Q: In last month's newsletter, you recommended Nolvasan® for dipping the foal's navel stump. What about iodine?
A: The Nolvasan® solution used at the U of M Veterinary Medical Center (VMC) contains 2% chlorhexidine, so 3 parts water must be mixed with 1 part Nolvasan® prior to use as an umbilical dip. Nolvasan Teat Dip Concentrate® may also be used; since it contains 4% chlorhexidine, 7 parts water must be added to 1 part Teat Dip prior to use.
As compared to dips containing povidone-iodine or tincture of iodine, 0.5% chlorhexidine kills more bacteria on the umbilical stump. Its effects persist for a longer period of time, and it is less likely to provoke skin irritation. Some foals develop severe skin scalding and even sloughing in response to iodine dips, especially when very strong products are used (e.g. 7-10%). These products can also dry the stump out too quickly, causing premature breakage and a higher incidence of patent urachus (a condition in which urine leaks from the navel stump).
At VMC, we believe that 0.5% chlorhexidine offers the best balance between disinfection and avoidance of tissue injury. Iodine solutions are still considered good disinfectants, but at low concentrations (e.g. 2% tincture of iodine or 1% povidone-iodine solution) they fail to kill some important bacteria, and at high concentrations (e.g. 7% tincture of iodine) they can cause chemical burns to delicate foal skin. When iodine is used, attention must be paid to the product's concentration.
By Christie Ward, DVM, University of Minnesota
The information given is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by University of Minnesota Extension is implied.