Overview
- Neutrophils phagocytose and digest foreign material in acute infectious or non-infectious inflammation.
- The degree of [neutrophil] increase (neutrophilia) and presence or absence of left-shift provides a valuable diagnostic (in combination with other tests) and prognostic tool in many diseases.
- Regenerative left-shift : mature neutophils outnumber bands
, and are elevated or normal. - Degenerative left-shift : excessive neutrophil consumption → bands and/or less mature forms outnumber mature neutrophils.
- Marked left-shift (bands and metamyelocytes)
→ acute to peracute, suppurative diseases. Any stage younger than the metamyelocyte is not capable of phagocytosis.
- Neutrophils are short-lived (approximately 4 days).
Uses
In combination
- With other red and white blood cell parameters as part of routine hematological screen (CBC).
- Infections - in combination with leukogram.
- Septicemia and overwhelming bacterial infections may have leukopenia with degenerative left-shift.
- Corticosteroids - in combination with leukogram (eosinopenia, lymphopenia and monocytosis) and biochemistry.
- Inflammation - usually with left-shift (acute); may or may not see eosinopenia.
- Leukemias and lymphoproliferative disorders (recognition of abnormal lymphocytes and lymphoblasts or immature and atypical myeloid cells).
- Hemolytic or hemorrhagic anemia - neutrophilia with left shift often seen.
- Chronic infection/inflammation (anemia of chronic disease).
Other points
Neutrophil kinetics
- Proliferating pool: myeloblast, progranulocyte (promyelocyte) and myelocyte.
- Maturation pool: metamyelocyte, band neutrophil and segmented granulocyte.
- Marginal neutrophilic pool (MNP) - 1 neutrophil for each neutrophil circulating in small blood vessels.
- Circulating neutrophilic pool (CNP) - in larger blood vessels. Half-life approximately 6-7 hours, ie entire population replaced 2.5 times daily.
- Tissue migration within 2 hours of injury. Neutrophils do not return to circulation, but either enter body cavities (gut, pulmonary secretions, urine, saliva) or are phagocytozed.
- Leukocytosis due to neutrophilia.
- 'Leukemoid reaction' (appearance of earlier devopmental forms) may appear with excessive neutrophil demand, eg pyometra .
- Numbers from immature to mature forms progressively increase, ie more mature neutrophils than band forms, more band forms than metamyelocytes, etc.
- Leukopenia common, but may see normal leukogram or leukocytosis (rarely).
- The number of immature neutrophils exceeds the number of mature forms.
Result data
Normal (reference) values
- May vary with age, sex or breed.
- 3-11.5 x 10*9/L.
- 2-6.5 x 10*9/L (Greyhound).
Abnormal values
- Acute infection, especially with pyogenic bacteria, usually results in the appearance of band forms (left-shift), and sometimes earlier forms in very severe cases.
- Chronic infections have mature neutrophils with smaller or absent left shift and often monocytosis.
- Infection (especially pyogenic bacteria).
- Tissue inflammation/necrosis.
- Hyperadrenocorticism or corticosteroid treatment.
- Stress (endogenous corticosteroid release) - total leukocyte count usually <30-35 x 10*9/l.
- Leukoerythroblastic responses.
- Autoimmune hemolytic anemia .
- Drug toxicity - estrogen (acute).
- Neoplasia.
- Leukemia .
- Neutrophilia may also be due other to non-inflammatory disorders, eg intoxication, anesthetics and occasionally metabolic disorders.
- Excessive destruction or utilization, sequestration, reduced granulopoiesis, impaired movement out of bone marrow and congenital defects.
- Overwhelming acute or chronic bacterial infection.
- Viral infection (acute), eg canine parvovirus .
- Hypersplenism.
- Shock - endotoxic, septic , anaphylactic.
- Drugs.
- Estrogen-producing testicular tumors, ie Sertoli cell tumors.
- Toxemia, eg uremia.
- Neoplasia.
- Myelokathexis (neutropenia resulting from bone marrow retention in the face of adequate reserves).
- Cyclic neutropenia in the Grey Collie.
Sources
Publications
Refereed papers
- Brown M R & Rogers K S (2001) Neutropenia in dogs and cats - a retrospective study of 261 cases. JAAHA 37 , 131-139.
Other sources of information
- Cowell R L, Tyler R D & Meinkoth J H (1999) Diagnostic Cytology and Hematology of the Dog and Cat. 2nd edn. Mosby, St Louis.
- Duncan J R, Prasse K W & Mahaffy E A (1994) Veterinary Laboratory Medicine Clinical Pathology. 3rd edn. Iowa University Press, Ames, Iowa.
- Jain N C (1993) Essentials of Veterinary Hematology. Lea & Febiger, Philadelphia.
