Introduction

Gasterophilus is from Gasterophilidae fam- ily and has 9 species that could cause a myia- sis in gastrointestinal tract (Zumpt, 1965). They are distributed worldwide and especially in Afrotropical and Palearctic and could live   in the equids about 10 months (Akele et al., 2018). Clinically, myiasis have been divided into 5 groups; sangvinivorous myiasis, dermal and subdermal myiasis, nasopharyngeal myia- sis, intestinal myiasis, and urogenital myiasis (Zumpt, 1965). Numerous larvae of Gaster- ophilus could cause pathologic reaction in host. First stage of Gasterophilus is not a myia- sis infection but with the formation of inflam- matory reactions, it will become myiasis. Al- though larvae that have been swallowed with feed and indirectly pass way with feed wheth- er they were alive or not, have not been cause of true myiasis and biological larvae of para- site have not been parasite temporarily mode  of life (Zumpt, 1965). Larvae of stage 2 and    3 of Gasterophilus intestinalis live in equine gastric and have outspreaded worldwide, how- ever, there were a few reports about cause of death for this species (Sc and Ph, 1972a). First stage of Gasterophilus larvae were drowned blood from host dermal and continued his way to oral cavity and finally reached the gastro- intestinal tract (Zumpt, 1965). Diagnosis of clinical findings about stage of migration and stage of maturing are difficult but could cause harmful disorders in different species (Tavas- soli and Bakht, 2012). Overall, Gasterophilus could cause problem in swallowing, ulcers in gastric and duodenum, obstruction in intestine, volvulus, rectal prolapse, anemia, diarrhea and digestion problem (Otranto et al.,  2005).

Materials and Methods

Population study

Twenty  rural horses with different  gender

and age near Tabriz were selected by sim-  ple random method. Rural horses are most-  ly used in carrying heavy staff and passing long distances and they do not have basic care like horses in horse breeding centers or Jockey clubs. The type of feed consumed by horses was alfalfa, barley and grain which was given in four meals. All horses belonged to private owners and gastroscopy and all of the clinical examinations in the field were done with their permission. After study, all animals were returned back to their owners  in the village. Specifications such as gender, age, circumstance of keeping, type of feed, History of colic, coat condition,  deworm-  ing plan and time of using were recorded in pre-designed table. For facilitation of study, age was aggregated in 1-3, 4-6, 6-8 and 9 years and up.

Gastroscopy

The horses were kept fasted for 12 h be- fore endoscopic examination by VET3M OLYMPUS (Japan). Before the gastroscopy each of the horses was sedated by injection of Detomidine (Detomo Vet ® Ceva-Spain) 0.1ml/100kg via IV. In video  endoscopy right part of gastric around Margo plicatus, dorsal part of fundus, great curvature around Margo plicatus, less curvature around Margo plicatus and glandular part of stomach were examined.

Statistical Analysis

Data was analyzed by IBM SPSS statis- tics 24. Statistical analysis of the data was performed with 95% confidence level and p

Results

Gastroscopy

                        20 horses were studied, 13 (65%) were males and 7 (35%) were mares. All of the horses did nothave colic history and were kept in stables and had good coat. Accord- ing to endoscopic observation 9 (45%) of the horses,3 mares and 6 males, had gastric ulcer and 11(55%) of the horses, 4 mares and 7 males, did nothave gastric ulcer[Table 1].I In video endoscopic  examination  all  of the ulcers were in squamous portion of stomach, 4 (45%) of the ulcers were in great curvature of squamous portion, 4 (45%) ulcers were in less curvature of    squamous

Figure 2. 12 years old mare with gostric uncer    (severity

2) and Gasterophilus spp.(botfly)

portion and 1 (10%) ulcer were in both less and great curvature of squamous portion of stomach [Table 2]. Based on Macalister and Andrew’s pattern frequency of ulcer score  in this study is: 0 score 70%, 1 score 5%,

3 score 15%, 4 score 10% and by ulcer   se-

verity frequency: 0 (55%), 1(15%), 2(15%),

3(5%) and 4(10%) [Table 3]. Overall, 4 (20%) head of the horses had Gasterophilus spp. and all of them showed presence in the horse with no deworming plan  [Figure1-2].

Statistical Analysis

There is not any relation between pres- ence of Gasterophilus spp. using anti-para- site drug (p=0.20) and gastric ulcer  (p=0.8)

Figure 1. 12 years old mare with gostric uncer (severity 2)

and Gasterophilus spp.(botfly)

Table 1. Frequency of gastric ulcer in both mare and male

Table 2. Portion of ulcers in non-glandular part of stomach

Table 3. Frequency of scoring of ulcers that found in the endoscopic exam- ination: 0 score 70%, 1 score 5%, 3score 15%, 4 score 10%

and, based on the results, there was no asso- ciation between presence of Gasterophilus with occurrence of Gastric ulcer  (P>0.05).

