The Shih Tzu eye: Ophthalmic findings of 1000 eyes.

PURPOSE: To evaluate the frequency of ophthalmic disorders in Shih Tzus. ANIMALS: Five hundred client-owned Shih Tzu dogs (1000 eyes). PROCEDURES: Medical records of 500 Shih Tzu dogs were reviewed and ophthalmic examination data were collected and analyzed. RESULTS: In total, out of 1000 eyes, 964 (96.4%; OD: 480 eyes, OS: 484 eyes) had at least one ophthalmic abnormality, and only 36 eyes (3.6%; OD: 20 eyes, OS: 16 eyes) were diagnosed as normal. A total of 1375 individual ophthalmic abnormalities were observed in 964 diseased eyes. Fifty-nine different unique diagnoses were made in the study population, and only three conditions [medial canthal entropion (10.4% of eyes; bilateral in 10.2% of dogs), caruncular trichiasis (21.1% of eyes; bilateral in 20.2% of dogs), and reduced tear film breakup time (17.6% of eyes; bilateral in 17.4% of dogs)] affected 49.1% of the eyes. CONCLUSION AND CLINICAL RELEVANCE: Findings suggested that the most prevalent disorders for the Shih Tzus were hairy caruncle, reduced TBUT, medial canthal entropion, keratoconjunctivitis sicca, pigmentary keratitis, lagophthalmos, and mature cataract.

Tear film breakup time and Schirmer tear test in normal dogs: Effects of age, sex, reproductive status, skull type, and nasolacrimal duct patency.

OBJECTIVE: The present study aimed to determine the effects of age, sex, reproductive status, skull type, and nasolacrimal duct (NLD) patency on tear production and tear film breakup time (TBUT) in normal dogs. ANIMALS STUDIED: The ophthalmic data of 82 healthy adult dogs were evaluated in this study. PROCEDURES: Age, sex, breed, and reproductive status were recorded. Schirmer tear test (STT) and TBUT were assessed in all dogs, and interferometry was available for the selected dogs. The Jones test was used to evaluate NLD patency. The cephalic index (CI) was calculated for each dog (skull width/skull length ×100). RESULTS: Mean (SD) values for the STT results for the right (OD) and left (OS) eyes were 20.6 (2.7) and 20.2 (2.7) mm/min, respectively. Mean (SD) TBUT values for OD and OS were 6.5 (2.5) and 6.1 (2.3) mm/min in all dogs, respectively. Sex and reproductive status had no significant effect on STT and TBUT (P[OU] > 0.05). Skull type significantly affected TBUT in both eyes (P(OD)  = 0.01, P(OS)  = 0.003), but had no effect on STT (P[OU] > 0.3). Age had no correlation with STT and TBUT in either eye (P[OU] > 0.05). STT and TBUT had no correlation in either eye (P[OU] > 0.2). NLD patency had no significant effect on STT or TBUT (P[OU] > 0.1). CONCLUSIONS: The results of this study showed lower TBUT values in brachycephalic breeds than in non-brachycephalic breeds. A compensatory increase in STT values was observed in dogs with low TBUT values.

Effects of long-term oral administration of melatonin on tear production, intraocular pressure, and tear and serum melatonin concentrations in healthy dogs.

OBJECTIVE: To evaluate the effects of long-term (30-day) oral administration of melatonin on tear production, intraocular pressure (IOP), and concentration of melatonin in the tears and serum of healthy dogs. ANIMALS: 20 healthy sexually intact adult male dogs. PROCEDURES: 10 dogs were given melatonin (0.3 mg/kg, PO, q 24 h, administered in food at 9 am), and 10 dogs were given a placebo. Tear and serum melatonin concentrations, IOP, and tear production (determined with a Schirmer tear test) were recorded before (baseline) and 30 minutes, 3 hours, and 5 hours after administration of melatonin or the placebo on day 1 and 30 minutes after administration of melatonin or the placebo on days 8, 15, and 30. RESULTS: Data collection time had significant effects on tear production, IOP, and tear melatonin concentration but not on serum melatonin concentration. Treatment (melatonin vs placebo) had a significant effect on tear melatonin concentration, but not on tear production, IOP, or serum melatonin concentration; however, tear melatonin concentration was significantly different between groups only 30 minutes after administration on day 1 and not at other times. CLINICAL RELEVANCE: In healthy dogs, long-term administration of melatonin at a dosage of 0.3 mg/kg, PO, every 24 hours did not have any clinically important effects on tear production, IOP, or serum or tear melatonin concentrations.

