Leukocyte Dynamics, Pathogens, and Myeloproliferative Disorders

Comprehensive vocabulary flashcards covering the hematology lecture notes: leukocyte functions, differential counts, leukogram dynamics, blood parasites, and myeloproliferative disorders.

Hemogram

A primary diagnostic profile that provides a real-time snapshot of the body's internal environment and systemic health by evaluating leukocyte and thrombocyte populations.

Neutrophil

The primary effector leukocyte against infectious agents and the body's first responder to bacterial and protozoal pathogens.

Eosinophil

A leukocyte that mediates allergic and parasitic inflammatory responses, and can also be identified as a component of specific granulocytic neoplastic processes.

Monocyte / Macrophage

Phagocytic cells responsible for processing pathogens that serve as a critical bridge between innate and adaptive immunity, often hosting complex protozoal life stages.

Lymphocyte

A white blood cell essential for immune surveillance, antibody production, and coordinating the specific (adaptive) immune response.

Basophil

A circulating granulocyte involved in hypersensitivity reactions and the broader systemic inflammatory narrative.

Platelet / Thrombocyte

The fundamental cellular element of the hemostatic response, essential for maintaining vascular integrity and initiating clot formation.

Relative Differential Count

A percentage-based leukocyte count that is mathematically secondary and potentially misleading when total leukocyte counts are abnormal.

Absolute Differential Count

The diagnostic metric calculated by multiplying the total white blood cell count by the percentage of a specific cell type, revealing true cell line deficiencies or overabundances.

Neutrophil:Lymphocyte (N:L) Ratio

A hematologic metric in domestic animals that provides predictive insight into an animal's capacity to mount a defense against infectious burden or physiological stress.

Physiological Shifts

Alterations in the leukogram profile driven by non-pathogen endocrine events, specifically corticosteroid release (stress) or epinephrine release (excitement).

Stress-Induced Leukogram

A leukogram profile characterized by mature neutrophilia often accompanied by lymphopenia, lacking toxic changes and left shifts.

Left Shift

An increased circulation of immature (band) neutrophils indicating that the bone marrow is releasing reserves early to meet intense peripheral tissue demand.

Sepsis Leukogram Profile

A high $\text{N:L}$ ratio accompanied by an active left shift and morphological toxic changes reflecting extreme bone marrow demand.

Neutrophilia

An absolute increase in circulating neutrophil numbers triggered by infectious agents, non-infectious inflammation, or primary myeloproliferative neoplastic transformation.

Non-Infectious Inflammation (Neutrophilia Triggers)

Pathological systemic insults that trigger neutrophilia without living pathogens, such as tissue necrosis, burns, or immune-mediated diseases.

Toxic Change

Morphological alterations in neutrophils—comprising cytoplasmic basophilia, vacuolation, and Döhle bodies—indicating that severe inflammation forced accelerated marrow maturation.

Cytoplasmic Basophilia

A manifestation of toxic change in neutrophils reflecting accelerated maturation in the marrow that bypasses standard quality-control mechanisms.

Döhle Bodies

Distinct morphological inclusions in neutrophils characteristic of toxic change caused by accelerated maturation under intense inflammatory pressure.

Marrow Reserve

The capacity of the bone marrow to sustain leukocyte output, which clinicians gauge by evaluating toxic changes and leukocyte shifts.

Blood Smear

The definitive diagnostic preparation used to identify pathognomonic inclusions and parasites that automated hematologic counters misclassify as cellular debris.

Canine Distemper Inclusions

Large viral nucleocapsid aggregates visible during the acute disease phase inside erythrocytes, leukocytes, and epithelial cells.

Hemotropic Mycoplasmas

Epicellular bacterial parasites belonging to the genus Mycoplasma that attach to red blood cell membranes across various animal species.

Mycoplasma hemofelis

Feline hemotropic mycoplasmas appearing as paired cocci, short rods, or small rings ($0.5\text{--}1.5\,\mu\text{m}$) on RBC membranes, common in FeLV-positive patients.

Mycoplasma hemocanis

A canine hemotropic mycoplasma that is often an incidental finding on blood smears, appearing as small cocci or chains.

Eperythrozoonosis

Hemotropic mycoplasma infections affecting livestock and camelids, caused by agents such as M. suis, M. ovis, and M. haemolama.

Mycoplasma suis

A hemotropic parasite of swine that in severe infections causes capillary blockage leading to gangrene of the ears.

Mycoplasma ovis

The hemotropic mycoplasma species responsible for eperythrozoonosis in sheep.

Mycoplasma haemolama

The specific hemotropic mycoplasma species that causes eperythrozoonosis in camelids.

Babesiosis (Piroplasmosis)

A tick-borne protozoal infection of red blood cells caused by various intraerythrocytic Babesia species.

Babesia bigemina

A large bovine piroplasm measuring $4\text{--}5\,\mu\text{m}$ that typically joins in pairs at an acute angle within the erythrocyte.

Babesia bovis

A bovine piroplasm that is smaller than B. bigemina, occasionally pairs at an obtuse angle, and possesses zoonotic potential.

