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Topic:Larvae
Larvae in relation to horses refers to the immature stages of various parasitic organisms that can infect equine hosts. These larvae can originate from different species of internal and external parasites, such as gastrointestinal nematodes and bots. The presence and development of larvae in horses can lead to various health issues, including digestive disturbances, weight loss, and colic. Common parasitic larvae affecting horses include those of Strongylus vulgaris, Parascaris equorum, and Gasterophilus spp. Understanding the life cycle, transmission, and impact of these larvae is essential for effective parasite management and control in equine populations. This page compiles peer-reviewed research studies and scholarly articles that explore the biology, pathology, and management strategies related to larval parasitism in horses.
Anthelmintic efficacies of a tablet formula of ivermectin-praziquantel on horses experimentally infected with three Strongylus species. 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. ...
Mechanical recovery of inhibited cyathostomin larvae from equine intestinal tissue. The Stomacher is very widely used in food and medical research for extracting tissues. To determine whether nematode larvae were disrupted by the Stomacher, L3 larvae of Haemonchus contortus were homogenised for up to 40 min at full power but no larval disruption occurred. Therefore, tissue from the mucosa and submucosa of the caecum of horses collected from a licenced abattoir was treated to determine whether inhibited cyathostomin larvae could be extracted. The optimum time on full power for a 10-g sample was 20 min, and in three out of five caecal samples from different horses, significantl...
Biological control of horse cyathostomin (Nematoda: Cyathostominae) using the nematophagous fungus Duddingtonia flagrans in tropical southeastern Brazil. The viability of a fungal formulation using the nematode-trapping fungus Duddingtonia flagrans was assessed for the biological control of horse cyathostomin. Two groups (fungus-treated and control without fungus treatment), consisting of eight crossbred mares (3-18 years of age) were fed on Cynodon sp. pasture naturally infected with equine cyathostome larvae. Each animal of the treated group received oral doses of sodium alginate mycelial pellets (1g/(10 kg live weight week)), during 6 months. Significant reduction (p<0.01) in the number of eggs per gram of feces and coprocultures was foun...
In vitro development of cyathostomin larvae from the third stage larvae to the fourth stage: morphologic characterization, effects of refrigeration, and species-specific patterns. A mixed population of equine cyathostomin (Nematoda, Strongyloidea) infective third stage larvae (L3) was cultured in vitro using a cell-free medium. Some L3 were cultured immediately after Baermann collection from fecal cultures, while others were kept in water at 4 degrees C for 7 days before initiating the in vitro cultures. Cultures were examined daily for viability. At days 2, 7, 14 and 21 larvae were collected for identification of developmental stage and morphological changes, using both light and scanning electron microscopy. Larvae were classified as early L3 (EL3), developing L3 (DL3...
Comparison of two fecal egg recovery techniques and larval culture for cyathostomins in horses. To compare the McMaster and centrifugal flotation techniques and larval culture for recovery of cyathostomin (small strongyle) eggs from the feces of horses. Methods: Fecal samples from 101 horses. Methods: In experiment I, homogenized fresh feces from a single horse were randomly subsampled by use of each technique for 10 replicates. In experiment II, samples from 43 horses that had no anthelmintic treatment were analyzed by use of McMaster, centrifugal flotation, and larval culture techniques. In experiment III, 57 horses were treated with an anthelmintic by owners, and fecal samples were an...
Morphometric identification of equid cyathostome (Nematoda: Cyathostominae) infective larvae. The prevalence of infection with cyathosthomes of horses is high worldwide. Identification of species on infective larvae based on available morphological keys is not fully accurate and the aim of the present study was to provide a reliable identification key of cyathostomes infective larvae. At the abattoir, horse large intestines were examined and the cyathostomes females extracted and identified. The eggs from uteruses of identified cyathostomes females were used for breeding the infective larvae. Morphological parameters of Cyathostominae infective larvae, i.e. the length of the larvae wit...
Trichinella britovi and Trichinella spiralis mixed infection in a horse from Poland. Trichinella infections in horses continue to represent a health problem and, despite the rarity of infection, it is necessary to continue to control properly horse meat. In 2008, a 10-year-old horse imported from Poland to Italy for consumption found to have been positive at the digestion test. Both Trichinella britovi and Trichinella spiralis larvae in a proportion of 4:1 were detected in the horse muscles. This is the first report of a mixed Trichinella species infection in a horse. The epidemiological investigation revealed that the infected horse originated from a small farm about 120km fr...
