Photodynamic detection of canine mammary gland tumours after oral administration of 5‐aminolevulinic acid

Abstract

Abstract 5‐Aminolevulinic acid (5‐ ALA ) is widely used in photodynamic detection ( PDD ) and therapy. We evaluated the pharmacokinetics of 5‐ ALA ‐induced porphyrins and its effectiveness in PDD in dogs with mammary gland tumours ( MGTs ) following oral administration. Healthy dogs and those with MGTs (nine each) were orally administered 4 mg kg −1 5‐ ALA . Protoporphyrin IX ( PpIX ) was not detected in the plasma of healthy dogs but it peaked in dogs with MGT at 2 h after 5‐ ALA administration. In the PDD study, 16 dogs with MGT were orally administered 40 mg kg −1 5‐ ALA , and MGT but not normal tissue showed red fluorescence after 2–4 h. Photon counts were 6635–63 890 and 59–4011 (median, 19 943 and 919) for MGT and non‐tumour tissues, respectively. Cell density strongly correlated with PpIX photon counts of MGT tissue of the dogs ( R = 0.743, P = 0.0009). We suggest that 5‐ ALA‐PDD might be an effective diagnostic tool for MGTs .