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Schalm's Veterinary Hematology - Jain
Students should be able to perform the following tasks upon completion of this section:
Now that you have examined the erythrocytes and have a good understanding about their origin and function in health and disease, let us now examined the leukocytes. The total number of leukocytes present in the blood is far less than that of erythrocytes. This total number varies with species and with physiologic and pathologic states of individuals of the same species. Factors such as stress, exercise, feeding and age can cause great fluctuations in total leukocyte count. To account for normal variation in the total WBC count, the number of leukocytes per microliter of blood for a particular species is presented as a range. The generally accepted ranges for the domestic species are listed in the table of normal values located in the appendix of this syllabus.
The term "Leukocyte" includes all white blood cells and their precursors. The granulocytes - neutrophils, eosinophils, and basophils - have their origin in bone marrow. Lymphocytes are produced in the spleen, lymph nodes, and lymphocytic foci scattered throughout the body. The origin of the monocyte is debatable, but its phagocytic potentialities point to the reticuloendothelial system as a most likely source. The leukocytes use the blood stream as a means of transport from point of origin to their destination in tissues.
Leukocytes function as a first line of defense against foreign protein entering the body.
Neutrophils are the most active leukocytes in the initial stages of inflammation. In severe infections, immature forms of neutrophils, namely, myelocytes, metamyelocytes, and band neutrophils, may appear in peripheral blood; this is referred to as a "shift to the left." The neutrophils destroy bacteria, especially the cocci forms, by phagocytosis.
Eosinophils are found at the port of entry of foreign materials, that is, in the gut wall, subcutis, and lining of the respiratory tract. They accumulate at the site of antigen-antibody reactions and they inactivate histamine or histamine-like toxic materials. They increase in situations involving decomposition of body protein and this may reflect a function of detoxification.
Monocytes are macrophages and their special enzyme systems are called upon to handle difficult pathogens, such as, fungi, protozoa, and tubercle bacilli. They digest tissue debris. Monocytosis indicates chronicity of the inflammatory process or infection with higher bacteria or fungi.
The total white blood cell count is essential if one is to determine if there has been an increase or decrease in the number of leukocytes in circulation. The total white blood cell count varies from one species to another.
An increase in the total white blood cell count above the normal range is referred to as a leukocytosis. The leukocytosis is most frequently due to an increase in neutrophils, although, it may on occasions be due to an increase in one of the other main types. The total white cell count is elevated due to excitement, especially in the cat and horse (physiologic). Therefore, specimen should be obtained when the animal is calm.
A decrease in the total white blood cell count below the normal range in a given species is referred to as a leukopenia. A leukopenia is often associated with viral diseases but may be the result of an overwhelming bacterial infection or bone marrow exhaustion. In addition, numerous drugs and chemicals have been associated with a leukopenia (chloramphenicol, sulfonamide). An important point to remember here is that the bovine will show a leukopenia in acute bacterial infection such as acute mastitis.
An increase in a particular cell type may be associated with a number of diseases and/or conditions to include the following:
The stained blood smear is examined under the microscope to determine the relative number of the various types of leukocytes. This is essential if one is to determine which type of leukocyte has increased. In order to do the differential, at least one hundred leukocytes are observed and classified according to type. The results are recorded as the percent of the total which each type represents.
When the differential count is reported as the percentage of each cell type which makes up the total, it is called a "relative differential count".
The absolute differential count cannot be misinterpreted the way the relative count can. It consists of representing the various cell types according to the actual number of each type which is in the blood.
Serious misinterpretations may result when one uses the relative differential count alone for diagnostic purposes. Let us consider this analogy:
If we have 75 white balls and 25 black balls in a jar; 75% of the balls are white, 25% are black. Then if we take away 50 white balls, we have 25 of each type left or 50% of each. The black balls changed from 25% to 50% of the total even though there was no change in their number. Whenever there is a significant change in one cell type in the differential, there will always be an opposite change in the percentage of the other cells too, even though they did not really change in number at all.
To determine the absolute count, one multiplies the total count by the percentage of each type which is present.
Example:
Total white count = 10,000/ul
Mature Neutrophils = 75%
Lymphocytes = 25%
The absolute count of neutrophils is 10,000 x 75% = 7500/ul The absolute count of lymphocytes is 10,000 x 25% = 2500/ul
The following example should indicate the misinterpretation that results from inspection of only the relative differential count:
Neutrophils 80% 60-77%
Lymphocytes 5% 12-30%
Eosinophils 15% 21-10%
Quick inspection of the differential suggests that this dog has a neutrophilia, a lymphopenia, and an eosinophilia. Can all of this be true?
