Lomustine for treatment of mast cell tumors in cats: 38 cases (1999-2005)

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 > or = 50 mg/m(2). 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/m(2) in 22 cats and 60 mg/m(2) in 16 cats. Median administered dosage of lomustine was 56 mg/m(2) (range, 48 to 65 mg/m(2)), 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.     

Cardiac lymphoma and pericardial effusion in dogs: 12 cases (1994-2004)

OBJECTIVE: To determine clinical characteristics and clinicopathologic findings, including results of pericardial fluid analysis, and determine the outcome associated with pericardial effusion caused by cardiac lymphoma in dogs. DESIGN: Retrospective case series. ANIMALS: 12 dogs. PROCEDURE: Medical records of affected dogs were reviewed for echocardiographic findings, radiographic findings, results of pericardial fluid analysis, clinicopathologic findings, treatment protocols, and outcomes. RESULTS: Pericardial effusion was detected by echocardiography in all 12 dogs, and lymphoma was detected by cytologic examination of the effusion (11/12 dogs) or histologic examination of pericardium (3/12). Large-breed dogs were overrepresented; median weight was 40.5 kg (89.1 lb). Most hematologic and biochemical changes were mild and non-specific. Survival time for dogs treated with combination chemotherapeutic agents was 157 days and for dogs that did not receive chemotherapy survival time was 22 days. This difference was not significant, but several dogs had long-term survival. CONCLUSIONS AND CLINICAL RELEVANCE: Cardiac lymphoma is an uncommon cause of pericardial effusion, and results suggest that cardiac lymphoma does not always warrant the poor prognosis of other stage V, substage b lymphomas.     

Evaluation of intracranial meningioma resection with a surgical aspirator in dogs: 17 cases (1996-2004)

OBJECTIVE: To determine results of intracranial meningioma resection by use of a surgical aspirator and assess prognostic factors associated with intracranial meningiomas in dogs. DESIGN: Retrospective case series. ANIMALS: 17 dogs. PROCEDURES: Medical records of dogs that underwent resection of an intracranial meningioma by use of a surgical aspirator were reviewed. Information pertaining to signalment, imaging findings, clinical signs, duration of clinical signs, preoperative treatment, location of the tumor, results of histologic assessment, outcome, and necropsy results was obtained from the medical record. Clients and referring veterinarians were contacted via telephone for information on recurrence of clinical signs and postoperative survival time. RESULTS: 16 dogs were > 7 years of age, and all 17 dogs had seizures before surgery. The most commonly affected breed was the Golden Retriever, represented by 6 of the 17 dogs. Median survival time was 1,254 days. Of the data collected, only histologic subtype of the tumor was prognostic. Analysis of survival times according to histologic tumor subtypes indicated that the order from most brief to longest was as follows: anaplastic, 0 days; fibroblastic, 10 days; psammomatous, > 313 days; meningothelial, > 523 days; and transitional, 1,254 days. CONCLUSIONS AND CLINICAL RELEVANCE: Use of a surgical aspirator to resect intracranial meningiomas in dogs was associated with longer survival times than those achieved with traditional surgery alone or traditional surgery combined with radiation therapy. Dogs with meningothelial, psammomatous, or transitional intracranial meningioma subtypes appeared to have a better prognosis than dogs with other subtypes of meningioma.     

Procarbazine as adjunctive therapy for treatment of dogs with presumptive antemortem diagnosis of granulomatous meningoencephalomyelitis: 21 cases (1998-2004)

