Why do horses foam?

Some horses when worked become covered in white foam, what does it mean?

Horse sweat is unusual in that it contains a large amount of protein called ‘latherin’. This protein acts like a detergent and helps the sweat spread over the horse. It is perfectly normal and does not indicate any nutrient deficiency or excess in the diet. Some horses foam more than others and the amount of foaming depends on:

• Fitness (usually unfit horses foam more and horses that are worked hard and are regularly sweating do it less)

• Timing (the protein is highest in the first initial sweat and horses often foam for a short time and then stop)

• Coat condition (shampoos, conditioners, brushing, clipping etc can all affect how much the horse will foam)

To sum up, it is perfectly normal. It makes a horse look hot and bothered but it is not a problem. You don't tend to see it much in endurance horses because they are sweating regularly, have short coats and are washed and rugged regularly.

References

Beeley JG, Eason R and Snow DH (1986) Isolation and characterization of latherin, a surface-active protein from horse sweat Biochem J. 1986 May 1; 235(3): 645–650
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1146737/pdf/biochemj00280-0028.pdf

McDonald RE, Fleming RI, Beeley JG, Bovell DL, Lu JR, Zhao X, Cooper A, Kennedy MW (2009) Latherin: A Surfactant Protein of Horse Sweat and Saliva PLoS ONE 4(5)
http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0005726

Contact details:

Carol Layton B.Sc, M.Ed
Balanced Equine Nutrition

Phone: 02 4953 2580
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