Page 1044 - Clinical Small Animal Internal Medicine

982 Section 9 Infectious Disease

History and Clinical Signs
VetBooks.ir Cutaneous lesions in mycobacteriosis vary. Leproid

granulomas can be single or multiple nodules with or
without ulceration and frequently occur on the head and
limbs. The most common manifestation of tuberculosis
and saprophytic mycobacterial infections in cats is the
cutaneous form that results in the development of sub-
cutaneous masses, often with draining sinuses and a
regional lymphadenopathy. Skin lesions are usually
mobile, firm, raised, moist, and without odor. The sapro-
phytic mycobacterial agents have a predilection for
adipose tissue and often cause a panniculitis of the ven-
tral abdomen and inguinal area in cats (Figure 108.1).
Ocular lesions are frequently reported in cats with the Figure 108.2 Acid‐fast bacilli in a sample from a cat with feline
leproid syndrome. Pulmonary, gastrointestinal or leprosy.
disseminated granulomatous lesions can result from
infection with tuberculous and saprophytic group organ- Suspicion of mycobacteriosis should be raised in
isms. Abdominal and pleural effusions often develop animals with consistent presenting signs whenever pyo-
with progressive disease.
granulomatous inflammation is identified on cytologic or
histopathologic examination. Provisional diagnosis is
based on the identification of acid‐fast bacilli within tis-
Diagnosis sue samples, exudates or blood smears (Figure 108.2).

Clinical pathologica results are generally nonspecific, and Definitive diagnosis requires organism identification and
may include a neutrophilia with a left shift, nonregenera- is imperative in mycobacterial infections in connection to
tive anemia, decreased albumin:globulin ratio, and hyper- their treatment and zoonotic potential. Like acid‐fast
calcemia. Where there is systemic involvement, diagnostic staining, culture for mycobacteria must be specifically
imaging findings are consistent with nonspecific infiltra- requested from the laboratory.
tive disease of the abdominal and/or thoracic cavities While RGM are often difficult to identify cytologically
with possible organ and lymph node mineralization. due to the scant number of organisms seen, they can
Tuberculin intradermal testing in dogs and cats is gener- generally be cultured within seven days. Conversely,
ally unrewarding. However, immunodiagnostic assays for SGM may be abundant on tissue cytology but cannot be
diagnosis of M. bovis in cats, including semiquantitative cultured readily, if at all. Molecular techniques, particularly
interferon‐gamma production and point‐of‐care qualita- 16S rRNA sequencing, provide rapid and accurate iden-
tive antibody detection tests, have shown positive results, tification of mycobacteria which is of particular impor-
although further evaluation is required. tance in potential zoonotic infections. However, bacterial
culture and susceptibility testing should still be attempted
to determine appropriate antimicrobial therapy.

Therapy and Prognosis

The zoonotic potential and implications of treating
infected animals must be considered before treatment
(see later). Recommendations for treatment of tubercu-
lous and saprophytic infections include triple agent anti-
microbial therapy (a fluoroquinolone, a macrolide, and
rifampicin) for three months followed by continued
administration of two of these agents for an additional
six months (see Table 108.3). Other antimicrobials,
including doxycycline, aminoglycocides, third‐generation
cephalosporins, and chloramphenicol, have been
Figure 108.1 Inguinal panniculitis in a cat. reported to have been used in combination protocols or