BACKGROUND: Granulomatous meningoencephalomyelitis (GME) is an idiopathic inflammatory disease of the central nervous system. Remission often is short-lived in dogs treated with glucocorticoids. Procarbazine is T cell-specific and crosses the blood-brain barrier. HYPOTHESIS: Dogs with presumptive antemortem diagnosis of GME given procarbazine as adjunctive therapy to prednisone will have improved long-term outcome compared with dogs given no treatment or glucocorticoids alone. ANIMALS: Two groups were studied: (1) Dogs with presumptive antemortem diagnosis of GME treated with procarbazine and prednisone (n = 21); (2) Dogs that had a histologic diagnosis of GME at postmortem examination and received no treatment (n = 11). METHODS: Dogs with presumptive GME treated with procarbazine were identified retrospectively from medical records of 2 veterinary referral hospitals. Selection criteria required all dogs have a neurologic examination, blood work, cerebrospinal fluid analysis, and brain imaging (MRI or CT). RESULTS: Median survival time for all dogs studied was 5.0 months. Median survival time for dogs treated with procarbazine was 14.0 months and for untreated dogs, 0.73 months. Treatment with procarbazine was significantly correlated with survival time (P < .001). Procarbazine was the only independent predictor of survival. Prednisone was reduced in dosage or discontinued in 17 dogs. Adverse reactions to procarbazine therapy included myelosuppression in 7 dogs and hemorrhagic gastroenteritis in 3 dogs. CONCLUSION: These data suggest that procarbazine treatment of presumptive GME may result in greater improved long-term outcome than has been previously reported for glucocorticoid treatment alone and may complement other immunomodulatory therapies. Procarbazine-treated dogs must be monitored for adverse reactions.     

Hemophagocytic syndrome in dogs: 24 cases (1996-2005)

OBJECTIVE: To determine the frequency, potential causes, and clinical and clinicopathologic features of hemophagocytic syndrome in dogs. DESIGN: Retrospective study. ANIMALS: 24 client-owned dogs. PROCEDURES: Records for dogs in which diagnostic bone marrow specimens (including an aspiration smear and core biopsy material) were obtained from 1996 to 2005 were reviewed. Inclusion criteria were presence of bicytopenia or pancytopenia in the blood and > 2% hemophagocytic macrophages in the bone marrow aspirate. RESULTS: Of 617 bone marrow specimens evaluated, evidence of hemophagocytic syndrome was detected in 24 (3.9%). The Tibetan Terrier breed was overrepresented among dogs with hemophagocytic syndrome. Clinical signs associated with hemophagocytic syndrome included fever, icterus, splenomegaly, hepatomegaly, and diarrhea. Hemophagocytic syndrome was associated with immune-mediated, infectious, and neoplastic-myelodysplastic conditions and also occurred as an idiopathic condition. Overall, dogs with infection-associated hemophagocytic syndrome had better 1-month survival rates than dogs with immune-associated and idiopathic hemophagocytic syndrome. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that hemophagocytic syndrome may occur more frequently in dogs than has previously been suspected on the basis of the paucity of reported cases. Although most dogs had definable underlying disease conditions, idiopathic hemophagocytic syndrome was also identified. Hemophagocytic syndrome of any cause is potentially life-threatening; however, the prognosis should be adjusted on the basis of the associated disease process and potential for successful treatment.     

Vacuolar hepatopathy in dogs: 336 cases (1993-2005)

OBJECTIVE: To determine disorders associated with vacuolar hepatopathy (VH), morphologic hepatic and clinicopathologic abnormalities, and affiliation with steroidogenic hormone excess in dogs. DESIGN: Retrospective case series. Animals-336 dogs with histologically confirmed moderate or severe VH. PROCEDURES: Information on signalment, results of diagnostic testing, definitive diagnoses, and exposure to glucocorticoids (ie, exogenous glucocorticoid administration or high endogenous concentrations of steroidogenic hormones) was obtained from medical records. Dogs were grouped by underlying disorder, glucocorticoid exposure, acinar zonal distribution of lesions, and histologic severity. RESULTS: 12 disease groups (neoplastic, acquired hepatobiliary, neurologic, immune-mediated, gastrointestinal tract, renal, infectious, cardiac disease, diabetes mellitus, portosystemic vascular anomaly, adrenal gland dysfunction, and miscellaneous disorders) were identified. There were 186 (55%) dogs with and 150 (45%) dogs without evidence of glucocorticoid exposure. Acinar zonal distribution of hepatic vacuolation and clinicopathologic values did not differ between dogs with and without evidence of glucocorticoid exposure. However, a 3-fold increased likelihood of severe VH was associated with steroidogenic hormone exposure. Of 226 dogs with high serum alkaline phosphatase activity, 102 (45%) had no evidence of glucocorticoid exposure. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that neoplasia and congenital or acquired hepatobiliary disease are common in dogs with VH and provide support for the suggestion that VH, high alkaline phosphatase activity, and illness-invoked physiologic stress may be associated. Histologic confirmation of VH should initiate a diagnostic search for a primary disease if glucocorticoid treatment and hyperadrenocorticism are ruled out.     

