Prevalence of nephrotoxicosis associated with a short-term saline solution diuresis protocol for the administration of cisplatin to dogs with malignant tumors: 61 cases (1987-1989).

The study reported here was undertaken to determine the nephrotoxicosis associated with the administration of cisplatin, an antineoplastic agent, to dogs when administered during 6-hour saline solution diuresis. Cisplatin (70 mg/m2 of body surface, IV, every 21 days) was given to 61 dogs with malignant neoplasia with a total of 185 doses in 1 (n = 9 dogs), 2 (n = 26 dogs), 3 (n = 4 dogs), 4 (n = 9 dogs), 5 (n = 2 dogs), and 6 (n = 11 dogs) treatments. The cisplatin was given over a 20-minute period after 0.9% NaCl solution (saline solution) was administered IV for 4 hours at a rate of 18.3 ml/kg of body weight/h. After the cisplatin infusion, saline solution diuresis was continued at the same rate for 2 hours. Before each treatment with cisplatin, dogs were evaluated with at least a physical examination, CBC, determination of serum urea nitrogen concentration, and in most cases, determination of serum creatinine concentration and urine specific gravity. Four of the 61 dogs (6.6%) developed clinically evident renal disease after 2 (1 dog), 3 (2 dogs), and 4 (1 dog) doses of cisplatin were administered. Three of the 4 dogs had preexisting disease of the urinary tract prior to the start of treatment. The survival time in dogs that developed renal disease (median, 145 days; range, 15 to 150 days) was similar to that of all dogs in this study (median, 154 days; range, 30 to 500 days), with 13 dogs still alive at the conclusion of the study.(ABSTRACT TRUNCATED AT 250 WORDS)     

Weekly administration of low-dose doxorubicin for treatment of malignant lymphoma in dogs

Nine dogs with intermediate- or high-grade lymphoma were prospectively entered into a protocol to be given a total of 15 weekly doses of doxorubicin (10 mg/m2 of body surface, IV) in an attempt to eliminate all clinical evidence of neoplasia, with minimal risk of drug toxicity. Eight of these dogs did not complete the protocol because of progression of the disease. The median number of doses administered to dogs that developed progressive disease before the regimen was completed was 5 (range, 2 to 9). Seven dogs achieved partial (n = 5) or complete (n = 2) remission, with median duration of 14 days (range, 7 to 231 days). The dog that was given all 15 weekly treatments remained in complete remission for 231 days. Complete remission that lasted for 14 days was observed in another dog. Toxicosis developed in 3 dogs; signs of toxicosis were generally mild and included colitis (n = 1), vomiting (n = 1), neutropenia (n = 1), and lethargy (n = 1). The lowest neutrophil count (1,876 cells/microliter) was seen in one dog after 7 doses of doxorubicin were given. Doxorubicin at dosage of 10 mg/m2/wk appears to be safe, but is generally ineffective for treatment of lymphoma.     

Evaluation of Single-Agent Mitoxantrone as Chemotherapy for Relapsing Canine Lymphoma

Many chemotherapeutic regimens will induce remission in dogs with lymphoma, but almost all dogs suffer relapse. Mitoxantrone was selected for evaluation as single-agent chemotherapy for relapsing canine lymphoma based on its use in humans undergoing salvage chemotherapy for non-Hodgkin's lymphoma and its tumoricidal effect against canine lymphoma. Dogs entered into study had multicentric lymphoma, and all had been treated solely with a standard combination chemotherapy protocol. At 1st relapse, all dogs were again staged and underwent lymph node biopsy. Mitoxantrone was administered IV at 6 mg/m² every 21 days. Dogs were evaluated for lymphadenopathy before each dose of mitoxantrone. Fifteen dogs were entered into study. The average age (±SEM) of the dogs studied was 7.7 ± 0.91 years, and most dogs were large (mean ± SEM weight, 24.44 ± 2.15 kg). Twelve dogs (80%) had B-cell lymphoma, and 3 had T-cell lymphoma. Dogs were staged IV (n = 12) or V (n = 3). The median duration of chemotherapy before entry into the study was 98 days. Overall median duration of response after mitoxantrone chemotherapy was 21 days. Complete responses were attained in 7 of 15 dogs (47%) with a median response duration of 84 days. Nine of 15 (60%) dogs attained a complete remission with additional chemotherapy after failing mitoxantrone chemotherapy. Mild toxicities were observed after mitoxantrone administration. No adverse reactions were observed during mitoxantrone infusions. The results of this study demonstrate that mitoxantrone, as a single agent, has limited value for dogs with lymphoma at 1st relapse after conventional multidrug chemotherapy.     

