Normal ocular features, conjunctival microflora and intraocular pressure in the Canadian beaver (Castor canadensis)

The ocular pyogranulomatous lesion in a Gentoo penguin (Pygoscelis papua) from the Antarctic Peninsula: evaluation of microbiological and histopathological analysis outcomes

In this study, it was aimed to present the results of microbiological, cytological, histopathological, and immunohistochemical analyses of ocular samples from an Antarctic (Ardley Island, King George Island) Gentoo penguin chick (Pygoscelis papua) with a pyogranulomatous lesion in the right eye. Samples were taken from both the healthy left eye and the lesion in the right eye. Conventional culture methods and phenotypic and molecular tests were used for bacterial isolation and identification, respectively. None of the isolates could be identified phenotypically. As a result, four of the five isolates obtained from the right eye were considered to belong to putative novel bacterial species and taxa as their similarity to GenBank data was below 98.75%. The isolates were considered to be Pasteurellaceae bacterium, Corynebacterium ciconiae, Cardiobacteriaceae bacterium, Actinomyces sp., and Dermabacteraceae bacterium. The only isolate from the left eye was identified as Psychrobacter pygoscelis. The cytological analysis demonstrated cell infiltrates composed mostly of degenerate heterophils, reactive macrophages, plasma cells, lymphocytes, and eosinophils. Based on histopathological findings, the lesion was defined as a typical pyogranulomatous lesion. Immunohistochemistry demonstrated that the granuloma was positive for TNF-α, IL-4, MMP-9, IL-1β, and IL-6. This is the first documented report of the unilateral pyogranulomatous ocular lesion in a Gentoo penguin chick, living in its natural habitat in Antarctica. This report also describes the isolation of four bacteria from the infected eye, which are considered to belong to novel Genus, species, or taxa. The primary bacterial pathogen that caused the ocular lesion was not able to be detected and remains unclear.

Anatomical, histological and computed tomography comparisons of the eye and adnexa of crab-eating fox (Cerdocyon thous) to domestic dogs

An understanding of species' morphological and physiological parameters is crucial to developing conservation strategies for wild animals kept in human care. Detailed information is lacking for crab-eating fox (Cerdocyon thous) eyes and adnexa. Therefore, the aim of this study was to describe anatomical, histological and computed tomography (CT) features of the eye and adnexa in crab-eating fox, compared to domestic dogs. CT of the eye and adnexa of one live animal and a frozen specimen was performed for anatomical identification. In addition, the heads of five animals of each species were fixed in 10% buffered formalin for gross anatomical description of the eye and adnexa using topographic dissection and exenteration techniques. All steps were photographed and features such as location, shape, and distances and relationships between structures were described. For histological evaluation, two eyes of each species were fixed in 10% buffered formalin, processed by routine paraffin inclusion technique and stained with hematoxylin and eosin. The CT scan was difficult to evaluate, mainly that of the frozen head, which did not provide good definition of the soft tissues; nevertheless, it demonstrated the potential for structure visualization and description. The gross anatomical and histological evaluations showed the presence of eyelashes on the upper eyelid and of upper and lower lacrimal points, an incomplete orbit with supraorbital ligament, slightly exposed sclera with discretely pigmented limbus and pigmentation throughout the conjunctiva, and a slit-shaped pupil. Hematoxylin and eosin staining demonstrated structural similarities between the crab-eating fox and domestic dog. Thus, the possibility of using the domestic dog as a study model for the preventive and therapeutic management of wild dogs kept in human care is demonstrated.

