Changes

==Description==

==Description==

Lymphocytosis refers to an increase in the number of circulating lymphocytes in the blood.  The major causes of lymphocytosis are:

Lymphocytosis refers to an increase in the number of circulating lymphocytes in the blood.  The major causes of lymphocytosis are:

*Several types of '''neoplasia''' may result in increases in the number of blood lymphocytes, including:

**Several types of tumour may result in increases in the number of blood lymphocytes, including:

**Stage V (leukaemic) [[Lymphoma|lymphoma]]

***Stage V [[Lymphoma|lymphoma]]

**Acute lymphoblastic and chronic lymphocytic leukaemia

***Acute lymphoblastic and chronic lymphocytic leukaemia

**Bovine Leukosis caused by bovine leukaemia virus (BoLV)

***Bovine Leukosis caused by bovine leukaemia virus

*'''Stress''' may result in the release of lymphocytes into the circulation, especially in young horses and cats.  This response is mediated by the release of adrenaline from the adrenal medulla and it should not be confused with the stress leucogram produced by the release of the glucocorticoid hormones cortisol from the adrenal cortex.

*Stress

*Some cases of '''chronic infection''' may be associated with lymphocytosis but

** Following adrenaline release in fear, excitement and so on.

reactive hyperplasia in associated lymph nodes may not correlate with the numbers of circulating lymphocytes.

*Chronic infection

*'''Physiological''' lymphocytosis is common in young animals of many species.  In growing pigs, this may be associated with [[Mycoplasma]] infection.

** In some cases of chronic infection.

*In '''premature''' or '''dysmature equine neonates''', the normal neutrophil: lymphocyte ratio of approximately 2: 1 may be reversed to produce an apparent lymphocytosis.  Such animals will also have an increased mean corpuscular volume (MCV) of their red blood cells.

*** However, reactive hyperplasia in associated lymph nodes may not correlate with the numbers of circulating lymphocytes.

*Physiological

** Commonly in growing swine.

*** Possibly associated with aMycoplasma infection.

*Equine neonates

[[Category:Haematology Changes]][[Category:To Do - James]]

[[Category:Haematology Changes]][[Category:To Do - James]]