THE term cellulitis, rather than pyoderma, is preferred in this condition as it is sterile and does not respond to antibacterial treatment alone.
Some have classified the disease as a “pseudopyoderma”. The cause is unknown but dysfunction of the immune system is suspected.
Clinical features
Dachshunds, Golden retrievers, Labrador retrievers, Gordon setters, Pointers and Beagles may be predisposed but the disease can occur in any breed including cross breeds.
The onset is sudden, usually affecting puppies between three weeks and four months of age and may affect one or several puppies in the litter. There is an acute swelling of the face, affecting the muzzle, lips and eyelids.
A frequent feature is a marked submandibular lymphadenopathy (giving rise to the term puppy strangles). Within 48 hours vesicular, pustular, crusting and serous lesions appear with extensive exudation (Figures 1 and 2).
Lesions typically form fistulae that drain. The lesions are generally oedematous and other areas involved include the pinnae, with the development of otitis externa, and occasionally the prepuce and anus. The lesions are painful but not pruritic.
Severely affected puppies, such as the one depicted in Figures 1 and 2 may be depressed and anorectic. Less severe cases appear well apart from the skin lesions.
Diagnosis
The differential diagnosis includes:
- Chin pyoderma
- Demodicosis
- Dermatophytosis
- Angioedema
- Adverse cutaneous drug reaction
- Canine distemper
The history and clinical findings, particularly the sub-mandibular lymphadenopathy, are suggestive. Diagnostic tests that are helpful are:
- Cytology of exudate. This will reveal a purulent to pyogranulomatous inflammation. Secondary infection may be seen.
- Cytology of lymph node aspirate. Similar findings to cytology of exudate but no infectious agents are seen.
- Histopathological examination demonstrates pyogranulomatous dermatitis and panniculitis in the absence of infectious agents.
- Bacterial culture is sterile unless there is secondary bacterial infection. Little or no improvement is seen with systemic antibacterial therapy alone.
Clinical management
- Glucocorticoids at high doses are the cornerstone of therapy. Most cases respond to prednisolone given at a dose of 2mg/kg once daily. This dose is continued until resolution of lesions (usually between 2 and 4 weeks). The same dose is then given on an alternate day dose for a few weeks before tapering over a further few weeks. Figure 3 is the same dog seen in Figures 1 and 2 after four weeks of treatment. Treatment should not be stopped too soon as it risks a relapse.
- Occasional cases seem to do better with oral dexamethasone at a dose of 0.2mg/kg once daily.
- Secondary infections are treated with systemic antibiotics such as cephalexin or clavulanate potentiated amoxicillin.
- Cyclosporine (5-10mg/kg) may be beneficial, although this is rarely necessary.
Suggested reading
Hnilica, K. A. (2011) Small Animal Dermatology. In: A Color Atlas and Therapeutic Guide (3rd edition): pp345- 347. Elsevier.
Miller, W. H., Griffin, C. A. and Campbell, K. L. (2013) In: Muller and Kirk’s Small Animal Dermatology (7th edition): pp708-709. Elsevier.
