*Review* **Large Animal Models of Inherited Retinal Degenerations: A Review**

### **Paige A. Winkler, Laurence M. Occelli and Simon M. Petersen-Jones \***

Department of Small Animal Clinical Sciences, Veterinary Medical Center, Michigan State University, East Lansing, MI 48824, USA; winkle38@msu.edu (P.A.W.); occelli@msu.edu (L.M.O.)

**\*** Correspondence: peter315@msu.edu; Tel.: +1-517-353-3278

Received: 1 March 2020; Accepted: 31 March 2020; Published: 3 April 2020

**Abstract:** Studies utilizing large animal models of inherited retinal degeneration (IRD) have proven important in not only the development of translational therapeutic approaches, but also in improving our understanding of disease mechanisms. The dog is the predominant species utilized because spontaneous IRD is common in the canine pet population. Cats are also a source of spontaneous IRDs. Other large animal models with spontaneous IRDs include sheep, horses and non-human primates (NHP). The pig has also proven valuable due to the ease in which transgenic animals can be generated and work is ongoing to produce engineered models of other large animal species including NHP. These large animal models offer important advantages over the widely used laboratory rodent models. The globe size and dimensions more closely parallel those of humans and, most importantly, they have a retinal region of high cone density and denser photoreceptor packing for high acuity vision. Laboratory rodents lack such a retinal region and, as macular disease is a critical cause for vision loss in humans, having a comparable retinal region in model species is particularly important. This review will discuss several large animal models which have been used to study disease mechanisms relevant for the equivalent human IRD.

**Keywords:** large animal model; inherited retinal disease; progressive retinal atrophy; retinitis pigmentosa; Leber congenital amaurosis; achromatopsia; congenital stationary night blindness
