Changes

===Using Fluorescein to Identify Cats Responsible for Urine Marking or Elimination===

===Using Fluorescein to Identify Cats Responsible for Urine Marking or Elimination===

When ingested, fluorescein dye is excreted intact in urine, and can be made to fluoresce using a UV lamp. This can be used to identify the cat responsible for leaving urine deposits. A dose of 50mg/cat once daily is given, which is equivalent to the amount of dye in the tips of six fluorescein test stops (commonly used for ulcer detection in ophthalmology)<ref>Neilson, J. (2003) Feline House Soiling: Elimination and Marking Behaviors. "Veterinary Clinics of North America: Small Animal Practice". 33(2):287-301.</ref>day as a single dose with food is recommended. However, the fluorescence of fluorescein varies considerably with pH<ref>Sjoback, R., Nygren, J., Kubista, M. (1995) Absorption and fluorescence properties of fluorescein. "Spectrocmicia Acta Part A". 52. 7-21.</ref>, such that it only strongly fluoresces in a neutral or alkaline solution; in an acidic solution it may hardly fluoresce at all. Spots may therefore need to be sprayed with a buffer solution of sodium bicarbonate (baking soda), which will produce a pH of around 8, before testing with a UV lamp.  

When ingested, fluorescein dye is excreted intact in urine, and can be made to fluoresce using a UV lamp. This can be used to identify the cat responsible for leaving urine deposits. A dose of 50mg/cat once daily is given, which is equivalent to the amount of dye in the tips of six fluorescein test stops (commonly used for ulcer detection in ophthalmology)<ref>Neilson, J. (2003) Feline House Soiling: Elimination and Marking Behaviors. "Veterinary Clinics of North America: Small Animal Practice". 33(2):287-301.</ref>day as a single dose with food is recommended. However, the fluorescence of fluorescein varies considerably with pH<ref>Sjoback, R., Nygren, J., Kubista, M. (1995) Absorption and fluorescence properties of fluorescein. "Spectrochimica Acta Part A". 52. 7-21.</ref>, such that it only strongly fluoresces in a neutral or alkaline solution; in an acidic solution it may hardly fluoresce at all. Spots may therefore need to be sprayed with a buffer solution of sodium bicarbonate (baking soda), which will produce a pH of around 8, before testing with a UV lamp.  

* Fluorescein is available as large sterile paper strips, for ophthalmic examination. These contain approximately 9 mg of fluorescein per tip, but this should be checked with the manufacturer.

* Fluorescein is available as large sterile paper strips, for ophthalmic examination. These contain approximately 9 mg of fluorescein per tip, but this should be checked with the manufacturer.