Medical management and resolution of perinatal bilateral exophthalmia and secondary corneal ulcers in an Antillean manatee (Trichechus manatus manatus) neonate from Puerto Rico

OBJECTIVE

To present a novel case of perinatal bilateral exophthalmos and corneal ulcers in a neonate Antillean manatee and describe the medical treatment that led to the resolution of the observed clinical signs and vision restoration.

ANIMAL STUDIED

A manatee stranded alone in Puerto Rico on July 5, 2020.

RESULTS

The manatee was found in critical condition with pronounced exophthalmos, lagophthalmos, and corneal opacification of both eyes (OU). Vision impairment was evident due to the lack of ocular menace reflex and bumping into the tank's walls. Biomicroscopy revealed conjunctival hyperemia and chemosis, limited third eyelid movement, but had viscous tears present OU. Dense, full-thickness, white to cream-colored cellular infiltrates affected 70% of the cornea with peripheral active vascularization OU. Rubeosis iridis was also present OU. Treatment consisted of supportive medical management, including nutritional support and topical treatment for ulcerative keratitis. Resolution of the corneal ulcers and functional vision were achieved after 6 weeks of therapy. Currently, bilateral, mild, intermittent exophthalmos is observed with no adverse clinical signs, and the calf is in good health.

CONCLUSIONS

The extent of bilateral corneal disease on a neonatal calf may be a result of an intrauterine infection or possible trauma at or right after birth. While the latter may have led to exophthalmia and consequent corneal disease, the exact cause could not be determined. Supportive therapy and medical management of infectious keratitis were successful and led to vision recovery. This is the first report of ocular pathology in a neonatal manatee.

For Better, For Worse: Manatee-Associated Tursiocola (Bacillariophyta) Remain Faithful to Their Host

With the advent of more comprehensive research into the microbiome and interactions between animals and their microbiota, new solutions can be applied to address conservation challenges such as husbandry and medical care of captive animals. Although studies on epizoic algae are relatively rare, and the function and role of those mainly photosynthetic organisms in the animal microbiome is not well understood, recent surveys on epizoic diatoms show that some of them exhibit traits of obligate epibionts. This study explores diatom communities on captive-born manatees from the Africarium in Wroclaw, Poland. Light and scanning electron microscopy analyses revealed that skin of all animals sampled was dominated by apochlorotic Tursiocola cf. ziemanii, an epizoic species described recently from Florida manatees, that reached 99,9% of the total diatom abundance. Despite using media with a wide range of salinity (0-34), the isolated Tursiocola cells did not grow, whereas the normally pigmented Planothidium sp., that was only occasionally found on the animal substratum, survived in all culture media tested. Our observations provide direct evidence that manatee-associated Tursiocola endure the dramatic salinity changes that occur regularly during their host life cycle, and can thrive in an artificial captive setting, if the manatee substratum is available. The impact of practices and routines used by the Africarium on manatee-associated diatoms, as well as ultrastructure of areolae in Tursiocola, are briefly discussed.

Melanothamnus maniticola sp. nov. (Ceramiales, Rhodophyta): an epizoic species evolved for living on the West Indian Manatee

Over 35 macroalgae have been documented growing epizoically on sea turtles, and macroalgae are also known to grow on the West Indian Manatee, but the number and identity of these latter species have not been determined. Analysis of DNA sequences of 12 samples collected from different manatees captured in three areas of Florida indicated that they represented a single undescribed species within the Rhodomelaceae genus Melanothamnus. Morphological analysis revealed Melanothamnus characteristics but also a previously undescribed combination of character states. These include eight to nine, but as many as 11, pericentral cells; heavy cortication restricted to the base of thalli, and a sharp transition between the corticated and ecorticate sections of the thallus; cells surrounding the ostiole being similar in size to the outer pericarp cells immediately below, and robust rhizoids that have no terminal lobes and develop from central axial cell filaments instead of pericentral cells. The unique characteristics of the rhizoids may be evolutionary adaptations for anchoring the thalli to manatee epidermis. This species is described as M. maniticola sp. nov.