Prognostic factors for tumor remission and survival in dogs after surgery for primary lung tumor: 76 cases (1975-1985)

The association of various prognostic factors with remission and survival after the excision of lung tumors was evaluated in 76 dogs. Overall, the median survival time of treated dogs was 120 days; 72% had tumor that underwent remission (median duration of remission, 120 days). Dogs with tumors that underwent remission had significantly (P = 0.001) increased survival time (median, 330 days vs 28 days for dogs with tumors that did not undergo remission). The finding of normal-sized lymph nodes at the time of therapeutic thoracotomy was significantly (P = 0.001) correlated with increased remission probability (85.4% remission rate vs 43.6% in dogs with large lymph nodes). Use of various diagnostic methods to find normal regional lymph nodes before surgery indicated that such finding was significantly (P less than or equal to 0.01) correlated with increased remission duration (median remission duration, 365 days, vs 60 days for tumors in dogs with large lymph nodes), and the finding of normal lymph nodes at the time of surgery was significantly (P less than or equal to 0.01) correlated with increased survival time (median, 345 days, vs 60 days for dogs with large lymph nodes).     

Survival in Dogs with Nasal Adenocarcinoma: 64 Cases (1981–1995)

Case records of 64 dogs with nasal adenocarcinoma were reviewed. The effects of age, gender, tumor stage, presence of metastatic lesions, and treatment method on survival time were examined. Surgery groups included rhinotomy (n = 9), transnasal curettage (n = 29), and no surgery (n = 26). Chemotherapy groups included fluorouracil-cyclophosphamide combination therapy (n = 15), mitoxantrone (n = 7), and no chemotherapy (n = 42). Fifty-three dogs received fractionated cobalt 60 radiation therapy. Surgical procedure, chemotherapy group, and stage of primary tumor were not significantly associated with survival time ( P > .05). Dogs that received radiation therapy had a significantly longer median survival time (424 days) than dogs that did not (126 days) ( P = .0001). The presence of either regional lymph node or pulmonary metastasis was associated with significantly shorter median survival time (109 days) when compared to dogs without metastases (393 days) ( P = .0125). When only dogs that had received radiation therapy were considered, neither surgical treatment nor chemotherapy group was associated with significant changes in median survival time. An alternate staging system emphasizing the presence or absence of metastases is proposed. Key words: Chemotherapy; Metastasis; Radiotherapy.     

Treatment of canine mast cell tumors with CCNU (lomustine)

The efficacy and toxicity of CCNU (1-[2-chloroethyl]3-cyclohexyl-1-nitrosourea) were evaluated in 23 dogs with measurable mast cell tumors (MCT). Twenty-two dogs had cutaneous MCT and 1 dog had an intranasal MCT Nineteen (83%) dogs had biopsy of their original mass performed and 4 (17%) had aspiration cytology of masses. Of the 19 tumors histologically graded, 1 (5%) neoplasm was classified as grade I, 10 (53%) were grade II, and the remaining 8 (42%) were grade III. Dogs were treated with CCNU at a dosage of 90 mg/m2 body surface area every 3 weeks. Response could be evaluated in 19 dogs. Eight of the 19 dogs (42%) had a measurable response to CCNU. One dog had a durable complete response for 440 days. Seven dogs (37%) had a partial response for a median and mean duration of 77 days and 109 days, respectively (range, 21-254 days). Treatment with CCNU resulted in stable disease in 6 dogs (32%) for a median and mean duration of 78 days and 122 days, respectively (range, 42-347 days). The acute dose-limiting toxicity was neutropenia 7 days after administration of CCNU. The median and mean neutrophil counts 7 days after CCNU were 1,452 cells/microL and 1,683 cells/microL, respectively (n = 17). Other toxicoses were uncommon. CCNU should be considered an active agent in the treatment of MCT in dogs.     

