Parasites in lungs of dead equids in Kentucky: emphasis on Dictyocaulus arnfieldi

Prevalence of natural infections of parasites from the lungs of 488 dead Thoroughbreds in Kentucky was investigated. The horses varied from 1 to 32 years of age; 419 horses were from 215 farms and 69 horses were from 68 individual sources for which a specific farm was not identified. Examinations of the lungs were made from Mar 1, 1983 through Feb 29, 1984. Dictyocaulus arnfieldi was recovered from 56 (11%) of the horses. Other parasites found were larvae of Parascaris equorum in 37 (8%) and of Habronema/Draschia in 67 (14%) of the horses. The possible effect of ivermectin treatment on the prevalence of D arnfieldi in the lungs is discussed. Presence of D arnfieldi in 20 other selected dead equids was also investigated.     

Critical tests and clinical trials on oxibendazole in horses with special reference to removal of Parascaris equorum.

The efficacy of oxibendazole given at dose level of 10 mg/kg of body weight was determined by 10 critical tests in foals and by 2 clinical trials in 20 foals (16 treated, 4 nontreated), with special interest in the drug activity against Parascaris equorum. The drug was uniformly efficacious (100%) against P equorum in the 10 critical-test foals, each having between 22 and 236 ascarids. Posttreatment reductions of ascarid egg counts in fecal samples were also 100% in suckling foals treated with oxibendazole given as a drench. Ascarid eggs did not reappear in fecal samples until the 8th week after foals were treated. A paste formulation of oxibendazole at 10 mg/kg also eliminated ascarid eggs from feces of 12 suckling foals. Strongyle EPG were markedly reduced by oxibendazole in the 10 critical-test foals and in 16 treated sucklings in the clinical trials. Egg and larval count data on foals in both the critical tests and the clinical trials also indicated oxibendazole was active against Strongyloides westeri. Untoward effects of treatment with oxibendazole were not observed.     

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-resistant small strongyles were evaluated; 1 was population B in 2 horses and the other was population S in 5 ponies. Removal of the 5 species of population B was 49-91% in the animal treated with fenbendazole paste alone and 100% (4 of these species present) in the animal treated with the combination. For population S, 2 of the 5 resistant species were present in small numbers in 1 animal treated with fenbendazole paste alone and all were removed; the 1 animal receiving fenbendazole suspension alone had removals of 0-70% for the 5 benzimidazole-resistant species. Also for population S, the 5 resistant species were present in 2 animals treated with the paste combination and removal was 98-100% and of 4 of the 5 resistant species in 1 animal, removal was 76-99%. Removal of large strongyles (Strongylus vulgaris and Strongylus edentatus) was 92-100% for fenbendazole paste alone or in combination with piperazine in the 5 infected animals. For Oxyuris equi, present in 1 animal treated with the combination, there was 91% removal of immature and 100% removal of mature specimens. There probHably was no activity by fenbendazole alone or the combination against bots, tapeworms, and parenteral stages of S. vulgaris and S. edentatus. The combination may have had some activity against immature Habronema spp. and mature abronema muscae.     

Identification of the DDAH2 Protein in Pig Reproductive Tract Mucus: A Putative Oestrus Detection Marker

Precisely detecting oestrus is important for artificial insemination. The aims of this study were to identify oestrus‐specific sow mucus proteins to determine the optimal time for artificial insemination. The proestrous‐ and oestrous‐stage mucus proteins were purified and analysed with proteomic tools such as two‐dimensional gel electrophoresis and matrix‐assisted laser desorption/ionization–time‐of‐flight analyses. Among the differentially expressed proteins, the dimethylarginine dimethylaminohydrolase 2 (DDAH2) protein showed a 3.6‐fold increase during the proestrous stage compared to that during the oestrous stage. A western immunoblot study revealed that two of three sow mucus samples clearly showed negative anti‐DDAH2 antibody activity during the oestrous stage. This study demonstrated that the pig DDAH2 mucus protein exists during the proestrous stage, but not during the oestrous stage, suggesting that mucus DDAH2 could be useful as an oestrus detection marker.     

Infiltrating Foxp3+ Regulatory T cells and Histopathological Features in Canine Classical and Spermatocytic Seminomas

In humans, regulatory T (T reg) cells are known to play a critical role in both the regulation of immune homoeostasis and the progression of cancer. However, there is little information about the identification, characterization and the function of T reg cells in canine tumours. We identified T reg cells in 28 canine seminoma samples using a Forkhead box P3 (Foxp3) antibody and investigated the relationship between T reg cell infiltration and histopathological features of classical and spermatocytic seminomas (SE and SS, respectively). The Foxp3 protein showed nuclear immunostaining in infiltrating lymphocytes, and Foxp3+ cells were diffused or focally distributed in seminoma tissues. Foxp3+ cells were frequently present in the SS histotype, in seminomas that showed no evidence of tumour cell invasion into the vessels and in seminomas showing a diffuse growth pattern with three cell types. Neither the SE/SS histotype nor the histopathological features of the tumour correlated with Foxp3+ cell counts. These results indicate that Foxp3+ T reg cells may be associated with a less malignant histological phenotype or may not play a critical role in the immune response of canine seminomas. Moreover, Foxp3+ T reg cells may be associated with SS seminoma, but further studies, involving a larger number of samples, are required to better understand whether these cells play a critical role in the immune response in canine seminomas. This is the first report to demonstrate the characteristics of T reg cell infiltration in canine seminoma.     