Presence of Gasterophilus species in Arabian horses in Sanliurfa region. In this study, ivermectin was administered orally to112 Arabian horses for detection of Gasterophilus species in the Sanliurfa region between June-July 2006. Eleven (9.82%) Arabian horses were found to be infected by larvae of Gasterophilus spp. A total of 409 third stage larvae (L3) were collected from fecal samples. In the Sanliurfa region, the prevalence of three species of Gasterophilus was identified as follows: Gasterophilus intestinalis (6.25%), G. nasalis (2.67%) and G. pecorum (0.89%).
Protein expression profile of Gasterophilus intestinalis larvae causing horse gastric myiasis and characterization of horse immune reaction. Little information is available on the immunological aspect of parasitic Gasterophilus intestinalis (Diptera, Oestridae) larvae causing horse gastric myiasis. The objectives of this research were to analyze the protein content of larval crude extracts of the migrating second and third larvae (L2 and L3) of G. intestinalis in order to characterize the immune response of horses. Results: The proteomic profile of L2 and L3, investigated by using one and two dimensional approaches, revealed a migration pattern specific to each larval stage. Furthermore, Western blots were performed with horse sera...
The little-known scenario of anthelmintic resistance in equine cyathostomes in Italy. Cyathostomes (Nematoda, Cyathostominae) cause colic, decreased performance and growth, peripheral edema, and dysorexia in equids. Also, the synchronous emergence of cyathostome larvae encysted in the colon and cecal wall causes larval cyathostominosis, which is characterized by protein-depriving enteropathy, chronic diarrhea, edema, weight loss, colitis, and may be fatal. In the past few decades, drug resistance in cyathostomes has become widespread, especially for benzimidazoles. Resistance to tetrahydropyrimidines is still confined to a few areas, and the recent reports of reduced efficacy i...
Morphology and diagnosis of some fourth-stage larvae of cyathostomines (Nematoda: Strongyloidea) in donkeys Equus asinus L. from Ethiopia. Fourth-stage larvae of four species of the Cyathostominae Nicoll, 1927 parasitic in donkeys Equus asinus L. from Ethiopia were identified mainly using moulting specimens. They are Cylicocyclus asini Matthee, Krecek & Gibbons, 2001, C. auriculatus (Looss, 1900) Chaves, 1930, Cyathostomum tetracanthum (Mehlis, 1831) Molin, 1861 (sensu Looss, 1900) and Cylindropharynx brevicauda Leiper, 1911. The larva of Cylicocyclus asini is similar to those of C. nassatus (Looss, 1900) Chaves, 1930 and C. leptostomum Kotlán, 1920, but differs from the former by the shape of the dorsal tooth in the oesopha...
[Strategic control of Amblyomma cajennense (Fabricius, 1787) (Acari: Ixodidae) on horses, Minas Gerais, Brazil – Part I]. The aim of this study was to verify the efficiency of a strategic control program of Amblyomma cajennense in horses under field conditions. Acaricide treatments were applied at seven days intervals and divided in two series, the first one beginning in April 2004 (eight treatments), and the second one beginning in July 2004 (five treatments), aiming to control larvae and nymphs of the tick. A pyrethroid chemical base cypermethrin 0.015% was used for spraying the horses. There was a reduction of 44.85% in the adults infestation of the tick in the period of October 2004 to March 2005, and 59.74%,...
Identification of a LIM domain-containing gene in the Cyathostominae. The Cyathostominae are a complex group of nematodes and are the primary parasitic pathogens of horses. Little is known of their basic biology. As part of an investigation into mechanisms involved in reactivation of mucosal larval stages, we identified a gene encoding a predicted LIM domain-containing protein (Cy-LIM-1). LIM domains are cysteine- and histidine-rich motifs that are thought to direct protein-protein interactions. Proteins that contain these domains have a wide range of functions including gene regulation, cell fate determination and cytoskeleton organization. The Cy-lim-1 mRNA wa...
The ecology of horse cyathostomin infective larvae (Nematoda-Cyathostominae) in tropical southeast Brazil. Experimental studies about the recovery, survival and migration to pasture of cyathostomin infective larvae (L(3)) from fresh feces depositions were conducted from February 2005 to March 2007 in a tropical region of southeast Brazil. Grass and feces were collected weekly at 8 a.m., 1 and 5 p.m. and processed by the Baermann technique. Multivariate analysis (principal components method) showed the influence of time and environmental variables on the number of infective larvae recovered from the feces and pasture. In the rainy period (October-March), more infective larvae were recovered on the f...
