Pathologic sideroblasts and siderocytes associated with chloramphenicol therapy in a dog

Siderotic granules were recognized in blood erythrocytes from a male Boxer dog with suppurative prostatitis, cystitis and pyelonephritis that was being given high dosage chloramphenicol therapy. Siderotic inclusions were recognized in the cytoplasm of 96% of the rubricytes and metarubricytes in a bone marrow aspirate. Siderotic inclusions were numerous and in some cases formed a ring around the nucleus. This perinuclear location suggested that pathologic mitochondrial iron accumulation had occurred, resulting in the formation of "ringed" sideroblasts. The occurrence of pathologic sideroblasts was confirmed by electron microscopy. Blood siderocytes and bone marrow sideroblasts disappeared after cessation of chloramphenicol therapy.     

Myelodysplastic syndrome with sideroblastic differentiation in a dog

A dog with myelodysplastic syndrome had microcytic hypochromic anemia, with siderocytes, poikilocytosis, hypersegmented neutrophils and giant platelets in peripheral blood. In bone marrow, the erythroid series showed immaturity, asynchronous maturation and sideroblasts. Dysgranulopoiesis and dysthrombopoiesis also were present, and hemosiderin was increased. Serum iron concentration was high, and both iron deficiency and lead toxicity were excluded as the cause of dyscrasia. This case represents a unique variant of myelodysplastic syndrome, best described as sideroblastic myelodysplasia. We propose the terms dyserythropoiesis, sideroblastic dyserythropoiesis, dyserythropoiesis with excess blasts, myelodysplasia and sideroblastic myelodysplasia to describe and categorize myelodysplastic syndromes in dogs.     

Sideroblastic anemia in 7 dogs (1996-2002)

Sideroblastic anemia is an anemic condition characterized by chronic hypochromic anemia and the presence of large iron deposits in erythroid cells. Seven dogs with sideroblastic anemia were evaluated retrospectively. Historical, clinical, and clinicopathologic findings were reviewed to determine whether the condition was idiopathic or associated with disease conditions or drug or toxin exposure. Associated diseases were identified in 6 affected dogs and included acute hepatitis, pancreatitis, acute hepatitis and pancreatitis, inflammatory disease, glomerulonephritis, and myelofibrosis. None of the dogs had a history of recent exposure to drugs or toxins. One dog had no evidence of associated disease. Regardless of the associated disease condition, sideroblastic anemia was characterized by moderate to severe nonregenerative and frequently hypochromic anemia with prominent dysplastic features in bone marrow that were most prominent in the erythroid series. Survival varied from days to years. Identification of large numbers of siderocytes or sideroblasts in blood or bone marrow is inconsistent with a diagnosis of iron deficiency and should prompt a search for inflammatory disease conditions, including hepatitis, pancreatitis, and glomerulonephritis.     

Hereditary nonspherocytic hemolytic anemia in beagles

Three Beagles with chronic anemia and reticulocytosis were studied. The dogs originated from a large breeding colony and appeared clinically normal with the exception of splenomegaly. The PCV ranged from 30 to 39% (normal, 46 to 56%), with reticulocyte indices of 2.3 to 9.9. Red blood cells were morphologically normal, and examination of marrow aspirates revealed erythroid hyperplasia. Shortened chromium-51 RBC life-spans (7.2 to 15.4 days in anemic dogs; 22.2 to 25.2 days in control dogs) documented a hemolytic anemia. Acquired causes of hemolytic anemia were ruled out. Red blood cells had normal glycolytic enzyme activities, no evidence of unstable or abnormal hemoglobin, and had altered osmotic fragility curves. The breeding of 2 anemic dogs resulted in offspring with anemia and reticulocytosis. Polyacrylamide gel electrophoresis revealed no abnormalities in RBC membrane cytoskeletal proteins in all anemic adult dogs and in 3 offspring.     

