Frequency and severity of mastocytemia in dogs with and without mast cell tumors: 120 cases (1995-1997).

OBJECTIVE: To elucidate frequency of detection on blood smears and severity on quantitative buffy coat evaluation of mastocytemia between dogs without mast cell tumors (MCT) and dogs that had MCT, and to expand the list of diseases associated with mastocytemia in dogs without MCT. DESIGN: Retrospective study. ANIMALS: 94 dogs without MCT and 26 dogs with MCT. PROCEDURE: Medical records of all dogs with mast cells detected on blood or buffy coat smears during a 2-year period were reviewed. Dogs with mastocytemia were grouped by disease into dogs with MCT and dogs without MCT. Twenty-five of the dogs without MCT that had mast cells detected on blood smears also had evaluations of buffy coat smears. Quantitative buffy coat results of the 25 dogs without MCT were compared with those of the 26 dogs with MCT. RESULTS: 95.5% of blood smears with mast cells detected during CBC determination were from dogs without MCT. For these dogs, diagnoses included inflammatory disease (28.2%), regenerative anemia (27%), neoplasia other than MCT (25.9%), and trauma (11.8%). Dogs with MCT had a mean of 71.4 mast cells/buffy coat smear, whereas dogs without MCT had a mean of 276.2 mast cells/buffy coat smear. The 2 highest counts of mast cells/buffy coat smear were for dogs without MCT. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of results of quantitative buffy coat evaluations, severity of mastocytemia in dogs without MCT often exceeds that detected during tumor staging in dogs with MCT. Random detection of mast cells in blood smears during CBC determination in dogs is usually not secondary to MCT.     

Determination of the number of mast cells in lymph node, bone marrow, and buffy coat cytologic specimens from dogs.

Cytologic samples of popliteal lymph node, proximal femoral bone marrow, and the buffy coat fraction of blood were obtained from 56 dogs. The number of mast cells on 1 slide of each sample was determined by microscopic examination. Eleven of 46 slides of lymph node aspirate contained mast cells (range, 1 to 16; mean, 6.4; median, 5 mast cells/slide). Fifty-one bone marrow aspirate slides were evaluated. Two of these contained a single mast cell. None of the 53 buffy coat smear slides examined contained any mast cells. These results indicated that in clinically normal dogs, a few to several mast cells may be encountered in smears of lymph node aspirate, mast cells are rare in smears of bone marrow aspirate, and mast cells are absent from smears of buffy coat.     

Bone marrow mastocytosis in dogs with myelosuppressive monocytic ehrlichiosis (Ehrlichia canis): a retrospective study

BACKGROUND: Bone marrow mastocytosis has been reported rarely in naturally occurring canine monocytic ehrlichiosis (CME). OBJECTIVES: The aims of the present study were to estimate the prevalence and magnitude of bone marrow mastocytosis in a case series of dogs with natural CME and to assess the association, if any, between mastocytosis and the clinical severity of the disease. METHODS: Seventy-six dogs with confirmed CME (Ehrlichia canis) were included in the study. Affected dogs were allocated into group A (n = 51) without bone marrow hypoplasia and group B (n = 25) with bone marrow hypoplasia. Twenty clinically healthy Beagles not previously exposed to E canis served as controls (group C). The main inclusion criteria for group A were documentation of normocellular to hypercellular bone marrow and complete clinical cure following a 4-week treatment with doxycycline, while those for group B were bone marrow hypoplasia and lack of response to doxycycline. Bone marrow aspirate smears from all 96 dogs were Giemsa-stained and examined for the presence of mast cells, which were calculated as a percentage of 1,000 nucleated cells (NCs). The prevalence of mastocytosis was compared among the 3 groups by the Pearson's chi-square test. RESULTS: Bone marrow mastocytosis (>0.1% of NCs) was found in 5 (20%) dogs in group B (range, 0.5-2.5% of NCs; median, 1% of NCs). One dog in each of groups A and C had 0.1% mast cells in the marrow. The prevalence of bone marrow mastocytosis in dogs in group B was significantly higher (P = .004) than in groups A and C. CONCLUSION: Bone marrow mastocytosis can be seen in a substantial number of dogs with E canis-induced myelosuppression.     

