The evaluation of normal ocular parameters in two breeds of hedgehogs

OBJECTIVES

The purpose of this study was to evaluate conjunctival microflora and measure normal tear production and intraocular pressure (IOP) in two breeds of hedgehogs (long-eared hedgehogs and Brandt's hedgehogs).

METHODS

Forty-eight hedgehogs from two different breeds were chosen for the study. Tear production was measured using the Schirmer tear test (STT) and phenol red thread test (PRTT) in both eyes. IOP was measured using a rebound tonometer. To perform microbiological sampling one drop of tetracaine was instilled in the eyes. Two sterile microswabs were used to collect samples for the microbial and fungal culture. All the microswab samples were transferred in phosphate-buffered saline (PBS) to the laboratory for culture. Two MacConkey and two blood agar media plates were employed for each eye. Oneplate of sabouraud dextrose agar (SDA) was used for the fungal culture for each eye. Standard biochemical tests were performed to identify the isolated organisms.

RESULTS

The mean STT and PRTT values were 1.6 ± 0.1 mm/min and 2.4 ± 0.3 mm/15 s in long-eared hedgehogs and 2.2 ± 0.1 mm/min and 2.5 ± 0.3 mm/15 s in Brandt's hedgehogs, respectively. Mean (SD) Intraocular pressure of right eyes in long-eared hedgehog and Brandt hedgehog were 19.7 ± 1.4 mmHg and 19.2 ± 2.4 mmHg, respectively. In the left eyes of long-eared hedgehog and Brandt hedgehog mean (SD) IOP were 19.8 ± 1.5 mmHg and 19.5 ± 2.1 mmHg, respectively. In long-eared hedgehogs, the most common bacteria were Staphylococcus epidermidis and Bacillus spp. In Brandt's hedgehogs, 24 out of 48 eyes had Staphylococcus epidermidis, which was the most commonly isolated bacterial species.

CONCLUSIONS

This study established reference intervals for IOP, STT and PRTT in hedgehogs and recognised and compared ocular conjunctival microflora in two breeds of hedgehogs.

An Extensive Study of Phenol Red Thread as a Novel Non-Invasive Tear Sampling Technique for Proteomics Studies: Comparison with Two Commonly Used Methods

Tear samples are considered in recent publications as easily, noninvasively collectible information sources for precision medicine. Their complex composition may aid the identification of biomarkers and the monitoring of the effectiveness of treatments for the eye and systemic diseases. Sample collection and processing are key steps in any analytical method, especially if subtle personal differences need to be detected. In this work, we evaluate the usability of a novel sample collection technique for human tear samples using phenol red threads (cotton thread treated with the pH indicator phenol red), which are efficiently used to measure tear volume in clinical diagnosis. The low invasiveness and low discomfort to the patients have already been demonstrated, but their applicability for proteomic sample collection has not yet been compared to other methods. We have shown, using various statistical approaches, the qualitative and quantitative differences in proteomic samples collected with this novel and two traditional methods using either glass capillaries or Schirmer’s paper strips. In all parameters studied, the phenol red threads proved to be equally or even more suitable than traditional methods. Based on detectability using different sampling methods, we have classified proteins in tear samples.

Ophthalmic examination, biometry, and histologic findings in captive inland bearded dragons (Pogona vitticeps)

OBJECTIVE

To report ophthalmic examination, biometry, phenol red thread test (PRTT), intraocular pressure (IOP), and histologic findings from a private collection of inland bearded dragons (Pogona vitticeps).

ANIMALS STUDIED

Fourteen inland bearded dragons.

PROCEDURES

Complete ophthalmic examinations were performed on all animals, including slit-lamp biomicroscopy, indirect ophthalmoscopy, fluorescein stain, phenol red thread test, and rebound tonometry. B-mode ultrasonography was used to measure anterior chamber depth, axial lens thickness, vitreal chamber depth, and axial globe length. Horizontal corneal diameter was estimated using ImageJ software. Histologic assessment was obtained for one of the bearded dragons that died following the study period.

RESULTS

The median PRTT value was 7.27 mm/15 seconds. Mean IOP was 6.29 ± 1.60 mm Hg and 2.14 ± 1.37 mm Hg using the dog and undefined calibration settings, respectively. Median axial globe length was 11.75 mm. Mean anterior chamber depth and mean lens thickness were 2.06 ± 0.35 mm and 3.38 ± 0.45 mm, respectively. Median vitreal chamber depth was 6.79 mm. Mean horizontal corneal diameter was 5.138 ± 0.346 mm. Two distinct ocular phenotypes were observed, with two of the bearded dragons having corneal globosa, deep anterior chambers, and tufts of iridal vessels and fibrillar material extending into the anterior chamber.

CONCLUSIONS

The ultrasound biometry, PRTT, and rebound tonometry results may serve as a guideline for ophthalmic parameters in healthy bearded dragons. Examination and testing of greater numbers of animals are necessary to establish true reference ranges and determine if the observed ocular phenotypes represent normal variants or pathologic changes.

