Severe Nonregenerative Anemia Research Articles

Parasitism and rumen impaction in a 5-month–old Yankasa ewe: A clinico-pathological report

We report concurrent acariosis, helminthosis and foreign body rumen impaction of multiple aetiologies in a 5-month-old Yankasa ewe from a multispecies flock on semiintensive management system. The clinical findings were tachycardia, hypothermia, bradypnea, diarrhoea, emaciation, lethargy, pale mucous membranes, and heavy tick infestation attached to the skin of the forelimb, hind limb, inguinal region, and the ears. Severe non-regenerative anaemia, marked neutrophilia and lymphocytopenia characterized the blood picture. The ewe was treated for endo and ectoparasites, along with fluid therapy. However, the ewe died in the course of treatment and the carcass was subsequently presented for necropsy. Gross findings included the presence of numerous ticks attached to the skin of the outer ears and interdigits, indigestible foreign materials in the rumen and numerous worms in the rumen, abomasum and the intestine. Laboratory analysis revealed that the ticks were Rhipicephalus sp. and Amblyomma sp. The rumen worms were identified as Paramphistomum sp., the worms from the abomasum were identified as Haemonchus contortus, and those of the intestine were identified as Moniezia expansa. Histopathologically, there was hypertrophy of the chief cells of the abomasum. There was a section of Haemonchus contortus surrounded by eosinophils within the mucosa of the abomasum. The villi of the intestine sloughed-off into the lumen. Based on the clinicopathological findings, the diagnoses of acariosis, helminthosis and foreign body rumen impaction were arrived at. The remaining animals in the herd were treated accordingly and the farmer was advised to ensure good farm management practices.

Successful long-term management of late-stage precursor-targeted immune-mediated anemia with prednisolone and mycophenolate mofetil in a dog

A 13-year-old neutered male Maltese dog presented to our hospital with lethargy and anorexia. Laboratory abnormalities included severe non-regenerative anemia (hematocrit, 12.9%; reticulocyte count 12.8 K/μL). The cytology of bone marrow revealed erythroid hypercellularity with mild myelofibrosis. Therefore, late-stage precursor-targeted immune-mediated anemia (PIMA) was diagnosed. Multimodal treatment including 2 immunosuppressant drugs (prednisolone and mycophenolate mofetil), antithrombic drug (clopidogrel), and blood transfusion was performed. The dog showed complete remission from PIMA, and the total duration of follow-up was 622 days. This is the first case report of canine PIMA managed successfully with prednisolone and mycophenolate mofetil in Korea.

Acute hemolytic reaction due to A‐B mismatched transfusion in a cat with transient AB blood type

To document a case of transient AB blood type indicated by immunochromatography in a type B cat following administration of an incompatible type A transfusion. A 7-month-old neutered male domestic longhair cat was evaluted for anemia, pigmenturia, and intravascular hemolysis 1 day after receiving a feline whole blood transfusion. Neither blood donor nor patient had been blood-typed or crossmatched. The cat presented in shock with a severe non-regenerative anemia, hyperlactatemia, hyperbilirubinemia, hemoglobinemia, hemoglobinuria, and a positive saline slide agglutination test. Immunochromatographic blood typing tests initially indicated the cat had type AB blood, but crossmatch tests with blood from type A and type B donors suggested that the cat was type B. The cat was transfused with type B packed red blood cells without apparent complications and clinically improved. The cat's blood type reverted to type B once all the previously transfused type A cells were cleared from circulation. Furthermore, the original donor was subsequently identified as a Siamese cat and confirmed to have type A blood. While the cause of the original anemia remained unknown, the cat completely recovered and regained a normal hematocrit. This is the first documented report of transient AB blood type diagnosed using immunochromatography after a transfusion mismatch and shows the utility of crossmatching or back-typing to identify the cat's correct blood type during the hemolytic transfusion reaction.

