Nocardiosis is not an uncommon bacterial disease in cats, caused by a genus of weakly-staining Gram-positive, catalase-positive, rod-shaped bacteria found worldwide in soil that is rich with organic matter. Most Nocardia infections are acquired by inhalation of the bacteria or through traumatic introduction. Although serological tests can be run to determine strain identities, the generic name is usually used alone.
Colonies form grains within pyogranulomatous reactions.
In dermatological cases, signs may occur on the face, abdomen and limbs. They are characterised by ulcerated lesions, draining tracts and pus containing white and yellow granules. Systemic signs usually accompany dermatological lesions, including pyrexia, regional lymphadenopathy and dyspnoea if pyothorax is present.
Pathogenesis of the organism is assumed to be through lung infection with microabscess formation and hematogenous spread from the lungs to other organ systems. Unfection may also occur via a scratch or bite. In immunosuppressed cats, infection seems to spread via the respiratory system. Vertebral osteomyelitis has been reported as well as lesions of the hock. Lesions are usually those of skin chest or bone infections; suppurative abscesses, effusive pleurisy and chronic suppurative osteomyelitis.
The radiographic picture is similar to that of other forms of chronic suppurative osteomyelitis. Two patterns of disease are noted with nocardia: introduction of the organism from the soil into tissue by local invasion may result in a large tumorlike mass on the extremities characterized by many numerous sinuses. The pulmonary form or gastrointestinal forms are caused by ingestion or inhalation of the organism and are the forms seen most commonly.
Diagnosis is made by culture or blood agar plates and direct Gram stain of pus from an abscess or draining sinus.
Successful treatment of the disease has been reported with large doses of penicillin and streptomycin. Sulfadiazine is also used in the treatment over a prolonged 6- to 12-week period. Surgery may be indicated to remove large masses associated with the disease. According to the literature, recovery may be anticipated but prognosis remains guarded.
- ↑ Guaguere, E, Hubert, B & Delabre, C (1980) Vet Dermatol 3:1-12
- ↑ Scott, DW J Amer Anim Hosp Assn 16:331-459
- ↑ Guaguere, E & Prelaud, P (2005) A practical guide to feline dermatology. Merial, France
- ↑ Penn Uni