Hematopathology in dogs experimentally infected with a Swedish granulocytic Ehrlichia species

Seven, adult, female beagles were inoculated with a Swedish granulocytic Ehrlichia organism closely related to Ehrlichia equi and E. phagocytophila. Blood and bone marrow changes were evaluated throughout the acute phase of infection. All dogs developed moderate to severe thrombocytopenia during the parasitemic period. The mean platelet volume and platelet distribution width increased, and large platelets were seen on blood smears when platelet numbers were low. In bone marrow, absolute numbers of megakaryocytes and immature megakaryocytes were increased. These results suggested the thrombocytopenia was caused by increased platelet destruction. The dogs also developed mild, normocytic, normochromic anemia, with simultaneous decreases in serum iron concentration and total iron-binding capacity that resembled the anemia of inflammation. In bone marrow, there was a slight increase in immature erythroid cells and no erythroid hypoplasia; iron stores were normal to increased. Myeloid hyperplasia was seen in all infected dogs, despite neutropenia in peripheral blood. Lymphopenia occurred early in the parasitemic period, but lymphocytes responded strongly and numbers increased above baseline levels by the end of parasitemia. Blast-transformed lymphocytes (5% to 20%) were seen in peripheral blood for a few days. Experimentally-induced canine granulocytic ehrlichiosis caused cytopenias of short duration, coincident with the appearance of ehrlichial inclusions in neutrophils.     

Evaluation of the erythroid regenerative response in two different models of experimentally induced iron deficiency anemia

Anemia was induced in weanling Sprague Dawley rats either by feeding an iron-deficient diet or by chronic phlebotomy. The erythroid regenerative response was then evaluated before and after a hemolytic event, and results were compared with those of a third group of control nonphlebotomized rats fed an iron-replete diet. Diet and phlebotomy groups developed a similar degree of anemia (mean hemoglobin concentration 7.9 g/dL and 7.8 g/dL, respectively; controls, 13.9 g/dL) and hypoferremia (mean serum iron concentration 25.4 microgram/dL and 34.9 microgram/dL, respectively; controls, 222.0 microgram/dL). However, the anemia in diet rats was nonregenerative (reticulocyte count, 83.1 X 10(3) cells/microliter) and associated with bone marrow erythroid hypoplasia; whereas the anemia in phlebotomy rats was regenerative (reticulocyte count, 169.6 X 10(3) cells/microliter) and associated with bone marrow erythroid hyperplasia. Thrombocytosis was seen in diet rats (1,580 X 10(3) cells/microliter) but not phlebotomy rats (901 X 10(3) cells/microliter) when compared with controls (809 X 10(3) cells/microliter). To further evaluate the regenerative capability, phenylhydrazine (PHZ) was administered to induce hemolysis. Erythrocyte mass declined approximately 25% in all groups, including controls. The reticulocytosis (265.3 X 10(3) cells/microliter) seen in phlebotomy rats was earlier and significantly greater than that seen in either diet or control rats. Hemoglobin concentration returned to pre-PHZ concentrations (7.9 g/dL) in phlebotomy rats within 4 days posthemolysis. In diet rats, the maximal regenerative response (176.3 X 10(3) cells/microliter) was not seen until 8 days posthemolysis, and hemoglobin (7.5 g/dL) did not return to pre-PHZ concentrations during the 8-day study. In many aspects, the anemia seen following diet- or phlebotomy-induced iron deficiency was similar. However, the erythroid regenerative capability varied depending on the mechanism by which anemia was induced and furthermore altered the efficiency of hemoglobin production following a hemolytic event. These results suggest that the availability of iron in the diet may modulate the pathogenesis of iron deficiency anemia.     

Characterization and quantification of blood cells from the umbilical cord of dogs

BACKGROUND: Models for the study of hematopoietic stem cells in dogs provide important information for bone marrow transplantation in humans. Recent studies have reported the importance of human umbilical cord blood (UCB) as an alternative to allogenic bone marrow for hematopoietic reconstitution. However, there are no studies on the UCB cells of dogs. OBJECTIVE: The aim of this experiment was to characterize and quantify the blood cells of the umbilical cord of dogs. METHODS: The blood of the umbilical cord of 20 neonatal dogs, delivered at term, with a median gestation time of 58 days, was collected with a 5-mL syringe containing EDTA. Total RBC, WBC, and platelet counts, HCT, hemoglobin (Hgb) concentration, and RBC indices were determined using an automatic cell counter. The differential leukocyte count was determined manually in blood smears stained with May-Grünwald-Giemsa. Reticulocyte percentages were determined on blood smears stained with brilliant cresyl blue and counterstained with May-Grünwald Giemsa. RESULTS: The MCHC and numbers of RBCs, WBCs, neutrophils, and eosinophils in UCB were lower as compared with reference values for the peripheral blood of healthy neonatal and adult dogs; whereas, the MCV and reticulocyte percentages were higher. CONCLUSION: Erythrocyte macrocytosis and hypochromasia in UCB were consistent with marked reticulocytosis and indicative of high erythropoietic activity. The results of this study are an important first step in the characterization of UCB from neonatal dogs.     

