Objective—To evaluate splenic mast cell tumors
(MCT) of cats for activating mutations in the protooncogene
Sample Population—10 formalin-fixed, paraffinembedded
splenic MCT from cats in the pathology
database of the Veterinary Medical Teaching Hospital
at the University of California, Davis.
Procedure—Genomic DNA was isolated from tumor
specimens, and the polymerase chain reaction (PCR)
procedure was performed for exons 11, 12, and 17.
The PCR products were analyzed by use of agarose
gel electrophoresis and then directly sequenced.
Results—We did not identify mutations in the juxtamembrane
domain (encoded by exons 11 and 12) or
catalytic domain (encoded by exon 17) of c-kit in any
of the splenic MCT specimens.
Conclusions and Clinical Relevance—Although
mutations in the proto-oncogene c-kitoccur frequently
in naturally developing MCT in dogs and aggressive
mastocytosis in humans, the data reported here documented
that dysregulation of Kit function through
activating mutations is unlikely in splenic MCT of cats.
Therapeutic strategies aimed at inhibiting Kit signaling
(ie, kinase inhibitors such as imatinib [STI571]) may
not be of benefit for the treatment of this disease in
cats. (Am J Vet Res 2002;63:1129–1133).
Objective—To determine whether there was a
decline in the percentage of dogs undergoing necropsies
and whether there was substantial agreement or
disagreement between clinical and pathologic diagnoses.
Procedure—Medical records of hospitalized dogs
that died or were euthanatized and necropsied at a
veterinary teaching hospital in 1989 and 1999 were
reviewed. Clinical and pathologic diagnoses were
recorded and compared.
Results—There was a significant decline in the
necropsy rate of hospitalized dogs that died or were
euthanatized in 1999, compared with 1989. In both
1989 and 1999, there was disagreement between the
clinical and pathologic diagnoses in approximately a
third of the cases.
Conclusions and Clinical Relevance—Despite
improved diagnostic methods, the accuracy of diagnosis
did not improve significantly in 1999, compared
with 1989. Necropsy is the best method to assess
overall diagnostic accuracy. Increased availability of
teaching funds may promote efforts to have necropsies
performed in veterinary teaching hospitals. ( J Am
Vet Med Assoc 2004;224:403–406)
Objective—To determine clinical activity and toxic effects of lomustine when used to treat cats with mast cell tumors (MCTs).
Design—Retrospective case series.
Animals—38 cats with measurable, histologically or cytologically confirmed MCTs treated with lomustine at a dosage ≥ 50 mg/m2.
Procedures—Medical records were reviewed to determine response to treatment and evidence of drug toxicoses. The Kaplan-Meier method was used to estimate remission duration.
Results—26 cats had cutaneous MCTs, 7 had MCTs of the mesenteric lymph nodes, 2 had gastrointestinal tract MCTs, 2 had hepatic MCTs, and 1 had MCTs involving multiple organs. Targeted lomustine dosage was 50 mg/m2 in 22 cats and 60 mg/m2 in 16 cats. Median administered dosage of lomustine was 56 mg/m2 (range, 48 to 65 mg/m2), and median number of doses administered was 2 (range, 1 to 12). Seven cats had a complete response and 12 had a partial response, for an overall response rate of 50%. Median response duration was 168 days (range, 25 to 727 days). The most common toxicoses were neutropenia and thrombocytopenia.
Conclusions and Clinical Relevance—Results suggested that lomustine had activity against MCTs in cats and was well tolerated. Further, findings suggested that treatment with lomustine should be considered for cats with MCTs for which local treatment is not an option.
Objective—To determine outcome of dogs with presumed primary hepatic lymphoma treated with various multiagent, doxorubicin-based chemotherapeutic protocols and identify factors associated with prognosis.
Design—Retrospective case series.
Animals—18 dogs with presumed primary hepatic lymphoma.
Procedures—Medical records were reviewed for information on signalment, treatment, and outcome.
Results—8 dogs had a complete remission (CR), with a median remission duration of 120 days. Dogs with leukocytosis, neutrophilia, hypoalbuminemia, hyperbilirubinemia, or a combination of hypoalbuminemia and hyperbilirubinemia were less likely to achieve a CR. Overall median survival time (MST) was 63 days (range, 2 to 402 days). In a multivariate analysis, response to treatment and serum albumin concentration were associated with MST. Dogs that did not achieve a CR had a significantly shorter MST than did dogs that did achieve a CR (13 vs 283 days, respectively). Dogs with serum albumin concentration < 2.5 g/dL at the time treatment was initiated had a significantly shorter MST than did dogs with serum albumin concentration within reference limits (10 vs 128 days, respectively). There was also a positive correlation between serum albumin concentration and survival time (r = 0.74).
Conclusions and Clinical Relevance—Results suggested that dogs with primary hepatic lymphoma that underwent chemotherapy had a poor prognosis, with a low response rate. Dogs that responded to treatment had a better prognosis, and dogs with hypoalbuminemia had a poorer prognosis.