Babesia canis

A large, piriform (pear-shaped) intraerythrocytic piroplasm that infects dogs.

Babesia gibsoni

A small, round intraerythrocytic piroplasm found in canine blood smears.

Babesia caballi

An equine piroplasm appearing inside red blood cells as piriform bodies measuring $2.5\text{--}4\,\mu\text{m}$ or round bodies measuring $1.5\text{--}3\,\mu\text{m}$.

Anaplasma marginale

A ruminant erythrocyte parasite appearing as dark blue-purple bodies measuring $0.3$ to $0.1\,\mu\text{m}$ situated along the cell margins.

Ehrlichia canis

A rickettsial WBC parasite characterized by the formation of intracytoplasmic morulae in canine neutrophils and lymphocytes.

Morulae

Cluster-like diagnostic inclusions formed by Ehrlichia canis within the cytoplasm of infected circulating leukocytes.

Hepatozoon canis Gametocytes

The diagnostic circulating life stage of Hepatozoon canis identified within the cytoplasm of host monocytes and neutrophils.

Hepatozoon canis Schizonts

Tissue stages of Hepatozoon canis found in cardiac muscle, skeletal muscle, and liver that form a pathognomonic 'cart wheel' or 'onion-skin' appearance.

Cart Wheel / Onion-Skin Appearance

The pathognomonic histologic pattern formed by Hepatozoon canis schizonts within skeletal muscle, cardiac muscle, and liver tissues.

Leishmania donovani

A protozoan pathogen whose amastigote forms are identified morphologically inside mononuclear phagocytes (macrophages).

Amastigote (Leishmania donovani)

The non-flagellated intracellular life stage of Leishmania donovani residing and multiplying inside host macrophages.

Cytauxzoon felis Piroplasms

Intraerythrocytic signet-ring or piroplasm forms of Cytauxzoon felis visible on feline blood smears.

Cytauxzoon felis Schizonts

Large diagnostic tissue structures of Cytauxzoon felis found within macrophages of the lung, liver, and spleen.

Toxoplasma gondii Tachyzoites

The rapidly replicating lytic stage of Toxoplasma gondii identifiable directly within neutrophils on blood films.

Babesia microti

A zoonotic piroplasm species that is not strictly host-specific and possesses the capability to infect human patients.

One Health Monitoring

The public health surveillance practice supported by blood smear identification of blood parasites possessing zoonotic potential, such as Babesia species.

Myeloproliferative Disorders

Bone marrow-originated leukemias involving non-lymphocytic hematopoietic cell lines, often associated with C-type leukemia viruses.

C-Type Leukemia Virus

An oncogenic retrovirus group—notably FeLV in domestic cats—frequently associated with the pathogenesis of myeloproliferative disorders.

Myelophthisis

The replacement and physical crowding out of normal bone marrow hematopoietic elements by neoplastic proliferation, leading to severe nonregenerative anemia.

Clinical Presentation of Myeloproliferative Disorders

A characteristic clinical triad in affected animals featuring progressive weight loss, emaciation, and severe nonregenerative anemia.

Acute Myeloid Leukemia (AML)

A category of rapidly progressive non-lymphocytic hematopoietic neoplasms diagnosed via quantitative blast and myeloid marrow thresholds.

AML Blast Cell Criterion

The diagnostic marrow requirement that blast cells must constitute $>30\%$ of the total nucleated cell population to confirm AML.

AML Myeloid Cell Criterion

The diagnostic marrow requirement that total myeloid cells must constitute $>50\%$ of the total nucleated cell population to confirm AML.

Acute Undifferentiated Leukemia

An AML subgroup characterized by the neoplastic proliferation of pluripotential stem cells lacking early morphological lineage markers.

Anti-D34 Antibody

A canine diagnostic reagent used to identify pluripotential stem cells and distinguish undifferentiated myeloid leukemia from lymphocytic precursors.

Acute Myeloblastic Leukemia

A recognized AML subgroup also termed granulocytic or neutrophilic leukemia, involving neoplastic proliferation of neutrophil precursors.

Erythroleukemia

A subgroup of acute myeloid leukemia involving malignant neoplastic transformation of the erythroid cell line.

Reticuloendotheliosis

The specific clinical terminology used in feline medicine to refer to erythroleukemia involving the erythroid line.

Granulocytic Sarcoma (Chloroma)

An extramedullary solid tumor formed by focal granulocytic neoplasms that frequently appears greenish grossly.

Canine Chloroma Sites

Extramedullary anatomical sites characteristically targeted by granulocytic sarcomas in dogs, specifically the lung, gut, and skin.

Bovine Chloroma Site

The characteristic anatomic structure targeted by granulocytic sarcoma in cattle, which is skeletal muscle.

Avian Chloroma Prevalence

The epidemiologic distribution of granulocytic sarcoma in birds, being relatively common in domestic fowl but rare in exotic birds.

Minimal Differentiation Diagnostic Challenge

An oncologic diagnostic pitfall where undifferentiated myeloid leukemias mimic lymphomas, requiring cytochemistry and immunophenotyping to prevent misclassification and ineffective chemotherapy.