Just a heads up: Vicks (see August 2009) contains camphor, an illegal substance for USEF competitions in any amount, no matter how minute. Thus, readers should take care when using it close to a rated horse show. While it should not go through the skin, it could be absorbed through mucus membranes. I’ve seen friends get in trouble for silly violations of the rules, just like this.
In the June 2009 issue there was a question about using bluing in water tanks for horses. I wonder if the author of the letter was actually talking about using copper sulfate. It does turn the water a slight blue color (dark blue if too much is used) and does inhibit algae growth in water tanks. Here in North Carolina, algae grows quickly in water tanks in the summer, so I have on occasion used maybe an eighth of a teaspoon of feed-grade copper sulfate in a 100-gallon tank for this purpose. Because of Dr. Kellon’s help I developed a custom-mineral mix for my hay, I have the copper sulfate on-hand. At the time of my consultation, I also found our area is deficient in copper, so in my case it seemed to be a good thing.
Veterinary Editor’s Note: The author of the original letter was discussing actual laundry bluing, but copper sulfate is fine to use.