Cytotoxic T-lymphocyte responses to subcellular antigens are enhanced when antigens are presented on cell-sized silica microbeads called large multivalent immunogens (LMIs). LMIs prepared with tumour cell membrane fragments have induced partial remissions in humans with melanoma and renal cell carcinoma. The purpose of this phase I study was to evaluate the safety of LMIs, prepared with autologous lymphoma cell membranes, along with subcutaneous interleukin 2 (IL-2) and granulocyte-macrophage colony stimulating factor (GM-CSF) in dogs with untreated B-cell lymphoma. After lymph node excision and induction chemotherapy, five dogs were vaccinated with three weekly doses of LMI alone; five with LMI and subcutaneous IL-2 and five with LMI, IL-2 and GM-CSF. No significant toxicity was noted, treatment did not adversely affect disease-free interval and half of the dogs showed measurable delayed-type hypersensitivity reactions to intradermal challenge with LMI, suggesting specific cell-mediated immunity.

Sarcoma of the prostate is a rare neoplasm that accounts for 0.1–0.2% of all primary prostatic malignancies in humans.5,9 Most prostate sarcomas (67%) are of muscle origin, with rhabdomyosarcoma occurring in children and leiomyosarcoma predominating in adults.11 In the dog, prostatic leiomyosarcoma is also rare; only 4 cases have been documented.4,6 In 1 report, a single leiomyoma but no leiomyosarcomas were noted among 23 canine prostatic tumors.8 The WHO Bulletin makes no specific reference to prostatic leiomyosarcoma in animals other than to state that poorly differentiated spindle cell tumors of the prostate could not be further classified.2 In this report, we document a primary prostatic leiomyosarcoma with metastasis in an adult dog. The histomorphologic diagnosis was verified using immunohistochemical techniques. A 10-year-old intact male Boxer was referred to the Veterinary Teaching Hospital, College of Veterinary Medicine, University of Minnesota, with a history of stranguria and urinary incontinence of 2 days duration. Physical examination revealed a distended urinary bladder. Clinicopathologic studies revealed a mature neutrophilic leukocytosis (25.7 3 103 neutrophils/ml; reference range, 2.1–11.2 3 103 neutrophils/ml),a increased serum creatinine (3 mg/dl; reference range, 0.5–1.5 mg/dl),b increased serum urea nitrogen (49 mg/dl; reference range, 7.0–28 mg/dl),b and hyperglycemia (213 mg/dl; reference range, 77–116 mg/dl).b A catheter was passed into the urinary bladder, and an estimated 2.5 liters of urine was removed. Urinalysis revealed dilute urine (1.016 urine specific gravity) and pyuria (10–12 white blood cells [WBC]/high-power field [HPF]; reference range, ,5 WBC/HPF). Abdominal radiographs revealed a large mid abdominal mass and a smaller calcified mass in the caudal abdomen. The dog died 12 hours after being hospitalized. Necropsy revealed gastric dilatation/volvulus and a distended urinary bladder. The prostate was asymmetrical, firm, and 7.0 3 5.0 3 3.0 cm. The cut surface revealed a pale capsular region and a mottled beige to tan parenchyma with multiple cysts 0.5–1.0 cm in diameter (Fig. 1). A large periprostatic cyst, 11.0 3 9.0 3 7.0 cm, was situated at the base of the prostate dorsocaudal to the urinary bladder. The cyst wall was mineralized, and the lumen contained many hard spike-like concretions and thick brown fluid. The left ureter was markedly dilated, about five times that of the right ureter, and multiple firm nodules, 0.3–0.5 cm in diameter, were scattered along the serosal surface. The urinary bladder was