Management of humeral and femoral fractures in dogs and cats with linear- circular hybrid external skeletal fixators

Linear-circular hybrid fixators were used to stabilize humeral and femoral fractures in 21 dogs and five cats. Twenty-two of 24 fractures with sufficient follow-up radiographic evaluation obtained union. Time to radiographic union ranged from 25 to 280 days (mean +/- standard deviation [SD] 110+/-69 days; median 98 days). Eleven animals developed minor and two dogs developed major pin and/or wire tract inflammation. Functional outcome was rated as excellent (n=16), good (n=5), and fair (n=3) at the time of final long-term assessment (range 4.5 to 60.0 months; mean +/- SD 28.4+/-15.4 months; median 28.5 months). Follow-up information was unavailable for two animals. Hybrid fixators were useful constructs for stabilization of humeral and femoral fractures, particularly fractures with short, juxta-articular fracture segments.     

PALLIATIVE RADIOTHERAPY FOR CANINE APPENDICULAR OSTEOSARCOMA

Fifteen dogs with appendicular osteosarcoma (presumptive diagnosis, n = 6 dogs; biopsy confirmed, n = 9 dogs) were treated with palliative radiotherapy. Treatment entailed a total of three 10 Gy fractions of ⁶⁰Co radiation delivered over a three week period on days 0, 7 and 21, for a total dose of 30 Gy. Twelve dogs experienced improvement in limb function 7–22 days after the start of treatment. Long term followup was available for nine of the twelve responders. The duration of response was 17–288 days (n = 9 dogs; median = 130 days; mean = 116 days). Response duration did not appear to be related to initial tumor size. Palliative radiotherapy can result in improved limb function in dogs with appendicular osteosarcoma.     

Samarium Sm 153 lexidronam for the palliative treatment of dogs with primary bone tumors: 35 cases (1999-2005)

OBJECTIVE: To evaluate survival times and palliative effects associated with the use of samarium Sm 153 lexidronam in dogs with primary bone tumors. DESIGN: Retrospective case series. ANIMALS: 35 dogs with primary appendicular (n = 32) or axial (3) bone tumors. PROCEDURES: 1 to 4 doses of samarium Sm 153 lexidronam were administered at a rate of 37 MBq/kg (16.8 MBq/lb), IV. Response to treatment, measured by lameness improvement, and survival time were determined. RESULTS: Of the 32 dogs with appendicular tumors, 20 (63%) had an improvement in the severity of lameness 2 weeks after administration of the first dose of radioactive samarium, 8 (25%) had no change in the severity of lameness, and 4 (12%) had a worsening. Overall median survival time was 100 days, with 3 dogs (8.6%) alive after 1 year. Median survival time for the 32 dogs with appendicular tumors was 93 days, with 3 (9.4%) alive after 1 year. This was not significantly different from the median survival time of 134 days for a historical cohort of 162 dogs with appendicular osteosarcoma that underwent amputation as the only treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that samarium Sm 153 lexidronam may be useful in the palliation of pain in dogs with primary bone tumors that are not candidates for curative-intent treatment.     

Antibiotic-responsive histiocytic ulcerative colitis in 9 dogs

Canine histiocytic ulcerative colitis (HUC) is characterized by colonic inflammation with predominantly periodic acid-Schiff (PAS)-positive macrophages. The inflammation results in colonic thickening, ulcerations, and distortion of normal glandular architecture. Resultant clinical signs consist of chronic large bowel diarrhea, tenesmus, and marked weight loss, and the disease frequently results in euthanasia. Conventional therapy consists of some combination of prednisone, azathioprine, sulfasalazine, and metronidazole. Nine dogs (8 Boxers and 1 English Bulldog) with histologic confirmation of HUC were treated with antibiotic therapy (either with enrofloxacin alone or in combination with metronidazole and amoxicillin). Clinical signs, physical examination findings, laboratory abnormalities, and the histologic severity of the disease were evaluated. Four of the 9 dogs had been treated previously with conventional therapy and had failed to respond favorably; then, these dogs were placed on antibiotic therapy (enrofloxacin, n = 1; enrofloxacin, metronidazole, and amoxicillin, n = 3) and had resolution of clinical signs within 3-12 days. Five dogs were treated solely with antibiotic therapy (enrofloxacin, n = 1; enrofloxacin and metronidazole, n = 1; enrofloxacin, metronidazole, and amoxicillin, n = 3), and clinical signs resolved in 2-7 days. Repeated biopsy specimens were obtained from 5 dogs after treatment, and all showed marked histologic improvement. The increase in body weight after treatment was statistically significant (P = .01). Three dogs currently are not on any treatment and have had resolution of clinical signs for up to 14 months. These observations suggest that an infectious agent responsive to antibiotics plays an integral role in the clinical manifestation of canine HUC, and they support the use of antibiotics in its treatment.     