Streptozocin for treatment of pancreatic islet cell tumors in dogs: 17 cases (1989-1999)

OBJECTIVE: To determine toxic effects of streptozocin given in combination with a diuresis protocol in dogs and establish whether streptozocin is efficacious in treatment of pancreatic islet cell tumors in dogs. DESIGN: Retrospective study. ANIMALS: 17 dogs. PROCEDURE: Medical records were reviewed to obtain information regarding signalment, tumor stage and staging tests performed, number of streptozocin treatments, adverse effects, results of biochemical and hematologic monitoring during streptozocin treatment, tumor dimensions, duration of normoglycemia, and date of death, when applicable. Dogs were compared with a historical control group of 15 dogs treated surgically and medically. RESULTS: 58 treatments were administered to the 17 dogs. Only 1 dog developed azotemia. Serum alanine aminotransferase activity increased in some dogs but decreased when treatment was discontinued. Hematologic toxicoses were rare. Vomiting during administration was uncommon but occasionally severe. Two dogs developed diabetes mellitus after receiving 5 doses. Median duration of normoglycemia for 14 dogs with stage-II or -III insulinoma treated with streptozocin was 163 days (95% confidence interval, 16 to 309 days), which was not significantly different from that for the control dogs (90 days; 95% confidence interval, 0 to 426 days). Two dogs had rapid resolution of paraneoplastic peripheral neuropathy, and 2 others had measurable reductions in tumor size. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that streptozocin can be administered safely to dogs at a dosage of 500 mg/m2, IV, every 3 weeks when combined with a protocol for induction of diuresis and may be efficacious in the treatment of dogs with metastatic pancreatic islet cell tumors.     

Bone marrow necrosis in dogs: 34 cases (1996-2004)

OBJECTIVE: To identify the incidence, potential causes, and clinical and clinicopathologic features of bone marrow necrosis in dogs. DESIGN: Retrospective study. ANIMALS: 34 client-owned dogs. PROCEDURES: Reports of cytologic examinations of bone marrow specimens performed between 1996 and 2004 were reviewed. All reports that indicated the presence of necrosis, stromal disruption, phagocytic macrophages, individual cell necrosis, or myelofibrosis were evaluated further. RESULTS: Of 609 reports of bone marrow evaluations performed during the study period, 34 (5.6%) had evidence of bone marrow necrosis. Nine dogs had no evidence of associated diseases or drug or toxin exposure, and 25 dogs had associated disease conditions or drug exposures. All 9 dogs with idiopathic bone marrow necrosis were anemic (mean Hct, 14%), but only 3 had neutropenia, and 3 had thrombocytopenia. All 9 had myelofibrosis. Of the 25 dogs with associated disease conditions or drug exposures, only 14 (56%) had anemia (mean Hct, 33%). In addition, 14 (56%) had neutropenia and 18 (72%) had thrombocytopenia. Only 10 (40%) had myelofibrosis. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that bone marrow necrosis may be common in dogs with hematologic disorders. In most dogs, bone marrow necrosis was associated with an underlying disease condition or drug exposure, but idiopathic bone marrow necrosis was also identified. Disease conditions that should increase suspicion of possible bone marrow necrosis include sepsis, lymphosarcoma, and systemic lupus erythematosus; drug exposures that should increase suspicion of possible bone marrow necrosis include chemotherapeutic agents, phenobarbital, carprofen, metronidazole, and mitotane.     

