Ophthalmic contributions to assessing eyes of two neotropical canids: Cerdocyon thous and Chrysocyon brachyurus

Morphological examination of the visual system and orbital region in the red panda (Ailurus fulgens fulgens)

OBJECTIVES

The red panda is currently the only surviving member of the Ailuridae family in the Caniformia suborder. In this study, we provide data on anatomical, morphometric, histological and histochemical examination of the orbital region, eyelids, orbital gland, and eye tunics in two adult males Ailurus fulgens fulgens from the Wroclaw Zoological Garden, Poland.

METHODS

The study involved morphometric analysis of the eyeball and selected accessory organs of the eye, along with analysis of the bony orbit, including its morphometry, macroscopic, and microscopic evaluation. Microscopic evaluation encompassed histological and histochemical staining, with the former involving hematoxylin & eosin (H&E), Movat pentachrome, picro-Mallory trichrome, Fontana-Masson, and the latter including PAS, AB pH 1.0, AB pH 2.5; AB pH 2.5/PAS, and HDI.

RESULTS

The upper (UE) and lower (LE) eyelids presented well-developed tarsal glands, sebaceous glands, and a characteristic simple alveolar gland (producing a mucous secretion). The palpebral part of the lacrimal gland was present. A single lymphoid follicle was observed only in the upper eyelids. The superficial gland of the third eyelid (SGTE) was a multilobar acinar complex that produces mucous secretion and is contained within the interlobular ducts of numerous aggregates of lymph nodes. The third eyelid (TE) was T-shaped and composed of hyaline tissue, containing CALT. The lacrimal gland (LG) also revealed a multilobar acinar complex that produced mucous secretion, with a single lymphoid follicle. The cornea consisted of 4 layers, as Bowman's membrane was absent. The Vogt palisades composed of 7-10 layers of epithelial cells were demonstrated. The pupil was horizontally ovoid at rest (post-mortem). The sphincter pupil and the dilator pupil were well developed. Macroscopically, the tapetum lucidum appeared as a milky, non-opalescent crescent. Histologically, the choroidal tapetum lucidum cellulosum consisted of 5 to 9 layers of loosely packed oval cells. The retina showed a composition similar to that of terrestrial nocturnal carnivores.

CONCLUSIONS

The results of our research indicate that the anatomical features of the eye and orbital region in the red panda share similarities with those described in the Musteloidea clade, as well as the Canidae and Ursidae families.

Rescue and rehabilitation of maned wolf (Chrysocyon brachyurus) in Paraguay: Case description

The maned wolf, Chrysocyon brachyurus, is the largest South American canid, with a natural distribution that stretches across Peru, Bolivia, Brazil, Argentina, Paraguay and Uruguay. The present study reports the case of a rescued specimen of maned wolf that underwent a rehabilitation process in Paraguay, starting in October 2020 with its rescue, and finalising in May 2021 with the reintroduction. Herein, we document findings regarding the general management, biometrics, feeding and environmental enrichment; chemical immobilisation and monitoring; haematology, blood biochemistry and specific serology-relevant pathogens; skin examination and bone marrow cytology; orthopaedic, ophthalmological and dental evaluation; abdominal and cardiac ultrasonography; radiology and copro-parasitology. Main findings include the feeding habits of the individual and enrichment opportunities. The animal weighed 7 kg on arrival, with an estimated age of 5 months, and 18 kg on reintroduction, with an estimated age of 1 year. The animal tested negative to serologic tests for Brucella canis, Dirofilaria, canine distemper, Toxoplasmosis and canine parvovirus. Leptospira testing showed antibodies against L. grippotyphosa on both samplings, L. wolffi and L. ictero on the first sampling, and L. pomona on the second sampling. Abdominal organs were examined and measured through ultrasound evaluation and kidneys showed no alterations. Echocardiography showed preserved mitral, tricuspid and aortic valve flows, but turbulent pulmonary valve flow. Copro-parasitology reported the presence of Lagochilascaris sp. and Balantidium sp. All the information gathered aided in diagnosing the health status of the individual, and the response to environmental enrichment helped assess the behaviour, which led to the suggestion of reintroducing the animal. These data constitute the first published health check of a maned wolf in Paraguay, which can contribute to the species' conservation in the country. The protocol presented in this study can serve as a basis for developing an action plan for the maned wolf in Paraguay.

