Robert Braun; Mike Paulson; Carlos Omphroy; Bruce Heath; William Gilmartin; Tim
Ragen; Marlee Breese; Cindy Driscoll
Introduction
In 1984, the National Marine Fisheries Service (NMFS) began collecting
undersized Hawaiian monk seal pups from the wild for rehabilitation on Oahu, Hawaii, to release
back to the wild population. Twelve pups are currently in captivity at the Oahu holding facility,
and nine have developed eye conditions consisting of severe bilateral corneal opacities,
resulting in corneal edema, transient glaucoma, bullous keratitis, and transient conjunctivitis.
This disease process has not previously been seen in wild or captive Hawaiian monk seals.
Observers have not seen this problem in the wild. The etiology of this disease process is under
investigation.
History
The twelve pups currently on Oahu were collected from French Frigate Shoals
(FFS) in the Northwestern Hawaiian Islands, between 27 May and 31 July, 1995. At FFS, the seals
were held for 2 to 21 days in a fenced shoreline pen. Three seals had conjunctivitis while in the
holding pen at FFS.
In the nine affected pups, eye problems were reported 7 to 31 days after
arrival to Oahu. Included were the three which also had reported eye problems at FFS. All nine
pups reported to have conjunctivitis in the first few weeks on Oahu, went on to develop corneal
edema, bullous keratitis, and transient conjunctivitis as well as eye pain 44 to 92 days
following the resolution of initial eye problems. Of the three pups which did not develop corneal
opacities, two had reports of eye problems but these symptoms were transient and did not involve
the cornea or inflammation of the conjunctive. The corneal opacities and associated edema began
centrally and progressed outward to the limbus. Conjunctivitis, photosensitivity, and occurred
transiently after the entire cornea becomes opaque and a bullous keratitis developed. Vision is
severely impaired for about 7-10 days at this stage of the disease. In 7 of the 9 affected seals,
the right eye first demonstrated corneal opacity and edema; however, both eyes progressed
similarly and to the same extent through the course of this disease process.
The order of occurrence of corneal opacities roughly corresponded to the
seals' order and date of capture at FFS. Although the date of departure from FFS spans a 76 day
period, all cases of corneal opacity occurred approximately 100 days after being held at FFS
(93-119 days). The corneal opacities showed gross evidence of receding from the limbus in the
first two affected seals at 49 and 53 days after detection. All affected pups are progressing
toward resolution.
Diagnostic Efforts
At entry to the holding facility on Oahu, all 12 seals were evaluated
clinically and blood samples were collected for complete blood counts (CBC), serum chemistries
and, serology. Serology was done for toxoplasmosis, canine distemper, leptospirosis, Dirofilaria
immitis, and canine parvovirus. Fecal samples were evaluated for intestinal parasites and
Salmonella culture. None of these tests indicated disease.
During the initial period of conjunctivitis, after arrival on Oahu, the
symptoms were limited to the eyes. Appetite, activity, CBC, serum chemistries remained
essentially normal. CBC and serum chemistries were normal. Symptoms resolved in 3 - 4 days. About
80 days later when corneal opacities were observed an intense diagnostic effort began.
A botanist identified plants surrounding the holding pools and believed them
not to be the cause for eye problems. Review of the paints, solvents and abrasives used
previously on the pools found them not to be involved. The source water for these holding pools
has the same source as is used for other pinnipeds (including four adult Hawaiian monk seals).
Coliform counts are similar to previous years of pup rehabilitation. There has been no
significant exposure to fresh water. The sunlight reflected from the walls and bottom of the pool
is the same as in previous years. The diet of herring is from the same source as in previous
years and is the same as is being fed to numerous other pinnipeds and cetaceans. Feral cats,
mongoose, and mice from the vicinity of the holding pools have been necropsied. No ocular
pathology was observed.
External ocular testing has been done. Conjunctival and corneal swabs have
been evaluated by scanning electron microscopy and were unrevealing. Aerobic bacterial cultures
have not identified a pathogen. Chlamydia culture/antigen testing and mycoplasma cultures have
been done and are negative. Immediately prior to the bullous keratitis phase the intraocular
pressures were elevated in two of the affected seals. Non anesthetized and restrained pups
without corneal opacities had intraocular pressures of approximately 28 mmHg. Pups in the active
bullous keratitis phase had intraocular pressures, when restrained, of approximately 56 mmHg.