Prevalence of Setaria equina microfilaraemia in horses in Hungary. Peripheral blood samples were collected randomly from 195 horses in various parts of Hungary, and the presence of microfilariae was evaluated by the Knott technique. On the basis of morphological identification 18 of the horses (9.2 per cent) were infected with Setaria equina, and the infection was confirmed in 10 animals by pcr and sequencing. The level of microfilaraemia was between 1 and 1138 larvae in 2 ml of blood. There was no correlation between the time of sampling or the sex of the animals (stallions versus mares) and the prevalence of infection, but the prevalence decreased with age....
Selective inhibition of butyrylcholinesterase in vivo in horses by the feed-through larvacide Equitrol. The organophosphate insecticide tetrachlorvinphos (TCVP, Rabon) is the active ingredient in "feed-through" larvacides (e.g., Equitrol) for fly control around horse stables. As with other organophosphates, TCVP elicits toxicity by inhibiting acetylcholinesterase, leading to accumulation of the neurotransmitter acetylcholine and cholinergic signs. Relatively little is known, however, on the effects of TCVP-containing larvacides on acetylcholinesterase or other esterases in horses. Previous in vitro studies indicated that horse plasma cholinesterase activity was substantially (>10,000-fold) mo...
Molecular diagnosis of equid summer sores. Equine cutaneous habronemosis, also known as "summer sores", is a parasitic infection caused by larvae of Habronema microstoma and Habronema muscae (Nematoda, Spirurida) released by dung-inhabiting fly vectors on abraded skin, skin wounds or muco-cutaneous transition sites. Larvae induce a local inflammatory reaction characterised by itching, granulomatous, ulcerated and, often non-healing, lesions. The diagnosis of summer sores may be unreliable mainly because of the limits of clinical and microscopic examination. The applicability of a semi-nested PCR assay developed for the diagnosis of gas...
Equine stomach worm, Drashia megastoma (Spirurida: Habronematidae): first SEM report. Drashia megastoma (Spirurida: Habronematidae) occurs in nodules in the stomach wall and rarely free in the stomach of the horse, mule and zebra throughout the world. D. megastoma develops in the housefly Musca domestica and causes gastric haemorrhage or even perforation of the stomach. Larvae of this nematode may be found in the lung, skin and eye of the host. Scanning electron microscopy (SEM) was used to study the surface ultrastructure of adult worms of this nematode. In both sexes, the head end was separated from the rest of the body by a constriction. The stoma was infundibuliform with a ...
Viability and infectivity of Trichinella spiralis muscle larvae in frozen horse tissue. Many aspects of the biology and epidemiology of Trichinella infection in the horse are poorly understood, including survival of Trichinella spp in horse muscle. In this study, we have assessed the freeze tolerance of T. spiralis in horse meat stored at 5, -5, and -18 degrees C for 1 day to 24 weeks. Results demonstrate a steady reduction in the number of live ML recovered from the cold stored meat samples. On Day 1, recovery of live larvae had been reduced by 18.6%, 50.1%, and 37.2%, and by 4 weeks, recovery of larvae had been reduced by 65.4%, 66.5%, and 96.2% in samples stored at 5, -5, and ...
Larval viability and serological response in horses with long-term Trichinella spiralis infection. The horse is considered an aberrant host for the nematode parasite Trichinella spiralis, and many aspects of the biology and epidemiology of Trichinella infection in the horse are poorly understood. It has been reported that experimentally-infected horses produce a transient serological response to infection and that muscle larvae are cleared more rapidly than in parasite-adapted hosts such as the pig and humans. However, limited numbers of animals have been studied, and both the longevity of larvae in horse musculature and the immune response to Trichinella larvae remain unclear. In this stud...
The involvement of mast cells and mast cell proteinases in the intestinal response to equine cyathostomin infection. Cyathostomins (Cyathostominae) are regarded as the most pathogenic equine nematode worldwide. These nematodes are difficult to control in equine populations due to emerging anthelmintic resistance and evasion of encysted larval cyathostomins to regular modern anthelmintics. Mast cells and their proteinases have been shown to play a role in the mammalian immune response to nematode infections. Involvement of mast cells and mast cell proteinases in the equine immune response to cyathostomin infection is proposed. A technique was established to perform immunohistochemical staining using polyclona...