First report of Cytauxzoon sp. infection in domestic cats in Switzerland: natural and transfusion-transmitted infections

BackgroundCytauxzoonosis is an emerging tick-borne disease of domestic and wild felids. Cytauxzoon felis induces severe and often fatal disease in domestic cats. In Europe, clinical and subclinical infections caused by Cytauxzoon sp. are described. We report the first cases of Cytauxzoon sp. infection in domestic cats in Switzerland.MethodsClinical and laboratory data and results of PCR analyses were collected from Cytauxzoon sp. PCR-positive cats and the cats followed for up to 851 days.ResultsThe cases were three two-month old kittens from the same litter (Cases 1–3) and two adult domestic shorthair cats (Cases 4 and 5). The cats originated from the north-west and west of Switzerland. Cases 1–3 presented with moderate to severe regenerative anaemia and intraerythrocytic inclusions. Cytauxzoon sp. was confirmed by PCR and sequencing. The kittens made a clinical and haematological recovery after blood transfusion and/or treatment with azithromycin and atovaquone, but erythroparasitaemia persisted. Case 4 presented with severe non-regenerative anaemia. Case 5 was healthy and used as a blood donor for Case 4. Following blood transfusion, Case 4 showed intraerythrocytic inclusions, and Cytauxzoon sp. was confirmed in both Cases 4 and 5 using PCR and sequencing. Case 4 achieved clinical and haematological remission after treatment with azithromycin, atovaquone and immunosuppressive drugs. Eight months later, Case 4 was presented again with anaemia but tested Cytauxzoon sp. PCR-negative. Sequencing of 1637 bp of the 18S rRNA gene of Cytauxzoon sp. revealed 100% nucleotide sequence identity among isolates of Cases 1–3 and between isolates of Cases 4 and 5, and 99% sequence identity between isolates of all cases. Phylogenetic analysis revealed the closest relationship of the Swiss isolates to Cytauxzoon sp. isolates from domestic cats and wild felids from France, Spain and Romania and to Cytauxzoon manul from a Pallas’s cat.ConclusionsThis is the first report of Cytauxzoon sp. infection in domestic cats in Switzerland. It is also the first report of infection in very young kittens and transmission of Cytauxzoon sp. to an adult cat by transfusion of blood from an asymptomatic cat. The cats recovered but some developed chronic asymptomatic erythroparasitaemia for up to 28 months. Domestic cats may act as reservoirs for Cytauxzoon sp. in Europe and blood donor cats should be screened for this agent by PCR.

Pure red cell aplasia in a Holstein calf

A 3-month-old Holstein calf presented with lethargy. Hematological examination showed severe non-regenerative anemia without reduction in white blood cell and platelet counts. Serum biochemical analysis revealed both high erythropoietin activity and high serum iron concentration. Bone marrow examination revealed selectively decreased erythroid precursors and an increased myeloid:erythroid ratio of 7:1. Lesions that could have caused anemia were found only in bone marrow by necropsy. The calf was diagnosed with pure red cell aplasia (PRCA) based on these clinical and pathological findings. Although the cause of PRCA was not identified, this is the first confirmed clinical report of PRCA in a Holstein calf.

Increased Serum Alkaline Phosphatase in a FeLV-Positive Cat

Background: Feline Leukemia Virus (FeLV) is an oncogenic virus that usually invades bone marrow causing non-regenerative anemia and thrombocytopenia. In FeLV positive cats, the myeloid leukemia is characterized by intense proliferation of blast cells in a bone marrow with myeloid precursor predominance and several malignancies degree. The leukocyte alkaline phosphatase is found secondary granules of mature neutrophils of humans, horses and cows but not in dogs and cats,which demonstrate the enzyme activity in myeloblast and promyeloblasts cells. In this case is describing a FeLV-positive case with leukemic disorder accompanied by extremely high levels of serum alkaline phosphatase.Case: A 8-year-old castrated male Domestic Short Hair cat with a 3-month history of convulsions, pica, vomits, lethargy, hypodipsia and anorexia was examined and showed mild dehydration, severe jaundice and hyperpnoea. Laboratory results evidenced severe normocytic hypochromic non-regenerative anemia, moderated leukocytosis with severe degenerativeneutrophil left shift, moderated lymphocytosis and severe thrombocytopenia. Serum biochemical profle showed mild hyperalbuminemia, moderated increment in alanine transaminase and severe increment in alkaline phosphatese. The cat waspositive for ELISA point of care FeLV antigen and negative for FIV antibodies. Urinalysis revealed moderated bilirubinuria and proteinuria. The bone marrow cytology showed high cellularity, increased of M:E ratio, rare megakaryocyte lineage, erythroid hypoplasia, myeloid hyperplasia with blast excess and dysgranulopoiesis.Discussion: FeLV is a virus that usually causes cytopenias and in this case this was well evidenced through a severe non regenerative anemia and thrombocytopenia. Generally, anemia is a non-neoplastic complication of FeLV mainly related to suppressive effects hematopoietic and stromal cells of the bone marrow. Nevertheless, in this case, the anemia also maybe attributable to the observed acute myeloid leukemia. Neutrophilia is an uncommon fnding in FeLV-infected cats, even more with the severe degenerative left shift as in the present case. This fnding could be associated to a myeloid hyperplasia. Some biochemical alterations, as hyperalbuminemia and increment in values of serum ALT could be explained by clinical observations like dehydration and some degree of hepatic enlargement, respectively. However, the excessive value forserum alkaline phosphatase activity is an unpublished fnding in cats. In humans high levels of ALP has been associated with neutrophilia and it is quite likely that a great amount of degenerative neutrophils may contribute for high leakage of ALP than in other circumstances of neutrophilia. This is the frst report of a FeLV-positive cat exhibiting extremely high serum values of the enzyme ALP, possibly attributable to acute myeloid leukemia.Keywords: neutrophilia, cytopenia, non-regenerative anemia, acute leukemia.