Retrospective evaluation of partial parenteral nutrition in dogs and cats

The purpose of this retrospective study was to evaluate the use of partial parenteral nutrition (PPN) in dogs and cats. The medical records of all dogs and cats receiving PPN between 1994 and 1999 were reviewed to determine signalment, reasons for use of PPN, duration of PPN administration, duration of hospitalization, complications, and mortality. Complications were classified as metabolic, mechanical, or septic. One hundred twenty-seven animals (80 dogs and 47 cats) were included in the study, accounting for 443 patient days of PPN. The most common underlying diseases were pancreatitis (n = 41), gastrointestinal disease (n = 33), and hepatic disease (n = 23). Median time of hospitalization before initiation of PPN was 2.8 days (range, 0.2-10.7 days). Median duration of PPN administration was 3.0 days (range, 0.3-8.8 days). Median duration of hospitalization was 7 days (range, 2-20 days). In the 127 animals receiving PPN, 72 complications occurred. These included metabolic (n = 43), mechanical (n = 25), and septic (n = 4) complications. The most common metabolic complication was hyperglycemia (n = 19), followed by lipemia (n = 17) and hyperbilirubinemia (n = 6). Most complications were mild and did not require discontinuation of PPN. Ninety-three (73.2%) of the 127 patients were discharged. All 4 animals with septic complications were discharged from the hospital. The presence, type, and number of complications did not impact the duration of hospitalization or outcome. However, animals that received supplemental enteral nutrition survived more often than those receiving PPN exclusively. Although PPN seems to be a relatively safe method of providing nutritional support, future studies are warranted to determine its efficacy.     

Zinc intoxication in dogs: 19 cases (1991-2003)

OBJECTIVE: To determine physical examination findings, clinicopathologic changes, and prognosis in dogs with zinc toxicosis. DESIGN: Retrospective case series. ANIMALS: 19 dogs with zinc toxicosis. PROCEDURES: Medical records from 1991 through 2003 were searched for animals with a diagnosis of zinc toxicosis. Information concerning signalment, body weight, historical findings, initial owner complaints, physical examination findings, clinicopathologic findings, blood zinc concentrations, source of zinc, treatments given, duration of hospital stay, and outcome was collected. RESULTS: Records of 19 dogs with zinc toxicosis were reviewed.The most common historical findings were vomiting (n = 14) and pigmenturia (12). The most common clinicopathologic findings were anemia (n = 19) and hyperbilirubinemia (12). Median age was 1.3 years, and median weight was 5.6 kg (12.3 lb). The prognosis was favorable, with 17 dogs surviving after a median hospital stay of 2 days. CONCLUSIONS AND CLINICAL RELEVANCE: Hemolytic anemia as a result of zinc toxicosis appeared to affect young small-breed dogs more frequently than older large-breed dogs. The prognosis with treatment is good, and most affected dogs had a short hospital stay.     

ULTRASONOGRAPHIC AND CLINICOPATHOLOGIC FINDINGS IN 21 DOGS WITH INTESTINAL ADENOCARCINOMA

In a retrospective study of 21 dogs with intestinal adenocarcinoma, the signalment, clinical presentation, laboratory findings, ultrasonographic features, treatment, and outcome were reviewed. Anorexia (n = 16), vomiting (n = 15), diarrhea (n = 10), and weight loss (n = 9) were the most common clinical signs reported. Ultrasonographic features that were evaluated included location, length, wall thickness, echogenicity, regional motility, layering, regional lymphadenopathy, and fluid accumulation proximal to the lesion site. All lesions were transmural and associated with complete loss of wall layering. Maximum wall thickening at the lesion site ranged from 7 to 17 mm (median 12 mm, mean 11.9 mm). Most of the dogs had a lesion measuring from 23 to 63 mm in length, (median 40 mm, mean 42 mm). Most intestinal lesions were poorly echogenic and had an irregular lumen. Fluid accumulation proximal to the lesion site was identified in 17 of 21 dogs, and in 13 of 17 dogs the fluid accumulation was considered moderate to severe. Regional lymphadenopathy and/or nodular mesentery/omentum were noted in 12 of 21 dogs. The tumor was located in small intestine for 15 dogs and in the colon for the remaining 6 dogs. Fifteen dogs were treated by surgical resection of the intestinal mass. Their median survival time was 233 days. Only gender appeared to influence survival. Female dogs lived a median of 28 days, whereas male dogs lived a median of 272 days.     