The total white count is 4000/ul. Knowing this may give us some different ideas but will probably just confuse the issue.
Absolute differential count on this patient:
Neutrophils 80% x 4000/ul =3200 3,000-11,000
Lymphocytes 5% x 4000/ul = 200 1,000- 4,800
Eosinophils 15% x 4000/ul = 600 100- 1,250
In terms of actual numbers of cells, the following has occurred:
The administration of these steroids to animals induces a marked change in the leukogram (leukocyte blood picture). These changes include:
The release of ACTH from the pituitary under conditions of stress and disease, stimulates the release of corticosteriods from the adrenal gland. Leukocyte responses under conditions of stress are characterized by a leukocytosis with a neutrophilia, eosinopenia, and lymphopenia. A monocytosis may be observed in the dog and cow. The hemogram of animals being treated with steroids may be misinterpreted when the effects due to the drug are not understood. The following changes were observed in the hemograms of animals given ACTH intra-muscularly:
The increase in total leukocytes is due to an increase in the output of mature neutrophils from bone marrow storage and maturation pool and a decrease in the output of these cells from the blood stream.
When antigen injures tissue cells, chemical substances are released which initiate and perpetuate the inflammatory reaction. Leukotaxine increases capillary permeability and, by chemotaxis, it attracts neutrophils into the area of injured cells. A leukocytosis-promoting factor, also produced from injured cells, is carried by the blood stream to the bone marrow where it stimulates granulopoiesis, thereby increasing the supply of neutrophils. In development of a severe inflammatory response, the need for neutrophils in large numbers is immediate. A neutrophil maturation and storage pool" exists in the bone marrow to meet the initial demand, whereas production of new neutrophils requires two to three days from the time of initial stimulus. Mature neutrophils are preferentially released over band cells from the maturation and storage pool into the peripheral blood. When the need for neutrophils exceeds the ability of bone marrow to supply that need in the form of mature neutrophils, then immature forms (band, metamyelocytes, etc.) are released to peripheral blood. Thus, the intensity of a disease process may be gauged by the extent of the shift to the left.
The ability of the bone marrow to respond to a bacterial infection is measured by the magnitude of the total leukocyte count; the intensity of the response is gauged by the extent of the left shift.
4.11.2.1 REGENERATIVE LEFT SHIFT
Characterized by a leukocytosis due to a neutrophilia with the appearance of immature granulocytes in peripheral blood.
- 1. A slight left shift is limited to the occurrence of band neutrophils.
- 2. A moderate left shift includes both band and metamyelocytes.
- 3. A marked left shift includes myelocytes and progranulocytes.
4.11.2.2 DEGENERATIVE LEFT SHIFT
The total leukocyte count remains in the normal range or is only slightly elevated, while the immature granulocytes are markedly increased.
- 1. It reflects the inability of the bone marrow to response to the infection.
- 2. It is commonly seen in bacterial infection with septicemia.
4.11.2.3 LEUKOMOID BLOOD PICTURE
Similar to a regenerative left shift except the total white count is extremely elevated suggesting a granulocytic leukemia.
- 1. The process stimulating the count is other than leukemia.
- 2. A leukemoid hemogram may be seen in pyometra of the dog, abscess formation, severe hemorrhage or hemolytic crisis.
The severity of the infection is measured by the occurrence of toxic changes in the neutrophils. The following are recognized as manifestations of toxicity:
Interpretation of the leukocyte pattern in disease is difficult because of the species variation in the normal differential leukocyte count. The leukocyte pattern in health significantly affects the pattern of leukocyte response to disease. In the differential leukocyte count of the various domestic animals, the most significant species characteristic is the neutrophil:lymphocyte (N:L) ratio. Therefore, the magnitude of the total leukocyte count in response to disease correlates directly with the N:L ratio. Following are response characteristics of the various species.
4.11.4.1 DOG
- 1. The dog responds the greatest to infection and diseases of stress.
- 2. Total counts of 30,000 - 50,000 are common.
- 3. Counts of 50,000 - 100,000 in the dog are not rare.
- 4. This is understandable when it is realized that both neutrophils and monocytes increase in stress.
- 5. The N:L ratio is 3:1
4.11.4.2 CAT
- 1. The cat has a smaller N:L ratio than the dog (2:1)
- 2. Does not attain total leukocyte count as high as the dog
- 3. Total counts of 30,000 -50,000 are not unusual.
