Sixteen horses of either sex and different age groups coming to the clinics with the presence of eye worm in the anterior chamber were taken as the subject of the study. Animals were presented with the history of corneal opacity, corneal oedema, epiphora and presence of worm inside the eye (Fig. 1). A thorough examination of anterior chamber was done using direct and lateral illumination.

How to cite this article: Dabas, V.S., Tyagi, S.K., Jhala, S.K., Suthar, D.N. and Bhatt, R.H. (2021). Management of Ocular Setaria in horses: A review of 16 cases. J. Anim. Res., 11(1): 143-146. Source of Support: None; Conflict of Interest: None

Of the 16 horses affected, 10 were male and 6 were females. The percentage of male and female affected depends on the population of particular animal in particular area. In north India, the female population is more as they are used for social activities like marriages, whereas in western India, male horses are kept for sports purpose. Breedwise Marwari (n=5), Sindhi (n=4), Kathi (n=3), Sindhi x corneal desensitization Marwadi (n=2) and non-descript (n=2) breeds were recorded. All the cases presented were having unilateral affection with right side (n=9) affected comparatively more than left one (n=7). Though, involvement of the one eye is commonly observed but bilateral occurrence is also reported (Shin et al., 2002; Buchoo et al., 2005). Only one worm was observed in all the cases except for one horse; wherein two worms were retrieved from the anterior chamber of the same eye.

Mritunjay et al. 2011 have reported a higher prevalence of ocular setariosis in animals in summer and autumn seasons when the vectors (Anopheles peditaneniatus and Culexnil giricus) are most prevalent. A seasonal predisposition was also observed in the present study, wherein all cases were recorded from October to April and no cases were recorded in summer season.

The cases were presented within one week to three weeks of appearance of symptoms, except for two, which were presented one month after the onset of the symptoms. In these two cases the corneal opacity was extensive and it was very difficult to visualize the nematode, in addition, the fluid in the anterior chamber had also became viscous and the movement of the worms was also very sluggish. In one of these cases, the worm was not retrieved even after stab incision and the anterior chamber also collapsed. Later, the worm was removed using castrovejo’s eye forceps and the anterior chamber was reformed again by inflating air inside. Thus early presented cases have a better prognosis in terms of visualization of worm in addition to lesser trauma to the cornea by the worm and the surgical treatment should be performed as soon as possible to prevent complications.

A clear corneal stab incision was made with the help of B.P. blade number 11 in all the cases except for two where needle puncture was made using 16 number needle. Gopinathan et al. 2012 have also used these two techniques for removal of eye worm viz., stab incision by blade or puncture by 16 G needle.

No complication like eye ball shrinkage due to aqueous effusion was observed in the present study. In some cases the worm gets lodged at the site of incision and can be recovered using capsular forceps.

For the puncture with nick incision, 10-2 o’ clock or 3-9 o’ clock positions can be used and generally the corneal wound is left unstitched. Incision at 10-2 o’ clock position has been proposed by many workers (Jamelka, 1976; Kalpravidh et al., 1992; Patil et al., 2012) and it requires the animal to be recumbent requiring sedation or general anaesthesia. However, incision at 3-9 o’ clock position has also been used (Gopinathan et al., 2012).

There are reports on the successful removal of intraocular parasites by aspiration using a 16-gauge needle connected to a 5-mL syringe (Gangwar et al., 2008; Yang et al., 2014). In an earlier report, an 18-gauge needle was used but the worm could not be removed and additional incision on the cornea was required (Tuntivanich et al., 2011). However, in the present study, 16 gauge needle was used to puncture the anterior chamber near limbus and worm was removed, without aspiration and no additional incision was required to remove the worm.

The operated eyes developed a localized corneal oedema/ opacity at the site of corneal stab (Fig. 9), which resolved gradually. A combination of antibiotics and corticosteroids along with 6% sodium chloride was administered postoperatively to reduce intraocular inflammation and corneal edema/opacity. Similar findings of focal corneal opacity at the site of stab incision have also been reported in earlier studies (Sharma et al., 2005; Patil et al., 2012). All eyes showed uneventful recovery in terms of lacrimation, blepherospasm and restoration of corneal transparency within 20 to 30 days, as also reported by Buchoo et al.

(2005) and Jaiswal et al. (2006).

To conclude, equine ocular setariosis can successfully be managed surgically in xylazine sedated standing horses under retrobulbar nerve block through corneal puncture using stab incision by blade or needle puncture, near limbus anywhere between 3-9 o’clock position, depending upon the movement of the worm.