الفهرس 
Acknowledgment
TetrahydropyrimidinesOnly 14 pages are availabe for public view
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Abstract
Parasitic infestation is the most common problem that affecting equines. It affects the equines breeding and production causing heavy losses due to emaciation, with decreased physical performance, indigestion, abdominal distention, intestinal rupture, and death in cases of heavy infestation. Strongyle sp. infestation considered the main parasitic problem in equines specially donkeys. Veterinarians and owners used to depend on the affordable drugs which led to development of resistance.
A total number of 215 donkeys of different sexes, ages and in different locations at El Kharga city, El Wadi El Gadid Governorate were employed in this study for detection of Strongyle sp. infestation. 35 donkeys naturally infested with Strongyle sp. with a minimum FEC 250 EPG and more were used to investigate the efficacy of commonly used anthelmintic drugs for treatment of these worms.
Fecal samples were collected and examined using direct smear, floatation test and egg count using Mcmaster technique with a detection threshold of 50 eggs per gram of feces.
The overall prevalence of Strongyle sp. in El Kharga city, El Wadi El Gadid was 73.02% of examined donkeys by direct smear and floatation test.
Emaciation, poor performance, weight loss, rough coat, lethargy and anorexia signs were recorded in 93 of the tested positive donkeys. Only 2 donkeys suffered from intermittent diarrhea and their appetite varied from normal to anorectic, with normal body temperature, respiratory and heart rates. The fecal consistency of infested donkeys was normal (semi solid) except in the 2 cases suffered from diarrhea.
According to the degree of infestation with Strongyle sp. the results showed that 35.03% of donkeys were having mild infestation, 20.38% of donkeys showed moderate degree of infestation and 44.59% of donkeys showed severe degree of infestation.
In the present study we found that the sex of the examined animals had no effect in the percentage of infestation with Strongyle sp. worms. Prevalence of Strongyle sp. in female donkeys was 75.56% and 71.2 in males.
Effect of location was also investigated in this study and samples were collected from different areas in El Kharga city, El Wadi El Gadid as Al- Sherka55, Al-Thawra, Al-Mounira, Al-Osierat, Al-Qattara, Al-Mallaha and Al-Bostan. The highest prevalence rate was recorded at Al-Sherka55 (100%) followed by Al-Thawra (84.62%), then Al-Mounira and Al- Osierat (80%), and Al-Qattara (66.67%) and the lowest prevalence rates were at Al-Mallaha and Al-Bostan where it was 41.18% and 38.46% respectively.
The examined donkeys were classified in to three age groups (less than 3 years, 3-8 years old and more than 8 years old) There was a significant difference between age groups for Strongyle infestation. Animals under the age of 3 years old had a higher prevalence than animals 3 – 8 years old. Donkeys more than 8 years old showed no infestation Strongyle rate.
The therapeutic efficacy of ivermectin and doramectin injectable solution and pyrantel and piperazine citrate orally administrated at the manufacturers recommended dose were evaluated in a controlled experiment involving 35 donkeys naturally infested with Strongyle sp. worms. Animals were divided into four treatment groups and a control group. To measure the efficacy of the anthelmintic drugs, FECRT was
carried out. Calculations were done in the day zero (before treatment) and at the 7th, 14th, 21st, and 28th days (after treatment). In ivermectin treated group, the mean FECR% during the first 21 days after treatment were more than 95% resistance limit, but it reduced on day 28 to be 91.6%. Also, it has been found that small Strongyle EPG counts are returned much quicker (less than the initial approximate 8 weeks) than when the drug first was marketed.
The mean FECR % in doramectin treated group ranged from 98% to 100% during the 28 days period of treatment, so it remained above the 95%limit. Mean FECR % in pyrantel treated animals was less than 90% for the whole 28 days of treatment. Meanwhile, piperazine citrate treated group showed good mean FECR during the first 14 days reached to 96.67%, but then decreased to reach 86.67% by day 28. Comparing these results revealed that doramectin was highly efficient against Strongyle sp worm infestation than ivermectin and other anthelmintic drugs used in the study.
At necropsy pyrantel and piperazine citrate treated groups showed large number of mature parasites in the caecum and colon of treated donkeys after 28 days of treatment, while in ivermectin treated group showed few numbers of adult worms were recovered, but no worms could be recovered from doramectin treated donkeys. Only slight erosions, that may be caused by feeding of parasite worms could be seen in the mucosa of the caecum in pyrantel treated donkeys. Species of worms recovered from euthanized donkeys were: Strongyle sp., Oxyuris equi, Gastrophilus
larvae, Cylicostaphanus goldi, Cylicocyclus elongates, Cylicocyclus auriculatus, Cylicocyclus labratum and Cylicostaphanus longibursatus.