Liver lobe torsion in dogs: 13 cases (1995-2004)

OBJECTIVE: To determine history, results of diagnostic testing, surgical findings, complications, and outcome for dogs with liver lobe torsion (LLT). DESIGN: Retrospective case series. ANIMALS: 12 dogs (1 with 2 episodes). PROCEDURE: Signalment, clinical signs, clinicopathologic findings, radiographic and ultrasonographic findings, surgical and histologic findings, complications, and hospitalization time were evaluated. RESULTS: The most common clinical signs were nonspecific abnormalities (eg, vomiting, lethargy, and anorexia) of acute or chronic duration. All dogs were large-breed dogs (median body weight, 37.2 kg [82 lb]). Biochemical abnormalities included high alanine amino-transferase (n = 12) and aspartate aminotransferase (11) activities. Results of abdominal ultrasonography were supportive of the diagnosis in 5 of 8 cases. Affected lobes included the left medial lobe (n = 4), left lateral lobe (3), papillary process of the caudate lobe (2), caudate lobe (1), and right lateral lobe (1). Exploratory celiotomy and liver lobectomy were performed in 12 of 13 cases, and in 11 of those 12 cases, the dog survived. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that development of nonspecific clinical signs of vomiting, lethargy, and anorexia in conjunction with high serum hepatic enzyme activities and mature neutrophilia in a medium-sized or large-breed dog should increase the index of suspicion for LLT. Abdominal ultrasonography with Doppler assessment may be useful in establishing the diagnosis. The long-term outcome for dogs that survive the hospitalization period is excellent.     

Self-expanding nitinol stents for the treatment of tracheal collapse in dogs: 12 cases (2001-2004)

OBJECTIVE: To evaluate long-term outcome following nitinol stent placement in dogs with tracheal collapse. DESIGN: Retrospective case series. ANIMALS: 12 client-owned dogs with endoscopically diagnosed tracheal collapse refractory to medical management. PROCEDURES: Medical records were reviewed for 12 dogs in which 1 or more self-expanding nitinol stents were placed for the treatment of endoscopically diagnosed tracheal collapse. A total of 17 stents were placed. RESULTS: Survival times after stent placement ranged from 1 to 48 months. Three of 12 dogs died within 6 months after stent placement. Nine dogs survived > 1 year after stent placement, and 7 dogs survived > 2 years. Of the deceased dogs, 5 of 9 succumbed to tracheal disease. Other causes of death included congestive heart failure, cerebral neoplasia, cerebrovascular accident, and renal failure. Material failure (stent fracture) was a common complication (5/12 dogs). Other complications reported included excessive granulation tissue within the stent lumen, tracheitis, and pneumonia. CONCLUSIONS AND CLINICAL RELEVANCE: Placement of an intraluminal stent with self-expanding nitinol stents was a successful palliative treatment for tracheal collapse in dogs that did not respond to medical management. Disease progression is inevitable, but substantial improvement in respiratory function may be achieved for a period of months to years.     

Evaluation of a single subcutaneous infusion of carboplatin as adjuvant chemotherapy for dogs with osteosarcoma: 17 cases (2006-2010)