Ophthalmologic Diseases of Small Mammals

Ophthalmic examination of small mammals follows the same principles as in other species. Reference values for tear production and intraocular pressure are provided. Conjunctivitis and epiphora is common in rabbits. Numerous infectious organisms have been isolated from rabbits with conjunctivitis. Dental disease can be a cause for conjunctivitis in rabbits. Treatment consists of topical and oral antimicrobial agents and irrigation of the nasolacrimal system. Underlying dental disease needs to be addressed. Ulcerative keratitis, corneal dystrophy, membranous occlusion of the cornea and eosinophilic keratitis are described. Encephalitozoon cuniculi can cause phacoclastic uveitis in rabbits. A break in the anterior lens capsule exposes lens protein with subsequent anterior uveitis and cataract formation. Cataract surgery can be performed to remove the affected lens. Glaucoma is inherited as an autosomal recessive trait in rabbits. Orbital disease in rabbits may be associated with dental disease. Treatment is often difficult due to the caseous nature of the abscessed material. The most common ophthalmic diseases seen in ferrets include conjunctivitis, corneal endothelial cell degeneration, cataract formation, retinal degeneration and orbital disease. Ophthalmic diseases in guinea pigs include conjunctivitis, dermoids, cataract and osseous metaplasia of the mesectodermal trabecular meshwork. Exophthalmos may be related to dental disease in guinea pigs and chinchillas. Chromodacryorrhea is seen in rats and mice associated with inflammation of the Harderian gland. Sialodacryoadenitis virus is a highly contagious virus that may cause exophthalmos, epiphora and keratoconjunctivitis. Ammonia vapors from soiled bedding can cause keratoconjunctivitis in hamsters.

Effects of injectable dexmedetomidine-ketamine-midazolam and isoflurane inhalation anesthetic protocols on ocular variables in captive black-tailed prairie dogs (Cynomys ludovicianus)

OBJECTIVE

To evaluate the effects of injectable dexmedetomidine-ketamine-midazolam (DKM) and isoflurane inhalation (ISO) anesthetic protocols on selected ocular variables in captive black-tailed prairie dogs (Cynomys ludovicianus; BTPDs).

ANIMALS

9 zoo-kept BTPDs.

PROCEDURES

The BTPDs received dexmedetomidine hydrochloride (0.25 mg/kg, IM), ketamine hydrochloride (40 mg/kg, IM), and midazolam hydrochloride (1.5 mg/kg, IM) or inhalation of isoflurane and oxygen in a randomized complete crossover design (2-day interval between anesthetic episodes). Pupil size, globe position, tear production, and intraocular pressure measurements were recorded at 5, 30, and 45 minutes after induction of anesthesia. For each BTPD, a phenol red thread test was performed in one randomly selected eye and a modified Schirmer tear test I was performed in the other eye. Intraocular pressure was measured by rebound tonometry.

RESULTS

Compared with findings for the DKM protocol, pupil size was smaller at all time points when the BTPDs underwent the ISO protocol. Globe position remained central during anesthesia with the DKM protocol, whereas it varied among central, ventromedial, and ventrolateral positions during anesthesia with the ISO protocol. Tear production and intraocular pressure decreased significantly over time when the BTPDs underwent either protocol.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that ophthalmic examination findings for anesthetized BTPDs can be influenced by the anesthetic protocol used. The DKM protocol may result in more consistent pupil size and globe position, compared with that achieved by use of the ISO protocol. Tear production and intraocular pressure measurements should be conducted promptly after induction of anesthesia to avoid the effect of anesthetic episode duration on these variables.

Measurement of tear production and establishment of reference values in guinea pigs (Cavia porcellus) using a modified Schirmer tear test

BACKGROUND

Past studies have shown that 5-mm Schirmer tear tests (STTs) are difficult to interpret in guinea pigs. Modified 2.5-mm STT strips are more adequate for measuring the small volume of tear production in these animals. The aim of this study was to establish reference values for the modified 2.5-mm STT strips.

METHODS

Modified STT measurements were performed in random order in both eyes of 50 guinea pig patients. The wetting of the strip was noted at 30 seconds and at 1 minute.

RESULTS

The mean±sd STT values for both eyes were 7.58±3.19 mm at 30 seconds and 10.42±3.92 mm at 60 seconds. The median was 8 mm at 30 seconds and 10 mm at 60 seconds for both eyes. Animals under one year of age had lower STT values. STT values at 30 and 60 seconds can both be used. Both eyes should be measured when possible.

CONCLUSION

The authors recommend values above 8 mm at 30 seconds and 10 mm at 60 seconds to be considered normal when using a 2.5-mm STT strip. There are ambiguous areas at 5-8 mm and 6-10 mm. If in these ranges the results should be combined with clinical signs and judgement.

