of Babesia equi Laveran, 1901 within lymphocytes and erythrocytes of horses: an in vivo and in vitro study. The development of Babesia equi (Piroplasmia) in the vertebrate host was studied by electron microscopy. The tick-borne sporozoites initiated an exoerythrocytic schizogony in lymphocytes in vivo and in vitro. In lymphocyte cultures the schizonts of B. equi lay as fissured bodies directly within the host cell forming numerous cytomeres. These cytomeres were bordered by a single membrane and contained polymorphous nuclei. Merozoite differentiation was initiated at several places by protrusions appearing at the periphery of the cytomeres. The cytoplasm of the schizont merged progressively into th...
Cutaneous onchocerciasis in the horse: five cases in southwestern british columbia. Five horses were presented because of a dermatitis of the forehead. Unlike previous reports, ventral midline dermatitis was not the major problem, and was present in only two of five cases. All five horses responded to levamisole therapy at a daily dosage of 5.5 g for one week. Owners were cautioned that repeat therapy may be necessary.
Infectivity of sarcocystis from donkey for horse via sporocysts from dogs. The dog is the final host for sarcosporidia cysts from the oesophagus and diaphragm of donkeys from Sardinia. The prepatent period lasted 9 to 10 days. Sporocysts measured 12.2-13.8 X 9.2-9.9 microns. Infection of a horse with 10(5) donkey/dog sporocysts increased the rectal temperature to more than 40 degrees C on days 10 and 20 after infection. On day 138 p.i. predominantly immature cysts containing metrocytes were found, especially in the oesophagus. Infection on day 117 p.i. with 2 X 10(5) horse/dog sporocysts did not give rise to a temperature increase during the following 21 days. The fi...
Cambendazole for strongyle control in a pony band: selection of a drug-resistant population of small strongyles and teratologic implications. Cambendazole (CBZ) treatments (20 mg/kg) given at 8-week intervals were used for parasite control in a breeding band of ponies (n = 33 to 43) during the period July 1974 to August 1978. Pre- and posttreatment worm egg counts on feces were used to evaluate efficacy of treatments after every 2nd treatment interval by monitoring changes in strongyle egg counts. Initially, effective reductions (expressed as 92% to 96% fewer worm eggs) were lessened to 70% by the 9th treatment (18 months) and to 28% by the 12th treatment, and thereafter, they fluctuated between 0% and 38%. Critical tests on animals...
The prevalence of Gasterophilus intestinalis in horses in northern England and Wales. The stomachs of 448 horses from northern England and Wales were examined for Gasterophilus larvae, and 237 (52.7%) were found to be infected with G. intestinalis. Larvae were present in stomachs examined during each month of the year except August. Second instar larvae occurred from September through February and third instars were present from November through July. Adult fly activity began in August as indicated by the presence of eggs on horses. The life-cycle of G. intestinalis in northern England and Wales is outlined from the data presented. The mean instar burdens were 15.7 second and 3...
[Sarcocystis bertrami Doflein, 1901, a sarcosporidia of the horse. Equus caballus]. No abstract available
Development of Sarcocystis fayeri in the equine. 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...
Cyathostominae and other strongyles of horses in the Federal Republic of Germany. The faeces of 34 horses of the "Bavarian main and state studfarm Schwaiganger" (Group I) and 10 ponies (Group II) from various regions of the Federal Republic of Germany, were examined and 4 834 small strongyles were identified. Three species Cyathostomum catinatum, Cylicostephanus longibursatus and Cylicocylus nassatus, were found to be widely distributed. Although various modern anthelmintics with different effective components were used over the past 20 years, no remarkable change has been brought about in the composition of the parasitic species of the horses in the Federal Republic of Ger...
Effectiveness of ivermectin against later 4th-stage Strongylus vulgaris in ponies. Twelve pony foals were reared worm-free and inoculated with Strongylus vulgaris. Approximately 8 weeks after they were inoculated, 6 foals were given ivermectin IM at a dosage rate of 200 micrograms/kg of body weight and 6 were given a placebo. All foals were necropsied 35 days after treatment. Ivermectin was 98.9% effective in eliminating later 4th-stage S vulgaris larvae located near the origin of major intestinal arteries and in reducing clinical signs and permitting resolution of lesions associated with verminous arteritis. One pony foal reared on pasture and with evidence of arteritis of ...
Studies on Strongylus asini. I. Experimental infestation of equines. Infective larvae were harvested from a culture of eggs collected from adult Strongylus asini recovered from a free-ranging Burchell's zebra, Equus burchelli, in the Kruger National Park. Worm-free zebra, horse and donkey foals were successfully infested, but infestation failed in a mule foal. At slaughter, 117-125 days post-infestation, S. asini in their 4th moult were recovered from the liver and portal veins. This is the first report of successful experimental infestation of these hosts with S. asini.
Controlled tests of pastes of dichlorvos and thiabendazole against induced Strongyloides westeri infections in pony foals in 1973-1974. In 1973-1974, 4 controlled tests were performed in pony foals (n = 17) raised parasite-free and experimentally infected with Strongyloides westeri. Administration of infective larvae by stomach tube in 1 test resulted in low-grade infections and tended to invalidate the test. Intraoral and percutaneous (intra-aural) administration of larvae resulted in suitable test infections for 1 and 2 tests, respectively. A paste formulation of dichlorvos at 36.3 mg/kg of body weight removal from 4 ponies. Treatment of 4 the dosage rate of 44 mg/kg was consistently effective (greater than 99% to 100%) for ...
Ivermectin: activity against larval Strongylus vulgaris and adult Trichostrongylus axei in experimental infections in ponies. Activity of ivermectin, administered IM at the dosage rate of 200 micrograms/kg of body weight, was evaluated in controlled tests against migrating larvae of Strongylus vulgaris and adult Trichostrongylus axei in experimental infections in 6 ponies raised worm-free. Ponies were given 2,190 or 2,400 infective 3rd-stage larvae of S vulgaris at 7 days before treatment and 22,000 or 22,750 infective 3rd-stage larvae of T axei at 42 or 45 days before treatment. Three ponies were given ivermectin plus vehicle, and 3 ponies were given the vehicle only; the ponies were euthanatized 7 or 9 days after t...