Schirmer tear test values and tear film break-up times in cats with conjunctivitis

OBJECTIVES: (1) To document tear film break-up time (TFBUT) in a group of cats with conjunctivitis; (2) to determine if TFBUTs from cats with conjunctivitis vary significantly from previously established normal values for TFBUT in young cats without ocular disease; (3) to determine if a correlation exists between Schirmer tear test (STT) values and TFBUTs in cats with conjunctivitis; (4) to determine if the TFBUTs in cats with conjunctivitis are influenced by the detection of DNA from feline herpes virus-type 1 (FHV-1), Chlamydophila felis, Mycoplasma spp., and feline calicivirus. ANIMALS STUDIED: Fourteen cats between the ages of 0.8 years to 12 years with active, untreated conjunctivitis and without active keratitis or other ocular or systemic abnormalities were included in this study. Procedures Complete ophthalmic examinations, including TFBUT, were performed on all cats. Polymerase chain reaction (PCR) screening for FHV-1, Chlamydophila felis, Mycoplasma spp., and feline calicivirus was performed on conjunctival swabs from affected eyes and blood samples from all cats. RESULTS: Mean TFBUT for cats in this study was 8.9 (+/- 4.8) s in the right eye (OD) and 8.1 (+/- 4.6) s in the left eye (OS). No correlation existed between mean TFBUTs and mean STT values OD or OS. Conjunctival swabs from seven cats (n = 9 eyes) tested positive via PCR for one of the above infectious agents. Blood samples from nine cats tested positive for FHV-1. Mean TFBUTs for cats from which the DNA from FHV-1 was isolated from the blood were significantly lower than mean TFBUTs for cats from which no such DNA was isolated from the blood. CONCLUSIONS: In this study, the mean TFBUT in cats with conjunctivitis was significantly lower than previously established values for clinically healthy cats. This supports the theory that qualitative tear film deficiency, and thus tear film instability, may play a role in the pathogenesis of feline conjunctivitis. Qualitative tear film deficiency may predispose to the development of conjunctivitis or may occur secondarily to this condition.     

Tear film breakup times in young healthy cats before and after anesthesia

The objectives of this study were: (i) to determine tear film breakup times (BUTs) in young healthy cats; (ii) to determine tear film BUTs in feline eyes within 8-20 h following general anesthesia; (iii) to determine if tear film BUTs vary significantly preoperatively when compared with values obtained 8-20 h postoperatively; (iv) to determine if Schirmer tear test (STT) values correlate with tear film BUTs in young healthy cats; and (v) to determine if the isolation of particular etiologic agents from conjunctival swabs of healthy cats affects tear film BUTs. We studied eighteen healthy Domestic Short-haired (n=14) and Domestic Long-haired (n=4) cats, with normal ocular examinations, ranging in age from 0.5 to 3 years. Complete ophthalmic examinations, including tear film BUTs, were performed on all cats. Conjunctival swabs from each eye of all cats and blood samples from all cats were collected and submitted for polymerase chain reaction screening for feline herpes virus, Chlamydophila felis, Mycoplasma spp., and calicivirus. In 10 of 18 cats, STT values and tear film BUTs were measured before general anesthesia was administered and again within 8-20 h following the end of anesthesia. Mean preanesthesia tear film BUTs for all 18 cats were 17.4+/-4.6 s OD and 16.0+/-4.5 s OS. Mean postanesthesia tear film BUT results were 12.5+/-4.3 and 13.1+/-4.0 s OD and OS, respectively. Postanesthesia tear film BUTs were significantly more rapid than those measured before anesthesia (OD only). There was also a positive correlation, both before and after anesthesia, between STT values in both eyes (OU) and tear film BUTs OU. The isolation or lack of isolation of conjunctival microorganisms using PCR did not significantly affect tear film BUTs. Mean tear film BUT in young healthy domestic cats is 16.7+/-4.5 s. Tear BUT is positively correlated with STT values. Although mean tear film BUTs OD at 8-20 h following anesthesia were more rapid than preanesthesia values, this difference did not appear clinically relevant.     

