A Unifying Concept of Uveal Pigment Cell Distribution and Dissemination Based on an Animal Model: Insights into Ocular Melanogenesis.

Pigmented cells are derived from neural crest cells, which migrate along the peripheral nerve sheets into their specific final region. During their migration, cells progressively acquire pigment-producing capabilities, maturation, and the shape of melanocytes. These insights, along with specific clinical characteristics of melanocytic nevi, have led to new concepts of cutaneous, periocular, and iris nevogenesis. To further elucidate the specific ocular embryogenic melanoblast distribution and dissemination - that could explain the distinct distribution of uveal melanocytic neoplasms - we investigated the ocular pigmentation of dogs affected by a specific mutation called Merle, which results in either pigment- (wild type) or non-pigment- (mutated type) producing cells. Based on our observations, we propose a unifying concept of uveal pigment cell distribution and dissemination, which postulates melanoblast migration and maturation following the trigeminal V1 branch and, later, their entrance into the eye along the ciliary nerves and their finest iris branches. Our concept provides an explanation not only for the specific distribution of ocular melanocytic lesions, including uveal and iris nevi, but also for the different locations depending on the metastatic potential of the ocular melanoma. Though speculative, the higher metastatic potential of posterior uveal melanomas compared to iris melanomas may be related to a less differentiated stage in the maturation of migrating melanocytes in the posterior segment compared to the anterior segment of the eye. However, there is a need of further studies focusing on cell differentiation markers of melanocytes at different locations in the eye.

Uterine disorders in 50 pet rabbits.

Although the incidence of uterine disorders in pet rabbits is high there are only a few retrospective studies and case reports on genital tract disease in female rabbits. Uterine disorders were assessed in 50 pet rabbits. In 31 pet rabbits with suspected clinical uterine disease, medical records were further reviewed regarding clinical signs, diagnostic workup, treatment as well as the outcome itself. Uterine adenocarcinoma (54%) was most frequently diagnosed, followed by endometrial hyperplasia (26%). Serosanguineous vaginal discharge was the predominant clinical sign observed by the rabbit owners. In approximately 50% of the rabbits with suspected uterine disorders, abdominal palpation revealed enlarged and/or irregular masses in the caudoventral abdomen indicating uterine lesions. Out of 23 rabbits undergoing ovariohysterectomy, four were either euthanized or died shortly after surgery because they were clinically unstable. Overall, 80% of the ovariohysterectomized animals were still alive 6 mo after surgery. In female pet rabbits that are not breeding, either ovariohysterectomy should be performed at an early age or routine checks including ultrasonography of the abdomen are recommended on a regular basis.

Eosinophilic keratoconjunctivitis in two rabbits.

The purpose of this case report is to describe the clinical course and cytologic findings, treatment, and outcome of eosinophilic keratoconjunctivitis in two rabbits. Ophthalmic examination revealed ocular discharge, dacryocystitis, blepharitis, conjunctivitis, white conjunctival and corneal plaques, corneal vascularization, and stromal infiltration with different degrees of severity in each case. In case 2 there was also ulcerative disease of the cornea. Computerized tomography scan of the head, corneal biopsy for histopathologic examination with additional Luna and Giemsa stain were performed in case 2 and conjunctival as well as corneal specimens were obtained for bacteriologic culture and cytologic examination in case 1. Based on test results, a diagnosis of eosinophilic keratoconjunctivitis was made in case 2 and a tentative diagnosis of eosinophilic keratoconjunctivitis was made in case 1. Response to treatment with a topical steroid and topical cyclosporin was supportive of the diagnosis in both cases and shared many similarities with the response to treatment previously described in cats. Eosinophilic keratitis should be considered as part of a differential diagnosis list in rabbits with a history of keratitis.

Evaluation of healthy equine eyes by use of retinoscopy, keratometry, and ultrasonographic biometry.

OBJECTIVE: To assess natural variations in degree of refraction, corneal curvature, corneal astigmatism, corneal radius, and intraocular distance of healthy equine eyes. ANIMALS: 159 horses with healthy eyes that were admitted to a veterinary teaching hospital for nonophthalmic surgeries. PROCEDURES: Eyes of horses were examined with a retinoscope prior to anesthesia and with a keratograph and A- and B-scan ultrasonographic biometers during surgery. In addition, manual caliper measurements of horizontal and vertical corneal radii were obtained. RESULTS: Mean +/- SD degree of refraction in the horizontal meridian of eyes was -0.06 +/- 0.68 diopters (D). Vitreous body length and horse age correlated negatively with refraction values. The horizontal corneal radius (15.96 +/- 1.28 mm) was larger than the vertical corneal radius (15.02 +/- 1.09 mm). Accordingly, the vertical corneal curvature (21.56 +/- 1.68 D) was greater than the horizontal corneal curvature (22.89 +/- 1.65 D). Axial globe length (40.52 +/- 2.67 mm), anterior chamber depth (6.35 +/- 0.59 mm), lens thickness (12.30 +/- 0.83 mm), and vitreous body length (21.87 +/- 1.85 mm) were positively correlated with body weight, height, and age. Results of keratograph and caliper measurements correlated well for horizontal corneal diameter but poorly for vertical corneal diameter. Results of A- and B-scan ultrasonography differed by < or = 1 mm in 64% of measured eyes. CONCLUSIONS AND CLINICAL RELEVANCE: Results of keratometry and ultrasonographic biometry varied widely. Additional research is needed to validate the keratograph used in our study for measurements in equine eyes.