Wild Nutria (Myocastor coypus) Is a Potential Reservoir of Carbapenem-Resistant and Zoonotic Aeromonas spp. in Korea

The emergence and spread of antibiotic-resistant Aeromonas spp. is a serious public and animal health concern. Wild animals serve as reservoirs, vectors, and sentinels of these bacteria and can facilitate their transmission to humans and livestock. The nutria (Myocastor coypus), a semi-aquatic rodent, currently is globally considered an invasive alien species that has harmful impacts on natural ecosystems and carries various zoonotic aquatic pathogens. This study aimed to determine the prevalence of antibiotic-resistant zoonotic Aeromonas spp. in wild invasive nutrias captured in Korea during governmental eradication program. Three potential zoonotic Aeromonas spp. (A. hydrophila, A. caviae, and A. dhakensis) were identified among isolates from nutria. Some strains showed unexpected resistance to fluoroquinolones, third-generation cephalosporins, and carbapenems. In carbapenem-resistant isolates, the cphA gene, which is related to intrinsic resistance of Aeromonas to carbapenems, was identified, and phylogenetic analysis based on this gene revealed the presence of two major groups represented by A. hydrophila (including A. dhakensis) and other Aeromonas spp. These results indicate that wild nutrias in Korea are a potential reservoir of zoonotic and antibiotic-resistant Aeromonas spp. that can cause infection and treatment failure in humans. Thus, measures to prevent contact of wild nutrias with livestock and humans are needed.

THE EYE OF THE AZARA'S AGOUTI ( DASYPROCTA AZARAE): MORPHOLOGICAL OBSERVATIONS AND SELECTED OPHTHALMIC DIAGNOSTIC TESTS

The purpose of this study was to carry out a descriptive investigation of the Azara's agouti ( Dasyprocta azarae) eye and to establish reference values of select ophthalmic diagnostic tests and physiologic parameters. A total of 19 healthy agoutis were used. Select ophthalmic diagnostic tests were performed, including Schirmer tear test type I (STTI), analysis of the conjunctival bacterial microflora, corneal esthesiometry, and tonometry. B-mode ultrasonic biometry, fundus photography, optical coherence tomography, and gross and histologic analysis of two eyes were also performed. Reference range parameters found for the ocular diagnostic tests were esthesiometry, 4.50 ± 0.36 cm (0.7 ± 0.01 g/mm²); tonometry, 11.61 ± 0.44 mm Hg; palpebral fissure length, 1.70 ± 0.25 mm; STTI, 9.73 ± 0.47 mm/min; corneal thickness, 0.8 ± 0.003 mm; anterior chamber depth, 1.71 ± 0.07 mm; lens thickness, 5.03 ± 0.05 mm; vitreous chamber depth, 5.12 ± 0.01 mm; and globe axial length, 14.02 ± 0.01 mm. A paurangiotic, retinal, vascular pattern with a conspicuous pigment-laden optic disc was observed. The most frequent bacteria isolated were nonhemolytic Streptococcus sp. (36.84%), followed by Enterobacter harfinia (31.58%) and Escherichia coli (28.95%). No significant differences between genders or between left and right eyes were found for any of the results. Gross and histologic evaluation of two eyes confirmed the presence of melanocytic pigment granules between optic nerve fibers. The diagnostic values and the morphologic observations described here provide a reference to veterinarians to aid in the diagnosis of ocular disease.

EVALUATION OF CONJUNCTIVAL MICROBIOTA IN CLINICALLY NORMAL PERSIAN SQUIRRELS ( SCIURUS ANOMALUS)

This study aimed to evaluate the bacterial flora in the conjunctival fornix of clinically normal Persian squirrels ( Sciurus anomalus). Forty healthy Persian squirrels of equal gender distribution with similar ages (approximately 2 yr) were used for this study. A total of 80 conjunctival swabs were taken from both the right and left eyes of each squirrel for aerobic and anaerobic bacterial identification. A slit-lamp examination was conducted and no external ocular disease was identified. From 80 normal eyes, Staphylococcus spp. comprised the most frequently isolated organism (83%), while Corynebacterium spp. were the second most frequently isolated bacteria (56%), followed by Streptococcus spp. (53%), Chlamydia spp. (33%). Mycoplasma spp. (30%), Pseudomonas spp. (23%), Escherichia coli spp. (12.5%), Enterococcus spp. (7%), and Micrococcus spp. (4%) were also isolated. The most frequently isolated bacteria from the conjunctival fornix of healthy Persian squirrels were Staphylococcus spp. followed by Corynebacterium spp.