Anti-CD71 antibody immunohistochemistry in the diagnosis of acute myeloid leukemia,subtype acute erythroid leukemia with erythroid dominance (AML M6-Er), in a retrovirus-negative cat

CD71 is an immunohistochemical marker used in diagnosing acute myeloid leukemia (AML) M6-Er in humans; however, to our knowledge, it has not been reportedly used for immunohistochemistry in veterinary medicine. We evaluated the pathologic features of AML M6-Er in a retrovirus-negative cat and used CD71 to support the diagnosis. A 4-y-old spayed female Scottish Fold cat was presented with lethargy, anorexia, and fever. Whole-blood PCR assay results for pro feline leukemia virus/pro feline immunodeficiency virus and feline vector-borne diseases were negative. Early erythroid precursors were observed in the peripheral blood smear. Fine-needle aspiration of the enlarged spleen and splenic lymph node showed many early erythroid precursors. Bone marrow aspirate smears revealed erythroid hyperplasia with 68.4% erythroid lineage and 3.6% rubriblasts. Dysplastic cells infiltrated other organs. The patient was diagnosed with myelodysplastic syndrome, progressing to the early phase of AML M6-Er. The patient died on day 121 despite multidrug treatments. Postmortem examination revealed neoplastic erythroblasts infiltrating the bone marrow and other organs. Neoplastic cells were immunopositive for CD71 but immunonegative for CD3, CD20, granzyme B, von Willebrand factor, CD61, myeloperoxidase, and Iba-1. Although further studies are necessary for the application of CD71, our results supported the morphologic diagnosis of AML M6-Er.     

A hematological study on thirteen cats with myelodysplastic syndrome

Hematological abnormalities were investigated in 13 cats with myelodysplastic syndrome (MDS). Examination of the peripheral blood samples from the 13 cats revealed anemia in 11 cats, leukopenia in 9 cats, and thrombocytopenia in 9 cats. Four cats had pancytopenia (30.8%) and 9 cats had bicytopenia (69.2%). Dysplastic changes of erythrocytes, neutrophils, and platelets in the peripheral blood were found in 5, 10 and 8 cats, respectively. Bone marrow examination of the 13 cats revealed that ratios of blast cells to all nucleated cells (ANC) ranged from 0 to 20%. Ratios of erythroid progenitor cells to ANC were more than 50% in 3 cats and less than 50% in 10 cats. Eosinophils accounted for more than 5% of non-erythroid cells in 10 cats. Dysplastic changes in the granurocytic, erythrocytic, and megakaryocytic cells in the bone marrow were found in 11, 7 and 5 cats, respectively. Dysplastic changes in these cats included giant neutrophils, ring-nucleated neutrophils, binuclear myelocytes, hypersegmented and hyposegmented neutrophils, megaloblastoid erythroblasts, multinucleated erythroblasts, micromegakaryocytes, and segmented multinucleated megakaryocytes. Virological examination indicated the presence of feline leukemia virus antigen in the peripheral blood from all of the 13 cats with MDS. The peripheral blood cytopenias and dysplastic changes in each blood cell lineage in the bone marrow were shown to be important for the diagnosis of MDS in cats.     