Myeloperoxidase‐positive acute megakaryoblastic leukemia in a dog

A 16-month-old female spayed Labrador Retriever was referred to the University of Edinburgh for exercise intolerance, inappetence, and severe anemia. A CBC showed severe nonregenerative anemia and moderate numbers of atypical cells with morphologic features most consistent with megakaryoblastic origin. Similar cells were identified in a bone marrow aspirate and accounted for 23% of all nucleated cells. Atypical promegakaryocytes and megakaryocytes were also noted. Myelodysplastic syndrome affecting the megakaryocytic lineage was suspected. Cytologic examination of a fine-needle aspirate of the spleen revealed rare megakaryoblasts similar to those in blood and bone marrow. At necropsy, the bone marrow consisted of atypical megakaryoblasts and megakaryocytes that were also infiltrating spleen, liver, lymph nodes, renal perihilar tissue, and visceral adipose tissue, consistent with acute megakaryoblastic leukemia. Immunohistochemical analysis of splenic sections confirmed megakaryoblastic origin (immunoreactive for CD61 and von Willebrand factor). Some leukemic cells were also immunoreactive for myeloperoxidase (MPO). This aberrant immunophenotype suggested both megakaryocytic and granulocytic/monocytic differentiation of the leukemic cells. To our knowledge, this is the first report of MPO-positive acute megakaryoblastic leukemia in a dog.

A case of non-regenerative immune-mediated anemia treated by combination therapy of human immune globulin and mycophenolate mofetil in a dog

A 12-year-old female Shih Tzu dog was referred with diarrhea. Hematological examination indicated severe non-regenerative anemia. Bone marrow aspiration smears and core biopsy specimens revealed normal bone marrow. Based on those results, non-regenerative immune-mediated anemia was diagnosed. The dog was initially treated using prednisolone and cyclosporine. However, this treatment regimen did not prove effective. Nevertheless, the patient achieved a good hematological response after the administration of a combination therapy of human immune globulin and mycophenolate mofetil. Such a combination therapy may prove effective against non-regenerative immune-mediated anemia.

Besnoitia darlingi Infection in a Virginia Opossum (Didelphis virginiana)

This is a case report of natural infection with Besnoitia darlingi in a Virginia opossum (Didelphis virginiana) in Louisiana. Clinical pathologic data included a severe nonregenerative anemia, inflammatory leukogram, increased hepatocellular leakage enzymes, renal azotemia, hyperkalemia, hypoglycemia, hypoalbuminemia, and proteinuria. Tissue cysts containing bradyzoites were found in the majority of organs, especially the skin, mucous membranes, kidneys, adrenals, lungs, and heart. Images of the bradyzoites obtained by transmission electron microscopy were consistent with the previously described ultrastructure of Besnoitia darlingi. This opossum also suffered from an open phalangeal fracture and concurrent gastrointestinal parasites. Histopathologic findings included a glomerulonephritis and hepatic necrosis.