Ophthalmic parameters in adult lowland paca (Cuniculus paca) raised in captivity

OBJECTIVE

To investigate the ophthalmic parameters of lowland pacas, including the anatomic features, tear production, intraocular pressure, central corneal thickness, and morphology of the corneal endothelium.

ANIMALS STUDIED

Thirteen adult, anesthetized Cuniculus paca.

PROCEDURE

Eyes were evaluated using slit-lamp biomicroscopy, the Schirmer tear test I, digital applanation tonometry, binocular indirect ophthalmoscopy, and noncontact specular microscopy.

RESULTS

The biomicroscopy findings showed blue/brown pigmented bulbar conjunctivae, well-developed cilia (only in the upper eyelid margin), superior and inferior lacrimal puncta, brown irides, round pupils, and vestiges of the nictitating membrane. The results of the Schirmer tear test I revealed (mean ± SD) a lacrimation rate of 4.10 ± 0.44 mm/min. The intraocular pressure was 6.34 ± 0.43 mmHg. Central corneal thickness measured by specular microscopy was 0.35 ± 0.01 mm. The mean values of density, hexagonality, and the area of the endothelial cells were 2083.15 ± 42.47 cells/mm² , 67.07 ± 3.30%, and 486.30 ± 9.56 μm² , respectively.

CONCLUSIONS

The ocular parameters defined in this study may be used for reference in future studies and might also contribute to therapeutic approaches appropriate to this species.

Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes

In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.

Clinical and histologic description of ocular anatomy in captive black-tailed prairie dogs (Cynomys ludovicianus)

OBJECTIVE

To describe the clinical and histologic ocular anatomy of the black-tailed prairie dog (PD).

ANIMALS STUDIED

Seventeen captive black-tailed PDs (11 males and six females), ranging in age from approximately 4 months to 4.5 years.

PROCEDURES

Complete ocular examinations, including slit-lamp biomicroscopy, direct and indirect ophthalmoscopy, were performed under isoflurane anesthesia. The globes (n = 2) of one black-tailed PD were harvested immediately after euthanasia and processed after formalin fixation. Staining with hematoxylin-eosin, cytokeratin AE1/AE3, glial fibrillary acidic protein, chromogranin A, claudin-5, smooth muscle actin, and vimentin was performed for light microscopic evaluation.

RESULTS

A thick mucinous precorneal tear film was present on the ocular surface. A vestigial nictitating membrane was identified in the medial canthus area. The limbus was heavily pigmented, the iris was a dark homogenous brown, and the pupil was round. Funduscopically, there was no tapetum lucidum, the retinal vascular pattern was holangiotic, and a horizontally elongated optic disk was visualized. The most common ocular abnormalities were acquired eyelid margin defects, present in seven eyes of six black-tailed PDs (35.3%). On histologic examination, the retina was asymmetric, thicker below the optic disk and thinner above it.

CONCLUSIONS

The black-tailed PD fundus is atapetal with a holangiotic retinal vessel pattern and a horizontally elongated optic disk. Acquired lesions of the peri-ocular and eyelid region were the most common documented abnormality. Unique anatomic features of the globe and adnexa were confirmed with histologic and immunohistochemical analysis.

Similarities and seasonal variations in bacterial communities from the blood of rodents and from their flea vectors

Vector-borne microbes are subject to the ecological constraints of two distinct microenvironments: that in the arthropod vector and that in the blood of its vertebrate host. Because the structure of bacterial communities in these two microenvironments may substantially affect the abundance of vector-borne microbes, it is important to understand the relationship between bacterial communities in both microenvironments and the determinants that shape them. We used pyrosequencing analyses to compare the structure of bacterial communities in Synosternus cleopatrae fleas and in the blood of their Gerbillus andersoni hosts. We also monitored the interindividual and seasonal variability in these bacterial communities by sampling the same individual wild rodents during the spring and again during the summer. We show that the bacterial communities in each sample type (blood, female flea or male flea) had a similar phylotype composition among host individuals, but exhibited seasonal variability that was not directly associated with host characteristics. The structure of bacterial communities in male fleas and in the blood of their rodent hosts was remarkably similar and was dominated by flea-borne Bartonella and Mycoplasma phylotypes. A lower abundance of flea-borne bacteria and the presence of Wolbachia phylotypes distinguished bacterial communities in female fleas from those in male fleas and in rodent blood. These results suggest that the overall abundance of a certain vector-borne microbe is more likely to be determined by the abundance of endosymbiotic bacteria in the vector, abundance of other vector-borne microbes co-occurring in the vector and in the host blood and by seasonal changes, than by host characteristics.

