And is the "cold tar shampoo" specifically formulated for
dogs?
Human skin is about 100-120 degrees or steps more acid than dog skin (which is much more neutral). Using a shampoo formulated correctly for humans will be very incorrect and irritating to dogs' skin; for dogs, use only a shampoo specifically formulated for dogs -- no human baby shampoo, etc. -- otherwise it's too irritating.
Here's a copy of a post I've often made:
I'm sensitive about using human shampoo on dogs because I made that mistake with my black Lab, Bess. I used baby shampoo on her in the misguided belief it was gentle. As a result, she had fairly constant dandruff -- no doubt from the skin irritation caused by the shampoo (which I didn't realize until Puff).
The link below describes the pH scale which is the scientific measure of how acidic or alkaline a substance is. The scale ranges from 0.0 (most acidic) through 7.0 (neutral, like distilled water) to 14.0 (most alkaline AKA base/basic)
http://www.elmhurst.edu/~chm/vchembook/184ph.html
The graph in the link below compares the pH values for humans and various animals. You'll note that human skin has a pH value around 4.8 (acidic) while Labrador skin has a pH around 6.8.
Since pH values are on a logarithmic scale, a value on the scale that differs from another by as much as 1.0 (say 6.1 and 7.1 or 8.6 and 9.6) is 10X that of another that's 1.0 distant. So, since the skin of humans and Labradors are 2 whole integers apart (4.8 to 6.8 ) that's 10 x 10 = 100; so human skin is 100 times more acidic than Labrador skin.
http://publications.royalcanin.com/...102343&com=27&animal=0&lang=2&session=6478160