OBJECTIVE:To determine age, breed, sex, body condition score, and diet of dogs and cats examined at private veterinary practices in the United States during 1995, and estimate prevalences of the most common disorders for these animals.DESIGN:Cross-sectional study.ANIMALS:31,484 dogs and 15,226 cats examined by veterinary practitioners at 52 private veterinary practices.PROCEDURE:Information on age, breed, sex, body condition score, diet, and assigned diagnostic codes were collected electronically from participating practices and transferred to a relational database. Prevalence estimates and frequencies for population description were generated using statistical software.RESULTS:Dental calculus and gingivitis were the most commonly reported disorders. About 7% of dogs and 10% of cats examined by practitioners during the study were considered healthy. Many conditions were common to both species (e.g., flea infestation, conjunctivitis, diarrhea, vomiting). Dogs were likely to be examined because of lameness, disk disease, lipoma, and allergic dermatitis. Cats were likely to be examined because of renal disease, cystitis, feline urologic syndrome, and inappetence.CLINICAL IMPLICATIONS:Results can be used by veterinary practitioners to better understand and anticipate health problems of importance in cats and dogs they examine and to better communicate with clients regarding the most prevalent disorders in cats and dogs.

OBJECTIVE:To compare efficacy and toxicity of 2 multiagent chemotherapeutic protocols similar in all respects except that 1 incorporated dactinomycin and the other incorporated doxorubicin for treatment of dogs with malignant lymphoma.DESIGN:Randomized controlled trial.ANIMALS:45 dogs with malignant lymphoma.PROCEDURE:Dogs were randomly assigned to a doxorubicin or dactinomycin treatment group. Time to first remission, duration of first remission, survival time, and prevalence of toxicoses, particularly number of episodes of dose-limiting neutropenia and gastrointestinal toxicoses, were compared between groups.RESULTS:37 dogs received at least 1 dose of doxorubicin (21 dogs) or dactinomycin (16). Median time to first remission was not significantly different between groups, but median duration of first remission and median survival time were significantly longer for dogs in the doxorubicin treatment group than for dogs in the dactinomycin treatment group. Number of dogs that died, number of episodes of dose-limiting neutropenia, and number of episodes of gastrointestinal toxicoses were not significantly different between groups.CLINICAL IMPLICATIONS:A multiagent chemotherapeutic protocol incorporating doxorubicin was significantly more effective in dogs with malignant lymphoma than a similar protocol incorporating dactinomycin. Despite the lower cost and lack of cardiotoxicity, dactinomycin is not an equivalent substitute for doxorubicin in the initial treatment of dogs with malignant lymphoma.

Although interleukin 2 (IL-2) has been associated with modest anti-tumour responses in man, treatment-related toxicity has limited its widespread use. The local delivery of liposomal formulations of interleukin 2 to the lung as aerosols has been demonstrated to be non-toxic, biologically active, and associated with regression of spontaneous pulmonary metastases in dogs. This study was undertaken to evaluate the physical and biological characteristics of nebulized interleukin 2 liposomes. The aerosol droplet size distribution and the physical stability of interleukin 2 liposomes were examined in-vitro using an Andersen cascade impactor and studies of liposome entrapment of interleukin 2 before and after nebulization. The biological stability of interleukin 2 liposomes after nebulization was demonstrated using the CTLL-2 bioassay for interleukin 2. In-vivo studies of pulmonary biodistribution and clearance of inhaled technetium (99mTc)-labelled interleukin 2 liposomes were undertaken in a normal dog. Aerosols of free interleukin 2 and of interleukin 2 liposomes were compared in both in-vitro and in-vivo experiments. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) of interleukin 2 liposomes were 1.98 microns and 2.02, respectively. Independent analysis of aerosol particle-size distribution using the constitutive components of the interleukin 2 liposomes (interleukin 2: lipid:HSA) demonstrated a close correlation of size distributions (r = 0.9445; P < 0.001). The entrapment of interleukin 2 in liposomes was 93 +/- 4.3% before nebulization and 90 +/- 8.9% after. After delivery to an anaesthetized dog, interleukin 2 liposome aerosols were deposited evenly throughout the lung (mean +/- s.d. central lung-to-peripheral lung deposition was 1.12 +/- 0.03). After approximately 24 h inhalation, interleukin 2 liposomes were retained within the lung and were taken up in part by the spleen. The results of this study are indicative of the stability of this interleukin 2 liposome formulation to nebulization. Such nebulization might be an attractive immunotherapeutic strategy for treatment of pulmonary metastases and primary lung cancers.