O olho da coruja-orelhuda: observações morfológicas, biométricas e valores de referência para testes de diagnóstico oftálmico

Objetivou-se relatar características morfológicas do bulbo ocular e determinar valores de referência para testes oftálmicos selecionados em corujas-orelhudas (Asio clamator). Foram estudados 32 olhos de 16 corujas (Asio clamator), adultas e jovens, machos e fêmeas, de vida livre. Sendo compilados dados referentes a observações morfológicas do crânio, bulbo ocular e anexos, além de mensuração de testes oftálmicos, incluindo, Teste Lacrimal de Schirmer (TLS), cultura da microbiota normal da conjuntiva, estesiometria, pressão intraocular (PIO), espessura de córnea central (ECC), diâmetro horizontal da rima palpebral, diâmetro horizontal da córnea e oftalmoscopia indireta. Vinte e dois tipos de bactérias foram identificados em 12 corujas havendo predominância de microrganismos Gram-positivos. A média encontrada para o TLS foi de 5,03±3,28mm/min, para o diâmetro horizontal da rima palpebral em 16 corujas foi 21,24±1,17mm, e 15,7±2,74mm para o diâmetro horizontal da córnea. O valor médio para o teste de estesiometria foi de 0,80±0,59cm, a PIO média de 13,81±5,62mmHg e ECC média de 0,28±0,03cm. O estudo contribuiu para a caracterização da morfologia ocular e para o estabelecimento de valores de referências de testes diagnósticos oftálmicos em corujas-orelhudas, sendo necessário ainda o desenvolvimento de estudos complementares sobre histologia ocular desta espécie.

Conjunctival flora, Schirmer's tear test, intraocular pressure, and conjunctival cytology in neotropical primates from Salvador, Brazil

BACKGROUND

This study aimed to establish reference values for selected ophthalmic diagnostic tests in healthy neotropical primates from Salvador, Brazil.

METHODS

A total of 73 intact adults, including Callithrix jacchus (n = 31), Callithrix penicillata (n = 8), Cebus sp. (n = 22), and Cebus xanthosternos (n = 9) were used to evaluate the normal conjunctival bacterial flora. Cebus xanthosternos (n = 12) were used to evaluate tear production with Schirmer's tear test (STT), intraocular pressure (IOP), and conjunctival cytology.

RESULTS

For all animals evaluated, Gram-positive bacteria were predominant. Results of the diagnostic tests in Cebus xanthosternos were as follows: STT: 14.92 ± 5.46 mm/minutes, IOP: 19.62 ± 4.57 mmHg, and conjunctival cytology revealed intermediate squamous epithelial cells in great quantities.

CONCLUSIONS

These ophthalmic reference values will be particularly useful to diagnose discrete or unusual pathological changes in the neotropical primates eye.