Ophthalmological abnormalities in wild European hedgehogs (Erinaceus europaeus): a survey of 300 animals

In this study we aimed to examine wild European hedgehogs (Erinaceus europaeus) in rescue centres and to determine ocular abnormalities in this animal population. Three hundred animals varying in age from 2 months to 5 years were examined, 147 being male and 153 female. All animals were evaluated with direct and indirect ophthalmoscopy and slit lamp biomicroscopy in animals where lesions were detected. Tonometry using the Tonovet rebound tonometer was undertaken in selected animals as was assessment of tear production using the Schirmer I tear test. Four animals were affected by orbital infection, 3 were anophthalmic, 2 unilaterally and one bilaterally, 3 by conjunctivitis, 3 by non-ulcerative keratitis and 4 by uveitis with corneal oedema. Fifty seven animals were affected by cataract, 54 with bilateral nuclear lens opacities. Twenty six of these animals were young animals considered too small to hibernate. This report documents the first prospective study of ocular disease in the European hedgehog. The predominant finding was bilateral nuclear cataract seen particularly in young poorly growing animals. Investigation into the potential causation of cataracts by poor nutrition or poor feeding ability by lens opacification requires further study.

Measurement of Tear Production Using the Phenol Red Thread Test in the Common Mynah ( Acridotheres tristis )

To evaluate tear production in the common mynah ( Acridotheres tristis ) using the phenol red thread test (PRTT) and to make a comparison of measurements with the PRTT placed in the fornices of lower and upper eyelids, tear production of both eyes in 22 healthy adult captive mynah birds was evaluated. After positioning of threads in the fornices of upper and lower eyelids, the PRTT values of the birds were 17.5 ± 3.1 mm/15 s and 19.2 ± 2.5 mm/15 s, respectively. A significant difference was found between PRTT values for upper eyelids and lower eyelids (P = 0.01). This study provides novel data for normal reference ranges of PRTT values in healthy common mynah birds and shows that a difference is found depending on where the PRTT thread is placed.

Effects of short-term oral administration of trimethoprim-sulfamethoxazole on tear production in clinically normal Syrian hamsters

OBJECTIVE

To determine effects of 14 days of oral administration of trimethoprim-sulfamethoxazole on aqueous tear production in clinically normal Syrian hamsters.

ANIMAL STUDIED

Fifteen healthy adult Syrian hamsters.

PROCEDURE

Baseline phenol red thread test (PRTT) values were recorded 1 day prior to treatment. Eight hamsters in treated group received 15 mg/kg trimethoprim-sulfamethoxazole orally twice a day for 14 days. The remaining seven hamsters were used as untreated controls and received a placebo. All ophthalmic tests were performed without chemical restraint. PRTT values were evaluated in both eyes of all Syrian hamsters using a commercial PRTT strip of a single lot number.

RESULTS

The mean ± SD baseline PRTT values for treatment group and control group were 7.25 ± 1.3 mm/15 s and 5.42 ± 1.13 mm/15 s, respectively. After 14 days of drug administration, the mean ± SD PRTT values for treatment group and control group were 5.62 ± 1.5 and 5.64 ± 0.74, respectively. Significant decreases in the PRTT values, compared with baseline values, were observed in the treatment group on day 15 (P = 0.042).

CONCLUSIONS

Trimethoprim-sulfamethoxazole decreased tear production in the hamster in this study.

Differences in ocular parameters between diurnal and nocturnal raptors

OBJECTIVE

To establish and compare normal ocular parameters between and within diurnal and nocturnal raptor groups.

ANIMALS STUDIED

Eighty-eight ophthalmically normal raptors of six nocturnal and 11 diurnal species were studied.

PROCEDURE

Tear production was measured using Schirmer tear test (STT) and phenol red thread test (PRTT), and applanation tonometry was conducted. Ultrasonographic measurements of axial length (AL), mediolateral axis (ML), vitreous body (VB), and pecten length (PL) were recorded, and conjunctival cultures were obtained.

RESULTS

A weak correlation (R = 0.312, P = 0.006) was found between PRTT and STT. Tear production was significantly lower in nocturnal species (P < 0.001), but no difference was observed in intraocular pressure (IOP). VB and PL were significantly longer in diurnals (P < 0.001 and P = 0.021, respectively), and no significant difference was observed in AL and ML. When comparing results within these groups, there was a significant difference between most species for all parameters except IOP. Fifty-one percent of the examined raptors were positive for mycology or bacteriology, either on culture or PCR. The most common infectious agent isolated was Staphylococcus spp.

CONCLUSIONS

Phenol red thread test and STT are both valid methods to measure tear production; however, a separate baseline must be determined for each species using these methods, as the results of one method cannot be extrapolated to the other. Due to significant differences observed within diurnal and nocturnal species, it appears that a more intricate division should be used when comparing these parameters for raptors, and the classification of diurnal or nocturnal holds little significance in the baseline of these data.