Objective -To characterize diagnostic findings, test-retest repeatability, and correlations among lacrimal tests in dogs of diverse cephalic conformations.Animal studied -Fifty healthy dogs (25 brachycephalic, 25 non-brachycephalic).Procedures -A series of diagnostics were performed in each dog, allowing for a 10min-interval between tests and repeating each test 24h later under similar conditions: corneal tactile sensation (CTS), strip meniscometry test (SMT), phenol red thread test (PRTT), endodontic absorbent paper point tear test (EAPPTT), Schirmer tear test-1 without (STT-1) or with nasolacrimal stimulation (NL-STT1), and Schirmer tear test-2 (STT-2).Results -Mean ± SD test values were lower in brachycephalic vs. non-brachycephalic dogs (except for SMT; 7.4±2.0 mm/5s vs. 7.3±2.4 mm/5s), with statistically significant differences noted for CTS (1.8±0.5 cm vs. 3.4±0.8 cm), PRTT (37.2±4.0 mm/15s vs. 41.1±5.5 mm/15s), STT-1 (20.1±3.4 mm/min vs. 23.3 ±5.7 mm/min), STT-2 (13.0 ± 3.4 mm/min vs 16.9 ± 3.9 mm/min), and NL-STT1 (23.2±3.6 mm/min vs. 27.1±5.4 mm/min), and non-significant differences for EAPPTT (16.6±2.7 mm/15s vs. 17.5±2.9 mm/15s).Nasolacrimal stimulation increased STT-1 values by 18% on average. Correlations among tests were generally weak to moderate (r<0.70) except for a strong correlation between STT-1 and NL-STT1 (r=0.83, P<0.001). Tests reliability was good although test-retest repeatability was generally poor to moderate, as depicted by low intraclass correlation coefficients (ICC≤0.75) and wide 95% limits of agreement, except for CTS (ICC=0.91). Conclusions-Corneal sensitivity and aqueous tear secretion are lower in brachycephalic dogs. A comprehensive assessment of the ocular surface requires the combination of several diagnostic tests. The nasolacrimal reflex may provide a useful diagnostic and therapeutic tool in dogs.

Objective To characterize the ocular surface parameters and determine the prevalence of ocular pathology in Shih Tzu dogs. Animal Studied Fifty Shih Tzu dogs (28 male, 22 female). Procedures Each dog underwent a complete ophthalmic examination (recording any pathology) and a series of diagnostics, allowing for a 10 min‐interval between tests: intraocular pressure (IOP), blink rate, palpebral fissure length (PFL), corneal tactile sensation (CTS), Schirmer tear test and nasolacrimal reflex without (STT‐1, NL‐STT1) and with topical anesthesia (STT‐2, NL‐STT2), tear ferning, strip meniscometry test (SMT), tear film breakup time (TFBUT), and punctate fluorescein staining (PFS) of the cornea. Results Mean ± SD test values were as follows: IOP (17.9 ± 3.7 mmHg), blink rate (2.4 ± 1.4 blinks/min), PFL (23.8 ± 1.8 mm), CTS (1.8 ± 0.7 cm), STT‐1 (22.0 ± 5.5 mm/min), NL‐STT1 (24.2 ± 4.7 mm/min), STT‐2 (16.9 ± 6.5 mm/min), NL‐STT2 (18.5 ± 7.5 mm/min), SMT (7.5 ± 3.5 mm/5 s), TFBUT (5.3 ± 2.4 s), tear ferning (1.3 ± 0.7), and PFS (1.6 ± 0.6). PFL was significantly greater in male vs. female Shih Tzus (p< .001). Age was negatively correlated with TFBUT results (r = −0.31, p = .027). Lagophthalmos was observed in 82% eyes. Ocular surface pathology was common, including adnexal abnormalities (100% eyes with caruncular trichiasis and medial lower lid entropion) and corneal opacification (27% pigmentation, 20% fibrosis, 12% neovascularization). Conclusions Qualitative tear film deficiency (low TFBUT), along with several anatomical abnormalities that promote ocular irritation and reduce globe protection, together help explain the concerningly high prevalence of ocular surface disease in the Shih Tzu breed. Prophylactic measures (e.g., medial canthoplasty, topical lubrication) could be considered to improve ocular health in Shih Tzus.

Mean (±SD) STT1 was 3.4 ± 3.6 mm/min (95% confidence interval of 2.01-4.78 mm/min), intraocular pressure (IOP) was 12.9 ± 6.2 mmHg, NMIFT was 6.0 ± 3.5, EAPPTT was 17.1 ± 2.5 mm/min, PFL was 28.9 ± 3.0 mm, anterior chamber depth was 3.1 ± 0.3 mm, lens axial length was 8.4 ± 0.6 mm, vitreous chamber depth was 7.9 ± 0.7 mm and axial globe length was 19.9 ± 1.3 mm. For all animals evaluated, Bacillus sp., Diphteroids and Staphylococcus sp. were predominant.

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

The results of SMT, osmolarity, TFT, SDS-PAGE, and tear biochemistry may serve as a reference baseline for CM, and the data may serve as a basis for future experimental model evaluations.

The TFT is appropriate for dogs and can be performed using the three suggested sampling methods, with a higher frequency of Type I and Grade 1. Thus, it is possible to use both grading scales in the classification of tear ferning in dogs.

The established parameters may help in clinical and ophthalmic examinations of primates.

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.