Effect of topical 0.5% tetracaine hydrochloride on intraocular pressure in ophthalmologically normal cats.

OBJECTIVES: The aim of this study was to assess the effect of topical tetracaine hydrochloride 0.5% on intraocular pressure (IOP) in ophthalmologically normal cats. METHODS: Twenty domestic shorthair cats (40 eyes) were used in this study. Each cat was randomly allocated to one of two groups (treatment or control). Baseline IOP (T0) was measured in each cat, and then one drop of tetracaine hydrochloride 0.5% or artificial tears was administered into a randomly chosen eye of each cat in the treatment and control groups, respectively. Repeat IOP measurements were performed at 2 mins (T2), 5 mins (T5), 15 mins (T15) and 30 mins (T30) with a rebound tonometer. RESULTS: Mean baseline IOP in all eyes was 20.6 ± 2.5 mmHg. After the unilateral administration of tetracaine, mean IOP decreased significantly in the treated eye at T2 (P = 0.01). Mean IOP returned to baseline values at T15. The mean IOPs in the treated eyes at T0, T2, T5, T15 and T30 were 20.6 ± 3.3 mmHg, 18.2 ± 2.5 mmHg, 18.2 ± 3.4 mmHg, 20.2 ± 3.2 mmHg and 19.8 ± 2.7 mmHg, respectively. A significant difference in IOP was found at all time points between the tetracaine and control groups (P <0.03). CONCLUSIONS AND RELEVANCE: The results of the present study showed a statistically significant reduction in mean IOP 2 mins after the administration of tetracaine hydrochloride 0.5% in the treated eyes of the cats.

Effects of 0.0015% preservative-free tafluprost on the equine eye.

OBJECTIVE: The purpose of this study was to determine the effects and potential side effects of topical preservative-free (PF) tafluprost 0.0015% in ophthalmologically normal horses. ANIMALS: Five adult grade horses. PROCEDURES: One of the eyes of each horse was randomly chosen as the "treatment" eye, and consequently, the contralateral eye served as the "control." A single dose of PF tafluprost 0.0015% (0.2 mL) was instilled in the treated eye of each horse. Intraocular pressure (IOP), Schirmer's tear test (STT) levels of each eye, and an ophthalmic examination were performed at T0 (baseline), T30, T120, T24 h, and T48 h. RESULTS: The mean IOP values of the treated eyes at baseline (T0), T30, T120, T24 h, and T48 h were 25.4 ± 4.8 mmHg, 21.2 ± 1.92 mmHg, 15.20 ± 2.48 mmHg, 18.40 ± 1.51 mmHg, and 24.60 ± 1.94 mmHg, respectively. Significant differences were observed between the mean baseline IOP level and the T120 and T24 h time points (p = .001 and p = .009). The mean STT levels at each time point showed insignificant fluctuations during the study (p = .140). Adverse effects such as chemosis and episcleral injection were observed 30 min after the instillation of tafluprost 0.0015% (T30). Blepharospasm and conjunctival hyperemia were observed 120 min (T120) after the administration of the medication. CONCLUSION AND CLINICAL RELEVANCE: Tafluprost 0.0015% showed potential in reducing IOP, but due to its local side effects, it is not a good candidate for management of glaucoma in horses. Tafluprost did not notably affect STT.

Comparison of conjunctival microbiota of clinically normal Persian cats with and without nasolacrimal duct obstruction.

OBJECTIVE: This study was performed to determine the conjunctival microbiota of Persian cats with and without nasolacrimal duct obstruction (NLDO). ANIMALS STUDIED: Twenty-five Persian cats: 15 with bilateral NLDO (Group A) and 10 with no NLDO (Group B). PROCEDURES: All fifty eyes were assessed. Sterile swab applicators were used for the collection of specimens, which were cultured. PCR was performed on conjunctival swab and blood samples for the detection of Mycoplasma spp. and feline herpesvirus 1(FHV-1), respectively. RESULTS: FHV-1 was detected in two cats in Group A. Twelve eyes from Group A and four from Group B were Mycoplasma spp. positive based on the PCR results. Moreover, fungal culture was positive in six eyes from Group A and three eyes from Group B. The dominant fungus isolated was Aspergillus spp. (6 out of 11 fungal isolates). Other isolated fungi were Alternaria spp. and Cladosporidium spp. Twenty-three eyes had positive bacterial culture in Group A, while twelve eyes were positive in Group B. The most commonly isolated bacteria were Staphylococcus epidermidis (15 out of 38 bacterial isolates). ß-hemolytic Streptococcus spp., Corynebacterium spp., and Staphylococcus aureus were isolated in similar proportions in both groups. Escherichia coli was also present in both groups. CONCLUSIONS: Results of this study revealed same isolated fungal and bacterial spp. and in similar proportions in Persian cats with and without NLDO.