Therapy-resistant anaemia in congenital nephrotic syndrome of the Finnish type--implication of EPO, transferrin and transcobalamin losses

Congenital nephrotic syndrome of the Finnish type (CNF) is due to NPHS1 mutation and is responsible for a variety of urinary protein losses. We report the case of a 4-month-old girl with a particularly severe form (proteinuria approximately 150 g/l) of CNF. She developed severe non-regenerative anaemia requiring bi-monthly blood transfusions despite daily EPO (600 UI/kg) and iron supplementation. Epoetin pharmacokinetics revealed a urinary loss of 27% of the given dose within the first 24 h after IV injection. However, plasma levels remained increased after 24 h (228 UI/l). Plasma transferrin and transcobalamin levels were undetectable. Atransferrinaemia and atranscobalaminaemia seem to be responsible for disturbed erythropoiesis.

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.

Immune-mediated erythroid and megakaryocytic aplasia in a cat

A 6-month-old domestic shorthair cat was evaluated because of acute lethargy. Severe nonregenerative anemia and thrombocytopenia were identified. Cytologic examination of a bone marrow aspirate revealed selective erythroid and mega-karyocytic aplasia and a high number of apparently normal small lymphocytes. Infectious agents implicated in feline hematologic disorders were excluded on the basis of serologic tests or PCR amplification, including FeLV, Ehrlichia canis, Anaplasma phagocytophilum, Mycoplasma haemofelis, Candidatus Mycoplasma haemominutum, and Candidatus Myco-plasma turicensis. A 10-day course of prednisolone administration did not improve the hematologic disorder. Administration of human polyclonal immunoglobulins preceded increased reticulocyte count by 3 days. A second bone marrow examination confirmed restoration of erythroblasts and megakaryocytes. After 1 relapse, the disease was successfully controlled with prednisolone for > 3 years. Immune-mediated bone marrow aplasia is rare in cats and usually affects only erythrocyte progenitors. Concomitant involvement of erythroid and megakaryocytic cell lines can be successfully treated via immunosuppressive therapy. Human immunoglobulins seem to be well tolerated in cats; however, proof of a beneficial effect requires further study.

Chronic eosinophilic leukemia in a cat: cytochemical and immunophenotypical features

A 3-year-old, male, domestic shorthaired cat was presented with a 3-day history of anorexia and depression. The cat was moderately dehydrated, had pale, slightly icteric, mucous membranes, oral ulcerations, and mild hepatosplenomegaly. A feline leukemia virus (FeLV) antigen test was positive. CBC results obtained at initial presentation included severe normocytic, normochromic, nonregenerative anemia, severe thrombocytopenia, and marked leukocytosis (>100,000/microL) with 77% eosinophils. After 15 days of treatment with prednisone and doxycycline, the cat had persistent severe nonregenerative anemia (HCT 3.4%), thrombocytopenia (28,000/microL), and extreme eosinophilia (total eosinophils, 123.1 x 10(3)/microL; segmented 103.0 x 10(3)/microL; immature 20.1 X 10(3)/microL). Cytologic examination of aspirates from bone marrow, liver, lymph nodes, and spleen revealed a predominance of mature and immature eosinophils, many with dysplastic changes. The M:E ratio was 96.4. On histopathologic examination, multiple organs were infiltrated by eosinophilic granulocytes. Neoplastic cells in blood and bone marrow stained positive for alkaline phosphatase and were negative for myeloperoxidase, chloroacetate esterase, and alpha-naphthyl acetate esterase. On flow cytometric analysis of peripheral blood, the neoplastic cells were positive for CD11b and CD14. These findings were consistent with chronic eosinophilic leukemia. To our knowledge, this is the first report of chronic eosinophilic leukemia in a cat associated with naturally acquired FeLV infection, in which flow cytometry was used to characterize the neoplastic cells.