BACKGROUND:Systemic in vivo toxicity of interleukin-2 (IL-2) has been problematic. Antineoplastic activity of IL-2 has been modest. The authors have previously demonstrated the biologic activity and safety of aerosols of IL-2 liposomes in normal dogs. They now report objective regression of naturally occurring pulmonary metastases in dogs after 1 month of nebulized IL-2 liposome therapy. METHODS:Dogs with pulmonary metastases (n = 7) and primary lung carcinoma (n = 2) were treated with aerosols of IL-2 liposomes. Response to therapy was monitored with serial chest radiographs. Effector populations, collected by bronchoalveolar lavage (BAL) and from heparinized whole blood, were assessed for cell type, immunophenotype, and tumor cytolytic activity. Immunogenicity of human IL-2 and human serum albumin (HSA) in dogs was assessed by immunofluorescence assay. RESULTS:Two of four dogs with metastatic pulmonary osteosarcoma had complete regression of metastases; the regression remained stable for more than 12 and more than 20 months, respectively. One of two dogs with lung carcinoma had stabilization of disease for more than 8 months; the other had disease progression. Toxicity was minimal. BAL cell numbers increased more than fourfold (P = 0.01) and included significantly greater proportions and total numbers of eosinophils (P = 0.006) and lymphocytes (P = 0.008). Mean BAL effector lytic activity was significantly greater after 15 days of IL-2 liposome inhalation compared with pretreatment activity (P = 0.01); however, mean BAL lytic activity decreased after 30 days and was no longer significantly greater than pretreatment BAL lytic activity. No allergic reactions were associated with inhaled IL-2 liposome therapy. Canine antibodies against human IL-2 and HSA were detected in all dogs. CONCLUSIONS:Pet dogs with naturally occurring pulmonary metastases and primary lung carcinomas accepted inhalation treatments easily. Nontoxic and effective treatment of pulmonary metastases of osteosarcoma is possible with nebulized IL-2 liposomes.

OBJECTIVE:To characterize the frequency, clinical signs, biologic behavior, and response to treatment of tumors of the ear canal in dogs and cats.DESIGN:Retrospective analysis of medical records.ANIMALS:Medical records of 81 dogs (48 malignant tumors, 33 benign tumors) and 64 cats (56 malignant tumors, 8 benign tumors).PROCEDURE:Data were analyzed for cats and dogs with malignant tumors, and risk factors were analyzed for their potential impact on survival time.RESULTS:Malignant tumor types most commonly reported included ceruminous gland adenocarcinoma, squamous cell carcinoma, and carcinoma of undetermined origin. Median survival time of dogs with malignant aural tumors was > 58 months, whereas that of cats was 11.7 months. A poor prognosis was indicated by extensive tumor involvement (dogs) and by neurologic signs at time of diagnosis, diagnosis of squamous cell carcinoma or carcinoma of undetermined origin, and invasion into lymphatics or blood vessels (cats).CLINICAL IMPLICATIONS:Malignant tumors of the ear canal in dogs and cats have a propensity for local invasion, but tend not to metastasize. Squamous cell carcinoma and carcinoma of undetermined origin were the most locally aggressive tumors. Malignant tumors of the ear canal are best managed by aggressive surgical excision. Radiotherapy may be useful when tumors cannot be completely removed.