Effect of Topical 1% Tetracaine Hydrochloride on Intraocular Pressure in Ophthalmologically Normal Horses; a Pilot Study.

The aim of this study was to evaluate the effect of topical 1% tetracaine hydrochloride on the intraocular pressure (IOP) in ophthalmologically normal horses. Thirty eyes of 15 clinically normal horses were used for this study. The animals were randomly assigned to two groups (treatment and control). Prior to the instillation of 1% tetracaine or placebo, the baseline IOPs (T0) of each animal were recorded in both groups. Then one drop of tetracaine was instilled randomly into one eye of each horse in the treatment group (8 horses). In the control group (7 horses), one drop of artificial tear was instilled in one randomly selected eye. The measurements were repeated at 2 minutes (T2), 5 minutes (T5), 15 minutes (T15), and 30 minutes (T30) post instillation via a rebound tonometer. There was no significant difference in the treatment group (P = .3). The peak IOP measured at T2 returned to the baseline value at T30. No significant difference was found in the mean IOP values between the treatment and the control groups, or between the males and females on any of the occasions (P > .05). The Results of this study revealed a nonsignificant increase of the IOP 2 minutes post instillation of 1% tetracaine in horses.

Evaluation of tear production using the Schirmer tear test I in healthy cats; effect of age, life stage, sex, breed and neuter status.

BACKGROUND: The purpose of this study was to evaluate the values of Schirmer tear test (STT) and determine effects of age, life stage, sex, breed and neuter status on tear production in healthy cats. METHODS: Three hundred and forty-three domestic shorthair (DSH) and Persian cats, 50 days through 18 years old, were examined in this study. STT I was used to measure tear production in both eyes of each cat. RESULTS: A mean STT 14.9±4.8 mm/min was calculated for the eyes of all cats. There was a significant difference between STT values in kittens (≤6 months old) and cats of other age groups (P<0.001). A substantial number of cats with clinically normal eyes had STT values less than 10 mm/min. No significant difference was found between males (14.7±5.0 mm/min) and females (15.1±4.5 mm/min) in STT values (P=0.46). Significant differences were found between entire (14.4±4.2 mm/min) and neutered (16.2±4.1 mm/min) cats (P=0.001), and between STT values of DSH (14.6±5.0 mm/min) and Persian (16.5±3.1 mm/min) cats in the study population (P=0.001). CONCLUSIONS: This study documents the average STT values for a sizeable feline population demonstrating that, in contradistinction to the situation in dogs, a number of cats with clinically normal eyes have STT values below 10 mm/min.

Effect of Topical 1% Cyclopentolate Hydrochloride on Tear Production, Intraocular Pressure, and Pupil Size in Healthy Turkman Horses.

This study was performed to evaluate the effect of topical 1% cyclopentolate hydrochloride on tear production (STT), intraocular pressure (IOP), and vertical pupil diameter (VPD) in healthy Turkman horses. Forty eyes of 20 clinically normal horses were used for this study, which were randomly assigned to two groups. Before instillation of 1% cyclopentolate, the baseline STT, IOP, and VPD of each group were recorded. Then, one drop of cyclopentolate was instilled randomly into one eye of each animal, and the contralateral eye served as control. Measurements were repeated at 20 minutes, 60 minutes, 90 minutes, 120 minutes, 12 hours, and 24 hours, and every 24 hours up to 120 hours post drug instillation in all animals. There was no significant effect on STT over the time course measured in both the treated and untreated eyes of the treatment groups after unilateral instillation of 1% cyclopentolate when compared to baseline values. A significant increase in the IOP was observed after 20 minutes, which persisted for more than 90 minutes; then, the IOP insignificantly decreased below the baseline values after 120 minutes. Maximum VPD was recognized at 12 hours post instillation in treated eyes (15.8 ± 2.3 mm), which was significantly different in comparison to the baseline (P = .07). Cyclopentolate could be considered as a long term and potent cycloplegic drug in horses when taking into account the possible side effect of atropine.

