Platelet Abnormalities

The aetiology of primary thrombocytopenic disease is often uncertain.
- It is therefore also known as idiopathic thrombocytopenia.
- The cause may be automimmune.
Although the bone marrow contains adequate normal megakaryocytes, there is a reduced peripheral blood thrombocyte count.
Usually seen in young animals.

Secondary thrombocyopaenic disease is fairly common in adult and older domestic animals.
Associated with diseases which cause bone marrow depression.
The bone marrow is depleted or devoid of megakaryocytes, and there is a nil or markedly reduced peripheral blood thrombocyte count.
Secondary thrombocyopenic disease is seen in the following conditions:
1. Severe viral infections.
  - For examople, ICH, feline panleucopenia, mucosal disease, swine fever.
2. Severe protozoal infections.
  - For example, in the UK, Haemobartonella may be a cause.
3. Plant intoxications.
  - For example, bracken, kale, or ragwort poisoning.
4. Drug-induced conditions.
  - High doses of oestrogens and salicylate.
  - Prolonged use of phenyl butazone.
5. bone marrow neoplasia.
  - For example, lymphosarcoma or myeloid leukaemia.
6. Radiation.
  - May cause damage to the bone marrow if it is severe and generalised.
7. Other miscellaneous causes.
  - Severe bacterial infections.
    - For example, Staphylococci, and those Gram -ve bacteria producing endotoxins (e.g. Pseudomonas or Salmonella spp.).
  - Liver disease.

A rare inherited condition.
Recorded in the dog.
Characterised by defective thrombocyte formation.
- Poor adhesiveness.
- Poor aggregations.
- Poor platelet factor release.