Association of prognostic features and treatment on survival time of dogs with systemic mastocytosis: A retrospective analysis of 40 dogs

Systemic mastocytosis is a rare phenomenon, with limited information regarding prognostic features and effective treatment of canine patients with this disease. The objective of this study is to determine the impact of certain features and treatments on dogs with systemic mastocytosis. The medical records of 40 dogs from 4 northeastern US veterinary hospitals, with evidence of systemic mast cell disease, were evaluated retrospectively. Variables analysed with relation to overall survival and prognostic significance included treatment protocol used, substage, presence of a cutaneous or visceral tumour, presence of multiple cutaneous Mast cell tumours, grade of the primary tumour and metastatic site(s). Dogs with metastatic disease confined to distant lymph nodes lived longer than those with circulating mast cells in the blood (P = .001), and those with metastatic disease evident in more than 2 sites had a worse prognosis than those with disease in a single location (P = .005). Additionally, administration of chemotherapeutic agents led to increased survival over prednisone therapy alone (P = .008), with the combination of lomustine, vinblastine and prednisone prolonging survival over the tyrosine kinase inhibitor, toceranib phosphate (P = .002). Presence of mast cells in the blood and/or evidence of disease in more than 2 sites indicate widespread dissemination suggesting their use as negative prognostic features. Furthermore, a chemotherapy protocol including combination lomustine and vinblastine therapy may be more effective than toceranib phosphate for the treatment of dogs with disseminated mast cell disease. Overall, patients with systemic mastocytosis have a grave prognosis and more effective treatment options are needed.     

Clinical outcome of dogs with grade-II mast cell tumors treated with surgery alone: 55 cases (1996-1999)

OBJECTIVE: To determine outcome for dogs with grade-II mast cell tumors treated with surgery alone. DESIGN: Retrospective study. ANIMALS: 55 dogs. PROCEDURES: Medical records were examined, and signalment; location and size of tumor; staging status; dates of local recurrence, metastasis, death, or last follow-up examination; status of surgical margins; previous surgery; postoperative complications; and cause of death were recorded. Follow-up information was obtained via reexamination or telephone conversations with owners or referring veterinarians. Univariate analysis was performed to identify prognostic factors. RESULTS: 60 tumors in 55 dogs were included. Median follow-up time was 540 days. Three (5%) mast cell tumors recurred locally; median time to local recurrence was 62 days. Six (11%) dogs developed another mast cell tumor at a different cutaneous location; median time to a different location was 240 days. Three (5%) dogs developed metastases; median time to metastasis was 158 days. Fourteen dogs died; 3 deaths were related to mast cell tumor, and 7 were unrelated. The relationship with mast cell tumor was not known for 4. Median survival times were 151, 841, and 827 days, respectively, for these 3 groups. Forty-six (84%) dogs were free of mast cell tumors during the study period. A reliable prognostic factor could not be identified. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that additional local treatment may not be required after complete excision of grade-II mast cell tumors and that most dogs do not require systemic treatment.     

Type of smear may influence thrombopoietic cell counts in the bone marrow of clinically healthy dogs