Objective-To evaluate adverse effects and survival times in dogs with osteosarcoma that received a single SC infusion of carboplatin as adjunctive chemotherapeutic treatment following limb amputation or limb-sparing surgery. Design-Retrospective case series. Animals-17 client-owned dogs with spontaneously occurring osteosarcoma. Procedures-Medical records of dogs that underwent limb amputation or limb-sparing surgery followed by a single continuous SC infusion of carboplatin (total dose, 300 mg/m(2) infused over 3, 5, or 7 days) were evaluated. Signalment, tumor location, type of surgery (amputation or limb-sparing), duration of carboplatin infusion, results of hematologic and serum biochemical analyses, and adverse effects were recorded. Kaplan-Meier survival analysis was performed. Results-Median survival time for all dogs was 365 days. Nine dogs had adverse bone marrow-related (hematologic) effects, 1 had adverse gastrointestinal effects, and 7 had infections at the surgical site. No significant differences were detected in survival times of dogs grouped according to tumor location, type of surgery, duration of carboplatin infusion, or development of postoperative infection. Conclusions and Clinical Relevance-Median survival time and adverse effects in dogs with osteosarcoma that received a single SC infusion of carboplatin over a 3-, 5-, or 7-day period as adjunctive treatment following limb amputation or limb-sparing surgery were comparable to those of previously reported chemotherapy protocols requiring IV drug administration over several weeks. Further investigation is needed to evaluate the efficacy of this protocol as adjunctive treatment for osteosarcoma and other tumors in dogs.     

Outcome of cats with low-grade lymphocytic lymphoma: 41 cases (1995-2005)

OBJECTIVE: To evaluate factors associated with response to treatment, remission duration, and survival in cats with low-grade lymphoma affecting various organ systems. DESIGN: Retrospective case series. Sample POPULATION: 41 cats with histologically confirmed low-grade lymphocytic lymphoma. PROCEDURES: Medical records and biopsy specimens of cats with histologically confirmed low-grade lymphocytic lymphoma of various organ systems treated with prednisone and chlorambucil between 1995 and 2005 were reviewed. The Kaplan-Meier method was used to estimate remission duration and survival. Factors potentially associated with prognosis were compared. RESULTS: Common clinical signs were weight loss (83%), vomiting (73%), anorexia (66%), and diarrhea (58%). Seventy-eight percent of cats tested had low serum cobalamin concentrations. Lymphoma was confined to the gastrointestinal tract in 68% of cats. Fifty-six percent of cats achieved a complete response to treatment, and 39% achieved a partial response. Five percent of cats had no response. No association was found between any risk factors (including anatomic site) and response to treatment. Partial response was associated with shorter remission duration, compared with complete response; median remission duration was 428 days for cats achieving a partial response, compared with 897 days for cats achieving a complete response. No other factors were associated with remission duration. Overall median survival time was 704 days. No factors were significantly associated with survival time. CONCLUSIONS AND CLINICAL RELEVANCE: Most cats with lymphocytic lymphoma responded to treatment with prednisone and chlorambucil, and most factors evaluated were not associated with outcome.     

MOPP chemotherapy for treatment of resistant lymphoma in dogs: a retrospective study of 117 cases (1989-2000)

The purpose of this retrospective study was to evaluate the efficacy and toxicity of the MOPP chemotherapy protocol (mechlorethamine, vincristine, procarbazine, and prednisone) as a rescue regimen in dogs with lymphoma. One hundred seventeen dogs that had resistance to previously administered chemotherapy were evaluated. Before treatment with MOPP, all dogs received a median of 6 chemotherapy drugs for a median duration of 213 days. Thirty-one percent (36 of 117) had a complete response (CR) to MOPP for a median of 63 days, and 34% (40 of 117) had a partial response (PR) for a median of 47 days. Sixteen percent (19 of 117) had stable disease (SD) for a median of 33 days. Predictors for response to MOPP were not identified. Gastrointestinal (GI) toxicity occurred in 28% (33 of 117) of the dogs, and 13% (15 dogs) required hospitalization. Five dogs developed septicemia, and 2 died as a result. MOPP was an effective treatment for dogs with resistant lymphoma and was well tolerated by the majority of affected dogs.     