Correlation between corneal sensitivity and quantity of reflex tearing in cows,horses, goats,sheep, dogs,cats, rabbits,and guinea pigs

Objective Guinea pigs have a very low threshold of corneal sensitivity and at the same time nearly no reflex tearing compared to dogs, cats, and horses. The question arose whether there is a general correlation between corneal sensitivity and the quantity of reflex tearing. Animals studied Totally 160 animals of 8 different species (20 animals per species) were investigated. Procedures The corneal touch threshold (CTT) was measured with a Cochet–Bonnet esthesiometer. The palpebral fissure length (PFL) was measured with a calliper ruler. The Schirmer tear test (STT) was modified by adapting the width of the STT strip to the PFL of every species. For the STT II, 0.4% oxybuprocaine was applied. Results Corneal touch threshold: Cows (1.67 g/mm²), horses (1.23 g/mm²), sheep (1.13 g/mm²), goats (1.44 g/mm²), dogs (2.16 g/mm²), and cats (1.33 g/mm²) show similar CTT values. In contrast, rabbits (6.21 g/mm²) and guinea pigs (7.75 g/mm²) show a significantly lower CTT. Tear Production Difference STT I ? STT II: Rabbits have the greatest decline in tear production with 38.4%, followed by sheep (33.3%), dogs (31.1%), cats (24.7%), cows (23.7%), horses (18.0%), and goats (14.0%). Guinea pigs have no decline, but a slight increase of ?16.0%. Correlation CTT and STT II ? STT I Difference: Pearson’s correlation coefficient shows a small, but significant correlation. The coefficient of determination can only forecast a value with 7.1% certainty. Conclusions The high variance and low reproducibility of results suggest that the measuring devices are inappropriate to assess the evaluated parameters. Therefore, no assured correlation between the corneal sensitivity and the quantity of reflex tearing could be found.     

Results of Schirmer tear test in clinically normal llamas (Lama glama)

Purpose To determine the normal reference range for Schirmer tear test (STT) values in clinically normal llamas (Lama glama) Animals Nine captive llamas (Lama glama) (seven females and two males) were used in this study. Procedure Complete ophthalmic examinations were performed without chemical restraint. STT I values were evaluated in both eyes of all llamas using a commercial STT strip of a single lot number (Schirmer‐Tränentest^®, Germany). STT II value was also measured in both eyes of seven female llamas. Results No statistically significant differences among ages or between right and left eyes were found for any of the results. The mean ± SD STT I of 18 eyes of nine llamas was 17.3 ± 1.1 mm/min (Range 15–19 mm/min). The mean ± SD STT II of 14 eyes of seven llamas was 15.4 ± 1.7 mm/min (Range 12.5–17.5 mm/min). A paired samples t‐test demonstrated that there was a significant difference between the STT I and II values (P = 0.001). Conclusion This study provides novel data for normal reference ranges of STT I and II values in healthy llamas. Results of this study may assist veterinarians in the diagnosis of ocular surface disease and syndromes affecting the tear film in these species.     

Pharmacokinetics of famciclovir and penciclovir in tears following oral administration of famciclovir to cats: a pilot study