Acute megakaryoblastic leukemia with erythrophagocytosis and thrombosis in a dog

A 7-year-old, intact male Dachshund was presented to the Lyon veterinary school for lethargy and anorexia of several weeks duration. The main clinical signs were pale and icteric mucous membranes, hepatomegaly, splenomegaly, and lymphadenopathy. Results of a CBC and plasma biochemistry tests revealed severe nonregenerative anemia, thrombocytopenia, and increased alanine aminotransferase and alkaline phosphatase activities. Blood smear evaluation and cytologic examination of lymph node and bone marrow aspirate specimens revealed a large population of poorly differentiated blast cells with morphologic features suggesting megakaryocytic lineage. A low number of well-differentiated but dysplastic megakaryocytes also were observed in lymph node and bone marrow smears. A few blast cells were erythrophagocytic. Blast cells were positive for glycoprotein IIIa, factor VIII-related antigen, and factor XIII using immunocytochemistry. The dog was euthanized and necropsied. Histologic findings consisted of diffuse, massive infiltration of lymph nodes, liver, and spleen by megakaryoblasts and atypical megakaryocytes, with widespread thrombosis. This case confirms the usefulness of immunochemistry, including for factor XIII, in the diagnosis of megakaryoblastic leukemia, and demonstrates the unique features of tumor cell erythrophagocytosis and marked fibrinous thrombosis, which have not been reported previously in dogs.

Myelofibrosis in a cat

Extract A 2-year-old female domestic shorthair cat was presented with ill-health and marked ascites. Clinically, there was marked pallor of mucous membranes. Two haematological examinations and transudate-exudate analyses of peritoneal fluid were conducted 1 week apart, as well as a coagulation screen and routine serum biochemistry. The haematological examinations revealed a severe persistent non-regenerative anaemia. There were no abnormalities within the neutrophil and lymphocyte cell lines. Very occasional nucleated red blood cells (RBCs) in peripheral circulation and some RBC agglutination were seen. Analysis of peritoneal fluid disclosed a modified transudate, and small numbers of erythroid and myeloid precursors were observed on the second occasion. The cat was FIV/FeLV-negative, and there were no coagulation abnormalities. Following necropsy and histopathological examination, myelofibrosis and extramedullary haematopoiesis were seen. Thoracic masses were hyperplastic lymph nodes in which there was evidence of extramedullary haematopoiesis. The exact cause of the myelofibrosis was not obvious but it may have been a case of myeloid metaplasia, however not all the characteristics of this entity were present.

Idiopathic pure red cell aplasia and nonregenerative immune-mediated anemia in dogs: 43 cases (1988-1999).

To examine clinical features, laboratory test results, treatment, and outcome of dogs with pure red cell aplasia (PRCA) and idiopathic nonregenerative immune-mediated anemia (NRIMA). Retrospective study. 43 dogs with severe nonregenerative anemia. Medical records of dogs determined to have PRCA, NRIMA, or ineffective erythropoiesis on the basis of bone marrow analysis between 1988 and 1999 were reviewed. Criteria for inclusion were > or = 5-day history of severe nonregenerative anemia (Hct < 20%; < 60.0 x 10(3) reticulocytes/microliter) with no underlying diseases. Information was retrieved on signalment, clinical signs, laboratory test results, treatment, and outcome. Median age of the dogs was 6.5 years. Spayed females and Labrador Retrievers were significantly overrepresented. Median Hct was 11% with no evidence of regeneration (median, 1.5 x 10(3) reticulocytes/microliter). Direct Coombs' test results were positive in 57% of dogs. Biochemical abnormalities included hyperferremia and high percentage saturation of transferrin. Bone marrow findings ranged from PRCA (5%) to erythroid hyperplasia (55%). Myelofibrosis was common. Dogs were treated with immunosuppressive drugs and the response was complete, partial, and poor in 55, 18, and 27% of the dogs, respectively. Mortality rate was 28%. An immune-mediated pathogenesis should be considered in dogs with severe, nonregenerative anemia, normal WBC and platelet counts, hyperferremia, mild clinical signs, and no evidence of underlying disease. Bone marrow findings range from the rare PRCA to erythroid hyperplasia. Myelofibrosis is often detected in affected dogs and may prevent bone marrow aspiration.

Diagnostic and hematologic features of probable essential thrombocythemia in two dogs.

The clinical and hematologic features of two cases of probable essential thrombocythemia in the dog are described. Both dogs presented with hepatosplenomegaly, severe nonregenerative anemia, neutrophilia and Thrombocytosis. Mean platelet volume and percentages of large platelets were markedly increased in both dogs. Platelet aggregation studies demonstrated hyperaggregability in one dog; platelets from the other dog aggregated spontaneously, precluding further investigation. Cytologic and histologic examination of bone marrow showed pronounced megakaryocytic hyperplasia, with erythroid hypoplasia and relative myeloid hyperplasia. Megakaryocyte morphology was abnormal, with increased numbers of small mononuclear and binucleate cells. Normal to increased hemosiderin stores suggested that apparent macrocytosis in one dog, rather than being due to iron deficiency, resulted from the hematology analyzer counting large platelets as small red blood cells. Megakaryocytic infiltration of the spleen was evident in both dogs. The hematologic findings in dogs with essential thrombocythemia can mimic those associated with iron deficiency anemia, such that diagnostic investigations should be aimed at ruling out chronic blood loss and other causes of reactive Thrombocytosis.

