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==Causes of Neutrophilia==
==Description==
Neutrophilia refers to an increase in the number of [[Neutrophil|neutrophils]] in the blood. In many cases, neutrophilia is accompanied by the release of substantial numbers of immature neutrophils into the blood stream from the bone marrow. The nuclei of these '''Band cells''' are not segmented and they appear to be elongated bent tubes in the cytoplasm. The presence of band cells in the blood indicates that there is an intense need for neutrophils to maintain normal blood levels as they are lost in a purulent process somewhere in the body. When the percentage of the total neutrophil population that is contributed by these immature forms is high, the neutrophilia is described as having a '"regenerative left shift'".
Very severe diseases that deplete the neutrophils may also exhaust the reserve supply of these cells in the bone marrow. In such situations, there is a neutropenia without band cells in the circulation, a phenomenon called a '''degenerative right shift'''. Some severe localised infections (including pyometras) may cause a neutrophilia of much greater magnitude than is usually observed. This so-called '''leukaemoid response''' may precede a right shift.
There are numerous causes of neutrophilia and it is the most common and least specific abnormal finding when blood samples undergo haematological analysis. Common causes include:
*'''Purulent Foci''' and '''abscesses''' in the body produce substantial neutrophilia. Examples include pyometra, severe pyoderma and empyema (purulent inflammation of a body cavity). In severe cases of purulent inflammation, neutrophils may appear '''toxic''' when observed on cytological slides. These toxic cells have evident, blue-staining cytoplasmic granules and some cytoplasmic vacuolation. These cells have decreased bactericidal capability and do not respond as quickly to chemotactic stimuli.
* For example, [[Aspergillus spp.|aspergillosis]].
*'''Bacterial infection''' may result in neutrophilia as neutrophils are the major type of leucocyte that act to control this type of pathogen. Some bacteria, particularly Gram positive species, are particularly pyogenic due to their ability to resist intracellular killing by neutrophils.
* Neutrophils may be present, but are not the main component of inflammaory cells.
*'''Necrosis''' of any tissue will result in neutrophilia. Common causes of tissue necrosis include burns, malignancies and infections.
* Neutrophils may be present, but are not the main componentof inflammatory cells.
*'''Fungal infection''' with, for example ''[[Aspergillus spp.]]''.
* Neutrophils may be present, but are not the main component of inflammatory cells.
*'''Viral infection''' may cause a neutrophilia but neutrophils are often not the major type of inflammatory cell responding to the infection. Examples include [[Paramyxoviridae#Canine Distemper Virus (CDV)|canine distemper]], [[Herpesviridae|equine rhinotracheitis virus]] (EHV-1) and [[Herpesviridae#Bovine herpesvirus -1|infectious bovine rhinotracheitis]] (IBR or BHV-1).
* Other factors which will produce a neutrophilia are:
*'''Parasitic infection''' may cause a neutrophilia but neutrophils are often not the major type of inflammatory cell responding to the infection and [[Eosinophilia|eosinophilia]] is more likely. Examples include [[Fasciolosis|fasciolosis]] and [[Toxoplasmosis|toxoplasmosis]].
*'''Immune-mediated disease''' frequently causes a neutrophilia, often with a concurrent [[Monocytosis|monocytosis]]. Examples include [[Rheumatoid Arthritis|rheumatoid arthritis]], [[Systemic Lupus Erythematosus|systemic lupus erythematosus]] and [[Immune Mediated Haemolytic Anaemia|immune-mediated haemolytic anaemia]] (IMHA).
*'''Miscellaneous factors''' that can cause neutrophilia include:
**Excitement, fear and strenuous exercise in young animals.
**Corticosteroids as part of a stress leucogram with concurrent [[Monocytosis|monocytosis]], [[Eosinopenia|eosinopenia]] and [[Lymphopenia|lymphopenia]]. The corticosteroids may be endogenous (with pain, stress or [[Canine Hyperadrenocorticism - Cushing's disease|hyperadrenocorticism]]) or exogenous with medical therapy for a variety of other diseases.
**As a response to any cause of [[Anaemia - Introduction|anaemia]].
[[Category:Haematology Changes]][[Category:To Do - James]]
[[Category:Haematology Changes]][[Category:To Do - James]]