BACKGROUND: The expected number of thrombopoietic cells in normal canine bone marrow is poorly defined and there is no consensus on the most appropriate way to prepare cytologic smears to evaluate these cells nor on the optimum method for their quantification. OBJECTIVE: The purpose of this study was to determine total and differential counts of thrombopoietic cells in the bone marrow of clinically healthy Beagle dogs by comparing 4 different smear types and bone marrow core biopsies. METHODS: Twenty-two clinically healthy, male Beagle dogs, 10 to 12 months old, were used in the study. Following bone marrow aspiration and core biopsy from the iliac crest, Giemsa-stained smears were prepared by 4 techniques: drop-squash, particle-squash, buffy coat, and fat-layer smears. Thrombopoietic cells were counted in up to 100 low-power fields (LPF, X10 objective) in the aspiration smears and in all possible high-power fields (HPF, X40 objective) in H&E-stained biopsy sections. RESULTS: Mean total thrombopoietic cell counts were 2.76 cells/LPF (drop-squash), 1.55 cells/LPF (particle-squash), 8.05 cells/LPF (buffy coat), and 3.08 cells/LPF (fat-layer). Core biopsies yielded 5.31 cells/HPF but frequently failed to provide interpretable specimens. There was a significant difference in cell counts among the 4 smear types (P <.001). Based on evaluation of buffy coat smears, thrombopoietic cells included 1.23% megakaryoblasts, 8.77% promegakaryocytes, and 90% megakaryocytes, with a mean maturation index of 0.11. CONCLUSION: Thrombopoietic cell counts in canine bone marrow are influenced by the smear technique. Buffy coat and fat-layer smears may be useful to obtain cellular smears in hemodiluted or small aspirate samples.     

Pleural fluid from a dog with marked eosinophilia

A 12-year-old neutered male Shar-Pei was presented to the North Carolina State University Veterinary Teaching Hospital cardiology service with a 2-week history of coughing and a 2-day history of lethargy and anorexia. Pleural effusion and a mediastinal mass were detected with thoracic radiographs. Ten mL of fluid were removed via thoracocentesis, and cytologic examination of the fluid revealed marked eosinophilic inflammation and few atypical mast cells. Mast cell neoplasia was suspected. Aspirates of the mediastinal mass, abdominal lymph nodes, and bone marrow contained similar pleomorphic mast cells and increased numbers of eosinophils. The dog was diagnosed with systemic (visceral) mastocytosis, a rare form of neoplasia in dogs, and was euthanized. These tumors carry a poor to grave prognosis and the etiology is uncertain.     

Outcome of dogs with mast cell tumors in the inguinal or perineal region versus other cutaneous locations: 124 cases (1990-2001)

OBJECTIVE: To compare clinical outcome of dogs with cutaneous mast cell tumors (MCTs) in the inguinal or perineal region with outcome for dogs with MCTs in other cutaneous locations. DESIGN: Retrospective study. ANIMALS: 37 dogs with MCTs in the inguinal or perineal region and 87 dogs with MCTs in other cutaneous locations. PROCEDURE: Information obtained from the medical records included sex, breed, age, histologic grade of all tumors, number and location of all tumors, tumor size (ie, diameter of the tumor), completeness of surgical excision, treatments administered in addition to surgery, and outcome. In all dogs, the primary treatment consisted of surgical excision. RESULTS: Disease-free interval and survival time for dogs with MCTs in the inguinal or perineal region were not significantly different from values for dogs with MCTs in other cutaneous locations. Dogs with incompletely excised tumors, dogs with grade III tumors, and dogs that received systemic treatment were 2, 2.5, and 4 times as likely, respectively, to have a relapse. Factors significantly associated with a shorter survival time were age > 8 years, metastatic disease at the time of initial diagnosis, and tumor relapse. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the present study suggest that dogs with MCTs in the inguinal or perineal region do not have a worse prognosis in regard to disease-free interval or survival time than do dogs with MCTs in other cutaneous locations. Treatment recommendations for dogs with cutaneous MCTs should be based on confirmed predictors of biological behavior, such as histologic grade and clinical stage.     

Effects of platelet clumping on platelet concentrations measured by use of impedance or buffy coat analysis in dogs.