Pilot evaluation of the circadian rhythm of tear production in a population of healthy adult cats.

OBJECTIVES: The purpose of this study was to determine if a circadian rhythm exists in Schirmer's tear test (STT-1) values in a group of healthy adult cats. ANIMALS STUDIED: Twenty adult neutered Domestic Short-haired cats (DSH) were used in the study. PROCEDURES: Tear production was measured with the Schirmer tear test (STT-1) at 12 different time points over a 48-hour period. RESULTS: A significant difference (approximately 4.3 mm/min) was noted between STT-1 values measured between 4 pm (lowest) and 12 am (highest) on both day 1 (P = 0.02) and day 2 (P = 0.01), and substantial variation in STT-1 values was observed at different times during the 48-hour period. CONCLUSIONS: Significant variation in mean STT-1 values demonstrates that there is a circadian rhythm in tear production in cats and thus shows the importance of taking the time of day into account when measuring STT-1 in cats.

Seasonal Effects on the Corneoconjunctival Microflora in a Population of Persian Cats in Iran.

This study was performed to determine the normal seasonal aerobic and an-aerobic corneoconjunctival bacterial flora in cats. Thirty eyes of 15 clinically normal client-owned Persian cats were evaluated. All cats lived in a similar indoor/outdoor home environment being fed the same diet for the entire year. The cats did not receive any medications and were found to be clinically healthy 1 week prior to each microbial sampling. The cats were not exposed to other cats during the study period. Microbial samples were collected at the same time of day on the first day of the second month of each of the four seasons. During sample collection, a sterile swab was rolled over the corneoconjunctival surface avoiding contact with surrounding skin or hair. Immediately after sample collection, microbiologic aerobic and anaerobic cultures were initiated. Gram-positive bacteria were the most prevalent isolates. The most commonly isolated bacterial organisms across all seasons were Staphylococcus epidermidis (41/95; 43.2%), ß-hemolytic streptococcus (18/95; 18.9%), Staphylococcus aureus (17/95; 17.9%), and Escherichia coli (11/95; 11.5%). Twenty-five cultures of a total of 120 (20.8%) were negative. One negative culture was collected in the summer, while 21 cultures were negative in fall and winter. Gram-positive bacteria were the predominant micro-organisms of the normal ocular surface of healthy cats in all seasons in this study. This result is in agreement with previous publications.

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.

Comparison of the Schirmer tear test I values after placement in ventral and dorsal conjunctival fornices in healthy cats.

OBJECTIVES: The objective of this study was to compare the Schirmer tear test I values obtained from placement of Schirmer tear test (STT) strips in ventral and dorsal conjunctival fornices and to investigate any correlation between age, body weight and STT values in clinically normal cats. METHODS: Twenty-eight intact adult domestic shorthair and Persian cats were used in this study. The cats were gently physically restrained in a sternal position, and a Schirmer tear strip was placed on each eye in the ventral conjunctival fornix at one-third of the distance from the temporal to nasal canthus for 60 s. Then, the wetted portion of the strips was measured as mm/min (L-STT I). After 48 h, the same procedure was performed on each eye in the dorsal conjunctival fornix (U-STT I). RESULTS: Mean ± SD STT values of the ventral and dorsal conjunctival fornices were 20.80 ± 2.25 mm/min (range 14-25 mm/min; 95% confidence interval [CI] 19.92-21.67) and 18.28 ± 2.27 mm/min (range 15-22 mm/min; 95% CI 17.39-19.16) in all of the study population, respectively. A significant difference was found between STT values obtained from the ventral and dorsal conjunctival fornices ( P <0.001). There was no correlation between the age and body weight of the animals and STT I values. CONCLUSIONS AND RELEVANCE: This study compared the STT I values of the dorsal and ventral conjunctival fornices in cats. The difference was significant between the L-STT I and U-STT I values; however, the L-STT I and U-STT I values were within normal reference intervals. The U-STT I data have diagnostic value that might be of benefit in cases where there is a problem in the ventral conjunctival fornix.