The effect of topical cod liver oil ointment on the rate of wound epithelialisation and neovascularisation was studied using the hairless mouse ear wound model (experiment I).

The effect of local application of vitamin A in increasing concentrations was tested in the same model (experiment II).

Experiment I: Bilateral standardised full thickness dermal wounds were created on the ears of 42 mice divided into three groups: group I: 25% cod liver oil ointment (n = 10) applied topically to one ear and vehicle (vaseline) to the other; group II: 25% cod liver oil ointment (n = 10) and saline; and group III: vehicle (n = 22) and saline.

Experiment II: Using the same model and procedures wounds were made on 12 mice randomised to vitamin A treatment in various doses (250-3000 IU/g) on one ear and vehicle (vaseline) on the other ear. Using in-vivo microscopy and digitised planimetry, wound epithelialisation and neovascularisation were measured at regular intervals until the processes were complete.

Wounds treated with 25% cod liver oil ointment epithelialized significantly (p < 0.05) faster (mean (SEM) 8.9 (0.7) days) than control ears treated with vehicle alone (13.9 (1.9) days). Neovascularisation developed significantly faster (p < 0.01) in the ears treated with cod liver oil ointment (22.5 (1.3) days) compared with their vehicle control (29.1 (0.6) days). Neovascularisation was also significantly (p < 0.05) faster in the ears treated with cod liver oil ointment (23.1 (1.4) days) than in those treated with saline (26.8 (1.1) days).

There was no significant difference in speed of epithelialisation between cod liver oil ointment and saline. The vitamin A dose study showed that epithelialisation and neovascularisation of the vitamin A treated wounds pass at the same rate as wounds treated with cod liver oil ointment.

In conclusion, topical 25% cod liver oil ointment significantly accelerated both the epithelial and the vascular component of healing compared with saline. Vitamin A seems to have an important role in accelerating wound healing and could be the active component in cod liver oil.