Objective To validate a means of collecting tears from cats, develop an assay for quantifying famciclovir and penciclovir in tears, and to assess famciclovir and penciclovir concentrations and pharmacokinetics in the tears of cats being treated orally with famciclovir for suspected herpetic disease. Animals Seven client‐owned cats. Procedures Cats were treated orally with a median (range) dose of 40 (39–72) mg of famciclovir/kg three times daily for at least 24 h. At various time points following famciclovir administration, tear samples were collected using Schirmer tear test strips. Tear famciclovir and penciclovir concentrations were measured using liquid chromatography‐mass spectrometry, and concentration‐time profiles were analyzed noncompartmentally. The relationship between famciclovir dose and tear penciclovir concentration near its maximum was evaluated using least squares linear regression. Results Maximum tear famciclovir concentration of 0.305 μg/mL occurred at 2.64 h; elimination half‐life was 2.28 h. Maximum tear penciclovir concentration (0.981 μg/mL) occurred 2.25 h following oral administration of famciclovir; elimination half‐life was 2.77 h. A significant positive correlation was noted between famciclovir dose and tear penciclovir concentration at various time points between 0.5 and 3.75 h following drug administration (P = 0.025). Tear penciclovir concentration exceeded the concentration shown to have in vitro efficacy against feline herpesvirus (FHV‐1) (0.304 μg/mL) in about half of samples collected. Conclusions Oral administration of 40 mg of famciclovir/kg to cats resulted in a tear penciclovir concentration‐time profile that approximated the plasma penciclovir concentration‐time profile and frequently achieved a penciclovir concentration at the ocular surface likely to be effective against FHV‐1.     

Effect of topical tropicamide on tear production as measured by Schirmer's tear test in normal dogs and cats

Objective To evaluate the effect of a single dose of topical 1% tropicamide on tear production as measured by the Schirmer tear test (STT) in the normal dog and cat. Material and methods Twenty‐eight dogs and 32 cats received 50 µl : l of 1% tropicamide in one eye and the opposite eye served as the control. STTs were performed immediately before instillation of tropicamide and then at 1, 4, 8 and 24 h post drug instillation. STT results were compared between the control and treated eyes at the different times. Results Aqueous tear production in dogs, measured by STT, was not significantly reduced. The mean ± SEM STTs for the baseline time for control and tropicamide‐treated eyes were 19.9 ± 0.8 and 20.3 ± 0.8 mm wetting/min, respectively. For the control eyes, the subsequent mean ± SEM STT levels were 20.3 ± 0.9 (1 h), 21.1 ± 0.8 (4 h), 20.1 ± 0.9 (8 h), and 18.7 ± 0.7 (24 h). For the tropicamide‐treated eyes, the subsequent mean ± SEM STT levels were 19.4 ± 0.9 (1 h), 19.3 ± 0.9 (4 h), 20.0 ± 0.9 (8 h), and 18.4 ± 0.8 (24 h). Aqueous tear production of both eyes was significantly reduced in cats at 1 h but returned to baseline by 4 h post tropicamide instillation. The mean ± SEM STT levels for the baseline time in cats for control and tropicamide‐treated eyes were 14.9 ± 0.8 and 14.7 ± 0.8 mm wetting/min, respectively. Subsequent mean ± SEM STT levels for the control eyes were 6.4 ± 1.1 (1 h), 11.9 ± 1.0 (4 h), 13.9 ± 0.8 (8 h), and 16.4 ± 1.0 (24 h). For the tropicamide‐treated eyes, the subsequent mean ± SEM STT levels were 5.3 ± 0.8 (1 h), 10.2 ± 0.8 (4 h), 14.7 ± 1.0 (8 h), and 16.6 ± 1.0 (24 h). Conclusion Single dose 1% tropicamide does not significantly lower tear production rates, as measured by the STT, in normal dogs. However, in normal cats single doses of 1% tropicamide in one eye cause significant reductions in tear production of both eyes at 1 h that recovered to baseline levels by 4 h.     

Reference values for Schirmer tear tests I and II in clinically normal pigs

Objective To determine reference values for Schirmer tear tests I and II in clinically normal pigs. Animal studied Twenty clinically normal Landrace pigs (10 males and females) without ocular abnormalities were used in this study. Procedures In all pigs, Schirmer tear tests (STT) I and II were performed by using a sterile Schirmer tear test standardized strip (Schirmer‐Tränentest^®, Germany) placed in the lower conjunctival fornix for 1 min. Results For each test (STT I and STT II), no differences were observed between the right and left eyes (P ≥ 0.5). The mean ± SD STT I value was 15.6 ± 3.7 mm/min (range, 10–22 mm/min), while the mean STT II value was 12.4 ± 3.8 mm/minute (range, 5–18 mm/min). The mean STT II value was significantly lower than the STT I level (P < 0.001). Animal gender did not have a significant effect on STT I and II values (P = 0.52). The mean ± SD STT I/II values of 10 juvenile pigs were significantly lower than the mean ± SD STT I/II values of 10 adult pigs (P < 0.001). Conclusions This study of 20 Landrace pigs provided valuable information on normal STT I/II in this species. Knowledge of normal STT reference values in pigs enables the clinician to evaluate corneal pathology and diagnose tear deficiency syndromes with greater accuracy.     

