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Trichography (hair plucking)
Introduction
- Hair examination is a valuable aid to differential diagnosis of skin and hair disorders.
- Useful technique - analysis for fungal diseases, parasitic diseases, congenital/hereditary diseases.
- Differentiate self-trauma from other causes of hair loss/damage.
Uses
Definitive diagnosis- Self-inflicted (versus non-self-inflicted) hair loss.
- Trichorrhexis nodosa.
- Shaft disorder of Abyssinian cats Abyssinian.
- Pili torti.
Of diagnostic assistance in
- Some nutritional and congenital hair dysplasias.
- Dermatophytosis Dermatophytosis.
- Anagen defluxion Anagen defluxion.
- Telogen defluxion Telogen defluxion.
- Endocrine alopecia Skin: thyroid-responsive alopecia.
- Some pigmentary disturbances.
- Some ectoparasite infestations: cheyletiellosis Cheyletiellosis , lice Pediculosis , demodicosis Demodectic mange .
- Chediak-Higashi syndrome Chediak-Higashi syndrome of long-haired cats.
Advantages
- Easy technique.
- Inexpensive.
- Accurate.
- Alternatives may be expensive, eg biopsy, fungal culture; and more invasive, eg biopsy Biopsy: skin.
- For a definitive diagnosis of dermatophytosis it complements a positive culture as trichography (like biopsy) provides evidence of active infection while false positive cultures are possible due to contamination.
- A fur pluck may be more readily collected than a scraping Scraping: skin from cretain patients and certain areas of the body, eg face or feet and may be adequate to diagnose (but not to rule out) demodicosis.
Disadvantages
- Time consuming.
Technical problems
- Some expertise required for interpretation.
Alternative techniques
- Skin scraping Scraping: skin.
- Fungal culture.
- Skin biopsy Biopsy: skin.
Time required
Preparation
- 5-10 min.
- Experience required for choice of samples to be taken.
Procedure
- 15-60 min.
- Examination for some diseases will take less time.
Decision taking
Criteria for choosing test
- History and clinical examination will indicate which diseases are likely.
Requirements
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Preparation
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Technique
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Aftercare
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
Other sources of information
- Miller W H, Griffin C E & Campbell K E (2013) Muller and Kirk's Small Animal Dermatology. 6th edition. Philadelphia: W B Saunders. p 81-83. ISBN 0 7216 4850 9 (Detailed account with photographs of normal and abnormal hairs.)
- Moriello K A & Mason I S (1995) Handbook of Small Animal Dermatology. 1st edition. Oxford: Pergamon Press. pp 23-25. (Hair examination for fungal elements.)