Cabot rings as a result of severe dyserythropoiesis in a dog

An 11-year-old female Dachshund was presented with depression, diarrhea, weight loss, and radiographic evidence of masses involving the liver, spleen, and cranial lobe of the right lung. Results of a CBC included severe nonregenerative anemia (HCT 14.2%, hemoglobin, 4.3 g/dL, reticulocytes 66,000/microL) with marked metarubricytosis (nucleated RBCs 6.39 x 10(3)/microL). Examination of the peripheral blood smear revealed marked erythroid dysplasia, including marked anisocytosis with a prevalence of macrocytes, Howell-Jolly bodies, diffuse basophilic stippling, and multinucleated and atypical nucleated RBCs. Neutrophil hypersegmentation and giant forms were also noted. Numerous erythrocytes, particularly polychromatophilic cells, contained inclusions consistent with Cabot rings, which appeared as delicate red-purple ellipsoid or figure 8 structures. Rarely, Cabot rings were observed extracellularly. The dog was treated symptomatically with blood transfusions, prednisone, erythropoietin, and vitamin supplementation, but the anemia progressively worsened. The dog was euthanized 2 months after presentation. Bone marrow aspirate and core biopsy specimens obtained at the time of euthanasia revealed marked dysplastic changes in all cell lines, especially dyserythropoiesis, along with infiltrating carcinoma cells. A necropsy was performed, and histologic examination revealed poorly differentiated adenocarcinoma of the lung with multiple metastases to the marrow, spleen, and liver. The final diagnosis was marked myelodysplasia secondary to metastatic adenocarcinoma. Cabot rings are found rarely in humans with myelodysplasia, but have not been described previously in dogs. Based on the findings in this case, Cabot rings may occur rarely in dogs with severe dyserythropoiesis.     

Normal haematopoiesis,cellular components and stainable iron content in the bone marrow of camels (Camelus dromedarius)

Bone marrow samples were collected from the ribs of 20 healthy adult male Iranian camels (Camelus dromedarius). The bone marrow smears were stained using Wright's stain. Blood samples were collected at the same time for routine haematological examination. The development and morphology of the blood cells in the bone marrow of the camels were similar to those of other domestic species. The mean myeloid/erythroid ratio was 1.21, the mean erythroid percentage was 42.7% and the mean myeloid percentage was 52.0%. The mean percentage of other cells was 5.3%. The mean percentage of eosinophils in the myeloid series was higher than in other domestic species. Iron stores, estimated from Perl's stain, ranged from scant (1+) to moderate (3+) but most samples had 2+ iron content. All peripheral blood results were within reference ranges.     

Blood smear from a cat: features to "dys"cover

A 4-year-old, spayed female, domestic shorthair cat was presented for lethargy, nonregenerative anemia, and inappetence. Results of a CBC included macrocytic, normochromic, nonregenerative anemia and a glucocorticoid-associated leukogram. On blood smear examination, neutrophils had abnormal features including hyposegmentation and a diffuse chromatin pattern with nuclear filament formation and nuclear blebbing. Microscopic examination of a roll preparation of bone marrow revealed hypolobulated megakaryocytes with asynchronous maturation of nuclei. The granulocytic to erythrocyte (G:E) ratio was 76. Segmented neutrophils had asynchronous maturation and dysplastic features. The entire erythroid lineage was markedly decreased for the degree of anemia and rare dysplastic features were noted in erythroid precursor cells. The interpretation of bone marrow findings was erythroid hypoplasia, megakaryocytic dysplasia, and granulocytic hyperplasia with dysplasia. Histopathologic examination of a bone marrow core sample also revealed myeloid hyperplasia and erythroid hypoplasia. The result of a direct immunofluorescence assay for FeLV performed on the bone marrow roll preparation was positive. A diagnosis of dysmyelopoiesis associated with FeLV infection was made. This case was unique in that the dysplastic changes occurred in cell lines that did not have associated cytopenias. The dysmyelopoiesis most closely resembled myelodysplastic syndrome with refractory cytopenia (MDS-RC); however, secondary dysmyelopoiesis could not be ruled out.     