Qualitative tear film and conjunctival goblet cell assessment of cats with corneal sequestra

OBJECTIVES: To evaluate the tear film qualitatively and conjunctival goblet cell numbers in cats with and without corneal sequestra. ANIMALS STUDIED AND PROCEDURES: This was a prospective evaluation of 11 cats with corneal sequestra and 14 control eyes that were either the contralateral normal eye when the sequestrum was unilateral or from control cats of similar age with no ocular disease. All cats in this study were examined by a veterinary ophthalmologist. The ophthalmic examinations included a neuro-ophthalmic evaluation, Schirmer tear tests, fluorescein staining, tear film break-up times, applanation tonometry, biomicroscopy, and indirect ophthalmoscopy. The palpebral conjunctiva at the dorsal nasal, ventral nasal, dorsal temporal and ventral temporal fornices were biopsied after topical anesthetic was applied to the cornea and conjunctiva. The conjunctival biopsies were fixed in formalin and sectioned routinely and stained with hematoxylin and eosin, and periodic acid-Schiff. These slides were examined by light microscopy by a blinded examiner. Goblet cell numbers were compared to conjunctival basal epithelial cell numbers by region. The goblet cell numbers by region from the eyes with sequestra was statistically compared to those from eyes without sequestra, with a student's paired t-test. Conjunctival swabs were collected from the cats with corneal sequestra and submitted for polymerase chain reaction for Herpes felis, Chlamydia psiitticia, and Mycoplasma felis. The corneal sequestra were removed by surgical keratectomy and fixed and stained routinely, and examined by light microscopy. RESULTS: No neurologic abnormalities were detected in any of the cats. The Schirmer tear tests (eyes with sequestra 14+/-5.1 mm/min; normal eyes 15+/-6.8 mm/min) and intraocular pressures (eyes with sequestra 21+/-6.6; normal eyes 22+/-5.8) were within normal reference ranges for cats. Biomicroscopic examinations revealed varied sizes and depths of brown- and amber-colored corneal sequestra. No abnormalities were noted on indirect ophthalmoscopic examinations. The tear film break-up time was 21 s (+/-12) for the normal eyes (n=14) and 14 s (+/-13) in eyes with corneal sequestra (n=11). The average goblet/epithelial cell ratios by region for the normal eyes and the eyes with sequestra respectively were 0.66, 0.56 for the dorsal nasal fornix, 0.68, 0.57 for the ventral nasal fornix, 0.63, 0.48 for the temporal dorsal fornix, and 0.55, 0.49 for the temporal ventral fornix. There were no significant differences in tear film break-up times and goblet cell numbers in eyes with corneal sequestra and those without sequestra. Three conjunctival swabs from two of 11 cats with sequestra were positive with PCR for Herpes felis virus. These included one cat with bilateral sequestra and one cat with unilateral corneal sequestrum. CONCLUSIONS: The pathogenesis of feline corneal sequestra does not appear to be linked primarily to abnormal goblet cell numbers, qualitative tear film abnormalities, and accelerated tear film break-up time.     