Effect of Dimethyl Sulfoxide on Cell Cycle Synchronization of Goldfish Caudal Fin Derived Fibroblasts Cells

Several studies have previously been conducted regarding cell cycle synchronization in mammalian somatic cells. However, limited work has been performed on the control of cell cycle stages in the somatic cells of fish. The aim of this study was to determine the cell cycle arresting effects of several dimethyl sulfoxide (DMSO) concentrations for different times on different cell cycle stages of goldfish caudal fin‐derived fibroblasts. Results demonstrated that the cycling cells or control group (68.29%) yields significantly higher (p < 0.05) arrest in G0/G1 phase compared with the group treated for 24 h with different concentrations (0.5%, 1.0% or 1.5%) of DMSO (64.88%, 65.70%, 64.22% respectively). The cell cycle synchronization in the treatment of cells with 1.0% DMSO at 48 h (81.14%) was significantly higher than that in the groups treated for 24 h (76.82%) and the control group (77.90%). Observations showed that treatment of DMSO resulted in an increase in the proportion of cells at G0/G1 phase for 48 h of culture. However, high levels of apoptotic cells can be detected after 48 h of culture treated with 1% concentration of DMSO.     

Infectivity and persistence of an outbreak strain of Salmonella enterica serotype Typhimurium DT160 for house sparrows (Passer domesticus) in New Zealand

AIM: To examine the infective dose, incubation period and disease progression of an isolate of Salmonella enterica serotype Typhimurium definitive type 160 (DT160) originating from a naturally-infected house sparrow (Passer domesticus) during an outbreak of the disease in New Zealand.

METHODS: Thirty-six house sparrows captured from the wild and free of Salmonella spp were divided into six groups of six birds, housed individually, and inoculated orally with phosphate buffered saline (PBS) or 10¹, 10², 10³, 10⁵, 2 × 10⁸ colony forming units (cfu) of the outbreak strain of S. Typhimurium DT160. The birds were observed for 10 days for clinical signs and/or mortality, and faecal samples were collected to determine excretion of S. Typhimurium. The birds were eutha- nised 11 days post-inoculation (p.i.) and a wide range of tissue samples were collected for histopathological examination, and culture and typing of Salmonella spp. Macro-restriction profiling by pulsed-field gel electrophoresis (PFGE) using XbaI was performed for the epidemiological typing of S. Typhimurium DT160 isolates.

RESULTS: Mortality in house sparrows inoculated with S. Typhimurium DT160 was dose-dependent, and 2/6 birds inoculated with ¹⁰⁵ cfu and all six birds inoculated with 2 × 10⁸ cfu died during the study. Infected sparrows displayed few clinical signs, apart from diarrhoea and/or polyuria, fluffed plumage, and sitting on the floor of the cage. Faecal excretion of DT160 occurred briefly in two birds inoculated with 10² cfu and four birds inoculated with 10³ cfu, on most days in five birds inoculated with 10⁵ cfu, and continuously in six birds inoculated with 2 × 10⁸ cfu. DT160 was isolated from the livers of three birds which received 10³ cfu, five birds dosed with 10⁵ cfu, and all six birds given 2 × 10⁸ cfu. Following necropsy, histopathological lesions similar to those seen in the natural disease were observed in the liver or spleen of three birds which received 10³ cfu, and all birds dosed with ≥10⁵ cfu.

CONCLUSION: The results indicate that an isolate of S. Typhimurium DT60 originating from house sparrows in New Zealand is pathogenic to these birds and that the response is dose- dependent. The persistence and excretion of the pathogen may last for at least 10 days. This confirms that sparrows infected with DT160 could be a source of infection to humans and other in-contact animals.     

Critical and controlled tests of activity of moxidectin (CL 301,423) against natural infections of internal parasites of equids.

The activity of moxidectin was evaluated in 1988 and 1989 against natural infections of internal parasites in 20 critical tests (n = 20 equids) and three controlled tests (n = 20 equids). Two formulations, injectable administered intramuscularly (i.m.) or intraorally (i.o.) and gel i.o., were given at dose rates of 0.2, 0.3 or 0.4 mg kg-1 body weight. For the critical tests (all three dose rates evaluated), removals of second instar Gasterophilus intestinalis were 93-100%, except (89%) for the injectable formulation (i.m.) at 0.2 mg kg-1. Removals of third instar G. intestinalis were 88-100% for the injectable formulation given i.m. or i.o. and 93-100% for the gel formulation, except (53%) for one batch (0.4 mg kg-1). Activity was 100% for third instar Gasterophilus nasalis, Parascaris equorum, Strongylus vulgaris and Strongylus edentatus. For Oxyuris equi, removals were 91-100%, except (27%) for one batch of the injectable formulation given i.o. at 0.3 mg kg-1. There was apparent activity against migrating S. vulgaris and S. edentatus at various dose rates and routes of administration for both formulations. At necropsy, there were local reactions observed at the injection site of three equids. In the controlled tests, dose rates were 0.2 or 0.4 mg kg-1. Removal of third instar G. intestinalis was highest for the injectable formulation given i.m. All formulations and dose rates were highly effective against S. vulgaris and S. edentatus, but variable and incomplete against O. equi. Removal was excellent on Habronema muscae and on migrating S. vulgaris and S. edentatus, although incomplete on S. vulgaris. Gasterophilus nasalis third instars and P. equorum were present in low numbers in some non-treated equids, but none were recovered from treated equids. Toxicosis was not evident.