Persistent reticulocytosis in a case of poodle macrocytosis

A healthy 14‐year‐old, male neutered, Miniature Poodle was found to have a persistent erythrocyte macrocytosis and reticulocytosis with a normal and stable HCT. The hematologic features of macrocytosis, increased Howell‐Jolly bodies, and metarubricytosis, in the absence of anemia or other cytopenias, combined with the cytologic evidence of bone marrow erythroid dysplasia, including megaloblastosis, binuclearity, increased mitotic activity, and nuclear fragmentation, are consistent with previous reports of congenital dyserythropoiesis termed poodle macrocytosis. We speculate that the additional presence of persistent reticulocytosis in the absence of an identifiable stimulus for accelerated erythropoiesis may represent a phenotypic variation of this inherited condition, and the morphologic abnormalities of the dyserythropoiesis are described.     

Clinical, gross, and histological findings in herring gulls and Atlantic puffins that ingested Prudhoe Bay crude oil

Oral doses of 0, 1, 4, 5, 10, or 20 ml of Prudhoe Bay crude oil/kg body weight/day were given to herring gull and Atlantic puffin nestlings for 5 to 7 consecutive days. Gulls defecated substantial amounts of oil within 10 to 15 minutes after receiving a dose. Clinical signs and lesions occurred only in birds given greater than or equal to 10 ml oil/kg body weight/day. Gulls consumed less food and lost weight. Two categories of lesions were observed: those considered secondary to a primary toxic hemolytic disease, and those considered nonspecific reactions to stress. The former included phagocytosis of degenerate erythrocytes in the liver and spleen, hemoglobin resorption droplets in renal proximal tubule cells, and erythroid hyperplasia in the bone marrow; the latter included lymphocyte depletion in primary lymphoid tissues, an increase in heterophil: lymphocyte ratio in peripheral blood, lipid depletion and necrosis in adrenal steroidogenic cells, and an increased prevalence and severity of lesions in the bursa of Fabricius. These findings indicated that the primary target of oil toxicity was the peripheral red blood cell, but that significant stress-related lesions were also associated with ingestion of oil.     

Granulocytopenia associated with thymoma in a domestic shorthaired cat

A 5-year-old, spayed female cat was referred because of a mass in the cranial mediastinum noted on thoracic radiographs. A thymoma was diagnosed following ultrasound and biopsy of the mass. Treatment was initiated with coarse-fraction radiation therapy using external-beam therapy (four fractions of 5 Gy). The mass responded, but granulocytopenia developed. Bone marrow examination showed a myeloid to erythroid ratio of approximately 1:1, with a left shift within the myeloid line. These findings, as well as the lack of toxic changes within the peripheral blood neutrophils, suggested immune-mediated destruction of peripheral granulocytes. Immune suppression with prednisone and cyclosporine was instituted. After 7 weeks, the neutrophil count returned to normal. The tumor was removed, and cyclosporine was reduced and eventually discontinued 3 weeks postsurgery.     

Spontaneous Erythroid Leukemia in a 7-Week-Old Crl:CD (SD) Rat

A young male Crl:CD (SD) rat with erythroid leukemia that presented with emaciation, abdominal distension and a pale visible mucosal membrane was euthanized at 7 weeks of age. At necropsy, enlargement of liver, spleen and pancreatic lymph node was noted. Analysis of blood smear samples revealed many mono- or binucleated erythroblasts that had PAS-positive vacuoles in the cytoplasm. Histopathologically, neoplastic proliferation of atypical cells was observed in the hepatic sinusoids, splenic red pulp, bone marrow, pancreatic lymph node, kidney and lung. Neoplastic cells showed a round to spindle shape, and some neoplastic cells had deeply stained small nuclei and small cytoplasms and resembled erythroblasts. Immunohistochemically, many neoplastic cells were positive for hemoglobin. To our knowledge, this is the first report of erythroid leukemia in a rat of this age. The observed features were similar to those of pure erythroid leukemia in humans.     

Bone marrow response to large volume blood collection in the horse

Evaluation of erythropoietic regeneration in horses is difficult unless serial bone marrow aspirates are performed. To investigate the acute and chronic erythropoietic regenerative response of equine bone marrow following acute removal or loss of blood, sequential bone marrow aspirates over 4 weeks were taken from the sternum of five horses from which 20 ml kg(-1)of blood had been removed. We found that the total number of erythroid cells counted (expressed as a percentage of the total number of erythroid and myeloid cells counted) expanded initially by 13.7 per cent within 3 days after blood removal, the erythroid response peaking by 9 days with a further 13.5 per cent increase. This peak coincided with the lowest M:E ratio. Concomitantly, a shift from proliferative phase cells to maturing phase cells occurred, which appeared to persist beyond 31 days post collection. Thus, we found that the equine bone marrow mounted a regenerative erythropoietic response more slowly than previously determined and, also, regeneration of the erythroid compartment was incomplete 31 days after blood removal of this magnitude.     

