Page 1101 - Problem-Based Feline Medicine

52 – THE CAT WITH NON-HEALING WOUNDS 1093

Tumors may occur at any site, but the head is most fre- M. tuberculosis is a reverse zoonosis.
quently affected.
The method of transmission with M. avium and
Appearance varies from a discrete solitary nodule to M. microti is unknown. It may involve the cat’s natural
multiple papulonodular tumors to a plaque-like predation of rodents and birds.
mass.
Incubation period in natural infections is months to
Skin tumors may “enlarge” and become erythematous greater than one year.
after palpation or aspiration.
A breed susceptibility for M. avium infections has been
Paraneoplastic syndromes may be evident including reported in the Siamese cat.
gastrointestinal tract ulceration, delayed wound heal-
ing, hypotension, cutaneous flushing, local ulceration Clinical signs
and swelling and coagulation abnormalities.
Skin lesions are usually part of a more generalized dis-
Histiocytic mast cells tumors are uncommon, occur as ease, evident in 56% of cases.
multiple skin nodules around the head of cats less than
4 years of age (mean age 2.4 years) and Siamese are Single or multiple ulcers, abscesses, plaques or nod-
predisposed. ules with thick green or yellow purulent exudate.
Additional signs vary with route of entry and degree of
Diagnosis dissemination of the organism, and may include GIT,
respiratory, CNS or ophthalmic signs.
Diagnosis is based on demonstration of characteristic
mast cells associated with a skin mass. Fine-needle
aspirate shows round cells with granules, which stain Diagnosis
well with Wright’s stain.
Diagnosis is based on clinical signs and identification
Histopathological examination shows a round cell of the organism.
tumor with variable pleomorphism and granule for-
History, physical examination, radiography, urinalysis
mation, which is dependent on the grade of the tumor.
and blood testing (hematology and biochemistry) are
Abdominal radiology, ultrasound and laparotomy may important in the diagnostic work-up.
be useful for staging the tumor.
Cytological examination may reveal acid-fast bacilli
in skin aspirates or biopsies, or in urine.
CUTANEOUS TUBERCULOSIS
On microbiological culture the organisms are slow to
Classical signs grow, and require special media.
● Yellow/green thick purulent exudate from Intradermal skin testing with BCG or purified protein
skin lesions. derivative (PPD) is not reliable.
● Lymphadenopathy. Serological testing is unreliable in cats.
● GIT, respiratory, CNS or ophthalmic signs.

Pathogenesis EUMYCOTIC MYCETOMA

Mycobacterium bovis is the causative agent in 96% of
Classical signs
cases. M. tuberculosis, M. avium and M. microti have
also been reported. ● Papules or nodules on the limbs and face.
● Sinus formation.
The reservoir of M. bovis is infected cattle.
● White or black tissue grains in the
Cats are infected via ingestion of unpasteurized milk mycetoma.
or eating contaminated meat or offal.