Keratoconjunctival effects of diabetes mellitus in dogs

OBJECTIVES: To compare Schirmer tear test (STT) values, corneal sensitivity, tear film break up times (TFBUTs), and tear glucose concentrations in relation to conjunctival microflora, and conjunctival cytologic and histologic findings among diabetic cataractous, nondiabetic cataractous, and nondiabetic noncataractous dogs. Procedures Fifteen dogs in each category underwent neuro-ophthalmic examination; aerobic, anaerobic and fungal conjunctival cultures; assessment of corneal touch threshold (CTT), STT, tear glucose, TFBUT; and conjunctival cytology and histology (in certain cases only). Degree of cataract and uveitis were critically graded. Glycemic control was estimated using serum fructosamine and glycosylated hemoglobin. RESULTS: STT values were significantly lower in diabetic cataractous than nondiabetic noncataractous dogs. CTT of diabetic cataractous dogs was significantly lower than that of nondiabetic noncataractous dogs. Mean TFBUTs were significantly less in diabetic cataractous dogs than nondiabetic cataractous and nondiabetic noncataractous dogs. Tear glucose concentrations were significantly higher in diabetic cataractous dogs than nondiabetic cataractous and nondiabetic noncataractous dogs. Conjunctival microbial isolates did not differ among groups. There were no significant differences in degree of cataract or uveitis between diabetic cataractous and nondiabetic cataractous groups. There was mild submucosal inflammatory infiltrate in conjunctival specimens from diabetic dogs. Conjunctival epithelial dysplasia and/or squamous metaplasia was/were detected in conjunctival biopsies of 5/7 diabetic dogs. Reductions in conjunctival goblet cell (GC) densities were noted in 4/7 diabetic dogs; there were no significant differences in mean GC densities among the three groups. CONCLUSIONS: Diabetic cataractous dogs have significantly altered keratoconjunctival characteristics compared to nondiabetic cataractous and nondiabetic noncataractous dogs.     

Feline eosinophilic conjunctivitis

Objective To review 12 cases of histologically confirmed feline eosinophilic conjunctivitis, their clinical, cytologic, histologic and electronmicroscopic findings, results on PCR for FeHV‐1, treatment and outcome. Animals studied Twelve naturally occurring cases presented during a period of 26 months. Procedures Thorough ophthalmologic examination, conjunctival scrapings performed with the cytobrush method; histologic samples from the palpebral conjunctiva; PCR for FeHV‐1 on Schirmer Tear Test (STT) strips; saliva and nasal swabs, and retrospective evaluation of all results. Results The breed most commonly affected was the Domestic Shorthair (n = 8), followed by Persians (n = 2), Somali (n = 1) and Siamese (n = 1). Age at presentation was 1–15 years with a mean age of 7.2 years. Nine cats were castrated males; three cats were females: two of them were spayed. Unilateral (n = 7) or bilateral (n = 5) involvement with depigmentation and erosions of lid margin, blepharospasm, swelling and redness of conjunctiva and third eyelid were the most common clinical findings. Frequency of eosinophils in cytologic samples was more than 10% in every patient. PCR for FeHV‐1 on STT was negative in all cases. Histologically, eosinophils, lymphocytes, plasma cells, mast cells and macrophages were involved. On electronmicroscopy, viral particles were not detected. Ten cases needed long‐term anti‐inflammatory treatment. Conclusions The 12 reviewed cases suggest that feline eosinophilic conjunctivitis is a chronic inflammatory uni‐ or bilateral disease of the adult cat. Typically the lid margin was also involved, and was thickened, depigmented and erosive. Cytological examination of conjunctival scrapings was a valuable tool for detecting eosinophilic conjunctivitis. The cytological findings correlated well with the histopathological findings in our patients. Topical or systemic anti‐inflammatory drugs resolved the clinical symptoms in our cases within a short period of time. Neither electronmicroscopy nor PCR were able to detect involvement of FHV1 in the represented cases. The etiopathogenic role of FeHV‐1 remains undetermined.     

