What are these discolorations inside my cat’s mouth?

Question

My 1-year-old male Sphynx cat has what look like symmetrical grey ulcerations on his bottom gums, just behind where his upper canines align with his lower jaw. Is his orthodontia damaging the tissue of his gums? He eats and drinks normally and seems to be generally happy and healthy.

We also own his younger sister (same parents, different litter), who is ~4 months old. She has similar protrusions in her lower gumline that are a lighter color, which makes me alternatively wonder if these are normal-looking submandibular glands in the Sphynx breed that naturally darken over time.

Answer 1

After too much nervous pet-WebMD-ing, I turned on my research brain and tried to find evidence for my more rational explanation (that my cat’s oral mucosa is just naturally pigmented, since his sister has similar anatomical morphology in that region without the hyperpigmentation).

From Atlas of Feline Anatomy for Veterinarians, Hudson & Hamilton:

Until his next annual appointment at the vet, I’ll stick with Occam’s razor and assume that he’s just naturally pigmented in his oral mucosa and the alignment of his canines isn’t damaging the tissue of his gums.