Toggle rod stabilization for treatment of hip joint luxation in dogs: 62 cases (2000-2005)

OBJECTIVE: To determine outcome of open toggle rod stabilization in dogs with luxation of the hip joint. Design-Retrospective case series. ANIMALS: 62 dogs. PROCEDURES: Information on signalment, surgical procedure, and postoperative care was obtained from the medical records. A questionnaire was sent to all owners to solicit follow-up information. RESULTS: The distribution for time between luxation and surgery was bimodal, with 24 (39%) dogs examined < or = 2 days after injury and 23 (37%) examined > 7 days after injury. Postoperative complications developed in 16 of the 62 (26%) dogs, with complications developing within 1 week after surgery in 10 of the 16. The most common complication was reluxation, which occurred in 7 dogs. Dogs in which surgery time was < 2 hours were significantly less likely to have a reluxation (2/40 [5%]) than were dogs in which surgery time was > or = 2 hours (5/22 [23%]). When asked to rate current limb function (0 = no lameness and 5 = non-weightbearing lame) a minimum of 6 months after surgery, 23 of 27 (85%) owners indicated a score of 0 or 1. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the present study suggest that toggle rod stabilization is an effective treatment for hip joint luxation in dogs. However, complications, particularly reluxation, were common.     

Nasal and nasopharyngeal lymphoma in cats: 50 cases (1989-2005)

Lymphoma is the most common nasal cavity tumor in cats, yet few reports specifically address the anatomic, immunohistologic, and cytologic features of this neoplasm. Fifty cats were diagnosed with lymphoma at necropsy, via biopsy or by cytology alone. Ten cats displayed multiorgan involvement, and in 2 of these the involvement was limited to the cerebellum and frontal cortex, respectively. Of the tumors, 41 of 50 (82%) were classified as nasal lymphoma, 5 of 50 (10%) were classified as nasopharyngeal lymphoma, and 4 of 50 (8%) involved both nasal and nasopharyngeal tissue. Histologically, all were considered diffuse lymphoid neoplasms and no cats displayed features of follicular lymphoma. Of the 44 cases available for slide review by the pathologist, 40 of 44 (91%) were classified as immunoblastic lymphoma, 2 of 44 (5%) as diffuse large cell, and 1 as diffuse mixed; 1 was unclassified. Of the 45 cats for which immunohistochemical stains were available, 32 were uniformly positive for CD79a, 7 were uniformly CD3 positive, and 6 had a mixed population of CD79a and CD3 cells. Epithelioptropism was exhibited in 4 of 5 (80%) cats in which there was sufficient epithelium present for evaluation. Of those 4, 3 were B-cell and 1 was a granulated T-cell lymphoma. In the 21 cats which nasal cytology was performed, 15 were cytologically diagnosed with lymphoma; the diagnoses in the remaining five cats were inflammatory (n = 4), normal lymphoid tissue (n = 1), or nondiagnostic (n = 1). The most common biochemical abnormalities were panhyperproteinemia in 26/46 (57%) of cats and hypocholesterolemia in 11/46 (24%) of cats.     

Mechlorethamine,vincristine, melphalan and prednisone (MOMP) for the treatment of relapsed lymphoma in dogs

Eighty‐eight dogs with relapsed lymphoma were treated with the MOMP (mechlorethamine, vincristine, melphalan and prednisone) protocol on a 28‐day treatment cycle. The overall response rate (ORR) to the MOMP protocol was 51.1% for a median of 56 days (range 7–858 days). Twelve percent of dogs experienced a complete response for a median of 81 days (range 42–274 days) and 38.6% experienced a partial response for a median of 49 days (range 7–858 days). Dogs with T‐cell lymphoma had an ORR of 55% for a median of 60 days (range 49–858 days) while those with B‐cell lymphoma had an ORR of 57% for a median of 81 days (range 7–274 days) (P = 0.783). The overall survival time for all dogs was 183 days (range 17–974 days). Fifty‐four percent of dogs experienced toxicity with the majority classified as grade I. The MOMP protocol seems well‐tolerated and is an option for dogs with relapsed lymphoma.