Disseminated Mycobacterium genavense infection in a FIV-positive cat

An 8-year-old FIV-positive Australian cat was presented with coughing, periocular alopecia, pyrexia and inappetence. Skin scrapings demonstrated Demodex cati mites. Antibiotics were administered and it was treated successfully for periocular demodectic mange, but the cat continued to exhibit respiratory signs and lose weight. Further investigation revealed an ascarid infection and active chronic inflammation of undetected cause affecting the lower airways. Repetitive treatment with pyrantel failed to eradicate the ascarid infection. The cat became cachectic and developed moist ulcerative dermatitis of the neck, severe non-regenerative anaemia, leucopenia and thrombocytopenia. Necropsy and histopathology revealed mycobacteriosis affecting skin, lungs, spleen, lymph nodes, liver and kidney. Attempted culture of frozen tissues at a mycobacteria reference laboratory was unsuccessful. Paraffin-embedded, formalin-fixed tissue was retrieved and examined using PCR to amplify part of the 16S rRNA gene. A diagnosis of disseminated Mycobacterium genavense infection was made based on the presence of acid fast bacteria in many tissues and partial sequence of the 16S rRNA gene. Although M genavense has been identified previously as a cause of disseminated disease in AIDS patients, this is the first report of infection in a cat. It was suspected that the demodecosis, recurrent ascarid infections and disseminated M genavense infection resulted from an immune deficiency syndrome consequent to longstanding FIV infection.

Pure red cell aplasia in cats: 9 cases (1989–1997)

Objective To evaluate clinical features, laboratory test results, treatment, and outcome of FeLV-negative cats with pure red cell aplasia (PRCA) diagnosed by examination of bone marrow. Design Retrospective study. Animals 9 cats. Procedure Medical records and smears of bone marrow aspirates were reviewed to determine clinical features, laboratory test results, treatment, and outcome of this syndrome in cats. Results PRCA was diagnosed in 9 cats that were between 8 months and 3 years old. Cats had 2- to 16-day histories of lethargy and anorexia, and a severe normocytic, normochromic to hypochromic, nonregenerative anemia (Hct range, 6 to 15%; reference range, 25 to 45%). Other hematologic values were generally within reference ranges. Consistent changes in biochemical profiles included high aminotransferase activities and hyperferremia. Cats were seronegative for FeLV and feline immunodeficiency virus. Smears of bone marrow aspirates were characterized by absence of identifiable erythroid precursors and a high proportion of small lymphocytes. Abnormalities were not identified in megakaryocytes or myeloid cells. Treatment with immunosuppressive drugs (corticosteroids and cyclophosphamide or cyclosporin) resulted in resolution of anemia within 3 to 5 weeks. Most cats required long-term treatment to maintain Hct within reference range and tended to relapse when treatment frequency or dosage was decreased (especially if done rapidly) or treatment was discontinued. Clinical Implications PRCA is a rare syndrome in young FeLV-negative cats, and is characterized by severe nonregenerative anemia and absence of erythroid cells in bone marrow. The condition requires prompt, aggressive, often long-term treatment with immunosuppressive drugs for resolution. (J Am Vet Med Assoc 1999;214:75–79)

猫の急性骨髄単球性白血病 (M4) の1例

An 11-year-old male Persian cat with depression and anorexia showed severe nonregenerative anemia, neutrophilia, and monocytosis, and a number of blast cells and promonocytes appeared in the peripheral blood. Feline leukemia virus antigen and antibody to feline immunodeficiency virus were detected in serum, which was positive for direct Coombs' test. The bone marrow had an increased number of blast cells and marked depletion of erythroid precursors. The blast cells were positive for peroxidase while negative for nonspecific esterase. The immature cells in the peripheral blood and bone marrow were morphologically suggested to be precursors of either granulocytes or monocytes. The case was diagnosed as acute myelomonocytic leukemia (M4), that was negative for nonspecific esterase and rare in cats.