Discussion

Equine gastric ulcer syndrome (EGUS) terminology is divided in 2 parts, non-glan- dular ulcer and glandular ulcer (Sykes and Jokisalo, 2014). Factors mentioned above cause ulcer in non-glandular portion that could be increased in gastric acid secretion and excessive contact of gastric acid with squamous part and increased in VFA secre- tion (Sykes and Jokisalo, 2015). In glandu- lar portion ulcer might be Helicobacter spp, overuse of NSAIDs such as phenyl butazone, but cause of ulcer in this part is not clarified ( Sykes and Jokisalo, 2015). There are a lot of

clinical findings for gastric ulcer, for exam- ple, recurrent and sever colic, diarrhea, bad hair coat condition, anorexia, weightloss, change in behavior like a crib biting, depres- sion, decrease in performance and (Malm- kvist et al., 2012; Videla and Andrews, 2009; Wickens et al., 2013) and the best way for diagnosis of EGUS is endoscopy. Climate of Iran has suitable ecological factors and Ta- briz, Iran specifically, has a best weather for growing and spreading Gasterophilus, also most of the Gasterophilus spices have been recognized (G.intestinalis, G.haemorrhoid- alis, G.nasalis, G.inermis, G.pecorum, G. meridionalis G.nigricornis). The difference between spices, prevalence and larval bur- den of Gasterophilus in our study and other overseas studies may be because of  different

climate, management factors (anti parasite schedule), hosts (for example shade of ge- netics and irritant of host)  and differences  in genetics and population composition of parasite (Mashayekhi and Ashtari, 2013). Excess of larvae that presented in stomach may cause obstruction and colic and excess larvae that damaged the tissue of stomach or mucosa of intestinal and were limited vital nutrient may cause health problem in host ( Waddell, 1972). Ulcers and lesions studied  by Waddell revealed  similarity  with  ulcers in pigs that had a gastric  ulcer.  The ulcers  in pig stomach had bleeding but there was not any bleeding in ulcer site of horse gas- tric. Although this disease has high mortality in pigs, this disease  has less  pathogenicity  in horses (Waddell, 1972). In our study, no bleeding ulcer was observed in endoscopic finding. Depth of ulcers  caused  by  larvae do not have any association with thickness  of gastric and duodenum. Moreover, ulcers which were caused by larvae can affect thickness of layer. Cells proliferation under gastric ulcers and duodenum ulcer do not have any relation with depth of ulcers. Cells proliferation under gastric ulcer had more significant progress than ulcers in duode- num part. Histopathologic findings revealed severe fibrosis in ulcers and this finding in affected duodenum revealed severe dam-  age in submucosal glands around and below lesions. Fibrosis of the underlying lamina propria mucosa and tunica submucosa was distinctive but was not able to renew thick- ness of duodenum (Cogley and Cogley, 1999). The horse was necropsied and stom- ach adjacent to spleen had a gastritis, ulcers with 1cm were presented and all the ulcers were in non-glandular part  of gastric  (Dart et al., 1987). The study of Sequeira and his colleagues  was performed  in 95 horses  that

16.84% of which had a Gasterophilus nasa- lis and the lesions site of larvae attachment both microscopically and macroscopically was examined. Erosion, ulcers of stomach and proximal duodenum were mostly rec- ognized macroscopic. Based on microscopic findings, lesions of spectrum ranged from inflammatory reactions to necrosis and ul- ceration. Macroscopic findings revealed that lesions were scattered in duodenum and am- pulla part of proximal duodenum and lesions shape was circular  and  punctiform.  Also,  at higher levels of infestation, lesion had a different type (Sequeira et al., 2001). None  of our cases necropsy during the period of study, so we did not have any information about type of lesion in necropsy or histopa- thology. In study of 16 horses that were clin- ically suspected for gastric ulcer, five of the horses had presented both gastric ulcer and Gasterophilus and all of the horses died be- cause of cachexia. Gasterophilus was found in post mortem findings of three horses (Ma- shayekhi and Ashtari, 2013). We could not send the samples for parasitological study because all of the horses were alive and sam- ples were randomly selected without a histo- ry of colic. Nine mares of 80 horses in one herd that were fed in pasture died. Necropsy of gastrointestinal tract revealed a lot of bot flies that had adhered to esophagus mucosa and non-glandular part of gastric. Parasi- tological tests revealed 3rd stage larvae of Gasterophilus pecorum (Moshaverinia et al., 2016). Fortunately, none of the animals died during the period of our study. Also, in the study of 330 horses was done in Belgium during one year, 193(58%) horses had Gas- terophilus. Size of lesions was between 1cm2 and 17cm2 and most of the larvae were seen in Margo plicatus (Agneessens et al.,   1998).

S.R Felix et al   reported prevalence of  Gas-