Toe beans losing their color

October 11, 2022 9:48 PM

My cat Franklin is 12 years old this month. I noticed yesterday his all black solid black toe pads are losing color and there is a lot of pink. I went back thru old pics and his beans were still solid black as of late August.

He is taking Palladia currently for a cancer on his face and tail and maybe in his lungs. Im wondering if this is an “old cat” thing or a “cancer cat” thing and how worried I should be if at all. I will ask the onco vet when we go up in a couple weeks unless it seems urgent. I email her almost weekly about the growth on his face and don’t want to waste goodwill on something that’s nothing. He does not appear to be in pain from his paws or cancer.

cat tax

posted by misanthropicsarah to Pets & Animals (3 answers total)

Best answer: Definitely the Palladia.

Palladia is a receptor tyrosine kinase inhibitor, which means it blocks certain pathways by which cells use the amino acid tyrosine to synthesize other important compounds.

One of which happens to be melanin:

Melanins are natural pigments of skin, hair and eyes and can be classified into two main types: brown to black eumelanin and yellow to reddish-brown pheomelanin. Biosynthesis of melanins takes place in melanosomes, which are specialized cytoplasmic organelles of melanocytes - dendritic cells located in the basal layer of the epidermis, uveal tract of the eye, hair follicles, as well as in the inner ear, central nervous system and heart. Melanogenesis is a multistep process and begins with the conversion of amino acid L-tyrosine to DOPAquinone.

posted by jamjam at 10:40 PM on October 11, 2022 [7 favorites]

Wow, handsome. Tell Franklin I love him!
posted by kapers at 10:46 PM on October 11, 2022 [10 favorites]

Response by poster: the oncology vet confirmed yesterday it was definitely the palladia and that it's a rare side effect.
posted by misanthropicsarah at 7:13 AM on October 27, 2022