Page 415 - Problem-Based Feline Medicine

20 – THE CAT WITH ENLARGED LYMPH NODES 407

Clinical signs be subclinical or cause chronic weight loss, vomit-
ing, diarrhea and mesenteric lymphadenopathy.
Signs of aseptic or septic inflammation are present at
● The infection occasionally disseminates to virtu-
the foreign body site (cutaneous, subcutaneous or
ally all organs with corresponding systemic and
deeper) and local lymphadenopathy may or may not be
local signs.
present.
● Peripheral lymphadenopathy occurs with dis-
seminated disease.
Diagnosis
Leprosy is caused by M. lepraemurium and is charac-
Exploration of area reveals foreign body. terized by chronic single to multiple, freely moveable,
non-painful intact or ulcerated and abscessed fleshy
Lymph node biopsy reveals hyperplasia or uncom-
cutaneous nodules, with or without subcutaneous
monly lymphadenitis.
lesions. Systemic signs are rare.
● Painless regional lymphadenopathy is typical.
Differential diagnoses
Atypical mycobacteriosis is caused by several non-
Bite wound cellulitis, chronic bacterial and fungal infec- tubercular, non-lepromatous Mycobacterium sp., and is
tions, neoplasia and eosinophilic granuloma complex. usually characterized by chronic, local or regional
subcutaneous lesions with multiple draining tracts.
Differentiation is based on cytology, histology and culture.
Lesions are most often found on the caudal abdomen,
inguinal region or lumbar region, but also on the thorax.
Treatment Systemic signs are uncommon but may occur.
● Disseminated infection (systemic non-tuberculous
See The Cat With Skin Lumps and Bumps (page 1074).
mycobacteriosis), which is clinically similar to
tuberculosis, is most likely with organisms from
MYCOBACTERIAL INFECTIONS* the M. avium complex,
● Local, regional or generalized lymphadenopathy
Classical signs may occur.
● Chronic vomiting, diarrhea, mesenteric
lymphadenopathy (tuberculosis). Diagnosis
● Multiple chronic ulcerated fleshy
cutaneous nodules on head and limbs Cytology and histology of affected tissues reveal
(leprosy) and regional lymphadenopathy. granulomatous to pyogranulomatous inflammation.
● Chronic ulcerated subcutaneous lesions on
Lymph node biopsy reveals hyperplasia (all clinical
caudal abdomen, inguinal and groin
forms) or granulomatous lymphadenitis (tuberculosis,
regions (atypical mycobacteriosis) ± local
systemic non-tuberculous mycobacteriosis).
or regional lymphadenopathy.
Acid-fast bacteria are usually detectable in affected
See main reference, page 1085 (The Cat With Non- tissues with tuberculosis and leprosy, but may be diffi-
Healing Wounds). cult to find with atypical mycobacteriosis.
Culture is possible at selected laboratories, and
Clinical signs particularly useful for identifying fast-growing
mycobacteria, the most common causes of atypical
There are three categories of Mycobacterium sp. infec-
mycobacteriosis.
tion in cats: tuberculosis, leprosy and atypical.
Tuberculin testing is not reliable in cats.
Tuberculosis is caused by M. tuberculosis, M. bovis,
M. tuberculosis-bovis variant, and M. microti. It may Immunoassays may be available for some organisms.