Administration of interleukin 2 (IL-2) has been associated with potent in vitro antitumor effects. However, systemic in vivo toxicity has been problematic. Because local delivery and liposomal formulations of IL-2 may improve the therapeutic index, we used dogs to evaluate and compare immunological activation of inhaled free IL-2 and IL-2 liposomes. Twelve normal dogs were treated with nebulized IL-2 formulations and controls for 2 to 7 weeks. Cellular immune activation of peripheral blood mononuclear cells and bronchoalveolar lavage (BAL) effector leukocytes against tumor cell lines, changes in effector leukocyte populations, and toxicity were monitored. No toxicity was seen with either aerosolized free IL-2 or IL-2 liposomes. Free IL-2 given at 0.5 x 10(6) Biologic Response Modifier Program (BRMP) units twice daily to dogs resulted in increased peripheral blood mononuclear cell activation compared with saline control-treated dogs. IL-2 liposomes given at 0.5 x 10(6) BRMP units twice daily to dogs resulted in significantly increased BAL effector activation compared with IL-2 liposomes given at 1.0 x 10(6) BRMP units once daily (P = 0.018) and empty liposome controls (P = 0.016). The BAL leukocyte cell count was increased significantly after inhalation of IL-2 liposomes versus inhalation of free IL-2 (P = 0.011). BAL effector populations included a greater proportion and total number of lymphocytes and eosinophils after treatment with IL-2 liposomes. Nontoxic activation of pulmonary immune effectors for the treatment of cancer in the lung may be possible using nebulized IL-2 liposomes.

Fifty-four dogs with primary tumors of the rib were evaluated. Thirty-four dogs had osteosarcomas, 15 dogs had chondrosarcomas, three dogs had hemangiosarcomas, and two dogs had fibrosarcomas. Forty-nine dogs had en bloc excision. Within the osteosarcoma group, nine animals received postoperative adjuvant chemotherapy. These animals had significantly longer median disease-free intervals (225 days) and median survival times (240 days) than dogs with osteosarcoma treated by surgery alone (median disease-free interval, 60 days; median survival, 90 days). Chondrosarcoma had a better prognosis (median disease-free interval, 1,080 days; median survival, 1,080 days) than osteosarcoma, hemangiosarcoma, or fibrosarcoma of the rib. Age, weight, sex, number of ribs resected, tumor volume, and total cisplatin dose did not influence survival nor disease-free interval.

Serum and seminal plasma concentrations or activities of acid phosphatase (AP), prostate specific antigen (PSA), and canine prostate specific esterase (CPSE) were measured in normal dogs, dogs with benign prostatic hyperplasia (BPH), dogs with bacterial prostatitis, and dogs with prostatic carcinoma to determine if these assays would be of value in differentiating dogs with prostatic carcinoma from normal dogs, and dogs with other prostatic disorders. In addition, tissue sections of prostatic adenocarcinomas were stained with antiprostatic AP, anti-CPSE, and anti-PSA antibodies to determine if these would be suitable immunohistochemical markers of prostatic carcinoma. Prostate-specific antigen was not detected in canine serum or seminal plasma. Serum and seminal AP activities did not differ significantly between normal dogs and those with prostatic diseases, or among dogs with different prostatic disorders. Serum CPSE activities were significantly higher in dogs with BPH than in normal dogs. Mean serum CPSE activities in dogs with BPH, bacterial prostatitis, and prostatic carcinoma were not significantly different from each other. Slight to moderate immunohistochemical staining of canine prostatic adenocarcinomas was noted for prostatic AP and PSA; most tumors did not stain for CPSE. These results show that proteins of prostatic origin appear in the serum of dogs as a result of prostatic pathology, especially BPH. Canine prostatic adenocarcinoma does not appear to be associated with significant increases in CPSE or AP activities, possibly because of down-regulation of these enzymes by prostatic carcinoma cells. It is also possible that failure to detect significant differences resulted from limited statistical power for some groups and pairwise analyses because of the small number of dogs evaluated.