OBJECTIVE: To determine whether platelet clumps are homogeneously distributed in blood samples, and whether platelet concentrations (PC) obtained by use of impedance and buffy coat analysis can be considered minimum values when platelet clumps are present. DESIGN: Prospective study. SAMPLE POPULATION: 50 blood samples obtained from 30 dogs. PROCEDURE: 10 blood samples containing platelet clumps were used and 10 smears were made from each sample; amount of platelet clumping was graded for all 100 smears. Blood from each of 20 healthy dogs was divided between 2 EDTA tubes before and after platelet clumping was induced by adenosine diphosphate (ADP). The PC for each ADP-treated and untreated sample were measured, using impedance and quantitative buffy coat analyzers. RESULTS: Platelet clumps were evident in all 100 blood smears, but the amount of clumping varied considerably within some samples. Using the impedance analyzer, the PC of ADP-treated samples were significantly lower and never higher than the PC of untreated samples. Using the buffy coat analyzer, some ADP-treated samples had increased PC; however, significant differences were not detected between treated and untreated samples. CONCLUSIONS AND CLINICAL RELEVANCE: Platelet clumping was not homogeneous within blood samples. When platelet clumps were identified by direct examination of blood smears, the PC detected by use of the impedance analyzer could be considered minimum values. In contrast, the PC detected by use of the buffy coat analyzer were sometimes increased. Useful information can be obtained by measuring PC in blood with platelet clumps; values obtained by use of impedance can be considered minimums, and values obtained by use of buffy coat analysis may be either minimum values or reasonable estimates of PC.     

Systemic mastocytosis with subcutaneous hemorrhage and edema in a Greyhound dog: case report and review of diagnostic criteria

Systemic mastocytosis, characterized by infiltration of multiple organs by neoplastic mast cells, is a well-described entity in human medicine with specific criteria for diagnosis, but is ill defined in veterinary literature. Hemostatic disorders are reported in humans affected by systemic mastocytosis but have not been well described in veterinary literature. A 5-y-old, spayed female Greyhound dog had a 1-mo history of progressive ventral cutaneous edema, hemorrhage, and pain. Cytology of an antemortem aspirate from the subcutis of the ventral abdomen was suggestive of mast cell neoplasia, but no discrete mass was present. The dog was euthanized and submitted for autopsy; marked subcutaneous edema and hemorrhage were confirmed. The ventral abdominal panniculus and dermis superficial to the panniculus carnosus were infiltrated by a dense sheet of neoplastic mast cells. The neoplastic cells contained toluidine blue–positive granules and formed aggregates within the bone marrow and several visceral organs, including the liver, spleen, heart, and kidney. Diffuse edema and hemorrhage is an unusual presentation of mast cell tumors in dogs. Antemortem tests, including complete blood count, coagulation profile, and viscoelastic coagulation testing, were suggestive of a primary hemostatic defect. We discuss here the diagnostic criteria used in humans, how these can be applied to veterinary patients, and the limitations of the current diagnostic framework.     

The utility of staging in canine mast cell tumours

Current staging of canine mast cell tumours (MCTs) practiced by many veterinarians involves a minimum of lymph node (LN) assessment, abdominal ultrasound and thoracic radiography. Historically, some have advocated buffy coat and bone marrow evaluation. Two hundred and twenty dogs with MCT seen at a referral clinic were staged using LN palpation/cytology, thoracic radiography and abdominal ultrasound. The utility of each method was evaluated by considering prevalence of spread and future behaviour. At presentation, 30.9% of dogs had metastases to the local LN; 6.8% of all the dogs also had distant metastases. No dog had or developed distant metastasis in the absence of LN metastasis. No dog had convincing evidence of pulmonary metastasis. In this series, the local LN was sentinel to metastasis and in the absence of local LN metastasis, the utility of further staging was low. Thoracic radiography was not useful in the staging of canine MCT.     

A subcutaneous mass on the neck of a horse

A 25-year-old Arabian gelding was presented for investigation of a subcutaneous neck mass. Fine-needle aspirates and impression smears revealed mast cells with widely varying degrees of cytoplasmic granulation and scattered eosinophils. Histopathology revealed a poorly circumscribed mass composed of sheets and bundles of mast cells with a large population of eosinophils. The mast cells were separated into numerous lobules by a heavy collagenous stroma, and multifocal collagen necrosis was present. Strong reactivity of the tumor cells for both Giemsa and toluidine blue stains confirmed the diagnosis of a mast cell tumor, and a Luna stain accentuated the eosinophilic infiltrates. Cutaneous mast cell tumors are found in many domestic animals but are uncommonly encountered in horses. Equine cutaneous mast cell tumors are usually benign, and there are no reports of visceral metastasis. Surgical excision is thought to be curative.     

