Page 781 - Problem-Based Feline Medicine

34 – THE CAT WITH SIGNS OF LARGE BOWEL DIARRHEA 773

LYMPHOSARCOMA* Differential diagnosis
The primary differential for lymphoma in cats is
Classical signs severe lymphocytic plasmacytic IBD, and it is sus-
pected that this may be a precursor lesion to lymphoma
● Vomiting, small bowel diarrhea, weight
in some cats.
loss and anorexia are the most common
presenting signs. Other extra-intestinal causes of weight loss and vomit-
● Large bowel diarrhea alone is rarely ing must also be considered, including pancreatitis, renal
observed because the tumor is typically or liver disease, hyperthyroidism, diabetes mellitus, etc.
infiltrative throughout the GI tract.
Other less-common neoplastic diseases to consider in
cats are mast cell tumors, leiomyosarcomas and carci-
See main reference on page 317 for details.
noids.
Clinical signs
Treatment
Vomiting, small bowel diarrhea, weight loss and
Combination chemotherapy with cyclophosphamide,
anorexia are the most common presenting signs.
vincristine and prednisolone (COP protocol) is the
Large bowel diarrhea alone is rarely observed most commonly recommended regimen. Most cats
because the tumor is typically infiltrative throughout treated with this protocol are expected to live 6–9
the GI tract. months, with 20% living longer than 1 year. Asparaginase
or doxyrubricin can be added to increase the remission
Palpation may reveal thickened loops of bowel.
times or serve as the rescue.
Most cats with alimentary lymphoma are FeLV nega- ● Cyclophosphamide (300 mg/m PO q 3 weeks).
2
2
tive so associated clinical disease is uncommon. ● Vincristine (0.75 mg/m IV weekly for 4 weeks).
● Prednisone (2 mg/kg/day).
Occasionally, lymphoma will present as a solitary
2
● Doxyrubricin (25 mg/m IV q 3 wk).
mass in the small intestine or colon, which obstructs
2
● L-Asparaginase (10 000 IU/m IM).
the GI tract and must be differentiated from adenocar-
cinoma and other neoplastic or granulomatous diseases. Other protocols exist for induction, maintenance
and rescue, but the reader is referred to oncology texts
Diagnosis for additional information.
Supportive care in the form of nutrition is essential
Routine hematology and chemistry profiles are often
for cats with alimentary lymphoma because they tend
within normal limits.
not to eat and often vomiting precludes oral alimenta-
Survey radiographs of the abdomen may reveal thick- tion.
ened bowel loops or abnormal gas patterns, but they
Placement of jejunostomy tubes may be required in
also may be interpreted as normal.
these cats.
Ultrasound examination of the abdomen is especially
helpful in identifying enlarged lymph nodes, liver or
Prognosis
splenic changes in echogenicity, and measurement of
intestinal wall thickness. Guarded to poor. Survival times are shorter for cats
● Fine-needle aspirates may be obtained via ultra- with alimentary lymphoma than other forms of lym-
sound guidance that will facilitate a definitive phoma (e.g. multicentric or mediastinal), primarily
diagnosis and staging. because response to chemotherapy is more variable
with these tumors.
Endoscopy is also an important diagnostic tool in mak-
ing a definitive diagnosis, because multiple samples In one recent report, mean survival was 230 days, but
can be obtained for histopathologic examination. median survival was only 50 days.