Page 1299 - Small Animal Internal Medicine, 6th Edition

CHAPTER 76 Practical Chemotherapy 1271

multiagent chemotherapy and is associated with signifi- area (BSA) basis; exceptions are listed later. This appears to
cantly less toxicity. Examples include using carboplatin or provide a more constant metabolic parameter for comparing
VetBooks.ir doxorubicin as single agents in dogs with osteosarcoma; doses across species. It can be calculated using the following
formula:
chlorambucil alone for dogs with chronic lymphocytic
leukemia; and vincristine alone in dogs with transmissible
(
venereal tumors. Weight g() 23 × K constant) = m BSA
2
Another general concept of chemotherapy from the 10 4
standpoint of cell kinetics is that it is more effective in a
relatively small tumor than in a large one, even though the The constant is 10.1 for the dog and 10 for the cat. Table
inherent sensitivity to the drug or drugs may be the same. 76.1 is a conversion table of weight (in kilograms) to BSA (in
6
As can be seen in Fig. 76.3, a small tumor (e.g., 10 cells) is squared meters) for dogs. Table 76.2 is a conversion table for
11
more likely (e.g., 10 cells) to be completely eradicated by cats. When using drugs such as doxorubicin or carboplatin,
the drugs than a larger one because the smaller mass has doses determined on the basis of BSA usually lead to adverse
a higher MI, a higher GF, and consequently a shorter DT effects in very small dogs (i.e., those <10 kg) and in cats. A
than the larger mass (i.e., more cells are actively dividing at dose determined on the basis of weight (e.g., 1 mg/kg for
a given time). doxorubicin, 10 mg/kg for carboplatin) is more appropriate
Despite continued controversy, the doses of most che- in such small patients, resulting in a relatively lower adverse
motherapeutic agents are still determined on a body surface effect profile.

TABLE 76.1

Conversion of Body Weight to Body Surface Area in Dogs

2
2
BODY WEIGHT (kg) BODY SURFACE AREA (m ) BODY WEIGHT (kg) BODY SURFACE AREA (m )
0.5 0.06 26 0.88
01 0.10 27 0.90
02 0.15 28 0.92
03 0.20 29 0.94
04 0.25 30 0.96
05 0.29 31 0.99
06 0.33 32 1.01
07 0.36 33 1.03
08 0.40 34 1.05
09 0.43 35 1.07
10 0.46 36 1.09
11 0.49 37 1.11
12 0.52 38 1.13
13 0.55 39 1.15
14 0.58 40 1.17
15 0.60 41 1.19
16 0.63 42 1.21
17 0.66 43 1.23
18 0.69 44 1.25
19 0.71 45 1.26
20 0.74 46 1.28
21 0.76 47 1.30
22 0.78 48 1.32
23 0.81 49 1.34
24 0.83 50 1.36
25 0.85