Odontogenic parakeratinized cyst resulting in exophthalmos and palatine, maxillary, and zygomatic bone erosion in a dog.

A novel case of a canine odontogenic parakeratinized cyst (COPC) that resulted in exophthalmos and palatine, maxillary, and zygomatic bone erosion in a 5-year-old Chihuahua dog is reported. Final diagnosis was aided by cross-sectional imaging (magnetic resonance imaging and computed tomography) and confirmed with histologic examination of the cyst wall.

Golden retriever cystic uveal disease: a longitudinal study of iridociliary cysts, pigmentary uveitis, and pigmentary/cystic glaucoma over a decade in western Canada.

OBJECTIVES: To determine the incidence of iridociliary cysts, pigmentary uveitis (PU)/pigmentary cystic glaucoma (PCG) in golden retriever dogs in western Canada, the progression of iridociliary cysts to PU/PCG, and a mode of inheritance for this disorder. ANIMAL STUDIED: A total of 830 golden retriever dogs from Alberta, Saskatchewan, and Manitoba from 2004 to 2014 were studied. PROCEDURE: Data were compiled from Canine Eye Registry Foundation (CERF) or Orthopedic Foundation for Animals (OFA) records (n = 630) and clinical consultations (n = 200) for a retrospective assessment of iridociliary cysts, PU, and PCG. RESULTS: Total incidence of iridociliary cysts and PU from CERF/OFA data were 4.8% (n = 30/630) and 5.9% (n = 37/630), respectively. Incidence of PU increased with ages >4 years (12.7%, n = 32/251). Dogs diagnosed with thin-walled, attached iridociliary cysts had a high risk of being diagnosed with PU or PCG upon re-examination (56.5%, n = 13/23). No dogs diagnosed with thick-walled, anterior chamber cysts (n = 7) developed PU or PCG within the time frame of the study. Data from clinical consultations confirmed that PU carried a poor prognosis for the affected eyes as 44.9% (n = 22/49) of dogs progressed to PCG. PU- and PCG-affected dogs followed a familial pattern and there was an association with thin-walled iridociliary cysts. Pedigree analysis suggested an autosomal dominant mode of inheritance with partial penetrance. CONCLUSIONS: Thin-walled iridociliary cysts are associated with PU and PCG. All breeding golden retriever dogs should be examined annually by an ophthalmologist. The incidence of this disorder is higher in western Canada than previous reports in North America.

Sfrp1a and Sfrp5 function as positive regulators of Wnt and BMP signaling during early retinal development.

Axial patterning of the developing eye is critically important for proper axonal pathfinding as well as for key morphogenetic events, such as closure of the optic fissure. The dorsal retina is initially specified by the actions of Bone Morphogenetic Protein (BMP) signaling, with such identity subsequently maintained by the Wnt-ß catenin pathway. Using zebrafish as a model system, we demonstrate that Secreted frizzled-related protein 1a (Sfrp1a) and Sfrp5 work cooperatively to pattern the retina along the dorso-ventral axis. Sfrp1a/5 depleted embryos display a reduction in dorsal marker gene expression that is consistent with defects in BMP- and Wnt-dependent dorsal retina identity. In accord with this finding, we observe a marked reduction in transgenic reporters of BMP and Wnt signaling within the dorsal retina of Sfrp1a/5 depleted embryos. In contrast to studies in which canonical Wnt signaling is blocked, we note an increase in BMP ligand expression in Sfrp1a/5 depleted embryos, a phenotype similar to that seen in embryos with inhibited BMP signaling. Overexpression of a low dose of sfrp5 mRNA causes an increase in dorsal retina marker gene expression. We propose a model in which Sfrp proteins function as facilitators of both BMP and Wnt signaling within the dorsal retina.

Hmx4 regulates Sonic hedgehog signaling through control of retinoic acid synthesis during forebrain patterning.

Mutations in H6-homeobox (HMX) genes are linked to neural mispatterning and neural tube closure defects in humans. We demonstrate that zebrafish Hmx4 regulates the signaling of two morphogens critical for neural development, retinoic acid (RA) and Sonic hedgehog (Shh). Hmx4-depleted embryos have a strongly narrowed eye field and reduced forebrain Shh target gene expression. hmx4 morphants fail to properly transcribe the Shh signal transducer gli3, and have reduced ventral forebrain specification. Hmx4-depleted embryos also have neural tube patterning defects that phenocopy RA-deficiency. We show that Hmx4 is required for the initiation and maintenance of aldh1a2, the principal RA-synthesizing gene. Loss of RA is the primary defect in Hmx4-depleted embryos, as RA treatment rescues a number of the neural patterning defects. Surprisingly, RA treatment also rescues forebrain morphology, gli3 transcription, and Shh signaling. We propose that Hmx4 is a critical regulator of retinoic acid synthesis in a developing embryo, and that this regulation is essential for controlling Shh signaling and forebrain development.