- 4. Maximum counts level off at about 75,000/u1.
- 5. Physiologic leukocytosis, in which lymphocytes parallel and even exceed neutrophils, is common in frightened cats.
4.11.4.3 HORSE
- 1. The N:L ratio is 1:1.
- 2. The leukocyte response to infection is in the range of 15,000 - 25,000.
- 3. Marked leukocytosis in the horse is 25,000-30,000/ul
- 4. Extreme counts are in the range of 30,000 +.
4.11.4.4 COW
- 1. The cow is even less responsive to infection than the horse.
- 2. The N:L ratio is 1:2.
- 3. Often during infection the total count remains within the normal range of 4,000 - 12,000 accompanied by a neutrophilia of 50+% and a left shift.
- 4. Marked leukocytosis would be counts of 15,000 - 25,000.
- 5. Extreme leukocytosis would be counts above 25,000.
- 6. In cows, marked leukopenia with extreme left shift is not an unusual finding in the initial stages of acute inflammatory disease such as peritonitis, pericarditis, mastitis, and metritis. Neutrophils readily leave the blood to enter the lesion and lymphocytes are lysed due to the stress of the disease process. The bone marrow of the cow does not have a large reserve of mature neutrophils, and, therefore, immature neutrophils quickly make their appearance in the peripheral blood and often exceed the mature form (leukopenia with left shift 24 + hours). Leukocytosis with a neutrophilia may not be observed until 3-4 days later. Eosinopenia also occurs due to stress of the disease process.
Exists when the total leukocyte count in the peripheral blood falls below the normal range. Some common causes of leukopenia are:
A. The rickettsial organism, Ehrlichia canis, is responsible for the disease. Infections are frequently complicated by concurrent infections with babesia and Haemobartonella. The disease has the following characteristics:
B. Clinical findings are:
This disorder involves many tissues and cell types. It occurs in man, mink, cattle, and mice. Most attention has been focused on abnormal granules in peripheral blood. These are giant granules shown to be abnormal lysosomes in neutrophils, eosinophils, basophils, monocytes and lymphocytes. These animals are very susceptible to infections. The disease is inherited by an autosomal recessive gene. All affected individuals are partial albinos. In mink, the coat color of this partial albinism is known as aleutian or "blue" and all aleutian mink have the Chediak-Higashi syndrome.
This is a hereditary trait in man, dogs and cattle and is characterized by failure of the nucleus of granulocytes, especially the neutrophil, to undergo normal maturation to the segmented from. This results in a state of permanent left shift in neutrophils. Affected individuals have no health problems. Cells are able to phagocytize.
4.11.11.1 GENERAL INFORMATION
- 1. Leukemia is a neoplastic disease involving one or more of the cell types of the hematopoietic tissues.
- 2. Leukemia results from a failure to maintain an orderly differentiation from the stem cell to a definitive mature cell. This leads to a non-steady state of cell proliferation.
- 3. Leukemia may be induced by the following:
- a. Viruses such as RNA or DNA type
The C-type oncornavirus (RNA) in the cat population may make the cat uniquely susceptible to leukemia development at periods when regeneration of bone marrow cells is taking place; such as during recovery from panleukemia and hemabartonella felis infections. Immature cells or young cells are more susceptible to leukemogenic effects.
- b. Exposure to X-rays
Restricted to disorders of lymphocytic (e.g., lymphoma, acute lymphoblastic leukemia, reticulum cell sarcoma, Hodgkin's) or plasma cell (e.g., multiple myeloma) origin.
A myeloproliferative disorder is a primary bone marrow disease of unknown etiology and encompasses disorders of hematopoietic stem cells as well as of granulocytic, monocytic, erythrocytic and megakaryocytic series. The disease may involve any one or a combination of two or more of the different cell lines comprising the cytology of bone marrow. The schematic outline of the myelo-proliferative disease complex is indicated on the following page.
The clinical signs and symptoms might include the following:
4.11.11.2.1 Lymphoproliferative Disorders
a) BOVINE LYMPHOSARCOMA
Affects cattle of all ages but more commonly after 5 years of age. Bovine leukemia is almost exclusively lymphocytic (Granulocytic leukemia is essentially non existent in the bovine). Two main forms of lymphoma have been recognized:
- 1) Adult Form (Enzootic Bovine Leukosis)
- a) Condition seen in cattle between 2-18 years of age.
- b) Wide spread lymphadenopathy with involvement of the heart (right auricle is most vulnerable) abomasum, and intestines.