Acute myeloid leukaemia (M6B: pure acute erythroid leukaemia) in a Thoroughbred foal

A 10-week-old Thoroughbred filly was referred for anaemia of 4 weeks' duration. Haematology revealed severe anaemia and panleucopenia. Cytological examination of bone marrow smears revealed a myeloid to erythroid ratio <0.02:1 (reference range 0.5-2.4:1.0) and an abundance of erythroid precursor cells. The erythroid cell population included rubriblasts, prorubricytes and rubricytes, with only scant numbers of metarubricytes present. There were numerous mitotic erythroid cells, some of which were atypical and megaloblastic. These cytomorphological changes are consistent with pure acute erythroid leukaemia. No treatment was instituted and the filly died three days after presentation. This case illustrates the need to consider both haematology and bone marrow findings to establish a diagnosis of pure erythroid leukaemia. To our knowledge, there is no documented case of acute myeloproliferative disease in horses involving cells of erythroid lineage, but this condition should be considered a differential diagnosis for horses presenting with anaemia.     

Erythrocyte dysplasia in peripheral blood smears from 5 thrombocytopenic dogs treated with vincristine sulfate

Secondary dyserythropoiesis has been associated with vincristine administration in dogs. Evaluation of bone marrow aspirates for the presence of morphologic abnormalities in the erythroid lineage aids in the diagnosis. However, morphologic features of circulating erythroid precursors in these cases have not been described previously. The purpose of this report was to describe the cytologic features of dyserythropoiesis in peripheral blood and also bone marrow smears in a case series of dogs with immune‐mediated thrombocytopenia (IMT) treated with vincristine sulfate. Nineteen dogs receiving vincristine for treatment of IMT were identified by retrospectively searching a computerized medical record system. There were 5 dogs that had dysplastic erythroid precursors in peripheral blood smears within 7 days of vincristine treatment. Two of those 5 dogs also had evidence for erythrodysplasia in modified Wright's‐stained bone marrow smears obtained postvincristine administration. Morphologic changes included bizarre or inappropriate mitotic figures, abnormal nuclear configurations (fragmentation, elongation, indentation, and binucleation), atypical nuclear remnants (Howell‐Jolly bodies), or nuclear and cytoplasmic asynchrony within the erythroid precursors. A brief review of the literature with discussion of the etiologies for dyserythropoiesis is provided. The dyserythropoiesis was clinically insignificant in all 5 cases and resolved. However, pathologists and clinicians should be aware of these potential findings to prevent misdiagnosis of other conditions.     

Hematologic and bone marrow changes after short- and long-term administration of two recombinant bovine granulocyte colony-stimulating factors.

Colony-stimulating factors are a category of glycoproteins that are instrumental in the regulation of hematopoiesis and inflammation. This investigation documented the clinical bone marrow and peripheral blood responses to short-term and long-term administration of a recombinant bovine granulocyte colony-stimulating factor (rb-GCSF) and an analog, where the cysteine at position 17 was substituted with a serine (rb-GCSF ser17). The colony-stimulating factors produced the expected changes in the hematologic findings of the bovine subjects in the study, and there was a cell-specific response to the compounds. The sustained neutrophilia in the long-term study indicates that the bovine species can tolerate the administration of recombinant forms of bovine GCSF for extended periods of time without detectable adverse side effects. The neutrophils from the short-term study revealed no apparent fluctuation, either as enhanced or reduced capability to reduce nitro blue tetrazolium as compared to pretreatment neutrophils. The administration of both recombinant forms of GCSF produced large increases in the bone marrow myeloid:erythroid (M:E) ratio concomitantly with the neutrophilias. This is the first preliminary report documenting the bone marrow response of cattle to the native and recombinant (rb-GCSF ser17) forms of bovine GCSF.