Haematopoietic system Flashcards
What is myeloid tissue?
- Bone marrow
- Blood cells
- Mononuclear-phagocyte system
What is lymphoid tissue?
- Lymph nodes
- Spleen
- Thymus
- Accessory lymphoid tissue
What infectious agents can cause anaemia?
- Equine infectious anaemia
- Anaplasmosis
- Haemotropic mycoplasma
- Babesiosis
- Trypanosomiasis
- Theileriosis
What is the function of lymph nodes and what do they contain?
Function:
* Filtration of lymph
* Immune response
Structure:
* Outer cortex -> follicles (mostly B cells)
* Inner cortex -> paracortex (mostly T cells)
* Medulla -> mostly B cells and macrophages
What is lymphadenopathy?
- Enlargement of lymph node(s) of unknown cause
- Can be localised or generalised
What can cause enlarged lymph nodes?
- Lymphadenitis
- Lymphoid hyperplasia
- Hyperplasia of the monocyte/macrophage system
- Primary neoplasia
- Secondary Neoplasia
What can cause lymph nodes to decrease in size?
- Lymphoid atrophy
- Lymph node degeneration/necrosis
- Lymph node hypoplasia
What causes acute lymphadenitis? (inflammation)
- Usually the result of a regional lymph node draining a site of inflammation and becoming infected.
What is an example of chronic suppurative lymphadenitis?
Strangles -strep equi var equi
if spreads to viscera = bastard strangles
can drain to guttural pouch = guttural pouch emphysema
What causes caseous lymphadenitis?
Corynebacterium pseudotuberculosis - enters via shearing wound
-enlargement of LN - onion ring look - becomes systemic with time
what can cause nodular granulomatous lymphadenitis?
- Mycobacterium bovis (bovine tb)
- Mycobacterium avium subsp.
Paratuberculosis (Johne’s disease) - Actinobacillus lignieresii (wooden tongue)
- Migrating parasitic larva
What can cause Diffuse granulomatous lymphadenitis?
- Porcine Circovirus type 2
- Histoplasma capsulatum
- Blastomyces dermatitidis
- Cryptococcus neoformans
What can lymph nodes metastasis occur from?
- Common with carcinomas, melanomas, mast cell tumours
What is a lymphoid leukaemia and lymphoma?
- Lymphoid leukaemia = neoplastic lymphocytes in bone marrow/ blood
- Lymphoma (lymphosarcoma) = Neoplastic lymphocytes in tissues/ organs
What lymphoma is notifiable?
Enzootic bovine lymphoma
What are the 3 types of sporadic bovine lymphoma?
1.Calf form - <6m/o, symmetrical lymphadenopathy
2.Juvenile form - yearlings - mediastinal mass
3.Cutaneous form - 2-3y/o - skin only
What is the function of the thymus?
- Proliferation and maturation of T cells
When does thymic hypoplasia occur?
- Occurs as part of severe combined
immunodeficiencies (SCID) in foals and
some breeds of dogs
When does thymic atrophy occur?
- Shrinkage of thymic organ by: inadequate nutrition,
intoxications, infectious agents (eg canine distemper
virus), lack of antigenic stimuli, drugs etc.
What is a thymoma?
- Neoplastic proliferation of epithelial cells
- Less common- dogs, sheep, goats
- Slow growing, encapsulated
What is a thymic lymphoma?
- Neoplastic proliferation of T- cells (lymphocytes)
- Often younger animals (cats, calves, and dogs)
- Malignant behaviour
What is the structure and function of the red pulp of the spleen?
Structure
* Sinusoids/vascular spaces
* Splenic cords
Function
* Filters blood- removal of foreign material (phagocytosis)
* RBC storage
* Haematopoiesis (EMH)
What is the structure and function of the white pulp of the spleen?
Structure
* Periarterial lymphatic sheaths (PALS) (T-cells)
* Lymphoid nodules (B-cells)
* Marginal zone (Macrophages)
Function
* Immune response
What are the miscellaneous diseases of the spleen?
*Splenic amyloidosis - friable and waxy -orange discolouration
*Splenic torsion - twist around gastrosplenic ligament
*Siderotic plaques - firm encrustations on the surface
*Splenic haematoma - from splenic rupture, haemoabdomen,
hypovoloaemic shock
*Accessory spleens
