This study documents the presence of comedones and
follicular cysts of palmar and plantar interdigital skin as an underlying cause of recurrent
dermatitis, and describes the use of a
carbon dioxide laser to surgically remove lesions. The 28 dogs included in the study had: (i) recurrent lameness,
pain, and nodules, or draining sinuses in the dorsal interdigital skin, (ii) failed to respond to
antibiotic therapy, and (iii) were negative for Demodex mites and dermatophytes. All 28 had
laser surgery; nine dogs had two
surgical procedures and two dogs had three
surgical procedures for lesion recurrence. Fifteen dogs had skin samples collected for histopathology. Clinical features in ventral interdigital skin included
alopecia, callus-like thickening, and comedones. Histological features included hyperkeratosis, acanthosis, comedones and
follicular cysts,
furunculosis, draining sinuses, and
scarring. Surface
trauma to the ventral interdigital skin appeared to contribute to lesion development.
Laser surgery allowed removal of multiple layers of
cysts and adjacent hair follicles and the tracking and removal of sinuses. One dog was euthanized for orthopaedic lameness 1 month after
laser surgery, but post-surgical follow-up (1.0-8.0 years - mean 3 years) from the remaining 27 dogs revealed that
laser therapy of affected skin and adjacent hair follicles resulted in resolution of interdigital lesions in 25. Two dogs continued to develop interdigital
cysts.