In which conditions can haematopoiesis in the spleen continue after birth?
- Where there is nodular hyperplasia
- When there is increased demand (ex. severe anaemia)
In which condition will extramedullary myelopoiesis occur?
Where these is excessive demand for neutrophils
Ex. on going sepsis
What primarily forms the bone marrow in adult animals?
How does this differ from the young/diseased animal
Fat
Bone marrow is very cellular in young and diseased animals
How can you identify a cellular sample of bone marrow with a simple test?
A cellular sample of bone marrow will sink when placed in formalin
Normal, fatty, marrow will float
Define myeloproliferative disease
A non-specific term describing disordered proliferation of one or more of the haemopoietic cell lines in the bone marrow
What is the term for inflammation of the bone marrow?
Myelitis
List 3 forms of anaemia
- Haemorrhagic
- Haemolytic
- Non-regenerative
List the 5 major pathological features/changes of anaemia
- Pallor
- Myocardium (fatty degeneration)
- Liver (periacinar hepatic necrosis)
- Spleen (shrunken or enlarged)
- Muscle (paler)
Describe the mechanism of periacinar hepatic necrosis in anaemia
When an animal is anaemia, there is not enough circulating oxygen
The central area (periacinar region) of the hepatic lobule is most susceptible to such low levels of oxygen, and therefore we see necrosis
List 3 specific pathological features of haemolytic anaemia
- Jaundice
- Bone marrow hyperplasia
- Spleanomegaly
Compare the pathological changes to the spleen in haemorrhagic and haemolytic anaemia
Haemorrhagic: spleen appears smaller because it is contracting to try and release more RBCs
Haemolytic: spleen appears larger because it is trying to make more RBCs
List possible causes for wet, uniform splenomegaly
- Congestion
- Barbiturate euthanasia
- Torsion
- Anthrax
List possible causes for firm, uniform splenomegaly
- Chronic stimulation (ex. infectious disease)
- Diffuse neoplasia
- Extramedullary haematopoiesis
List possible causes for wet, nodular splenomegaly
- Haematomas
- Neoplasia
List possible causes for firm, nodular splenomegaly
- Nodular hyperplasia
- Non-vascular neoplasia
- Inflammation and/or abscesses
What is a common pathology of the spleen in old dogs?
Benign nodular hyperplasia
List 2 neoplasms of mesenchymal origin that can arise in the spleen
- Fibrosarcoma
- Leiomyosarcoma
What are the primary sites of haemangiosarcoma’s in the dog?
- Spleen
- Right atrium
- Liver
- Skin
List 2 potential consequences of haemangiosarcomas
- Haemorrhage
- Metastases to distant sites
List 5 other classes of splenic pathologies
I.e., not neoplasia or inflammation
- Atrophy
- Splenic rupture
- Siderofibrosis
- Infarcts
- Contraction (i.e., shock)
Define lymphadenopathy
Regional or generalised lymph node enlargement of unspecified causes
Explain the difference between a reactive lymph node and lymphadenitis
A reactive lymph node is enlarged in response to surrounding inflammation/presentation of antigens
Lymphadenitis is specific inflammation of the lymph node itself
List 3 general reasons why a lymph node may be enlarged
- Hyperplasia
- Inflammation
- Neoplasia
List 3 consequences of lymphadenitis
- Resolution
- Abscess
- Scarring
