Case series: periocular habronemiasis in five horses in the Netherlands

Abstract

In tropical and subtropical climates, infection of periocular tissue by larvae is a recognised cause of conjunctivitis or blepharitis. To the authors' knowledge, only a few cases of habronemiasis have been described in Western Europe, and it has not been documented previously in the Netherlands. The objective of this report is to describe the occurrence of five cases of (peri)ocular habronemiasis in the Netherlands, of which four date from the past few years. The diagnosis was based on the history, clinical signs and histopathologic examination of biopsy specimens. A granulomatous conjunctivitis/dermatitis and sulphur-like granules were present in all cases. Histopathology showed an eosinophilic granulomatous inflammation, and three out of five (60 per cent) samples revealed one or more nematodes on section. Treatment combinations with surgical excision, local corticosteroid and/or anthelmintic drugs were used. Furthermore, all horses received ivermectin or moxidectin. Treatment resulted in healing of the lesions in four horses. One case, which was refractory to treatment, resolved spontaneously after the onset of colder weather. This case series suggests an increased prevalence of (peri)ocular habronemiasis in the Netherlands. This diagnosis should therefore be considered when being presented with a horse with granulomatous conjunctivitis/dermatitis in Western Europe, especially during the summer months.

Habronematidosis in Equids: Current Status, Advances, Future Challenges

“…This form is only apparently uncommon; five cases of (peri)ocular habronematidosis have been recently published in the Netherlands ( 33 ) but we speculate that many other cases might have not been published. Affected horses may show profuse mucopurulent discharge, and from moderate to evident blepharospasm and/or epiphora.…”

“…Gross lesions are ulcerative and granulomatous with so-called sulfur-like granules within and around the lesion (from 5 mm to 1.5 cm in diameter up to 25 × 10 cm) that appear on the palpebral conjunctiva of the medial canthus (33,55). The histological examination shows a marked infiltration of multifocal to coalescing eosinophilic granulomas, and a nucleus of eosinophilic necrotic debris together with many degenerate eosinophils delimited by epithelioid macrophages with few lymphocytes and plasma cells in the adjacent tissue, with occasionally multifocal moderate to large clusters of coccoid bacteria in most of the affected animals (33). When the prepuce, urethral process, vaginal fornix are affected, animals show dysuria and frequent urination due to the presence of different degrees of fibrosis (56,57).…”

“…The description of these cases is often limited to single cases, for instance in UK ( 30 , 31 ), Belgium ( 32 ), and Italy ( 12 ). An increase of (peri)ocular habronematidosis has been recently suspected in the Netherlands ( 33 ).…”

“…Other drugs (ivermectin, echothiophate, and trichlorfon) have been described for treating cutaneous or mucocutaneous forms ( 33 ); in addition, corticosteroids were used to reduce inflammatory hypersensitivity reactions. These molecules can be used mostly in ocular habronematidosis and administered systemically, topically, intra-lesionally or sub-conjunctivally ( 33 , 55 ).…”

Co‐occurrence of papillomas related to Equus caballus papillomavirus type 2 and cutaneous habronemiasis

“…However, there are few data on the prevalence of equine cutaneous or mucocutaneous habronemiasis because the description of these cases is often limited to case reports, for instance, in the UK, Belgium and Italy (Barlaam et al 2020). An increase in (peri)ocular habronemiasis has been recently suspected in the Netherlands (Verhaar et al 2018). Cases of cutaneous habronemiasis conoccurrent with equine sarcoids have been reported worldwide only twice before: in Italy and Brazil (Corteggio et al 2012;Firmino et al 2016).…”