After the acute phase, intraocular pressures while restrained were similar or slightly less than
those of unaffected pups. During the bullous keratitis phase the roughened cornea retained
fluorescein stain.
Extensive serological evaluations have been done and some are still pending.
Serum protein electrophoresis suggested immunocompetence but was otherwise unremarkable. Serum
neutralizing antibody tests for canine distemper, canine parvovirus, canine corona virus, and
infectious canine hepatitis were negative. Serological tests for leptospirosis, Dirofilaria
immitis antigen, toxoplasmosis, and brucellosis were also negative. Serum neutralizing antibody
tests for phocid calici virus and herpes simplex 11 were similar in affected as well as
unaffected pups and to sera of pups from previous years. Serum vitamin A (sk) levels (30-33
mcg/dl) were similar for unaffected and affected pups. Serology for feline rhinotracheitis,
feline calici virus, adenovirus panel, phocid distemper, and phocid herpes is still pending.
These pups were examined by eight veterinarians involved with marine mammals
and several biologists. Their differential diagnostic list resulted in the previously stated
testing. In addition five of the twelve pups were anesthetized with isoflurane and had complete
ocular examinations by both a veterinary and human ophthalmologist. These examinations were
documented by fundic, macro and still photography. Also there was video documentation of the
anesthetic protocol and eye exams.
Tonometry found anesthetized intraocular pressures in unaffected and
resolving eyes to be similar at approximately 12-15 mmHg. Slit lamp examination revealed corneal
opacities and associated vascularization was limited to the anterior cornea) stroma. The corneal
endothelium and immediately adjacent stroma was normal. In addition, the anterior eye chamber,
iris, and lens were normal. Gonioscopy found no evidence of closed filtration angle, senechia, or
filtration angle inflammation. Iris dilation was achieved with topical 10% neo Synephrine and 0.5
ml of 1/10,000 epinephrine. Fundic examination found a normal posterior chamber including macula,
optic disc, tapetum, and retina. Aqueous humor (0.5 ml) was taken from each eye for further
evaluation. Four 6 mm diameter, thin layer, corneal biopsies were taken. Three were preserved in
10% buffered formalin and one in glutaraldehyde. Five conjunctival biopsies were also taken. Four
were preserved in 10% buffered formalin and one in glutaraldehyde. Anti Hawaiian monk seal
antibody is being prepared for potential immuno histopathology. The formalin preserved biopsy
samples are being investigated with light microscopy. No cells were found in the aqueous humor.
Scanning electron microscopy on the aqueous humor is pending. Virus isolation of aqueous humor is
still pending.
Treatments
At the Oahu holding facility during the initial conjunctivitis problems
four of the nine affected pups were treated with topical triple antibiotic ointment for 3-5 days.
Once the corneal opacities were observed oral Baytril (20 mg/kg ) and topical 1% chloramphenicol
ointment were administered twice daily. Topical 1% chloramphenicol was discontinued and
hyperosmotic sodium chloride ointment was substituted. After 5 days gentocin ophthalmic ointment
was applied. After much consultation, oral (20 mg/kg twice daily) and topical 1% chloramphenicol
were administered in conjunction with oral prednisone (0.50 mg/kg twice daily). One pup just
beginning to display corneal opacities was given just oral prednisone (0.50 mg/kg twice daily).
Subjectively none of these therapies altered the eventual progression of this disease process.
The one pup treated with only oral prednisone has had a longer progression of the same
pathological changes as those not similarly treated. Topical treatment with the nonsteroidal
anti-inflammatory drug Profenal twice daily greatly reduced pain, photophobia, and see trauma to
the eye. The use of Timoptic, lopidine, and Daranide did not grossly affect the progression of
the corneal opacities.
Summary
While waiting for the serology, histopathology, electron microscopy, and
virus isolation we continue to define the associations of different individuals at different
periods of potential contagiousness. We have ruled out many etiologies in our investigation and
many are still pending. We now have a well defined understanding of the pathology of this disease
process as well as much more basic understanding of the anatomy of a Hawaiian monk seal eye. At
this point in the investigation, all pathological changes are limited to the anterior cornea. Eye
lesions on all affected pups are resolving. It is expected that all twelve pups will have vision
compatible with survival in their natural habitat.
A definitive diagnosis and etiology are an extremely important element in the
decision process for the release of these pups back to their native habitat. Along with our
diagnostic efforts, decisions as to release criteria; evaluation of data in light of those
criteria; and identification of qualified individuals who will participate is equally
important.