Determination of intraocular pressure and Schirmer tear test and the comparison between the applanation tonometer (Tono-Pen AVIA®) and the rebound tonometer (TonoVet Plus®) in mini lionhead rabbits

OBJECTIVE

To determine intraocular pressure (IOP) and tear production, as well as to compare the IOP obtained with the TonoVet Plus® (rebound) with the Tono-Pen Avia® (applanation) tonometers.

ANIMALS

Twenty-five Mini Lionhead rabbits (n = 50 eyes).

PROCEDURE

Tear production was measured at 6:00 a.m. and 6:00 p.m. by using the STT. The IOP reading was performed with the rebound tonometer, followed by the applanation tonometer, at 6:00 a.m., 9:00 a.m., 12:00 p.m., 3:00 p.m., and 6:00 p.m. Regression analysis, analysis of variance (anova) and Bland-Altman statistics were used.

RESULTS

Daily tear production was 10.25 ± 3.75 mm/min, with no differences among the moments evaluated. Average daily IOP was 17.7 ± 3.08 mmHg with the TonoVet Plus® and 11.5 ± 4.56 mmHg with the Tono-Pen Avia®. IOP values were higher at the beginning and end of the day with both tonometers.

CONCLUSION

The IOP values are higher with the TonoVet Plus® tonometer. The reference values of IOP and tear production obtained in this work may support the diagnosis, treatment, and monitoring of ocular disorders in pet Mini Lionhead rabbits.

Accuracy of data in abstracts of veterinary ophthalmology research articles published in peer-reviewed journals

OBJECTIVE

Assess the accuracy of abstracts in published veterinary ophthalmology articles.

PROCEDURES

Abstracts and contents of 204 original research articles in veterinary ophthalmology published in seven peer-reviewed journals between 2016-2020 were reviewed. Abstracts were considered inconsistent if they contained data that were either missing from or inconsistent with corresponding data in the article's body. Each abstract was graded between 0 (inaccurate) to 3 (accurate), and each inconsistency was subjectively classified as minor or major. The influence of selected variables was assessed: journal, impact factor, year of publication, number of words in abstract, study type (prospective/retrospective), and characteristics of the corresponding author [institution (academia/private practice), country of domicile (native/non-native English), number of publications].

RESULTS

Most abstracts were accurate, with 1%, 4%, 9% and 86% receiving a score of 0, 1, 2 and 3, respectively. When detected, most inconsistencies were considered minor (77%). Although not statistically significant (p ≥ .130), the proportion of articles with a perfect score (=3) was higher in prospective (88%) vs. retrospective (81%) studies, academia (88%) vs. private practice (78%), and studies from corresponding authors domiciled in English (89%) vs. non-English (83%) speaking countries. A significant but very weak (r = -0.15 to -0.19; p ≤ .034) negative correlation was found between accuracy score and number of words, as well as 1-year and 5-year impact factors.

CONCLUSIONS

Although relatively uncommon, data in abstracts that are inconsistent or missing from the article's body do occur in veterinary ophthalmology articles, and could adversely influence a reader's interpretation of study findings.

Morphology and Histology of the Orbital Region and Eye of the Asiatic Black Bear (Ursus thibetanus)—Similarities and Differences within the Caniformia Suborder

In this study, we present first data concerning the morphological observations of the orbital region, eye tunics, upper and lower eyelids, superficial gland of the third eyelid with the third eyelid, and lacrimal gland in captive adult male Asiatic black bear. The following research methods were used in the work: the eyeball morphometry, the orbital region description, macroscopic description, morphometric and histological analysis of the eye tunics and selected the accessory organs of the eye (Fontana–Masson, hematoxylin & eosin (H&E), Methyl-green-pyronin Y (MGP Y), Movat pentachrome, and picro-Mallory trichrome) as well as histochemical examination (PAS, AB pH 1.0, AB pH 2.5, AB pH 2.5/PAS and HDI). The eyeball of the Asiatic black bear was a spherical shape, while the periorbita was funnel/conical-shaped and the eye socket was of the open type. The cornea was absent of the Bowman’s membrane similar to all domestic dogs and some wild dogs. There were palisades of Vogt in the corneal limbus epithelium similar to the Canidae. Degenerative choroidal tapetum lucidum similar to ranch mink (Mustelidae) has been found. The pupil was big and round in shape. The ciliary muscle, dilatator and sphincter muscle were well developed, similar to the pinnipeds. The lens was biconvex round, similar to the Canidae. The retina was composed similarly to the diurnal terrestrial carnivores. In both eyelids were observed very well-developed tarsal glands, ciliary glands and sebaceous glands. The orbital zone in the eyelids was characterized by lymphoid follicles, diffuse lymphocytes and specialized high endothelial venules. In the anterior palpebral margin of the upper eyelid, soft and short eyelashes were observed, while in the lower eyelids they were absent. The third eyelid was T-shaped and composed of the hyaline tissue, and it contained CALT, similar to that in Canidae. The superficial gland of the third eyelid was a multilobar alveolar branched complex with seromucous nature, while the lacrimal gland was also a multilobar acinar branched complex gland, but producing a mucous–serous secretion. The results of our research indicate that the features of the anatomy of the eye and orbital region in Asiatic black bear are also typical of the Ursidae family. Moreover, a detailed analysis of the morphological eye region may be useful in comparative studies and veterinary diagnostics in this bear species.