Immunohistochemical detection of p53 tumor-suppressor protein is a poor indicator of prognosis for canine cutaneous mast cell tumors

Eighty-three canine cutaneous mast cell tumors were graded histologically and evaluated immunohistochemically for p53 tumor-suppressor protein expression. An avidin-biotin immunohistochemical protocol incorporated a rabbit polyclonal antibody (CM-1) directed against normal and mutant p53 protein. Positive staining was observed in 44.6% (37/83) of tumors and included 50% (12/24) of grade I (well differentiated) tumors, 46.9% (23/49) of grade II (intermediate differentiation) tumors, and 20% (2/10) of grade III (poorly differentiated) tumors. A statistically significantly higher proportion (P < 0.019) of tumors from the head and neck (83.3%, 10/12), stained positive for p53 than tumors from the thorax, back, abdomen, and axilla (39.4%, 13/33), legs (35.7%, 10/28), or prepuce, scrotal, or inguinal areas (44.4%, 4/9). No statistically significant difference between p53 labeling and histologic grade, breed, or tumor size was present. Survival data were available for 53/83 (63.9%) of dogs. Positive reactivity for p53 was observed in 47% (25/53) of tumors within this group, with 57.9% (11/19) of grade I, 43.3% (13/30) of grade II, and 25% (1/4) of grade III tumors labeled. Mean survival time for the 53 dogs was 12.1 months. The median survival time for dogs with grade III tumors or tumors >5 cm was statistically significantly shorter (P < 0.0001) than for dogs with grades I and II or smaller tumors. Although p53 protein abnormalities may play a role in tumor development or behavior in some canine cutaneous mast cell tumors, immunoreactivity was not associated with lack of tumor differentiation, tumor locations previously shown to demonstrate aggressive biological behavior, breed predisposition, or survival times.     

Recurrence rates and sites for grade II canine cutaneous mast cell tumors following complete surgical excision.

A retrospective study was performed on 31 dogs with completely excised, grade II, cutaneous mast cell tumors in order to determine recurrence rates and sites. Distant tumor recurrence developed in 22% of dogs, and local tumor recurrence developed in 11% of dogs; however, the vast majority of these animals were incompletely staged initially. Complete surgical excision of grade II mast cell tumors was associated with effective local control in 89% of these dogs. Therefore, adjuvant radiation therapy might not be indicated in the majority of dogs with complete surgical excision.     

Immunohistochemical and clinical evaluation of p53 in canine cutaneous mast cell tumors

One hundred twenty-six cutaneous mast cell tumors obtained by excisional biopsy from 106 dogs were evaluated using immunohistochemical staining for the presence of p53 protein. A standard avidin-biotin immunohistochemical protocol was used incorporating a polyclonal antibody of rabbit origin (CM-1) as the primary antibody. Histopathologic grading of tumors was performed on hemotoxylin and eosin-stained samples. There was a significant difference in the percentage of cells staining positive for p53 for the histopathologic grades (P = 0.0005). Grade III tumors had a significantly greater p53 content than did grade I or II tumors (P < 0.05). Clinical data obtained retrospectively was available for 54 dogs. Tumor recurred in 19 of 54 (35.2%) dogs. Twenty-nine dogs died by the end of the study; 9 of 29 (31.0%) died of mast cell tumor disease. Histopathologic grade showed a significant negative association with survival time. Both clinical stage and histopathologic grade showed a significant negative association with time to recurrence. The percentage of cells staining positive for p53 did not significantly improve the forward analysis. Immunohistochemical detection of p53 did not appear useful in characterizing the clinical association between cutaneous mast cell tumor cellular features and survival time or time to tumor recurrence in dogs.     