- 2) Sporadic Form
- a) Calf Form
- (1) Occurs between 1-6 months of age.
- (2) Characterized by generalized lympha-denopathy with gross changes in the bone marrow, liver and lymph nodes.
b) ADOLESCENT - THYMIC FORM
- (1) This form occurs between 6-3O months of age.
- (2) See infiltration of the thymus and bone marrow with neoplastic cells. Regional lymph nodes are also involved.
c) Cutaneous Form
- (1) Rare, Cattle 1-3 years of age.
- (2) See nodular leukemic infiltration of the dermis.
During the examination of the Peripheral blood smear, one should look for the following:
- - Significant increase in absolute lymphocyte number
- - Evidence of immaturity of the cells in the form of lymphoblast
- - Might see abnormal or atypical lymphocyte
Severe anemia usually does not occur since the life span of bovine red cells is 160 days. Also, the bone marrow is rarely involved in the adult form and the terminal phase is very rapid.
Bendixen, in Sweden, has used persistent lympho-cytosis as a preclinical sign in diagnosing bovine leukosis.
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Normal cattle under 2 years of age may have a few abnormal lymphocytes in peripheral blood that cannot bedifferentiatedfromcells occurring in lymphosarcoma.
4.11.11.3.1 Lymphoproliferative Disorders
a.CANINE LYMPHOSARCOMA
Lymphosarcoma is the most frequent tumor found in the dog. It occurs primarily in dogs 5 years of age and over. Characteristic features of the tumor include:
- 1)Bilateral painless swelling of superficial lymph nodes.
- 2)Usually there is no fever.
- 3)Anemia may be present but usually not severe
Two clinical forms can be identified:
1)MULTICENTRIC FORM
Is characterized by enlarged superficial lymph nodes, enlarged spleen and liver. Might see involvement of almost any organ in the body.
2)ALIMENTARY FORM
Involves the alimentary tract and mesenteric lymph nodes but rarely involves superficial lymph nodes or the spleen.
The total leukocyte count and the differential count may reveal a leukocytosis with a left shift and a modest monocytosis. Only about 20% of the dogs will show a lymphocytosis and 25% will show a frank lymphopenia. Approximately 53% of the dogs showed some degree of thrombocytopenia.
It is generally agreed that the peripheral blood examination is not diagnostic for canine lymphosarcoma. Neoplastic cells may appear irregularly in small numbers. Careful examination of the peripheral blood and the finding of lymphoblast and prolymphocytes might be more informative than the total leukocyte count. Lymph node impression smears and films from aspirated fluid from lymph nodes should be used in conjunction with the peripheral blood in making a diagnosis.
Bone marrow is not regularly invaded in lymphosarcoma. A few cases have been reported with total leukocyte count in excess of 100,000.
Boxers and Scottish Terriers appear more susceptible and Dachshunds less susceptible to lymphosarcoma.
b.BURKITT'S LYMPHOMA AND CANINE LYMPHOSARCOMA
This is a non-leukemic lymphoid tumor involving the visceral organs and bone marrow, particularly of the jaw. A characteristic feature is the scattering of phagocytic histiocytes among densely packed neoplastic lymphocytes, a pattern that gave rise to the descriptive "starry sky" effect". A large number of canine lymphomas also present the "starry sky" pattern indicating a possible related etiologic agent.
c.HODGKIN's DISEASE
This disease consists of a granulomatous process in the lymph nodes that begins with lymphocytic hyperplasia followed by a gradual loss of normal architecture with replacement of the lymphocytes as the disease progresses. Typical Hodgkin's disease has not been shown to occur in animals except one instance of canine malignant lymphoma simulating the disease. Multinuclear giant cells called "Reed-Sternberg cells"are Pathognomonic for the disease and their presence is essential for a diagnosis.
d.PLASMA CELL MYELOMA
This neoplasm arises in the bone marrow from plasma cells. Multiple foci throughout the skeleton have led to the designation "multiple myeloma." Pain, lameness, and sometimes fracture of weakened bones are common clinical signs. Neoplastic plasma cells commonly invade the liver, spleen, kidneys, and lymph nodes. The myeloma plasma cell synthesizes protein, so hyperproteinemia is to be anticipated. The hyperglobulinemia may be associated with Bence Jones Protein in the urine. Multiple myeloma is not a common disease of animals.
