Objective—To determine the effect of pamidronate
disodium on the in vitro viability of osteosarcoma
cells and non-neoplastic cells from dogs.
Sample Population—3 osteosarcoma and 1 fibroblast
cell lines derived from dogs.
Procedure—Cell counts and cell viability assays were
performed in cultures of osteosarcoma cells (POS,
HMPOS, and COS31 cell lines) and fibroblasts after
24, 48, and 72 hours of incubation with pamidronate
at concentrations of 0.001 to 1,000µM or with no
drug (control treatment). Percentage viability was
determined in cell samples for each concentration of
pamidronate and each incubation time. A DNA fragmentation
analysis was performed to assess bisphosphonate-
Results—Osteosarcoma cell viability decreased significantly
in a concentration- and time-dependent
manner at pamidronate concentrations ranging from
100 to 1,000µM, most consistently after 48 and 72
hours' exposure. In treated osteosarcoma cells, the
lowest percentage cell viability was 34% (detected
after 72 hours' exposure to 1,000µM pamidronate).
Conversely, 72 hours' exposure to 1,000µM
pamidronate did not significantly reduce fibroblast viability
(the lowest percentage viability was 76%). After
72 hours of exposure, pamidronate did not cause
DNA fragmentation in POS or HMPOS cells.
Conclusions and Clinical Relevance—Results indicate
that pamidronate may have the potential to inhibit
osteosarcoma growth in dogs, possibly through a
nonapoptotic mechanism. The clinical relevance of
these in vitro findings remains to be determined, but
administration of pamidronate may potentially be indicated
as an adjuvant treatment in chemotherapeutic
protocols used in dogs. (Am J Vet Res 2005;66:
Objective—To determine whether exposure of
canine osteosarcoma cells to deracoxib or piroxicam
results in decreased viability, whether the cytotoxic
effects of deracoxib and piroxicam involve induction
of apoptosis, and whether deracoxib is a more
potent inhibitor of osteosarcoma cell growth than
Sample Population—1 fibroblast and 3 osteosarcoma
Procedure—Cell counts and viability assays were
performed using osteosarcoma cells (POS, highly
metastatic POS, and canine osteosarcoma cell 31)
and fibroblasts after 72 hours of incubation with deracoxib
at concentrations of 0.5µM to 500µM or piroxicam
at concentrations of 1µM to 1,000µM.
Percentage viability was determined for each concentration.
A DNA fragmentation analysis was performed
to assess drug-induced apoptosis.
Results—Concentration of deracoxib required for
50% inhibition of cell viability (IC50) was reached in all
3 osteosarcoma cell lines and ranged from 70 to
150µM, whereas the IC50 for piroxicam was only
reached in the POS cell line at 500µM. Neither deracoxib
nor piroxicam induced sufficient toxicity in
fibroblasts to reach an IC50. Exposure of osteosarcoma
cells to cytotoxic concentrations of deracoxib and
piroxicam did not result in DNA fragmentation.
Conclusions and Clinical Relevance—Intermediate
and high concentrations of deracoxib and high concentrations
of piroxicam were cytotoxic to osteosarcoma
cells; neither drug inhibited cell viability at typical
plasma concentrations in dogs. Deracoxib inhibited
viability of cells at concentrations that did not
affect fibroblast viability. There was no evidence of
apoptosis induction for either drug; however, only 1
cell line was evaluated for apoptosis induction and
only for a limited selection of drug concentrations.
(Am J Vet Res 2005;66:1961–1967)
Objective—To determine whether thalidomide
inhibits the growth of primary and pulmonary
metastatic canine osteosarcoma in mice after xenotransplantation.
Animals—Athymic nude mice.
