Page 1345 - Small Animal Internal Medicine, 6th Edition

CHAPTER 80 Leukemias 1317

BOX 80.3
VetBooks.ir Chemotherapy Protocols for Dogs and Cats With
Acute Leukemias
Acute Lymphoblastic Leukemia
1. OP protocol
2
Vincristine, 0.5 mg/m IV once a week
2
Prednisone, 40-50 mg/m PO q24h for a week; then
2
20 mg/m PO q48h
2. COP protocol
2
Vincristine, 0.5 mg/m IV once a week
Prednisone, 40-50 mg/m PO q24h for a week; then
2
2
20 mg/m PO q48h
Cyclophosphamide, 50 mg/m PO q48h
2
3. LOP protocol
Vincristine, 0.5 mg/m IV once a week
2
Prednisone, 40-50 mg/m PO q24h for a week; then FIG 80.5
2
2
20 mg/m PO q48h Diff-Quik–stained blood smear from a 14-year-old dog with
L-Asparaginase, 10,000-20,000 IU/m IM or SC once CLL and chronic kidney disease. Note the predominance of
2
every 2-3 weeks well-differentiated small lymphocytes, smaller than the
4. COAP protocol eosinophil in the center of the field, the low platelet number
per field, and the presence of morphologic red blood cell
2
Vincristine, 0.5 mg/m IV once a week
Prednisone, 40-50 mg/m PO q24h for a week; then changes (acanthocytes and keratoacanthocytes) (×1000).
2
2
20 mg/m PO q48h
2
Cyclophosphamide, 50 mg/m PO q48h
Cytosine arabinoside, 100 mg/m SC daily for 2-4 examination findings in dogs with CLL include mild gen-
2
days* eralized lymphadenopathy, splenomegaly, hepatomegaly,
5. CHOP protocol pallor, and pyrexia; the last two are uncommon. The clinical
Vincristine 0.5-0.75 mg/m IV week 1 signs and physical examination findings in dogs with CML
2
2
Cyclophosphamide 200-250 mg/m IV or PO week 2 appear to be similar to those in dogs with CLL.
2
Vincristine 0.5-0.75 mg/m IV week 3 A terminal event in dogs with CLL is the development of
2
Doxorubicin 30 mg/m (1 mg/kg if <10 kg) IV week 4 a diffuse large cell lymphoma, termed Richter syndrome; in
Acute Myelogenous Leukemia humans Richter syndrome also includes prolymphocytic
1. Cytosine arabinoside, 5-10 mg/m SC q12h for 2-3 leukemia, acute leukemia, and Hodgkin lymphoma. In dogs,
2
weeks; then on alternate weeks Richter syndrome is characterized by massive, generalized
2
2. Cytosine arabinoside, 100-200 mg/m in IV drip over lymphadenopathy and hepatosplenomegaly. Once this mul-
4 hours; repeat every 2-3 weeks ticentric lymphoma develops, chemotherapy-induced, long-
2
3. Mitoxantrone, 4-6 mg/m in IV drip over 4 hours; lasting remissions are difficult to obtain and survival times
repeat every 3 weeks are short. In a recent report, the MST in dogs with Richter
syndrome was 41 days (Comazzi et al., 2017).
*The daily dose should be divided into two to four daily Blast crisis, which involves the appearance of immature
administrations. blast cells in blood and bone marrow, occurs in humans and
IM, Intramuscular; IV, intravenous; PO, by mouth; SC, dogs with CML months to years after the initial diagnosis is
subcutaneous.
made; in humans with CLL, acute leukemias are part of the
Richter syndrome. In humans with blast crisis associated
with CML, these blasts are of either myeloid or lymphoid
Clinical Features phenotype; the origin of the blast cell in dogs with blast
Like their acute counterparts, the clinical signs in dogs with crises has not been determined. Blast crises in CML are
CLL or CML are vague and nonspecific; however, there uncommon.
is a history of chronic (i.e., months), vague clinical signs
in approximately half of the dogs. Many cases of chronic Hematologic Features
leukemia are diagnosed incidentally during routine annual The most common hematologic abnormality in dogs with
health checks or presurgical evaluations in asymptomatic CLL is a marked lymphocytosis resulting in leukocytosis
dogs. Clinical signs in dogs with CLL may include leth- (Figs. 80.5 and 80.6). The lymphocytes are usually morpho-
argy, anorexia, vomiting, mildly enlarged lymph nodes, logically normal (see Fig. 80.5), although large granular
intermittent diarrhea or vomiting, and weight loss. As men- lymphocytes (LGLs) or “monocytoid” lymphocytes with
tioned previously, more than half of the dogs with CLL are abundant cytoplasm are occasionally present. The lympho-
asymptomatic and are diagnosed serendipitously. Physical cyte counts range from 8000/µL to more than 100,000/µL,