Ocular comparative anatomy of the family Rodentia

There is little information regarding ocular anatomy and histology in many of the rodent species. Histological analyses for morphologic features were performed in 31 globes from 18 rodent species submitted to and archived at the Comparative Ocular Pathology Laboratory of Wisconsin. The following measurements were taken: thickness of the cornea, corneal epithelium, corneal stroma, Descemet's membrane, and retina. H&E sections were evaluated for the following anatomical features: presence of pigmented epithelial cells in the peripheral cornea, presence and location of Schlemm's canal, presence of iridal sphincter and dilator and ciliary body muscles, presence of pars plicata and plana, presence of retinal vessels, presence of lamina cribrosa, and presence of tapetum lucidum. The springhaas was the only rodent in our collection that presented a well-developed tapetum lucidum fibrosum. The presence of retinal vessels was variable: vessels were observed in all of the members of the mouse-related clade, except the springhaas and the beaver, in all of the squirrel-related clade members, and in none of the Ctenohystrica. In the flying squirrels, blood vessels extended to the outer limiting membrane in the photoreceptor layer. Beavers, chinchillas, capybara, and guinea pigs lacked vessels within the retina; however, they had vessels within the optic nerve head. Ground squirrels have an optic nerve head, which is linear in the horizontal plane and an asymmetric retina. The tree-dwelling squirrels have a rounded but still elongated optic nerve, and the flying squirrel has a round optic nerve head like all the other rodents.

Periocular anterior adnexal anatomy and clinical adnexal examination of the adult Asian elephant (Elephas maximus)

Formalin preserved ocular-associated anterior adnexa tissues from five necropsied Asian elephants (Elephas maximus) were dissected with attention to the palpebrae, conjunctiva, nictitating membranes, nasolacrimal ducts, and periocular glandular tissues. Gross and histologic examination revealed that lacrimal and tarsal glands were not present. Evidence of the lacrimal drainage apparatus, including lacrimal punctae or any remnant of lacrimal sacs, was also absent. In contrast, well-developed sebaceous glands associated with accessory hairs along the palpebrae were exceptionally abundant. Mixed-secreting accessory lacrimal glands were noted in the deep stroma posterior to the tarsus of both palpebrae and the gland of the nictitating membrane. Apparently, the Asian elephant has developed a novel tear system in the absence of lacrimal and tarsal (meibomian) glands. Clinical examinations and bacterial cultures of the visible periocular tissues were performed on eight living adult Asian elephants to confirm the postmortem anatomic findings and provide guidance to the clinician during examination of the elephant conjunctiva.

Intraocular pressure and Schirmer tear test results in clinically normal Long-Eared Hedgehogs (Hemiechinus auritus): reference values

OBJECTIVE

The present study was undertaken to establish reference values for Schirmer tear test (STT) and intraocular pressure (IOP) in the long-eared hedgehog (Hemiechinus auritus).

ANIMALS

Fourteen healthy long-eared hedgehogs (H. auritus) of either sex were studied.

PROCEDURES

The hedgehogs were individually immobilized with an intramuscular injection of combined Ketamine (20 mg/kg) and Diazepam (0.5 mg/kg), and each animal underwent ophthalmic examinations including: STT, tonometry, biomicroscopy, and indirect ophthalmoscopy.

RESULTS

No significant effects of animal gender, weight, side (right vs. left eye) were found in this study. Mean (SD) STT values for all eyes (n = 28) were 1.7 ± 1.2 mm/1 min with a range of 0-4 mm/1 min. Mean STT in male animals was 2.2 ± 1.2. Mean STT in female Hedgehogs was 1.3 ± 1.1. Mean (SD) IOP values by applanation tonometry were 20.1 ± 4.0 mmHg (range 11.5-26.5 mmHg). Mean (SD) IOP values by applanation tonometry were 18.2 ± 4.0 and 22.0 ± 3.2 mmHg for males and females, respectively.

CONCLUSIONS

This study reports STT and IOP findings in long-eared hedgehogs (H. auritus).

Ocular bacterial flora, tear production, and intraocular pressure in a captive flock of Humboldt penguins (Spheniscus humboldti)

