Small Animal Dermatology, 3rd edition

CHAPTER 34 MYCOBACTERIAL INFECTIONS 513

Syndrome 2: initial localized or generalized skin nodules that do not ulcerate,

slowly progressive over months to years

Feline multisystemic granulomatous mycobacteriosis: diffuse cutaneous thick-

ening and multiple organ system involvement; caused byM. visibile

Syndromes may overlap in cats of all ages.

 Canine leproid granuloma:
One or more well-circumscribed painless nodules (2 mm–5 cm) in dermis or

subcutis; often on head or pinnae (especially dorsal fold), but may be anywhere

on the body; only very large lesions ulcerate (Figures 34.1–34.4)

Lack of systemic illness.

 Systemic nontuberculous mycobacteriosis:
Pulmonary and systemic infections reported rarely in dogs; may appear similar

to tuberculosis

Mycobacterial panniculitis: cutaneous: traumatic lesion that fails to heal with

appropriate therapy; most often ventral abdominal and inguinal regions; spreads

locally in the subcutaneous tissue (panniculitis); original lesion enlarges, form-

ing a deep ulcer or fistula that drains greasy hemorrhagic exudate; surrounding

tissue becomes firm; may form irregular ribbons or coalescing plaques; satellite

pinpoint ulcerations open and drain (Figures 34.5–34.7)

Wound dehiscence at surgery sites

Lack of systemic illness when localized; pyrexia and anorexia when disseminated

(immunodeficient host).

DIFFERENTIAL DIAGNOSIS

 Mycobacterial infections have different prognoses, treatment recommendations, and

public health consequences but may initially have similar signs, especially cutaneous

lesions.

 Focal or disseminated fungal infections (including dermatophytosis).

 Actinomycosis.

 Actinobacillosis.

 Nocardiosis (can be clinically identical to mycobacterial panniculitis).

 Bacterial pseudomycetoma.

 Leishmaniosis.

 Sterile pyogranulomatous dermatitis.

 Cryptococcosis.

 Neoplasia.

DIAGNOSTICS

Intradermal Skin Testing

 Tuberculosis (dogs only): intradermal skin testing with PPD or BCG on inner pinna.

 Test read at 48–72 hours post injection.