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 dose rate of 0.5mg aversectin preparation per kg body weight. Faecal sampling (200 g each) was performed at 24, 36, 48 and 60 h post treatment, and all nematodes expelled were collected and identified. The largest numbers of strongylids were expelled at 24--36 h after treatment. Twenty-five nematode species from the subfamilies Strongylinae and Cyathostominae were identified. The number of strongylid species found per horse ranged from 7 to 20, on an average 11+/-3.6 (S.D.). The number of cyathostomin species found per horse ranged from 7 to 16, on an average 10+/-2.3 (S.D.). Cylicocyclus nassatus and Cyathostomum catinatum were the most dominant species were found in 100% of horses, amounting to 36.3% and 17.6% of the total number of strongylids collected, respectively. C. longibursatus, C. ashworthi, Cylicostephanus calicatus, C. leptostomus and C. minutus were identified in more than 80% horses and represented 39.9% of the total number of strongylids collected. The dynamics of the different strongylid species expelled was irregular. Correlation between the time of cyathostomin species expulsion in faeces and their predicted localisation inside the horse intestine was found. Species mainly localised in the caecum were found in faeces later than those species localised in the dorsal and ventral colons. Larvae and adult Parascaris equorum, Oxyuris equi and botfly larvae from the genus Gasterophilus were also found in horse faeces. This investigation shows that is possible to study the horse strongylid community after deworming with aid of an aversectin drug. The results obtained here correspond to those recorded in previous autopsy surveys in other countries.

A redescription of Cylicocyclus triramosus (Nematoda: Strongyloidea): a parasite of the zebra, Equus burchelli antiquorum.

Cylicocyclus triramosus, a rare species of Cyathostominae from the southern African Burchell's zebra (Equus burchelli antiquorum) is redescribed, and a neotype is proposed. The external leaf-crown of the species consists of 30 elements and the internal leaf-crown numerous small and clear elements. The buccal capsule is cylindrical, oval in cross section, and approximately 3 times as wide as deep. The thin walls of the buccal capsule taper anteriorly from a large ringlike, hoop-shaped thickening around the posterior margin. The dorsal gutter is nipple-shaped. The mouth collar is notched dorsally and ventrally. The dorsal ray of the copulatory bursa is slightly elongate and distinctly set off from the lateral lobes. The branches of the dorsal ray have auxiliary branches. Appendages of the genital cone consist of 2 separated, large, semilunar plates with finger-shaped processes on the margins. The vulva-to-anus distance is greater than the tail length. The species is most similar to Cylicocyclus radiatus. Cylicocyclus triramosus differs from all similar species in the presence of dorsal and ventral notches in its mouth collar. In addition, C. triramosus also has a distinctive form of male genital cone appendage. Cylicocyclus radiatus differs further from C. triramosus in lacking a dorsal gutter and having a more elongate dorsal ray and a female tail nearly equal in length to the vulva-to-anus distance.

Benzimidazole resistance in cyathostomes in horses in the Ukraine.

The efficacy of treatment with cambendazole was tested in 1-year-old horses on a farm in Dubrovka, Ukraine. Thirty-five horses were treated. Their egg output was compared on the day of treatment and 14 days later with that of 33 untreated horses. Before treatment the mean number of eggs g-1 faeces was 614 in the controls and 766 in horses that had been treated. After 14 days the mean egg output in the controls was 580 and in the treated horses 369. This means a reduction of 54.5%. Only cyathostome larvae could be cultured from faeces collected after treatment. It can be concluded that benzimidazole resistance in cyathostomes is present in the Ukraine.

Coronocyclus ulambajari n. sp. (Nematoda: Strongyloidea) from horses of Mongolia.

Coronocyclus ulambajari n. sp. (Strongyloidea: Cyathostominae) from horses of Mongolia is described. The external leaf-crown (ELC) of the new species consists of 28 elements and the internal leaf-crown (ILC) of approximately 80 elements. A spindle-shaped (in optical section) mouth collar support is separated anteriorly from the buccal capsule and connected to it and elements of leaf-crowns by bundles of connective tissue. The buccal capsule is cylindrical, circular in cross-section, and approximately 3 times as wide as deep. A large, tongue-like dorsal cone protrudes from the floor of the buccal capsule overlying the large dorsal esophageal tooth. The duct of the dorsal esophageal gland opens at the tip of the dorsal cone. The tail and vagina of females are short, and the vulva is close to the anus. The buccal capsule and dorsal cone are most similar to Coronocyclus labratus, but differ significantly in size of dorsal cone and relative width and depth of the buccal capsule as well as characteristics of the leaf-crowns and female reproductive systems.

Morphology and differential diagnostics of parasitic larvae of some Strongylidae (Nematoda) of horses.

The morphology of L4 of Cylicostephanus minutus, Cylicotetrapedon bidentatus, Petrovinema poculatum, Cylicocyclus radiatus, C. triramosus, Cylicodontophorus euproctus, C. mettami, C. mongolicus, Poteriostomum imparidentatum, Gyalocephalus capitatus and Craterostomum acuticaudatum is discussed. The species are named in accordance with the new system, which is outlined in the introduction. The criteria for the identification of larvae killed during their 4th skinning include distinctive marks occuring in the 4th and 5th stages: gut morphology, position of cervical papillae, excretory opening, morphology of the caudal part of the female. For L4, generic characteristics have not been distinguished (except Petrovinema spp.). Larvae of small Strongylinae species are similar to those of Cyathostominae.