[First-time endoscopic detection of larvae of Gasterophilus spp. in the oral cavity in 14 warmblood horses]. Intraoral endoscopy is used as a standard diagnostic technique at the reporting clinics in horses presented with stomatological problems. Endoscopy of the oral cavity was performed using a chip camera, camera control unit, xenon cold light source and a rigid endoscope. In a three year period (2002 to 2004), second instars of Gasterophilus spp. were diagnosed in 14 warmblood horses 2 to 17 years of age. All horses were presented with masticatory problems or problems accepting the bit. In one horse oesophageal obstruction occurred in the course of larval migration. Oral endoscopy can not only be...
Field study on the survival, migration and overwintering of infective larvae of horse strongyles on pasture in central Ukraine. Experimental studies on the survival of infective stage larvae of horse strongyles and their ability to overwinter on pasture were carried out in central Ukraine (Poltavska oblast). Faecal pats (1.5 kg each) of naturally infected horses were placed on pasture, and samples of faeces and surrounding vegetation (10 g each) were collected each month, excluding the winter months, from November 2002 until April 2004. The number of infective third stage larvae was calculated in each sample and compared with that from the control faecal samples cultivated in the laboratory. In the control samples, the...
A new approach for the diagnosis of myiasis of animals: the example of horse nasal myiasis. The myiasis caused by larvae of Rhinoestrus purpureus and Rhinoestrus usbekistanicus (Diptera, Oestridae) are of importance in the horse medicine since it causes severe respiratory diseases. Therefore an accurate diagnosis of rhinoestrosis is central to its epidemiology and control. This paper describes concisely a molecular diagnostic tool that overcomes the current inherent diagnostic constraints and, therefore, is of importance to understand the actual incidence and epidemiology of this myiasis in live horses.
Muscle distribution of sylvatic and domestic Trichinella larvae in production animals and wildlife. Only a few studies have compared the muscle distribution of the different Trichinella genotypes. In this study, data were obtained from a series of experimental infections in pigs, wild boars, foxes and horses, with the aim of evaluating the predilection sites of nine well-defined genotypes of Trichinella. Necropsy was performed at 5, 10, 20 and 40 weeks post inoculation. From all host species, corresponding muscles/muscle groups were examined by artificial digestion. In foxes where all Trichinella species established in high numbers, the encapsulating species were found primarily in the tongu...
Analysis of the strongylid nematodes (Nematoda: Strongylidae) community after deworming of brood horses in Ukraine. Communities of intestinal helminths in horses are commonly studied post mortem. The study objectives were here to examine the species composition of the strongylid community in brood horses in Ukraine after deworming with an aversectin drug Univerm. The site distribution of the strongylid species was analysed according to dynamics of their expulsion in faeces. Forty-four horses of different ages from Poltavska oblast (22 horses), Kyivska oblast (17 horses) and Sumska oblast (5 horses) of Ukraine were included in the study. Horses were treated with Univerm anthelmintic (0.2% aversectin) at a do...
Species composition of Gasterophilus spp. (Diptera, Oestridae) causing equine gastric myiasis in southern Italy: parasite biodiversity and risks for extinction. Horse gastrointestinal myiasis caused by larvae of Gasterophilus spp. (Diptera, Oestridae) flies has a worldwide distribution and, where present, it is primarily caused by larvae of Gasterophilus intestinalis and Gasterophilus nasalis. Other species, i.e., Gasterophilus inermis, Gasterophilus pecorum and Gasterophilus haemorrhoidalis, present in different or in the same regions of the gastrointestinal tract, were only occasionally reported in very limited areas of eastern European Countries and in central Italy. With the aim to contribute data on the species composition of Gasterophilus and on...
Changes to oxfendazole chiral kinetics and anthelmintic efficacy induced by piperonyl butoxide in horses. The study of novel pharmacological strategies to control parasitism in horses is required since many parasite species have developed resistance to anthelmintic drugs. Objective: To evaluate the effects of piperonyl butoxide (PB) (a metabolic inhibitor) on the plasma availability and enantiomeric behaviour of oxfendazole (OFZ) given orally to horses, and to compare the clinical efficacy of OFZ given either alone or co-administered with PB in naturally parasitised horses. Methods: Fifteen naturally parasitised crossbred male ponies were allocated into 3 groups (n = 5) and treated orally as follo...
