adenitis in rabbits
Esther van Praag, Ph.D.
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The etiology of sebaceous adenitis – also
called inflammation of the sebaceous glands - is not well understood; it is
considered idiopathic, inherited or endocrine. In rabbits, the disorder
appears to have an inherited autoimmune origin, accompanied by a defect of
the fatty acids metabolism. An autoimmune origin also established in dogs,
after immunohistological analysis of skin samples, but also from the
successful treatment with cyclosporine, an immunosuppressant drug.
The first clinical manifestations of sebaceous adenitis resemble those
of skin allergy: inflamed sebaceous gland with progressive destruction of the
glands and the adjacent hair follicles, accompanied by inflammation of the
hair follicles (mural lymphocytic folliculitis). The condition worsens over
time. Hair growth stops, the fur is thinning, and alopecic patches appear.
The skin becomes erythematous, with abnormal thickening (hyperkeratosis).
Scales adhere tightly to the skin. Infiltration of lymphocytes into the basal
layer of the epidermis (interface dermatitis) is furthermore observed in
rabbits. This causes changes in the basal cells of that layer, necrosis of
keratinocytes and occasionally inflammation of the follicular-dermal
interface (interface folliculitis).
in rabbits can occur in patches or be progressive, starting with non-pruritic
scaling on the head. It later spreads to the neck, the pelvic region, and the
rest of the body. Lesions are often symmetrical over the head and abdomen.
Three forms of sebaceous adenitis have been identified in rabbits:
Type 1: Few
patches of scaly skin in a region of the body:
rabbit suffering from a few local patches of scaly skin in the pelvic region.
A biopsy confirmedsebaceous adenitis.
Generalized loss of fur over all the body and extensive scaling of the
alopecic regions. This type is often associated to thymoma,
a tumor originating from the epithelial cells of
Jenny with confirmed sebaceous adenitis all over
Type 3: In rabbits belonging to the rex breed, more rarely in other rabbits,
a smooth type of sebaceus adenitis is observed, The skin becomes alopecic, with minimal or no scaling of
the skin, and without development of crusts.
Pashosh, an 11.5 year
old Mini-Rex rabbit with suspected smooth sebaceous adenitis at the base of the ear region. A biopsy has not been taken due to her age, but bacterial and fungal (yeast)
dermatitis as well as the presence of skin parasites have all been ruled out.
Inflammation of the sebaceous glands is often mistakenly diagnosed as
skin allergy. As a result, it is treated inappropriately. Skin problems such
as fungal dermatitis, parasitic infestation or defluxion will often be
considered, when the proposed skin allergy treatment fails to bring an
improvement. This skin condition should furthermore be differentiated from thymoma-associated exfoliative dermatitis, cutaneous lymphoma, or
dermatitis caused by autoimmune hepatitis.
To avoid unnecessary distress of the rabbit, it is, therefore, important to do a biopsy of the skin. Microscopic analysis with the skin sample will confirm the presence of orthokeratotic hyperkeratosis, a rare intact sebaceous glands, destructed or absent sebaceous glands and mural lymphocytic folliculitis. Radiography of the chest will rule out thymoma.
There is no treatment for sebaceous gland inflammation, except good
care. In dogs, this problem is treated by cleaning the skin with a detergent
soap twice a week/month, clean its skin, followed by
an application of a chlorhexiderm solution, and baby oil. This helps loosen
the skin dandruff and provides the necessary fat to the skin.
A regular brushing also helps to remove the dandruff, which is a
source of secondary bacterial infection.
an antifungal, corticosteroid or an immunosuppressant drug did not bring
improvement. The administration of fatty acids, vitamin A or retinoids (e.g.
isotretinoin, etretinate) can be attempted, but the toxicity of these
compounds must be taken into account.
The combined administration of cyclosporine (5 mg/kg, PO, sid), medium chain triglycerides and essential fatty acids, accompanied by topical application of propylene glycol (spray) was successful in the treatment of sebaceous adenitis in a rabbit. Two months later, remission was observed, with new hair growth.
Since cyclosporine is an xpensive drug, mycophenolate has been successfully administred to affected rabbits in order to reduce the inflammatory reaction. After a loadind dosis of 42mg/kg twice a day PO, it was continued at a dosis of 10mg/kg BID, accompanied by the use of skin moisterers to remove the crusts and soften the skin.
Further options include the administration of omega-3 fatty acid supplements. Since
this treatment is costly, euthanasia should be considered as a humane
alternative, so as not to
the rabbit's pain and suffering.
If secondary bacterial infections develop, it
should be treated with antibiotics and/or an antibiotic cream (e.g. Fucidic
For detailed information on
sebaceous adenitis in rabbits,
see: “Skin Diseases of Rabbits”, by E. van Praag, A.
Maurer and T. Saarony
408 pages, 2010.
special thanks to Sarah Davoli, Lyne Lavigneur, Nancy LaRoche, Nancy Martin
and Debbie Hanson for sharing the pictures of their rabbits Coco, Lulu,
Jenny, and Bella, suffering from sebaceous adenitis.
1. Florizoone K. Thymoma-associated
exfoliative dermatitis in a rabbit. Vet Dermatol