Corneal Dystrophy in Dutch Belted Rabbits as a Possible Model of Thiel-Behnke Subtype of Epithelial-Stromal TGFß-Induced Corneal Dystrophy.

The International Committee for Classification of Corneal Dystrophies (IC3D) categorized corneal dystrophies in humans using anatomic, genotypic, and clinicopathologic phenotypic features. Relative to the IC3D classification, a review of the veterinary literature confirmed that corneal dystrophy is imprecisely applied to any corneal opacity and to multiple poorly characterized histologic abnormalities of the cornea in animals. True corneal dystrophy occurs in mice with targeted mutations and spontaneously in pet dogs and cats and in Dutch belted (DB) rabbits, but these instances lack complete phenotyping or genotyping. Corneal dystrophy in DB rabbits can be an important confounding finding in ocular toxicology studies but has only been described once. Therefore, the ophthalmology and pathology of corneal dystrophy in 13 DB rabbits were characterized to determine whether the findings were consistent with or a possible model of any corneal dystrophy subtypes in humans. Slit lamp and optical coherence tomography (OCT) imaging were used to characterize corneal dystrophy over 4 months in young DB rabbits. The hyperechoic OCT changes correlated with light microscopic findings in the anterior stroma, consisting of highly disordered collagen fibers and enlarged keratocytes. Histochemical stains did not reveal abnormal deposits. Small clusters of 8 to 16 nm diameter curly fibers identified by transmission electron microscopy were consistent with Thiel-Behnke (TBCD) subtype of epithelial-stromal transforming growth factor ß-induced dystrophies. Sporadic corneal dystrophy in DB rabbits appears to be a potential animal model of TBCD, but genotypic characterization will be required to confirm this categorization.

Sinus of Valsalva aneurysm in a Göttingen minipig.

A 26.6-kg, intact, 9-mo-old female Göttingen minipig was presented for a coronary stent study. Angiography revealed a sinus of Valsalva aneurysm (SVA) in the aortic root that involved both the left and noncoronary sinuses of the heart. Gross histologic examination of the heart revealed 2 regions of aneurysmal formation: one at the ostium to the left main coronary artery, with aortic sinus involvement, and the other at the dorsal aspect of the aortic root involving the noncoronary aortic sinus. With no history of any infectious diseases, and the microscopic findings showing no evidence of necrosis, degeneration, or infection, confirmed that the aneurysmal-like dilation of the sinuses was most likely a congenital anomaly. This case illustrates the diagnosis and comparative findings of a rare cardiac anomaly found in only a few species to date. To our knowledge, antemortem diagnosis of unruptured SVA involving both the left and noncoronary aortic sinuses of the minipig heart has not been reported previously.

Incidence of spontaneous ocular lesions in laboratory rabbits.

Laboratory rabbits are commonly used for ocular drug and device studies. The purpose of this study was to determine the incidence of spontaneous ocular lesions in laboratory rabbits with respect to sex, breed, and supplier. We retrospectively evaluated ophthalmic examination records of rabbits screened between April 2008 and April 2010. These 1840 records represented 572 black Dutch belted (DB), 1022 New Zealand white (NZW), and 246 NZW × New Zealand red F(1) crosses (WRF1). Rabbits were between 6 and 16 wk of age and had been received from 5 suppliers. Ocular structures evaluated were the cornea, lens, iris and vitreous with respect to sex, breed and supplier. A total of 177 rabbits (9.6%) and 233 eyes (6.3%) were effected. Of total rabbits, 15.3% males and 7.3% females were affected. The most common structure affected was the cornea in 5.7% of rabbits, (DB 11.7%, NZW 3.0%, and NZR 3.3%). The lens at 3.6% was second most common (DB 2.1%, NZW 4.6%, and NZR 3.3%). Both iris (0.2%) and vitreous (0.3%) were not significantly affected. Significant sex-breeder-supplier combinations were: cornea DB supplier D, supplier D females, supplier D males, DB males and NZR females; and lens: NZW females; and at least one affected ocular structure: NZW supplier D, supplier D females, DB males, NZW females, and NZR females. Breed, sex, and supplier were significant variables of ocular lesions in laboratory rabbits. Investigators should consider each of these variables when choosing rabbits for ocular studies.