Effect of acepromazine or xylazine on tear production as measured by Schirmer tear test in normal cats

Objective  To evaluate the effect of acepromazine or xylazine on Schirmer tear test 1 results in clinically normal cats.
Animals  Sixteen healthy cross-breed cats.
Procedure  The animals were randomly divided into two groups of eight cats each. The first group was sedated with acepromazine alone (0.2 mg/kg) and the second group received only xylazine (2 mg/kg). All cats had Schirmer tear test (STT) readings taken prior to sedation and at 15 and 25 min postsedation.
Results  Sedation with acepromazine or xylazine in cats with normal pre-sedation STT 1 values caused a statistically significant decrease in mean values of tear production in both groups. In acepromazine group the mean ± SEM STT at T₁₅ and T₂₅ were 4.31 ± 0.98 ( P  < 0.001) and 5.18 ± 1.07 ( P  = 0.002). The post-treatment mean ± SEM values in xylazine group were 2.18 ± 0.97 ( P  < 0.001) and 2.62 ± 1.17 ( P  = 0.001) at 15 and 25 min respectively. Comparison between T₁₅ and T₂₅ in acepromazine group ( P  = 0.49) and xylazine group ( P  = 0.56) revealed no significant differences.
Conclusion  These observations indicate that both acepromazine or xylazine significantly reduced tear production in clinically normal cats. In cats, clinicians should measure STT values prior to utilizing acepromazine or xylazine as sedatives in order to accurately assess the results. Moreover, sterile ocular lubricant or tear replacement should be used as a corneal protectant during sedation with these drugs.     

An eye on the Shih Tzu dog: Ophthalmic examination findings and ocular surface diagnostics

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.     

Reference values for selected ophthalmic diagnostic tests and clinical characteristics of chinchilla eyes (Chinchilla lanigera)

Objective To establish reference values for the Schirmer tear test I (STT I), the phenol red thread tear test (PRTT), the intraocular pressure (IOP) with rebound tonometry, to determine the corneal sensitivity for healthy chinchillas, and to describe clinical aspects of normal chinchilla eyes. Animals One hundred and twenty‐two eyes of 61 healthy pet chinchillas of different age and gender were investigated. Procedures A full ophthalmic exam including slit lamp biomicroscopy, ophthalmoscopy, measurement of STT I, PRTT, determination of the corneal touch threshold (CTT), and the measurement of the IOP (TonoVet®) was performed. The normal appearance of the lid, the iris, the lens, the fundus, and the optic nerve disc was evaluated. Results The results of the STT I were very low and not reliable, and the measurement was discontinued. The median value of PRTT was 14.0 mm wetting/15 s (mean 14.6 ± 3.5 mm wetting/15 s). The median CTT was 32.5 mm (mean 31.2 ± 7.0 mm) respectively 1.2 g/mm² (mean 1.5 ± 0.9 g/mm²). The median IOP was 3.0 mmHg (mean 2.9 ± 1.8 mmHg). The predominating iris color was brown. The fundus pigmentation varied. Few lens alteration were seen in otherwise healthy chinchilla eyes. Most chinchillas had myelinated discs. Optic nerve cupping was present in 62% of the animals. Conclusion Because of the small amount of tears, the PRT test is recommended for tear measurements in chinchillas. The IOP in chinchillas seems to be quiet is low in comparison to other rodents.     

Effect of lacrimal punctal occlusion on tear production and tear fluorescein dilution in normal dogs

