Conjunctival flora of healthy and diseased eyes of grey seals (Halichoerus grypus): implications for treatment

Abstract

Ocular pathology is relatively common in stranded seals admitted to wildlife rehabilitation hospitals. Some have pre-existing problems, while others develop eye problems in captivity, and in particular ulcerative keratitis, due to factors such as large prominent eyes, suboptimal water quality, trauma and infighting. Despite treatment, corneal ulcerations can rapidly progress to 'melting' ulcers with subsequent rupture of the globe. In this case series, 32 grey seals (Halichoerus grypus) had conjunctival swabs taken on admission to a UK wildlife hospital to identify ocular bacterial flora and nine had subsequent swabs taken after four weeks to see if this changed in captivity. Additionally, nine seals with ocular pathology were also swabbed. Although a wide range of bacteria were cultured on admission, the most common isolates were Gemella haemolysans, Escherichia coli and Clostridium perfringens All 'melting' ulcers were associated with Pseudomonas aeruginosa, which suggests this bacterial species may be significant in the pathogenesis of progressive stromal ulceration in grey seals.

Streptococcal Infections in Marine Mammals

“…A study of human S. agalactiae strains from fish, seals, a dolphin, and a frog indicated zoonotic and anthroponotic hazard by causing severe disease in fish and compromising food security [66]. Between 2012 and 2014, S. agalactiae was isolated from a stranded grey seal on the British coast with ocular pathology [67]. In the Waikiki Aquarium, Honolulu, Haiwaii, S. agalactiae was isolated from two male healthy Hawaiian monk seals (M. schauinslandi) as part of their aerobic bacterial flora in the nasal cavity [68].…”

“…mitis was isolated in 1985 from a blowhole swab of a captive, healthy white whale (Delphinapterus leucas) 139 days after captivity at the Mystic Marinelife Aquarium Connecticut, USA [140]. In 1985, it was isolated from lesions of a grey seal with peritonitis in North Rona, Scotland [62] and between 2012-2014 from clinically normal eyes of two grey seals stranded on the British coast [67]. These findings suggest that S. mitis might also be a commensal in some marine mammals.…”

“…uberis was found in dead free-ranging male Antarctic fur seals with pneumonia and extensive polymorphonuclear infiltrations and necrosis or very widespread abscess formation and frequently there was an associated fibrinous exudative pleurisy [63]. S. oralis was isolated and identified by API strips from three swabs taken from healthy eyes of free-ranging grey seals stranded on the British coast between November 2012 and February 2014 [67]. In a metagenome dataset of blood, muscle, and fecal samples of a living stranded sperm whale (Physeter catodon) S. anginosus, S. pneumoniae, and S. suis were detected in blood and fecal samples, but not in the muscles [168].…”

Conservation and the 4 Rs, which are rescue, rehabilitation, release, and research

“…Mammals carry pathogens (Siembieda et al. ; Fleming & Bexton ), including rabies (Kelly & Sleeman ; Schmidt‐French et al. ).…”