Surgical management of ocular setariasis in a goat: A case report

Introduction

Ocular setariasis is a vision-threatening ophthalmic condition in ungulates, particularly equines and occasionally ruminants, caused by the aberrant migration of Setaria spp., a genus of filarial nematodes (Gangwar et al., 2008; Radwan et al., 2016) [6,14] . Adult Setaria worms typically reside in the peritoneal cavity, but ocassionally migrate erratically and end up in unusual locations, like the eye, potentially causing blindness (Soulsby, 1982) [16] . The immature worm can also gain access to eye (Sreedevi et al., 2002; Tuntivanich et al., 2011) [17,20] through the vascular system (Townsend, 2013) [19] . The worm's serrated cuticle and vigorous movements within the eye's anterior chamber cause severe corneal trauma and inflammation, leading to corneal opacity and potentially resulting in blindness (Jaiswal et al., 2006) [8] . The infected animals typically exhibit symptoms such as photophobia and lacrimations (Basak et al., 2007) [2] . The incidence of ocular setariasis is highest during summer and autumn, when mosquito vectors are most prevalent (Mritunjay et al., 2011; Al-Azawi et al., 2012) [12,1] . While ocular involvement is commonly unilateral, bilateral cases have also been reported (Buchoo et al., 2005) [4] .

Materials and Methods

A 3-year-old male goat was presented to the Large Animal Section, Department of Surgery and Radiology, Veterinary College, Hebbal, Bengaluru, with a history of cloudiness and excessive lacrimation of the left eye for 3 days. Ophthalmic examination revealed a motile, white, thread-like structure in the anterior chamber suggestive of an eyeworm. Based on clinical findings, surgical correction was planned for the next day. The animal was advised 12 hours of preoperative fasting. Sedation was achieved using diazepam (0.3 mg/kg IV), followed by an auriculopalpebral nerve block using 2% lignocaine hydrochloride. The animal was restrained in lateral recumbency, and the site was prepared aseptically using 5% povidoneiodine scrub. Eyelids were retracted with an eye speculum to provide adequate exposure. A corneal stab incision was made with a 2.8 mm keratome slit blade at the 4 o'clock position, 1 mm away from the limbus (Fig. 1). The eyeworm was removed, and the incision site was left unsutured for natural healing. The anterior chamber was flushed with Ringer's lactate, and 2% viscomet solution was instilled to protect the corneal endothelium. Postoperatively, enrofloxacin (5 mg/kg IM) and meloxicam (0.2 mg/kg IM) were administered. Topical Ciplox-D eye drops were applied four times daily for 10 days, and fenbendazole (10 mg/kg PO) was given once.

Results and Discussion

The animal recovered uneventfully within 2 weeks, with a gradual reduction in the corneal opacity observed on the 3 rd and 7 th post operative day (Fig. 3 and Fig. 4). No post operative complications were observed. The recovered worm was sent to the Department of Parasitology and confirmed as setaria digitata on the basis of its morphological characteristics (Fig. 2). The adult species of Setaria is commonly seen in peritoneal cavity and was found to be harmless to the host (Mritunjay et al., 2011) [12] . However, erratic migration of larvae into anterior chamber causes changes in cornea leading to corneal opacity. surgical extraction of the worm, typically via needle paracentesis or corneal incision, performed under general or regional anesthesia, remains the preferred treatment method for ocular setariasis (Tuntivanich et al., 2011; Chaithra et al., 2024) [20,5] . Lumb and Jones (2001) [9] reported regional nerve blocks like supraorbital, auriculopalpebral and retrobulbar can be performed using 2% lignocaine hydrochloride as per standard method. [4,21,7] . In the present study, the worm was removed under sedation with diazepam and auriculopalpebral nerve block using 2% lignocaine hydrochloride, through a corneal stab incision using 2.8mm keratome slit blade given at 4 O'clock position 1mm away from the limbus was found to be effective. The animal showed recovery after 2 weeks of worm removal. Ivermectin administration (200-300 micrograms/kg body weight, orally) can help minimize the occurrence of filarial nematodes (Muhammad and Saquib, 2007) [13] . However, medical treatment alone is often deemed insufficient due to the slow resorption of dead parasites, which can trigger uveitis (Moore et al., 1983) [11] . Cattle and buffaloes in India are known to be commonly infected with Setaria digitata (Mohanty et al., 2000; Sundar et al., 2015) [10,18] . The goats exposure to infected cattle and mosquitoes during the rainy season probably heightened their risk of infection, leading to clinical disease (Bazargani et al., 2008; Smith et al., 2009) [3,15] . No incidence of the disease was reported earlier in the Karnataka local goats from the place of present reporting.

Conclusion

From the results of the present study, surgical removal through corneal incision at 4 o'clock position under mild sedation and auriculopalpebral nerve block yielded good result and is convenient for successful removal of eye worms in goat.

Conflict of Interest Not available

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