This species has been reported to invade dermis and even venules, but none were identified outside of follicles in this specimen. The mites are thought to first occupy hair follicles with intact hairs and then move into sebaceous glands to feed and reproduce. Increasing numbers of mites cause distention of glands and follicles eventually causing hair loss. Hairs typically are in anagen at this stage. The exact cause of the hair loss is not known, and a mite induced retardation of hair growth has been proposed.
Inflammation is present in some areas but is typically weak even when the dermis is invaded.
The superficial inflammation in this case may be secondary to pruritus, excoriation, and bacteria. The cause of this animal's debilitation is not known, but the demodecosis is likely secondary. Thanks to Dr. C. W. Ridky of the Maine Department of Agriculture, Department of Inland Fisheries and Wildlife for submission of the case and Dr. Tom Gidlewski of the National Veterinary Services Laboratory, Department of Pathobiology, Ames, Iowa for the referral. The key features for identification of mites in tissue section are chitinous exoskeleton, jointed appendages, skeletal muscle, and a hemocoelom. Most animals are parasitized by a Demodex species.