Intracorneal vacuoles in skin diseases with parakeratotic hyperkeratosis in the dog: a retrospective light‐microscopy study of 111 cases (1973–2000)

Abstract

Two recent case reports described a congenital keratinization defect (congenital follicular parakeratosis; CFP) in Rottweiler and Siberian Husky dogs. Skin biopsy specimens revealed marked parakeratosis targeting the hair follicle and numerous intracorneal vacuoles. A retrospective histopathological study was conducted on skin biopsy specimens from 111 dogs with diseases associated with parakeratotic hyperkeratosis to determine whether intracorneal vacuoles were present. Additional criteria evaluated were the size and location of the vacuoles and the degree of parakeratosis. Cases examined included dogs with primary idiopathic seborrhoea, necrolytic migratory erythema (NME), Malassezia dermatitis, zinc-responsive dermatosis, hereditary nasal hyperkeratosis of Labrador Retriever dogs, thallotoxicosis and CFP. Thirty-seven cases (37/111, 33%) had intracorneal vacuoles, including nine cases of primary idiopathic seborrhoea (9/29, 31%), 10 cases of NME (10/18, 56%), five cases of Malassezia dermatitis (5/19, 26%), five cases of zinc-responsive dermatosis (5/36, 14%), five cases of hereditary nasal hyperkeratosis (5/5, 100%) and three cases of CFP (3/3, 100%). If present, intracorneal vacuoles were found throughout all layers of the parakeratin. The sizes of intracorneal vacuoles varied among diseases, but large (> 5 microm) vacuoles only were present in CFP. Biopsies with a larger degree of parakeratosis were significantly more likely to have intracorneal vacuoles (P = < 0.001). Based on this study, intracorneal vacuoles are a common finding in many parakeratotic skin diseases of the dog, but large (> 5 microm) vacuoles are found only in CFP.

Hereditary nasal parakeratosis in Labrador Retrievers

“…The lipid nature of the vacuoles was determined in congenital follicular parakeratosis. However, the study by Senter et al 7 . did not determine whether the vacuoles found in other parakeratotic diseases also contained lipid.…”

“…Moreover, intracellular vacuoles were identified, which may represent lipids that were not secreted intercellularly, perhaps because of oedema or an abnormality in the cornification process. Recent studies report the presence of intracorneal vacuoles in canine skin diseases with parakeratotic hyperkeratosis 6,7 . The lipid nature of the vacuoles was determined in congenital follicular parakeratosis.…”

Effect of dietary supplementation with lysozyme on coat quality and composition, haematological parameters and faecal quality in dogs

“…Further analysis on amino acid coat content would be necessary to confirm this hypothesis and to determine the amino acid concentrations that would be at the origin of an improvement of coat quality in dogs following treatments based on lysozyme dietary supplementation. The typical symptom of zinc deficiency includes epidermis and follicles parakeratosis (Senter et al 2002), whilst copper deficiency leads to coat discolouration and thin coat (Zentek & Meyer 1991). Previous authors observed higher iron and copper concentration in the fur of mink treated with 5Á25 mg/ animal/day of lysozyme compared with the control group (Casciotti et al 1984).…”

Nasal hyperkeratosis in Griffon breeds: Clinical, histopathological features and the prevalence in the Swedish population compared to a control group and other brachycephalic breeds

“…In hereditary nasal parakeratosis of the Labrador Retriever, both larger and more frequent serum lakes are characteristically present compared to specimens from dogs with other hyperkeratotic or parakeratotic diseases. 13,14 The histopathological analysis is limited by the small sample, and the fact that two of the three dogs were old and euthanized due to other diseases. The concurrent disease and the old age may have affected the histopathology result.…”