How often do veterinarians assess the bodyweight and body condition of dogs?

Measurements of bodyweight and body condition are useful for monitoring the state of health of companion animals, but the frequency with which they are used by veterinarians in general practice is not known. Information derived from 148 dogs was analysed to determine how often their bodyweight and body condition had been assessed. Bodyweight had been measured at least once in 103 (70 per cent) of the dogs. The median time between the measurements was 114 days (range five days to 6.8 years), and the median number of consultations per measurement was four (range one to 44). Body composition had been assessed subjectively in 43 (29 per cent) of the dogs. The median time between the assessments was 216 days (21 days to 6.26 years) and the median number of consultations per assessment was seven (two to 43). A recognised body condition score had been assessed in only one dog on one occasion.     

Geographical, clinical, clinicopathological and radiographic features of canine angiostrongylosis in Irish dogs: a retrospective study

Background

Angiostrongylus vasorum infection is associated with high morbidity and mortality in dogs. Although recognised in Ireland, there are no large series of cases reported. The aim of this retrospective study was to identify pertinent clinical and geographical features in Irish dogs.

Results

The case records of dogs presenting to the University College Dublin Veterinary Hospital (1999-2010) were reviewed. A contemporaneous review of external faecal parasitology and post mortem submissions was also performed. A positive diagnosis of angiostrogylosis was identified in 49 dogs including 24 clinical, 10 post mortem and 15 external faecal sample cases. The majority (n = 44 (90%)) resided on the East Coast.In the clinical cases, the median age was 20 months, 29% of cases were older than 2 years. Clinical features included cardiorespiratory (63%), coagulopathic (71%) and other (63%) signs. Cough (n = 10), dyspnoea (n = 5) and tachypnoea (n = 3) were the most common cardiorespiratory abnormalities. Of animals with evidence of coagulopathy, excessive haemorrhage from a wound (n = 5), airway haemorrhage (n = 9), epistaxis (n = 3), haematoma (n = 4), suspected haemarthrosis (n = 3), neurological signs (n = 2) and haematuria (n = 1) were found. Ten dogs were anaemic, of which two were severe (haematocrit ≤ 0.20 L/L). Ten animals had thrombocytopenia, with four severely affected (≤50 × 10⁹/L). PT and APTT values were prolonged in 4 (24%) of 17 and a BMBT was prolonged in 5 (63%) of 8 cases. Vague signs of exercise intolerance (n = 6), lethargy (n = 6) and weakness (n = 2) were identified, with two (8%) animals having only these signs. In one animal the diagnosis appeared to be incidental. Thoracic radiographs (n = 19) identified abnormalities in 100% of cases. Four (17%) animals died before or within 24 hours of treatment and post mortem examinations confirmed angiostrongylosis. Fenbendazole was administered in 19 cases, 18 (95%) recovered. Two animals were euthanised, one which failed to respond to therapy and another in which an ante mortem diagnosis had not been made.

Conclusions

Angiostrongylosis is not uncommon in Ireland, is not confined to young dogs or the East Coast and can present with a wide variety of signs, particularly coagulopathic, respiratory or neurological signs.     

Clinical factors determining the efficacy of urinary bladder tumour treatments in dogs: surgery, chemotherapy or both?

In a study of 44 canine patients suffering from histopathologically proven urinary bladder tumour with a high incidence of transitional cell carcinoma (TCC) (n = 35), a close relationship was found either between the disease-free period and the age (r = -0.40) of animals or between the survival times and the age (r = -0.62) of animals after treatment. In addition to the dog breeds known to be prone to have urinary bladder tumour, we found an additional potentially sensitive breed, the Hungarian Vizsla. The median survival times obtained by the applied treatment types were as follow: 'surgery and chemotherapy' (n = 8/44) 475 days, 'surgery alone' (n = 19/44) 240 days, 'chemotherapy alone' (n = 7/44) 31 days, and 'no treatment' (n = 10/44) 7 days (P < 0.001). According to the findings, chemotherapy combined with surgery completed in time is the most effective protocol in the treatment of urinary bladder tumour cases in dogs. A rational and more effective procedure for the assessment and treatment of urinary bladder tumour cases is presented.     