Evaluation of surgical margins required for complete excision of cutaneous mast cell tumors in dogs

OBJECTIVE: To determine whether neoplastic mast cells extended into tissue 1, 2, or 3 cm laterally or deeper than 1 fascial plane from the visible edge of cutaneous mast cell tumors (MCTs) in dogs. DESIGN: Prospective study. ANIMALS: 21 client-owned dogs with > or = 1 cutaneous MCT PROCEDURES: After preparation for surgery, each dog's skin was marked 1, 2, and 3 cm from the tumor edge at 0 degrees, 90 degrees, 180 degrees, and 270 degrees. At each 3-cm mark, deep fascia was exposed and sutured to the skin; the tumor was excised in routine fashion and fixed in formalin. Tumors were graded; margins were examined histologically for neoplastic mast cells. RESULTS: 23 cutaneous MCTs in 21 dogs were included in this study. Fifteen (65%) tumors were located on the trunk, 5 (22%) on the hind limbs, and 3 (13%) on the head and neck. There were 3 (13%) grade-I and 20 (87%) grade-II tumors. All grade-I tumors were completely excised at all margins. Seventy-five percent of the grade-II tumors were completely excised at the 1-cm margin, and 100% were completely excised at the 2-cm margin. Two grade-II MCTs located on the hind limbs of dogs were excised with a complete but close (within 1 mm) deep margin. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a 2-cm lateral margin and a deep margin of 1 fascial plane appear to be adequate for complete excision of grade-I and -II MCTs in dogs.     

Immunofluorescence of bovine virus diarrhea viral antigen in white blood cells from experimentally infected immunocompetent calves.

A study to evaluate the detection of bovine virus diarrhea viral antigen using immunofluorescence testing of white blood cells was conducted. Five colostrum-deprived calves were inoculated intravenously with a cytopathic strain of the virus. Lymphocyte and buffy coat smears were prepared daily for direct immunofluorescent staining for detection of antigen. Lymphocytes were separated from heparinized blood using a Ficoll density procedure. Buffy coat smears were prepared from centrifuged blood samples collected using ethylenediaminetetraacetic acid as an anticoagulant. Bovine viral diarrhea virus antigen was detected by immunofluorescence between 3 and 11 days postinfection in lymphocyte smears and 3 to 12 days postinfection in buffy coat smears. Isolation of virus from both lymphocytes and buffy coat preparations correlated with detection of immunofluorescence. Serum neutralizing antibody to bovine virus diarrhea virus was detected on day 10 postinfection. Buffy coat smears were as sensitive as lymphocyte smears for the detection of antigen by immunofluorescence. It appeared that immunofluorescent staining of white blood cells was an effective method of detecting bovine virus diarrhea viral antigen.     

Vinblastine and prednisolone as adjunctive therapy for canine cutaneous mast cell tumors

Twenty-seven dogs with inadequately excised, cutaneous mast cell tumors (MCT; 20 residual microscopic disease, seven marginal excision) were treated with a vinblastine and prednisolone chemotherapeutic protocol. Twenty dogs were available for follow-up examination after 12 months. One dog suffered local recurrence of the tumor, four dogs developed new cutaneous tumors, and one dog had both events. Fourteen dogs were free of MCT. There was no confirmed tumor-related mortality. Although toxicity from the chemotherapy was generally mild, one dog died of sepsis during treatment.     

Radiation therapy for incompletely excised grade II canine mast cell tumors

Forty-five dogs with incompletely excised grade II mast cell tumors were treated with radiation using a cobalt 60 teletherapy unit (15 fractions of 3.2 Gy for a total of 48 Gy). Twenty-four of the dogs underwent prophylactic regional lymph node irradiation. Three (6.7%) dogs had tumor recurrence, two (4.4%) dogs developed metastasis, and 14 (31%) dogs developed a second cutaneous mast cell tumor. No difference in overall survival rate was observed between the dogs receiving and not receiving prophylactic irradiation of the regional lymph node.