536 DISEASES/DISORDERS
SIGNALMENT/HISTORY
Dogs and cats of any breed.
Lesions may initially develop in the area of previous injury.
Geographic distribution is worldwide.
CLINICAL FEATURES
Nocardiosis:
Cutaneous/subcutaneous: cellulitis, ulcerated nodules, abscesses that develop
draining sinuses; chronic, nonhealing wounds; often accompanied by fistulous
tracts; if extended, may result in lymphadenopathy, draining lymph nodes, pan-
niculitis, and osteomyelitis (Figures 36.1–36.3)
Pulmonary: pyothorax resulting in dyspnea, anorexia and emaciation, fever
Systemic/disseminated: most common in young dogs; usually begins in the res-piratory tract; lethargy, fever, and weight loss; cyclic fever may be characteristic;
CNS may be affected; pleural and/or abdominal effusion may occur. Actinomycosis:
Subcutaneous swelling or abscess on the head, neck, thorax, or flank
May have draining tracts or remain closed (Figure 36.4)
May discharge a malodorous exudate with or without sulfur granules.
DIFFERENTIAL DIAGNOSIS
Nocardiosis:
Cutaneous/subcutaneous:
Actinomycosis
Atypical mycobacteriosis
Leprosy
Bite wound abscesses
Draining tracts resulting from foreign bodies
Pulmonary:
Thoracic neoplasia
Bacterial pyothorax
Chronic diaphragmatic hernia
Systemic/disseminated:Feline infectious peritonitis
Systemic fungal infections. Actinomycosis:
Nocardiosis
Atypical mycobacteriosis
Leprosy