Efficacy of doxorubicin‐based chemotherapy for non‐resectable canine subcutaneous haemangiosarcoma

Eighteen dogs with measurable subcutaneous haemangiosarcoma (SQHSA) were treated with doxorubicin‐based chemotherapy. Response assessment was evaluated and compared using World Health Organization (WHO), Response Evaluation Criteria in Solid Tumours (RECIST) and tumour volume criteria. The overall response rate for all dogs was 38.8% using WHO criteria, 38.8% using RECIST criteria and 44% using tumour volume criteria. One dog had a complete response. The median response duration for all dogs was 53 days (range 13–190 days). Four dogs had complete surgical excision after neoadjuvant chemotherapy. The median progression‐free interval for dogs with complete surgical excision after neoadjuvant chemotherapy was significantly longer than those not having surgical excision (207 days versus 83 days, respectively) (P = 0.003). No significant difference in metastasis‐free interval or survival time was found between the groups. Doxorubicin‐based chemotherapy appears to be effective for non‐resectable canine SQHSA, although the response duration is relatively short.     

Carcinoma of the apocrine glands of the anal sac in dogs: 113 cases (1985-1995)

OBJECTIVE: To characterize the signalment, clinical signs, biological behavior, and response to treatment of carcinoma of the apocrine glands of the anal sac in dogs. DESIGN: Retrospective study. ANIMALS: 113 dogs with histologically confirmed carcinoma of the apocrine glands of the anal sac. PROCEDURE: Data on signalment, clinical signs, and staging were reviewed and analyzed along with treatment modality for potential association with survival time. RESULTS: Sex distribution was approximately equal (54% female, 46% male). One hundred four dogs underwent treatment consisting of surgery, radiation therapy, chemotherapy, or multimodal treatment. Median survival for treated dogs was 544 days (range, 0 to 1,873 days). Dogs treated with chemotherapy alone had significantly shorter survival (median, 212 days) than those receiving other treatments (median, 584 days). Dogs not treated with surgery had significantly shorter survival (median, 402 days) than those that underwent surgery as part of their treatment (median, 548 days). Dogs with tumors > or = 10 cm2 had significantly shorter survival (median, 292 days) than dogs with tumors < 10 cm2 (median, 584 days). Hypercalcemia was identified in 27% (n = 29) of dogs, and those dogs had significantly shorter survival (median, 256 days), compared with those that were normocalcemic (median, 584 days). Dogs with pulmonary metastasis had significantly shorter survival (median, 219 days) than dogs without evidence of pulmonary metastasis (median, 548 days). CONCLUSIONS AND CLINICAL RELEVANCE: Unlike most previous reports, this study revealed an approximately equal sex distribution, and results suggest a more favorable prognosis.     

Evaluation of ifosfamide for treatment of various canine neoplasms

lfosfamide (3-[2-chloroethyl]-2[(2 chloroethyl)amino]tetrahydro-2H-1,3,2-oxazaphosphorine 2-oxide) is an alkylating agent with a broad spectrum of antitumor activity. The efficacy and toxicity of ifosfamide were evaluated in 72 dogs with spontaneously occurring tumors. Forty dogs (56%) had lymphoma, 31 (43%) had sarcomas, and 1 had a metastatic carcinoma. Five dogs received ifosfamide at dosages <350 mg/m2 IV. Neither toxicity nor response were observed, and the remaining dogs received ifosfamide at 350 mg/m2 (n = 18) and 375 mg/m2 body surface area IV (n = 49). Saline diuresis and the thiol compound mesna were used to prevent urothelial toxicity. Fifty-two dogs had measurable tumors and could be evaluated for response. Complete responses were seen in 1 dog with metastatic leiomyosarcoma of the urinary bladder and in 1 dog with metastatic cutaneous hemangiosarcoma. One dog with lymphoma had a partial response for 112 days. Six dogs with splenic hemangiosarcoma received ifosfamide postsplenectomy and their median survival time was 147 days. The acute dose limiting toxicity was neutropenia 7 days after administration of ifosfamide. The median and mean neutrophil counts 7 days after ifosfamide at 350 mg/m2 were 2,035 cells/microL and 4,773 cells/microL, respectively (n = 12). The median and mean neutrophil counts 7 days after ifosfamide at 375 mg/m2 were 2,500 cells/microL and 3,594 cells/microL, respectively (n = 37). No dog developed clinical or microscopic evidence of hemorrhagic cystitis. Ifosfamide appears safe to use in tumor-bearing dogs, and the evaluation of combination chemotherapy protocols that include ifosfamide should be considered.