The purpose of this study was to determine normal ocular surface bacterial flora, tear production, and intraocular pressure in a captive flock of Humboldt penguins, Spheniscus humboldti. Twenty-eight healthy penguins were studied and equally divided between fresh- and saltwater habitats. The population consisted of 15 female and 13 male penguins, ranging from 3-20 years of age. Following complete ophthalmic exam, 4 penguins with cataracts were removed from the study. Eight penguins from each habitat were randomly selected for ocular surface aerobic bacterial culture. Corynebacterium spp. and Staphylococcus spp. were the most common isolates. Twenty-five organisms consisting of 17 species, and 15 organisms consisting of 9 species, were identified in fresh- and saltwater groups, respectively. Tear production and intraocular pressures were evaluated on 24 penguins with normal ocular exams. The range and mean (+/- standard deviation) tear production, measured with the Schirmer tear test, was 1-12 mm/min and 6.45 mm/min +/- 2.9, respectively. The mean tear production for penguins housed in the freshwater habitat was greater (8.5 mm/min) than those in saltwater (4.8 mm/min). The range and mean (+/- standard deviation) intraocular pressure, measured by applanation tonometry using a Tono-Pen XL tonometer, was 10-27 mmHg and 20.36 mmHg +/- 4.1, respectively. This data should be utilized as a reliable resource for those involved in avian and zoo medicine.

Results of diagnostic ophthalmic testing in healthy guinea pigs

OBJECTIVE-To report values for tear production, central corneal touch threshold (CTT), and intraocular pressure (IOP) in healthy guinea pigs and determine results of aerobic bacterial culture and cytologic examination of conjunctival swab specimens. DESIGN-Cross-sectional study. ANIMALS-31 Healthy guinea pigs (62 eyes) of various ages and breeds. PROCEDURES-Tear production was measured by the phenol red thread tear test (PRT) and Schirmer tear test (STT) before and after topical anesthetic application, CTT was measured with an esthesiometer, and IOP was measured by applanation tonometry. RESULTS-Combining data from all eyes, mean +/- SD PRT values before and after topical anesthetic administration were 21.26 +/- 4.19 mm/15 s and 22.47 +/- 3.31 mm/15 s, respectively, and mean IOP was 18.27 +/- 4.55 mm Hg. Median STT values before and after topical anesthetic administration were 3 mm/min (range, 0 to 12 mm/min) and 4 mm/min (range, 0 to 11 mm/min), respectively, and median CTT was 2.0 cm (range, 0.5 to 3.0 cm). Values did not differ between eyes for any test, but significant differences were identified for PRT values between males and females and between values obtained before and after topical anesthetic administration. Common bacterial isolates included Corynebacterium spp, Streptococcus spp, and Staphylococcus spp. Cytologic examination of conjunctival swab specimens revealed mainly basal epithelial cells; lymphocytes were common. CONCLUSIONS AND CLINICAL RELEVANCE-Results provided information on values for PRT, STT, CTT, and IOP in healthy guinea pigs and on expected findings for aerobic bacterial culture and cytologic examination of conjunctival swab specimens.

Reference values for selected ophthalmic diagnostic tests of the ferret (Mustela putorius furo)

PURPOSE

To perform selected ophthalmic diagnostic tests in healthy ferrets with the aim of establishing normal physiological reference values for this species.

METHOD

A total of 15 healthy, unrelated ferrets were used to test most of the parameters in this investigation. Eight of the 15 ferrets were used for central corneal thickness evaluation. Ages varied from 1.5 to 6 years of age. Selected diagnostic ocular tests were performed including Schirmer tear test, tonometry using an applanation tonometer (Tonopen), central corneal thickness using an ultrasonic pachymeter (Sonomed, Micropach, Model 200P +) and culture of the normal conjunctival bacterial flora.

RESULTS AND DISCUSSION

Staphylococcus sp. and Corynebacterium sp. were isolated from healthy conjunctival and eyelid margins, suggesting they are normal constituents of the conjunctival flora of the ferret. Results for selected ocular diagnostic tests investigated here for the ferret eye were as follows: intraocular pressure: 14.50 +/- 3.27 mmHg; Schirmer tear test: 5.31 +/- 1.32 mm/min; central corneal thickness: 0.337 +/- 0.020 mm. No statistically significant differences between ages or genders were found for any of the results. The reference data for the ocular tests obtained in this investigation will help veterinary ophthalmologists to more accurately diagnose ocular diseases in the ferret. Knowledge of these reference values will be particularly useful to diagnose discrete or unusual pathological changes of the ferret eye.