4.11.11.3.2 Myeloproliferative Disorders
a.GRANULOCYTIC (MYELOGENOUS) LEUKEMIA
This type of leukemia occurs primarily in young dogs. A truly leukemic blood picture has been a common finding in granulocytic leukemia in the dog. In the event the neoplastic cells are too primitive or bizarre to be classified as granulocytes, their granulocytic origin can be verified by a positive peroxidase stain. A positive reaction for alkaline phosphatase is viewed as evidence that the cells are leukemic granulocytes since normal granulocytes are alkaline phosphatase negative.
1)CLINICAL SIGNS
- a)Progressive weakness
- b)Weigh loss over a period of several months
- c)Moderate lymphadenopathy of peripheral lymph nodes
- d)Splenomegaly and sometimes hepatomegaly
2)TYPICAL BLOOD PICTURE
- a)Neutrophilia with a left shift to the myeloblast stage.
- b)May also see hypersegmentation of mature-like neutrophils
- c)Neoplastic neutrophils are susceptible to rapidly degenerative changes which consist of vacuolation of the cytoplasm
- d)Difficult to differentiate degenerating neoplastic neutrophils from monocytes.
- e)Severe anemia is a common feature
- f)Thrombocytopenia may also be seen
b. MAST CELL LEUKEMIA
Mast cell tumors are of common occurrence in dogs but mast cell leukemia is rarely seen. The total leukocyte count is usually normal but the differential contains numerous mast cells in the peripheral blood and bone marrow. Tissue section stained by Giemsa method revealed metachromatic cytoplasmic granules in the neoplastic cells. Ulceration in the GI tract may occur due to histamine release from the mast cells.
4.11.11.4.1 .Lymphoproliferative Disorders
a.LYMPHOSARCOMA
This neoplasm is the most frequently occurring form within the feline leukemia complex. General signs are depression, fluctuating temperature, and wasting and progressive anemia.
1)Its clinical manifestations are so varied that it has become routine to recognize three distinct pathologic forms.
a)THYMIC OR MEDISTINAL FORM
- (1) This form is usually seen in kittens under one year of age.
- (2) Large mass may develop in the thymus or in the anterior ventral portion of the thorax and extend into the thoracic inlet where it may become palpable.
- (3) May get pleural effusion containing lymphoblasts, prolymphocytes, and mitotic figures.
- (4) The anterior mediastinal lymph nodes are usually involved.
- (5) Occurs with great frequency.
b)ALIMENTARY OR ABDOMINAL FORM
- (1) This form is characterized by one or more solid tumors in the alimentary tract and enlarged mesenteric lymph nodes.
- (2) Occurs frequently in cats and involves the terminal ileum, spleen, liver and especially the kidney.
- (3) May see a membranous glomerulonephitis which is believe to be immunologically mediated.
- (4) Peripheral lymph nodes are not involved.
c)MULTICENTRIC FORM
- (1) This is the least frequent form seen.
- (2) May get peripheral lymphadenopathy as well as internal lymph node and organ involvement.
- (3) Spleen may be enlarged and the liver may contain numerous small foci of tumor cell infiltration.
2)The Laboratory Findings
- a)Leukemic cells in the peripheral blood and bone marrow in approximately 25% of the cases (lymphocytic leukemia).
- b)A nonregenerative anemia
- c)A variable white blood cell count from a leukopenia to a leukocytosis.
- d)Granulopoiesis is sometimes abnormal with large bizarre granulocytic cells.
3)Diagnosis of lymphoreticular neoplasm in cats requires a combination of blood studies to include the following:
- a)Peripheral blood examination - only in a few instances will the examination by itself confirm the diagnosis.
- b)Cytologic examination of pleura effusion - look for the presence of lymphoblast and prolymphocyte.
- c)Bone marrow aspiration - look for the presence of neoplastic lymphocyte. Remember that normal feline marrow may have between 5% to 15% of small mature lymphocytes
- d)A positive feline leukemia virus (FeLV) fluorescent antibody test which may be performed on blood or blood smears. This is a test for viral antigen in the cells and indicates current infection with the virus. It does not determine that the animal has lymphosarcoma because clinically normal cats and cats with other disease syndromes (myeloproliferative disease) can be FeLV positive.
b.MULTIPLE MYELOMA
This disease in cats is characterized by marked proteinuria and the presence of Bence Jones Protein in the urine. The blood occasionally contains plasma cells, and the bone marrow is infiltrated with highly pleomorphic plasma cells. The animal is anemic with spleen and lymph nodes enlargement.
