What about this?

code/modules/mob/living/carbon/human/species_types/lizardpeople.dm

@@ -226,6 +226,8 @@ Lizard subspecies: SILVER SCALED
 	examine_limb_id = SPECIES_LIZARD
 	///stored mutcolor for when we turn back off of a silverscale.
 	var/old_mutcolor
+	///stored horn color for when we turn back off of a silverscale.
+	var/old_horncolor
 	///stored eye color for when we turn back off of a silverscale.
 	var/old_eye_color_left
 	///See above
@@ -238,16 +240,19 @@ Lizard subspecies: SILVER SCALED
 
 /datum/species/lizard/silverscale/on_species_gain(mob/living/carbon/human/new_silverscale, datum/species/old_species, pref_load)
 	old_mutcolor = new_silverscale.dna.features["mcolor"]
+	old_horncolor = new_silverscale.dna.features["lizard_horn_color"]
 	old_eye_color_left = new_silverscale.eye_color_left
 	old_eye_color_right = new_silverscale.eye_color_right
 	new_silverscale.dna.features["mcolor"] = "#eeeeee"
+	new_silverscale.dna.features["lizard_horn_color"] = "#eeeeee"
 	new_silverscale.eye_color_left = "#0000a0"
 	new_silverscale.eye_color_right = "#0000a0"
 	. = ..()
 	new_silverscale.add_filter("silver_glint", 2, list("type" = "outline", "color" = "#ffffff63", "size" = 2))
 
 /datum/species/lizard/silverscale/on_species_loss(mob/living/carbon/human/was_silverscale, datum/species/new_species, pref_load)
 	was_silverscale.dna.features["mcolor"] = old_mutcolor
+	was_silverscale.dna.features["lizard_horn_color"] = old_horncolor
 	was_silverscale.eye_color_left = old_eye_color_left
 	was_silverscale.eye_color_right = old_eye_color_right
 	was_silverscale.remove_filter("silver_glint")