Page 764 - Problem-Based Feline Medicine

756 PART 9 CAT WITH SIGNS OF GASTROINTESTINAL TRACT DISEASE

granulomatous chorioretinitis, optic neuritis), central Treatment
nervous system (ataxia, seizures, circling, disorienta-
tion, anisocoria, paresis, decreased conscious proprio- Itraconazole (10 mg/kg PO q 24 h) is the drug of
ception), and occasionally skin (nodular or ulcerated choice for initial therapy. It is highly effective and has
lesions). minimal toxicity, but is relatively expensive and treat-
ment must be continued for 1 month (at least) beyond
Clinical signs the resolution of clinical signs and evidence of disease
(typically 6–9 months).
The most common clinical signs of histoplasmosis in
cats are multisystemic, including depression, weight Other treatment options include fluconazole, keto-
loss, anorexia, dyspnea or lameness. conazole and amphotericin B.

Other signs may include fever, pale mucous mem- The success rate with itraconazole therapy is
branes, peripheral lymphadenopathy, icterus, hepato- reported to be anywhere from 33% to >90%, but this
megaly, skin nodules or splenomegaly. depends in large measure on the severity of the infec-
tion at the time of diagnosis.
The organism can be most commonly found in the res-
piratory tract, bone, bone marrow, skin and GI tract.
INTUSSUSCEPTION
GI signs are not common in cats (as they are in dogs),
but when they occur chronic diarrhea, mesenteric
Classical signs
lymphadenopathy and anorexia are common.
● Abdominal pain, anorexia and vomiting.
Ocular changes may include conjunctivitis, anterior
● Diarrhea, weight loss, and lethargy occur
uveitis, retinal detachment or chorioretinitis.
in long-standing cases.
Diagnosis ● Intussusceptions are usually seen in young
cats or kittens.
The clinical signs of disseminated histoplasmosis are
consistent with systemic illness and are associated with See main reference on page 643 for details.
a wide variety of non-specific clinical and laboratory
changes.
Clinical signs
Anemia of chronic disease is the most common
With high intussusceptions, vomiting, abdominal dis-
hematologic abnormality.
comfort, anorexia, lethargy, dehydration and hypovolemia
Occasionally histoplasma organisms can be found in leading to shock are the most common clinical signs.
circulating mononuclear cells and eosinophils.
Low intussusceptions (at the iliocolic junction) typi-
Thrombocytopenia is also a common abnormality. cally present with bloody, mucoid diarrhea, tenesmus,
intermittent vomiting and weight loss. In many of these
Diagnosis of histoplasmosis by serology is unreliable
cases, the intussusception can be palpated.
as the sensitivity and specificity for the organism is poor.
Most intussusceptions are associated with acute dis-
The best method of diagnosis is to identify the organ-
ease, but sliding intussusceptions may result in
ism in cytologic or histopathologic examinations.
chronic, intermittent signs.
The best tissues for diagnosis of histoplasmosis in the
cat are bone marrow, lymph nodes, lung, liver or A palpable mass in the abdomen may be evident,
skin nodules if present. especially with low intussusceptions.

Differential diagnosis
Diagnosis
There are a wide variety of potential differentials due
to the different clinical presentation that may occur Hemogram and serum biochemistry profiles will be
depending on the organ system affected. variable depending on the severity and location of the