4.11.11.4.2 Myeloproliferative Disorders
A variety of cytologic patterns may occur in myelo-proliferative disease. The following syndromes may be recognized:
a.RETICULOENDOTHELIOSIS
It is a proliferation of pluripotential stem cells which may lead to accumulation of these cells in the blood and bone marrow showing no clear cut differentiation toward a recognizable cell line.
- 1)Typical cells have a reddish nucleus with a blue cytoplasm.
- 2)The nucleus occupies most of the cell and assumes an eccentric position. The nucleus may contain one or more nucleoli.
- 3)The chromatin pattern is suggestive of early precursor cells of the RBC series.
- 4)The cytoplasm of some cells contain few to many reddish azurophilic granules which is suggestive of the granulocytic cell series.
- 5)Erythroid, granulocytic and lymphocytic precursor cells appear in the peripheral blood.
- 6)In the BM, there is almost complete absence of recognizable maturation forms.
- 7)See also cytoplasmic pseudopod-like projection in some cells which contain azurophilic granules.
- 8)May also see reduction in granulopoiesis, vacuolation of granulocytes and an occasional giant metamyelocyte.
- 9)Must differentiate Vitamin B12 and folic acid deficiency and convalescent panleukopenia, toxemic diseases with leukopenia.
b.ERYTHREMIC MYELOSIS
This form of myeloproliferative disease may be suspected when in the presence of severe anemia, the peripheral blood morphology is characterized by marked anisocytosis without an accompanying polychromasia or reticulo-cytosis.
1)See many nucleated red cells in the peripheral blood with very few or no poly-chromatophilic cells
2)The bone marrow may exhibit erythroid hyperplasia with many immature erythroid cells, and large megaloblastic erythroid precursors characterized by an asynchronous maturation of nucleus and cytoplasm. Some of these cells may be present in the peripheral blood.
3)When the bone marrow is characterized by excessive proliferation of cells of the erythrocytic series, granulopoiesis is depressed and vacuolation of granulocytic precursor cells may be seen.
4)Erythremic myelosis in cat has been compared to the Diguglielmo syndrome in man.
5)Get differentiation of the abnormally proliferating cell into recognizable nucleated erythrocytes without significant participation of granulocytes. Get maturation arrest at the metarubricyte stage.
c.ERYTHROLEUKEMIA
There is no clear separation between erythremic myelosis and erythroleukemia.
The diagnosis is based on the finding of myeloblasts admixed with abnormal nucleated erythrocytes in peripheral blood.
d.GRANULOCYTIC LEUKEMIA
This disease is characterized by a leukocytosis with myelocytes, progranulocytes, and myeloblasts present in peripheral blood in significant numbers. Clinical signs and symptoms may include the following:
- 1)Severe anemia
- 2)Splenomegaly with liver involvement
- 3)Lymphadenopathy
In general, myelocytes predominate in the peripheral blood. The bone marrow is usually hypercellular with diffuse proliferation of granulocytes and numerous mitotic forms.
Diagnosis may present a problem in the cat that has a normal or leukopenia leukocyte count with a left shift that includes myelocytes, progranulocytes, and occasionally myeloblasts. The problem of diagnosis of subleukemic granulocytic leukemia in the cat is complicated by the fact that leukopenia with left shift to progranulocytes and myeloblasts occurs rather frequently in association with toxemic diseases and panleukopenia. When the bone marrow is hypercellular with maturation arrest at the myelocyte stage, granulocytic leukemia may be suspected. Such maturation arrest forms the basis for the leukopenia and intermittent left shift to myeloblasts in the peripheral blood. Leukemic granulocytic cells may be susceptible to rapid deterioration once the blood is withdrawn from the body and become vacuolated, giving the appearance of monocytes.
e.EOSINOPHILIC LEUKEMIA
This form of neoplastic leukemia is not of common occurrence in the cat. Eosinophils are observed in significant numbers in the peripheral blood contributing 14% to 20% of the total leukocyte count.
f.MONOCYTIC LEUKEMIA
This disease is a neoplastic proliferation of monocytes characterized by marked leukocytosis composed primarily of monocytoid cells. The bone marrow contains immature monocytes in large numbers. Diagnosis is based on demonstration of similar monocytoid or reticulum cells in the liver, spleen, lymph nodes and bone marrow. Anemia is also associated with the disease.
4.11.11.5 .LEUKEMIA COMPLEX IN THE HORSE, SHEEP AND GOATLYMPHOSARCOMA
This disease is of rare occurrence in the horse, sheep and goat. The hemogram is usually characterized by a moderate leukocytosis, due mainly to neutrophilia, but with atypical lymphocytes present in the blood.
