Sebaceous adenitis in rabbits
Esther van
Praag, Ph.D.
Warning: this file contains pictures that may be distressing to
some persons
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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. Clinical
characteristics 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). Sebaceous adenitis in rabbits
can occur in patches or be progressive, 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.
Sarah Davoli Coco, older rabbit
suffering from confirmed patchy sebaceous adenitis in the pelvic region. Diagnosis 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 important to do a biopsy of the skin, and have it
analyzed by a pathologist with knowledge of rabbit tissue specificities.
Radiography of the chest helps rule out thymoma. Treatment 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. Treatments
with 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 this treatment is costly, euthanasia should be considered
as a humane alternative, so as not to unnecessarily prolong the
rabbit's pain and suffering.
If secondary bacterial
infections develop, it should be treated with appropriate antibiotics and/or an
antiseptic cream.
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.
Acknowledgements A 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. Further reading 1.
Florizoone
K. Thymoma-associated exfoliative dermatitis in a rabbit. Vet
Dermatol 2005;16:281-284. 2. Jassies -
Van der Lee A, van Zeeland Y, Kik M, Schoemaker N. Successful treatment of sebaceous adenitis in a rabbit
with ciclosporin and triglycerides. Vet Dermatol 2009;20:67-71. 3. Quesenberry KE,
Carpenter JW. Ferrets, rabbits and rodents. Clinical Medicine and Surgery. St
Louis, USA: Saunders; 2004. 4. White SD, Linder KE, Schultheiss P, Scott KV, Page G, Taylor M, Best SJ, Walder EJ, Rosenkrantz W, Yager JA. Sebaceous adenitis in four domestic rabbits (Oryctalagus cuniculus).
Vet Dermatol 2000;11:53-60. |
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