A 9-year-old castrated male domestic shorthair cat with dysuria, anorexia, vomiting, and lethargy was admitted to the veterinary teaching hospital. A large, firm mass was palpable in the ventral cervical region. Hypercalcemia, azotemia, and nonregenerative anemia were evident on serum biochemical analysis and CBC, and multiple uroliths were detected by abdominal radiography. At necropsy, light microscopy of the ventral cervical mass revealed a parathyroid adenocarcinoma. Light microscopy of sections of the kidneys revealed multifocal, chronic, lymphocytic/plasmacytic, tubulointerstitial nephritis, as well as moderate multifocal acute tubular necrosis. On quantitative analysis, the uroliths were composed of calcium oxalate. Determination of serum calcium concentration is indicated in cats with calcium oxalate urolithiasis to aid in detection of primary hyperparathyroidism.

A flow cytometric platelet immunofluorescence assay (FC-PIFA) was compared with a previously developed microscopic platelet immunofluorescence assay (MI-PIFA) for detection of circulating platelet antibody. Both assays were performed on serum from 10 healthy dogs with normal platelet count, and on serum from 27 thrombocytopenic dogs-18 had primary immune-mediated thrombocytopenia (IMT), and 9 had IMT in addition to other immune-mediated disease (secondary IMT). Both assays yielded negative results for all control dogs. The MI-PIFA and FC-PIFA results were in agreement in 23 dogs with IMT (14 positive and 9 negative). There was linear correlation between MI-PIFA scores and FC-PIFA results (r = 0.873). Positive results were obtained for 55.5% of the dogs with suspected IMT using the MI-PIFA, compared with 67%, using the FC-PIFA; however, the dif ference was not statistically significant. Use of fresh or frozen fixed donor platelets as the antigen source yielded similar results in the FC-PIFA.

The effect of antiplatelet antibody on in vitro platelet function was investigated in 15 dogs with immune-mediated thrombocytopenia (ITP). Platelet aggregation was assessed after addition of serum from healthy dogs (n = 5) or dogs with ITP (n = 15) to platelet-rich plasma from a healthy donor dog. The aggregation responses to adenosine diphosphate, thrombin, and collagen/epinephrine were measured as the maximum aggregation observed after 2 minutes. In 13 of 15 dogs with ITP, maximal aggregation was significantly inhibited in response to ADP, thrombin, or collagen/epinephrine. The slope of the aggregation curve was decreased after addition of serum from 9 of 15 patients. A polyclonal rabbit anti-dog platelet antiserum induced inhibition of aggregation with all 3 agonists. Serum from control dogs neither inhibited nor activated platelet aggregation. Aggregation experiments were repeated with all 3 agonists after addition of patient immunoglobulin (Ig)G or IgG from a healthy dog to platelet-rich plasma. The IgG fraction from 9 of 10 dogs with ITP suppressed platelet aggregation. The IgG fraction from polyclonal rabbit anti-dog platelet antiserum inhibited platelet aggregation with all agonists. These results suggest that many canine ITP patients have circulating antibodies that, in addition to causing platelet destruction, may cause platelet dysfunction.

An indirect platelet immunofluorescence assay (PIFA) was developed for detection of circulating antiplatelet antibody in dogs with suspected immune-mediated thrombocytopenia (ITP). The PIFA was performed on 10 healthy dogs with normal platelet counts; 76 thrombocytopenic dogs, 20 of which were suspected of having ITP; and 18 dogs with other diseases and normal platelet counts. All normal dogs and negative test results. Fourteen (70%) of 20 dogs suspected of having ITP had positive test results. Fifteen of the remaining 56 thrombocytopenic dogs had positive test results, 9 had cancer and 6 had other immune-mediated diseases including systemic lupus erythematosus (SLE). In this study, the PIFA assay seemed to be more sensitive (70%) than the megakaryocyte immunofluorescence assay (41%) in the diagnosis of ITP. Of the 9 PIFA-positive dogs with neoplasia, 6 had lymphoproliferative disorders. The PIFA was positive in 5 of 18 diseased dogs with normal platelet counts. There was an inverse relationship between the platelet count and the intensity of fluorescence in the PIFA-positive dogs. We conclude that the PIFA is a sensitive screening method for detecting circulating antiplatelet antibody.

