Monocytes
Blood count (CBC) ·Also called: MONO, monocyte count
What it is
Monocytes circulate briefly before moving into tissue, where they mature into macrophages. They handle chronic problems: walled-off infection, fungal organisms, tissue breakdown, and the clean-up phase after injury or surgery.
Why your vet measures it
Monocytosis points towards chronicity or tissue damage rather than a fresh infection. In dogs it is also part of the steroid response, so it often appears alongside raised neutrophils and low lymphocytes on a stressed or treated patient.
What a high result can mean
- Chronic or deep-seated inflammation, such as an abscess or an internal infection
- Tissue damage, including recent surgery, trauma, or a necrotic tumour
- Steroid treatment or endogenous cortisol, particularly in dogs
- Immune-mediated haemolytic anaemia, where macrophages are busy clearing damaged red cells
What a low result can mean
- Not usually significant — healthy animals can have very few circulating monocytes
Dogs and cats differ
The steroid-driven rise in monocytes is a canine feature. Cats given steroids do not reliably show it, so a raised feline monocyte count leans more towards genuine chronic inflammation.
Questions worth asking your vet
- Does this suggest something long-standing rather than a new problem?
- Should we look for a hidden focus of inflammation?
Related terms
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