Regarding ocular surface mucins, which statement is accurate about dogs compared with humans?

• A. Mucins in dogs are less similar to humans than in rabbits.
• B. Mucins in dogs are more similar to humans than in other species.
• C. Mucins are identical across species.
• D. Mucins are not present in dogs.

Answer: (B)

The key idea is that ocular surface mucins show species-specific patterns, and dogs share a closer resemblance to humans in this system than many other animals. Humans rely on secreted mucins like MUC5AC from goblet cells and membrane-tethered mucins such as MUC1, MUC4, and MUC16 to form a protective, lubricating tear film. Dogs have a similar mucin setup and goblet cell–driven mucin production, providing comparable functional roles in tear film stability and ocular surface protection. Because of this shared mucin gene repertoire and expression pattern, dogs are relatively more similar to humans for ocular surface mucin biology than some other species, which is why this statement is accurate. Mucins are present in dogs, and mucins are not identical across species, so the other options don’t fit.