In a retrospective multiinstitutional survey of 26 dogs with primary bone tumors of the thoracic wall, 14 had osteosarcomas (OSA), nine chondrosarcomas (CSA), and three hemangiosarcomas (HSA). An accurate diagnosis was obtained from excisional or incisional biopsy when a large volume of tissue was collected, but less often when a small volume of tissue was obtained. Curative treatment was attempted by excision in 16 and by excision, radiation, and chemotherapy in one. Based on Kaplan-Meyer estimates of survival distribution, median survival time after surgery with curative intent was eight weeks overall, five weeks for OSA, and 15 weeks for CSA. Postoperative survival time was significantly longer for CSA than for OSA (p<0.05). The three with HSA survived 2, 16, and 112 weeks after surgery. From this sample, OSA appears to be the most common tumor of the thoracic wall, accounting for about 60% of the tumors, and its biological behavior is similar to OSA of appendicular origin. Chondrosarcoma appears to be the second most common, accounting for approximately 34% of rib tumors compared to 10% of appendicular bone tumors. Large-volume biopsy specimens are necessary to distinguish OSA from CSA and HSA.

Prostatic hemangiosarcoma (HS) appears to be rare in the dog. In 3 of 4 previously reported cases, the prostate was involved via metastasis. For 1 dog, the primary tumor presumably was located in the prostate gland, but no details were given. The present report documents what we believe is a primary HS of the prostate in a dog that presented with clinical signs of urinary tract disease. The prostate tumor and metastases had microscopic features of a poorly differentiated HS, and the diagnosis was confirmed by immunohistochemistry. An 11-year-old male Miniature poodle was admitted to a veterinary hospital because of straining to urinate and defecate and passing “ribbon-like” feces for approximately 1 month. Physical examination revealed prostatomegaly. The dog was castrated and given an injection of 0.25 mg of estradiol cypionate intramuscularly. Clinical signs persisted, and the dog was referred to the University of Minnesota Veterinary Teaching Hospital (UMVTH) 6 days after castration. Physical examination revealed a thin dog with prostatomegaly and a very distended urinary bladder. A complete blood count revealed a normochromic normocytic anemia (PCV = 23%, normal > 37%) without significant regenerative response. The dog was catheterized without difficulty, and 225 ml of yellow urine were removed. A urinalysis was consistent with urinary tract infection, and a urine culture revealed Klebsiella pneumoniae and Proteus mirabilis (> 10 colony forming units/ml). Prostatomegaly was identified on abdominal radiographs. A sonogram revealed diffuse prostatic hyperechogenicity with irregular multifocal hypoechoic masses. A prostatic biopsy was performed with a Tru-Cut biopsy needle via a perineal approach. Microscopic examination revealed neoplastic polyhedral and spindle cells of uncertain tissue type. Following a course of radiation therapy, which failed to shrink the prostate, the dog was euthanized. At necropsy, the prostate gland protruded from the cranial rim of the pelvis and was tightly adhered to the pelvic canal, especially on the right side. Although both lobes of the prostate were enlarged, the right lobe was more severely affected. The prostate was 10.5 x 6.0 x 4.0 cm and weighed 125 g. Transverse sections of the prostate revealed a large yellow core encircled by a rim of red tissue. Reddish-yellow tissue was present within the right obturator foramen. Soft red and white nodules 0.7 cm and 4 cm in diameter were found in the left and right medial thigh muscles, respectively.

The medical records of 31 dogs diagnosed with prostatic carcinoma at the teaching hospital between January 1970 and October 1987 were reviewed to determine whether gender status had an effect on the clinical features or biologic behavior of the disease. The only significant difference between sexually intact and castrated dogs was increased prevalence of pulmonary metastasis in castrated dogs.

Hypercalcemia was associated with a spindle cell thymoma in a six-year-old male English springer spaniel. Surgical excision of the thymoma caused resolution of the hypercalcemia. Pathophysiology of thymoma and its clinical behavior as well as hypercalcemia as a paraneoplastic syndrome are discussed.