OBJECTIVE: To evaluate effects of lacrimal punctal plugs positioned in either the upper, lower, or combination of upper and lower lacrimal canaliculi on plug retention and tolerance; tear production, as measured by the Schirmer tear test; and the dilution of fluorescein within the tear film in normal dogs. MATERIAL AND METHODS: Lacrimal punctal plugs were positioned in the lower, upper, or combination of lower and upper plugs in six laboratory-quality Beagles under topical anesthesia. Retention of plugs was evaluated daily from 8 to 23 days by visual inspection and slit-lamp biomicroscopy. Schirmer tear tests (STT 1 without topical anesthesia) were performed at 48-h intervals. Dilution of fluorescein was determined at 5- and 45-min post-fluorescein instillations once weekly. RESULTS: Lacrimal punctal plugs of 0.4 and 0.6 mm in diameter were retained for 14 (lower plugs: 100%) and 23 days (75%), and for the upper plugs at 8 days less often (75%), and were infrequently locally nonirritating. Combination of lower and upper plugs seemed to adversely affect retention of either plug. When loss of the plugs occurred, a next larger size plug was necessary suggesting some stretching of the lacrimal canaliculi occurred. Pre- and postplug placement STT results indicated no change with lower and combination lacrimal punctal plugs, but decreased levels following upper lacrimal punctal plugs. Tear fluorescein levels at 5 and 45 min in control eye (no punctum plugs) were 3.39% and 0.14%, respectively. With lower, upper, and the combination of lower and upper lacrimal puncta plugs, tear fluorescein levels at 45 min were higher than the controls (lower: 0.76%; upper: 0.45%, and combination 0.56%). CONCLUSION: Lacrimal punctal silicone plugs are retained for 8-23 days in the lower, upper, and combined lower and upper canaliculi at high rates. Effects on STT levels appear limited. Fluorescein within the tear film persists longer with all different positioned lacrimal punctum plugs than in the control eyes.     

Detection of Chlamydophila pneumoniae in cats with conjunctivitis

Objective To determine the presence of chlamydial species including recently described chlamydial agents as well as the human pathogen Chlamydophila pneumoniae in feline conjunctivitis. Animal studied Twenty five cats without and 49 cats with conjunctivitis were tested for chlamydia using a Chlamydiaceae real time (RT) PCR (targeting the 23S rRNA gene sequence), a Chlamydiales PCR (targeting the 16S rRNA gene sequence), and cell culture. The PCR products of all positive samples were sequenced and subsequently analyzed using a basic local alignment search tool search. Results Chlamydiaceae RT PCR and subsequent sequence analyses identified C. pneumoniae in five cats in the conjunctivitis group. The presence of Chlamydophila felis was shown in two cats with conjunctivitis. Chlamydiae related to uncultured members of Chlamydiales were detected in three conjunctivitis cases and in one cat without clinical symptoms. Conclusion This study detects for the first time, the known human pathogen C. pneumoniae in feline conjunctivitis cases using Chlamydiaceae RT PCR and sequence analyses.     

Infrared ocular thermography in dogs with and without keratoconjunctivitis sicca

Infrared thermography was used to measure temperature differences of the corneal surface between nasal and temporal limbus regions and central cornea of normal dogs and dogs with keratoconjunctivitis sicca (KCS), in order to establish temperature values in normal canine eyes and in patients with decreased Schirmer tear tests (STT) values. Dogs investigated were all either patients seen at the Veterinary Teaching Hospital of Federal University of Paraná or normal dogs that belonged to the same institution. STT were performed in all eyes. A total of 40 control eyes (STT ≥15 mm/min) and 20 eyes with low STT values (STT ≤14 mm/min) were examined. The mean STT value for eyes with normal STT values was 22.9 ± 3.9 mm/min (mean ± standard deviation), and the mean STT value for eyes with low STT value was 7.2 ± 4.8 mm/min. The mean corneal temperature was significantly lower in eyes with low STT values than in control eyes (P < 0.0001). The following significant correlations were found: (i) Schirmer and breakup time (BUT) (P = 0.0001, r = 0.5); (ii) STT values and corneal surface temperature (P = 0.001, r = 0.256); (iii) STT values and age (P = 0.0001, r = ?0.448); (iv) age and corneal surface temperature (P = 0.0001, r = ?0.281); and (v) BUT and corneal surface temperature (P = 0.0001, r = 0.36). Thermography is a method that can differentiate between eyes with normal and abnormal STT values. In the future, thermography might be incorporated as part of the ophthalmic examination and perhaps become a popular ancillary test for the diagnoses of ocular surface disorders.     

