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Small Animal Section: No. 8
CANINE LEPROID GRANULOMA SYNDROME
Definition
A poorly characterized mycobacterial syndrome
of dogs in which nodular mycobacterial granulomas are present in the dermis
and subcutis, mainly on the head and ears.
The causative
mycobacterial organism is demonstrated with histopathology and special staining
(Ziehl Neelson, acid-fast), but has not yet been cultured or further identified.
Clinical signs
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Single or multiple firm, painless nodules
that may ulcerate |
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Mostly on the head and dorsal surface of
the pinnae; less commonly on the distal limbs and trunk |
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Affected dogs are not systemically ill, and
internal organ or lymph node involvement not present |
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In the only retrospective study published
to date (Malik), over 90% of the dogs were short-coated breeds |
Diagnosis
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Histopathology: granulomatous or pyogranulomatous
dermatitis and/or pannicultitis with few to very acid-fast bacteria
in sections stained with Ziehl-Neelson. In one of our cases, a single macrophage
containing three rods was demonstrated after a long and thorough search
of the tissue sections |
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Fine needle aspirates: organisms are infrequently
identified |
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Culture was negative in all cases (Malik).
Possible cause: a number of related saprophytic mycobacteria with the capacity
to undergo limited proliferation in tissue following inoculation (by biting
flies or skin wounds?) |
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Unlikely that these mycobacteria pose any
public health risk |
Treatment
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Surgical excision |
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Spontaneous
remission after up to six months has been reported, with or without prior
surgical removal |
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Favorable response with doxycycline (57%)
or amoxicillin-clavulanate (63%) was reported (Malik). Suggested treatment
regimens: doxycyline, 5-10 mg/kg, 12-24 hours interval, for 4 weeks;
amoxicillin-clavulanate, 20 mg/kg twice daily for 4 weeks; enrofloxacin,
5-10 mg/kg twice daily for 4 weeks |
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Oral rifampicin
(5-15mg/kg/day) and clarithromycin (7-12mg/kg bid) combination for 1-3 months
may be used in severe or refractory cases |
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A topical
formulation containing clofazimine in petroleum jelly may be used as an adjunct
to systemic drug therapy |
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Despite treatment, chronic lesions may develop |
Differential diagnoses for leproid granuloma
syndrome
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Sterile idiopathic granuloma/pyogranuloma
syndrome (often dramatic response to glucocoticoids) |
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Nodular dermatophytic furunculosis |
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Pyoderma |
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Neoplasia: histiocytoma, basal cell tumour,
and mast cell tumour |
Other mycobacterial skin diseases in the
dog
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Atypical mycobacteriosis: rare; usually recurrent
abscesses, draining tracts, and nodules that ulcerate |
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Cutaneous tuberculosis: tracts, nodules, plaques,
abscesses, or ulcers: dogs are usually systemically ill |
References
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Lemarie SL (1999) Mycobacterial dermatitis;
Vet Clin North Am: Small Anim Prac 29:1291-1301 |
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Foley JE et
al (2002). Clinical, microscopic and molecular aspects of canine leproid
granuloma in the United States. Vet Pathol 39:234-239 |
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Malik R et al (1998). Mycobacterial
nodular granulomas affecting the subcutis and skin of dogs (canine leproid
granuloma syndrome). Aust Vet J 76:403-407 |
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Malik R et
al (2001). Treatment of canine leproid granuloma syndrome: preliminary
findings in seven dogs. Aust Vet J 79:30-36 |
For further information contact:
VetPath Veterinary Pathologists
P.O. Box 8464
Pretoria 0001
Tel: (012) 529
8345/6
e-mail:
info@vetpath.co.za |
Prof Andy Leisewitz
Department of Companion Animal Medicine
Faculty of Veterinary Science
Private Bag X 04, Onderstepoort 0110
Tel: (012) 529 8278 |
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