Page 1307 - Small Animal Internal Medicine, 6th Edition

CHAPTER 77 Complications of Cancer Chemotherapy 1279

VetBooks.ir COD CCNU

Neupogen

0
Jan 4, 2017 May 1, 2017

FIG 77.1
Leukocyte count in a Siamese cat with multicentric
lymphoma who had a severe, long-lasting myelosuppressive A
event associated with lomustine administration. COD,
Cyclophosphamide, vincristine, dexamethasone; CCNU,
lomustine; NEUPOGEN, granulocyte colony-stimulating
factor. The grey zone represents the reference interval for
the white blood cell count.

compatible with inflammation; for example, dogs with neu-
tropenia and bacterial pneumonia diagnosed on the basis of
cytologic and microbiologic findings in transtracheal wash
material often have normal thoracic radiographic findings
(Fig. 77.2). As a general rule, if a severely neutropenic animal
(neutrophil count <500/µL) is evaluated because of pyrexia
(>104° F [>40° C]), the fever should be attributed to bacte-
rial pyrogens until proved otherwise, and the patient should
be treated aggressively with antimicrobial therapy (see fol- B
lowing paragraphs). Neutropenic septic patients can also be
hypothermic.
All dogs and cats undergoing chemotherapy should be up FIG 77.2
Thoracic radiographs from a 5-year-old male, castrated
to date on their vaccines; it is controversial whether the use Boston Terrier with multicentric lymphoma treated with
of modified-live vaccines should be avoided because of the doxorubicin and dacarbazine (ADIC) chemotherapy. This
potential for inducing illness in immunosuppressed animals. dog presented as an emergency because of depression,
Recent evidence suggests that vaccinated dogs with cancer fever, and mild bilateral nasal discharge. The neutrophil
undergoing chemotherapy have protective serum antibody count on admission was 1500/µL. (A) Thoracic radiograph
titers for commonly used vaccines. findings were considered normal at the time, but a
transtracheal wash specimen contained bacteria. (B) Two
Hematologic monitoring of the patient receiving chemo- days later, when the neutrophil count increased to
therapy constitutes the most effective way to prevent (or 16,300/µL, focal areas of pneumonia became evident.
anticipate) severe, life-threatening sepsis or bleeding second- (From Couto CG: Management of complications of cancer
ary to myelosuppression. Complete blood counts (CBCs) chemotherapy, Vet Clin North Am 20:1037, 1990.)
should be obtained weekly or every other week (depend-
ing on the treatment protocol), and the myelosuppressive
agent or agents should be temporarily discontinued (or the and owner must weigh the pros and cons of temporarily
dose decreased) if the neutrophil count decreases to fewer discontinuing treatment.
than 1000 cells/µL or if the platelet count decreases to fewer Clinically, neutropenic patients are classified as febrile or
than 50,000 cells/µL. Discontinuing the offending agent or afebrile. Neutropenic, febrile patients should be managed
agents for two or three administrations usually allows suf- aggressively because they are usually septic; thus fever in a
ficient time for the cell counts to return to normal. When neutropenic patient constitutes a medical emergency. The
therapy is reinstituted, it is recommended that only 75% following protocol is the one currently used in such patients
of the initial dose be given and the doses increased during at our clinic. First, a thorough physical examination is per-
the next 2 to 3 weeks until the initially recommended dose formed to search for a septic focus, an indwelling intrave-
(or a dose that does not produce marked cytopenias) is nous (IV) catheter is placed aseptically, and IV fluids are
reached. Obviously, the drawback of discontinuing chemo- administered as required. All anticancer agents are discon-
therapy is the potential for tumor relapse, so the clinician tinued immediately, with the exception of corticosteroids,