TonoVet Plus®: Higher reliability and repeatability compared with Tono-Pen XL™ and TonoVet® in rabbits

OBJECTIVE

To evaluate the accuracy and repeatability of the Tono-Pen XL™, TonoVet® and TonoVet Plus® tonometers by manometric evaluation, and to establish adjustment equations for intraocular pressure (IOP) estimates in rabbits.

ANIMAL STUDIED

Rabbits.

PROCEDURES

A postmortem study was conducted on seven rabbit eyes to verify the correlation between manometry and tonometry with an artificial incremental increase in IOP from 5 and 60 mmHg. A clinical study was conducted to evaluate accuracy and to establish reference values for the species, with measurement of IOP in 17 animals, for 2 consecutive days, with the same tonometers and calibrations used in the postmortem evaluations.

RESULTS

There were strong linear trends for all evaluated tonometers. In the in-vivo evaluation, the mean IOP values were: 14.23 ± 1.75 (Tono-Pen XL™); 13.89 ± 2.07 (TonoVet® calibration mode 'd'); 8.88 ± 1.24 (TonoVet calibration mode 'p'); 18.59 ± 1.94 (Tonovet Plus®). There was a significant difference in the two evaluation times for the two TonoVet® calibration modes. The adjustment equations generated from the manometry for the evaluated tonometers were: Y = 0.2570X + 2.219 (Tono-Pen XL™), Y = 0.2289X + 2.389 (TonoVet® 'd'), Y = 0.4043X + 4.062 (TonoVet® 'p'), Y = 0.1233X + 0.3644 (TonoVet Plus®) (X is device-estimated IOP).

CONCLUSIONS

All evaluated tonometers were well correlated with the manometry, with an underestimation of IOP by all devices. Applying adjustment formulas may compensate for systematic errors. TonoVet Plus® was well tolerated, and showed better repeatability and reliability in successive evaluations.

Anatomical and morphometric evaluation of the orbit, eye tunics, eyelids and orbital glands of the captive females of the South African painted dog (Lycaon pictus pictus Temminck, 1820) (Caniformia: Canidae)

In this study, we present the first data concerning the anatomical, morphometrical, histological and histochemical study of the orbit, eye tunics, eyelids and orbital glands in South African Painted Dogs (Lycaon pictus pictus). The study was performed using eyeball morphometry, analysis of the bony orbit including its morphometry, macroscopic study, morphometry, histological examination of the eye tunics and chosen accessory organs of the eye and histochemical analysis. The orbit was funnel shaped and was open-type. There was a single ethmoid opening for the ethmoid nerve on the orbital lamina. The pupil was round, while the ciliary body occupied a relatively wide zone. The iris was brown and retina had a pigmented area. The cellular tapetum lucidum was semi-circular and milky and was composed of 14-17 layers of tapetal cells arranged in a bricklike structure. In the lower eyelid, there was a single conjunctival lymph nodule aggregate. One or two additional large conjunctval folds were observed within the posterior surface of the upper eyelids. The superficial gland of the third eyelid had a serous nature. The third eyelid was T-shaped and was composed of hyaline tissue. Two to three conjunctival lymph nodul aggregates were present within the bulbar conjunctiva of the third eyelid. The lacrimal gland produced a sero-mucous secretion. A detailed anatomic analysis of the eye area in the captive South African Painted Dogs females showed the similarities (especially in the histological examination of the eyetunics and orbital glands) as well as the differences between the Painted dog and the other representatives of Canidae. The differences included the shape and size od the orbita with comparison to the domestic dog. Such differences in the orbit measurements are most likely associated with the skull type, which are defined in relation to domestic dogs. The presented results significantly expand the existing knowledge on comparative anatomy in the orbit, eye and chosen accessory organs in wild Canidae.