Editing Tapetum lucidum (section)

=== Dogs ===
In canids, the tapetum lucidum is found in the dorsal half of the eye's fundus. It consists of 9-20 layers of specialized rectangular cells between the choroid and retinal pigment epithelium, thinning towards the periphery. The cells contain zinc-rich rodlets arranged in parallel. The structure appears yellow-green in adults, though blue in puppies until four months of age. Zinc concentration varies among species, with red foxes showing highest levels, followed by Arctic foxes, then domestic dogs. A hereditary zinc-deficiency condition in some beagles results in degenerated tapetal cells with disrupted rodlet arrangement.<ref name="a165">{{cite book |last1=Mowat |first1=Freya M. |title=Wild and Exotic Animal Ophthalmology |last2=Peichl |first2=Leo |publisher=Springer International Publishing |year=2022 |isbn=978-3-030-81272-0 |pages=181–214 |chapter=Ophthalmology of Canidae: Foxes, Wolves, and Relatives |doi=10.1007/978-3-030-81273-7_11}}</ref>