Procedure—Canine osteosarcoma cells were injected
SC in 50 mice. Mice were randomly placed into
the following groups: control group (n = 13; DMSO
[drug vehicle] alone [0.1 mL/d, IP]); low-dose group
(12; thalidomide [100 mg/kg, IP]), mid-dose group (13;
thalidomide [200 mg/kg, IP]); and high-dose group
(12; thalidomide [400 mg/kg, IP]). Starting on day 8,
treatments were administered daily and tumor measurements
were performed for 20 days. On day 28,
mice were euthanatized and primary tumors were
weighed. Lungs were examined histologically to
determine the number of mice with metastasis and
tumor emboli. Mean area of the pulmonary
micrometastatic foci was determined for mice from
Results—Primary tumor size and weight were not
significantly different among groups. The number of
mice in the mid-dose (200 mg/kg) and high-dose (400
mg/kg) groups with micrometastasis was significantly
less than the number of control group mice; however,
the number of mice with tumor emboli was not
affected by thalidomide treatment. Size of
micrometastasis lesions was not affected by thalidomide
Conclusions and Clinical Relevance—Mean area of
micrometastases was not affected by treatment;
however, growth of micrometastases had not yet
reached an angiogenesis-dependent size. Although
thalidomide did not affect growth of primary tumors in
mice after xenotransplantation of canine osteosarcoma
cells, our findings indicate that thalidomide may
interfere with the ability of embolic tumor cells to
complete the metastatic process within the lungs.
( Am J Vet Res 2004;65:659–664)
Objective—To evaluate postmortem surgery site leakage by use of in situ isolated pulsatile perfusion after partial liver lobectomies.
Animals—10 healthy mixed-breed male dogs.
Procedures—Dogs were anesthetized, and 5 surgical techniques (pretied suture loop, energy-based sealer-divider, harmonic scalpel, suction with clip application, or suction with use of a thoracoabdominal stapler) were used to perform 5 partial liver lobectomies in each dog. Dogs were euthanatized, and the portal vein and hepatic artery were cannulated and perfused with a modified kidney perfusion machine (pulsatile flow for arterial perfusion and nonpulsatile flow for portal perfusion). Lobectomy sites were inspected for leakage of perfusate, and time until detection of leakage was recorded. The techniques in each dog were ranked on the basis of time until leakage. Time until leakage and rankings for each surgical technique were analyzed by use of an ANOVA.
Results—Leakage of perfusate was recorded in 44 lobes at supraphysiologic pressures. Of the 6 lobes without leakage, a pretied suture loop procedure was performed in 5 and a harmonic scalpel procedure was performed in 1. Time until leakage and the ranking differed significantly between the pretied suture loop and the other techniques. Time until leakage and ranking did not differ significantly among the other techniques.
Conclusions and Clinical Relevance—Time until leakage of perfusate was greater for the pretied suture loop technique than for the other techniques, and that technique did not fail in 5 of 10 lobes. However, all techniques appeared to be safe for clinical use.
Objective—To biomechanically and histologically compare single-layer continuous Cushing and simple continuous appositional cystotomy closure in rats with xylene-induced cystitis.
Animals—40 female Sprague-Dawley rats.
Procedure—Rats were anesthetized, their urinary bladders catheterized and evacuated, and xylene instilled in each bladder for 5 minutes and then aspirated. Forty-eight hours later, ventral midline celiotomy and cystotomy (8 mm) were performed. Cystotomies were closed with 6-0 poliglecaprone 25 by use of a single-layer continuous Cushing or simple continuous appositional pattern (20 rats/group), and cystotomy times were recorded. Rats were allocated to healing durations (5 rats/group) of 0, 3, 7, and 14 days. Celiotomies were closed in a routine manner. After the allotted healing interval, another celiotomy was performed, the urethra cannulated, and ureters ligated. The cannula was secured to the urethra, and the bladder infused at 0.1 mL/min. Leak pressure volume, leak pressure, peak pressure volume, and peak pressure were recorded via a pressure transducer. Bladders were harvested and histologically assessed.
Results—Cystotomy time, biomechanical testing values, and overall inflammation scores did not differ between closure methods for any healing duration. Both methods had significantly greater leak pressures, with the appositional method also having significantly greater peak pressures on day 7, compared to day 0. Biomechanical testing values decreased from day 7 to 14 as a result of juxtaincisional weakening of the bladder and xylene-induced changes in collagen.
Conclusions and Clinical Relevance—Simple continuous appositional was equal biomechanically and histologically to continuous Cushing for all comparison variables. Poliglecaprone 25 was acceptable for cystotomy closure.