A challenging case: A febrile dog with a swollen tarsus and multiple skin lesions - Veterinary Medicine
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A challenging case: A febrile dog with a swollen tarsus and multiple skin lesions
The condition that these clinicians suspect in this Labrador is considered a late-onset manifestation, even though the dog is only 9 months old.


VETERINARY MEDICINE


Diagnosing juvenile cellulitis relies on support from the history, clinical findings, and results of cytologic examination, culture, and, most importantly, histologic examination. Cytologic examination of pustular lesions reveals pyogranulomatous inflammation with no infectious agents.1,3,6 The results of cultures of the pustules are expected to be negative. Skin biopsy samples demonstrate granulomatous to pyogranulomatous inflammation consisting of clusters of large epithelioid macrophages and neutrophils. As the inflammation progresses, adnexal glands (e.g. sebaceous and sweat glands) may be effaced, and suppurative changes in the superficial dermis with folliculitis and furunculosis may develop (as seen in this case). Focal to coalescing suppurative inflammation may also develop in the subcutis, resulting in panniculitis.1,6

The underlying cause and pathogenesis of juvenile cellulitis is unknown. Heritability is thought to play a role because of the predisposition of certain breeds and the familial association of the disease.1 Proposed causes include infectious, immunologic, and hypersensitivity reactions. In addition, trauma, endoparasitism, diet, and environmental triggers have all been proposed as possible causes, but no evidence is available to support these theories.4 Detection of infectious agents with special staining techniques, culturing, electron microscopic examination, and other diagnostic tools has not been successful. The inoculation of lymph node tissue from affected dogs into newborn puppies has failed to transmit the disease.6 Because of this lack of transmission and the typical dramatic response to immunosuppressive doses of glucocorticoids, it is unlikely an unidentified infectious agent is responsible.

An immune system deficiency has also been proposed, but several studies that attempted to investigate this by immunoglobulin concentration quantification, serum electrophoresis, and other methods failed to demonstrate any such deficiency.6,7 Although it has also been proposed that juvenile cellulitis may represent a hypersensitivity, such as an autoimmune or an allergic skin disease, juvenile cellulitis does not require long-term immunosuppression with glucocorticoid therapy or allergen elimination, respectively.4 Treating juvenile cellulitis requires early and aggressive immunosuppression with glucocorticoids until the disease is no longer active and then gradually tapering the medication. Typically, prednisone or prednisolone (2 mg/kg orally once a day) is administered for 14 to 21 days. Patients that have truncal panniculitis may require a longer course to resolve all lesions. As with other immune-mediated diseases, some dogs respond better to an alternative glucocorticoid, such as dexamethasone (0.2 mg/kg orally once a day). Concurrently administering a bactericidal antibiotic (e.g. cephalexin, amoxicillin trihydrate-clavulanate potassium) is indicated if there is cytologic or clinical evidence of secondary bacterial infection. Relapses are extremely rare.1

The dog in this case closely followed the typical clinical course expected with a case of juvenile cellulitis, but the case emphasizes that severe systemic involvement can occur and that juvenile cellulitis should be a differential diagnosis in dogs presenting with pustular dermatitis and lymphadenopathy, even in those older than 12 weeks of age.

Elisabeth C. Snead, DVM*
Carrie Lavers, DVM**
Department of Small Animal Internal Medicine
Atlantic Veterinary College
University of Prince Edward Island
Charlottetown, PEI C1A 4P3

Paul Hanna, DVM, MSc, DACVP
Department of Pathology and Microbiology
Atlantic Veterinary College
University of Prince Edward Island
Charlottetown, PEI C1A 4P3

Current addresses:
*Department of Small Animal Clinical Sciences
Western College of Veterinary Medicine
University of Saskatchewan
Saskatoon, SK S7N 5B4

**Animal Health Center
Box 1650
Swift Current, SK S9H 4G6

REFERENCES

1. Scott, D.W. et al.: Miscellaneous skin diseases. Muller & Kirk's Small Animal Dermatology, 6th Ed. W.B. Saunders, Philadelphia, Pa., 2001; pp 1163-1167.

2. Mason, I.S.; Jones, J.: Juvenile cellulitis in Gordon setters. Vet. Rec. 124 (24):642; 1989.

3. White, S.D. et al.: Juvenile cellulitis in dogs: 15 cases (1979-1988). JAVMA 195 (11):1609-1611; 1989.

4. Jeffers, J.G. et al.: A dermatosis resembling juvenile cellulitis in an adult dog. JAAHA 31 (3):204-208; 1995.

5. Malik, R. et al.: Concurrent juvenile cellulitis and metaphyseal osteopathy: An atypical canine distemper virus syndrome? Aust. Vet. Pract. 25:62-67; 1995.

6. Reimann, K.A. et al.: Clinicopathologic characterization of canine juvenile cellulitis. Vet. Pathol. 26 (6):499-504; 1989.

7. Barta, O.; Oyekan, P.P.: Lymphocyte transformation test in veterinary clinical immunology. Comp. Immunol. Microbiol. Infect. Dis. 4 (2):209-221; 1981.


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