Schirmer tear test results in normal horses and ponies: effect of age,season, environment,sex, time of day and placement of strips

Tear production was evaluated in 39 horses and 29 ponies using Schirmer tear test strips to determine whether diurnal or weekly fluctuations occur, whether location of strip placement has an effect, if values are the same for both eyes in an animal and whether sex, age, stabling vs. pasture and winter vs. summer had an effect. There was no test in which the raw score was less than 10 mm, although there were many occasions where tear wetting exceeded 35 mm. Analysis of the raw (continuous) scores by linear regression provided no evidence that signalment, housing or season or location of strip placement affected results. The distribution of tear test scores for a 'population' of eyes did not differ when the right eye was compared with the left eye or when the same eye was compared at different times on the same day. Individual test wetting values for opposing eyes measured at the same time, and also wetting values for the same eye measured at different times on the same day sometimes differed substantially. In winter maximum tear wetting exceeded 35 mm more frequently in the STT I than in the STT II even in housed horses and ponies, but there was no consistent significant difference. There appears to be wide variability in the STT I in normal horses and ponies.     

Determination of tear break-up time reference values and ocular tolerance of tetracaine hydrochloride eyedops in healthy horses

Reasons for performing study: Tetracaine hydrochloride (THCl) has been reported to cause irritation in dogs. In man, some topical anaesthetics have been shown to disrupt the tear film. Tear break‐up time (TBUT) is a useful test allowing an assessment of the quality of the precorneal tear film. Only one TBUT value has been reported in horses with no information on the technique used. Objectives: To provide a method for performing the TBUT in horses and to report any side effects of a single application of THCl in clinically normal horses, particularly on the stability of the tear film. Methods: In Study 1, one drop of 0.5 or 1% THCl was applied to one eye of 20 horses divided in 2 groups. Treated eyes were assessed for the development of side effects 2.5 and 5 min after treatment. In Study 2, the TBUT was measured in both eyes of 2 groups of 10 horses, before and 2.5 and 5 min after, instillation of one drop of either 0.5 or 1% THCl. Results: No animals developed any ocular side effect after instillation. Basal TBUT was 8.3 ± 1.3 s. TBUT decreased from baseline 5 and 2.5 min after application of one drop of 0.5% THCl and one drop of 1% THCl, respectively. Conclusions: A technique to measure the TBUT in healthy horses is described and normal range values that could be used as a reference were obtained. Potential relevance: THCl is well tolerated in horses but lowers the TBUT.     

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).     

Schirmer tear tests and intraocular pressures in conscious and anesthetized koalas (Phascolarctus cinereus)

Objective To estimate mean Schirmer tear test (STT) and intraocular pressure (IOP) values in healthy koalas both conscious and anesthetized. Methods Data were gathered from koalas in Victoria, Australia. Conscious examinations were performed on captive koalas. Free‐ranging (wild) koalas were examined under anesthesia. Anesthesia was induced using alfaxalone, and animals were maintained on oxygen and isoflurane if required. All animals were healthy and had no surface ocular pathology detectable during slit lamp biomicroscopy. STT I tests were performed using commercial STT test strips placed in the lower fornix for 1 min. IOP was measured using an applanation tonometer after topical anesthesia. The higher value of the two eyes for both STT and IOP was analyzed. STT was measured in 53 koalas (34 conscious, 19 anesthetized) and IOP was measured in 43 koalas (30 conscious, 13 anesthetized). A two‐sample t‐test was used to compare means. A P‐value <0.05 was regarded as significant. Mean ± SD is presented. Results The mean higher STT in conscious koalas was 10.3 ± 3.6 mm wetting/min and in anesthetized koalas it decreased to 3.8 ± 4.0 mm wetting/min (P < 0.0001). The mean higher IOP in conscious koalas was 15.3 ± 5.1 mmHg, and in anesthetized koalas it was 13.8 ± 3.4 mmHg (P = 0.32). There was no effect of sex on either STT or IOP. Conclusions The mean and SD of STT and IOP values for koalas both conscious and anesthetized were reported. The mean STT was significantly reduced by alfaxalone anesthesia.