New research from Brazil finds that amnion dressings can be useful in supporting wound healing in horses, particularly for injuries on the lower leg and other vulnerable areas.

Equine amniotic membrane (EAM)

Equine amnion, also called equine amniotic membrane (EAM), is the strong, flexible layer of tissue that envelops a fetus as it develops in utero. Amnion is increasingly popular in human regenerative medicine because it can serve as a “scaffold” of sorts for new tissue growth. Amnion tissue also has anti-inflammatory and anti-microbial properties.

Practical applications

To test the potential of EAM in treating equine wounds, researchers at the Federal Rural University of Rio de Janeiro collected amnion from six healthy mares. “The membranes can be collected from any healthy mare [immediately after foaling]. And it can be used in any horse,” says Marcos Vinícius Dias Rosa, DVM.

The team was particularly interested in learning whether storing the membrane at temperatures of 14 to -12 degrees Fahrenheit affects its efficacy. “Being frozen at temperatures obtained in standard refrigerators was the objective of the study,” says Dias Rosa. “The type of preservation will determine if the cells are still alive long after you’ve collected them or if you can only use the useful proteins and other byproducts within them.” After collecting the amnion, the research team cleaned, prepared and froze individual samples.

Storage options

For the second step of the study, the researchers carefully defrosted and rehydrated the amnion samples. Then they placed them on lower limb wounds. The researchers then monitored the healing process, comparing it to untreated wounds, over a two-month period. The data showed that wounds treated with amnion had better blood supply and more healthy new tissue.

Positive results

“The treated wounds had greater neovascularization, which is the creation of new blood vessels. This is important because without it, new cells cannot be formed. The lack of oxygen and nutrition is detrimental to the formation of new tissue,” explains Dias Rosa. “Fibroplasia is the formation of granulation tissue and that is a serious problem when it comes to horses. Horses often develop it way too early in the inflammatory process. That leads to the exuberant scarring [proud flesh] we often see, especially in the distal limbs. The proteins and other constituents of EAM alleviate this reaction in the early stages of inflammation. That makes it harder for this exuberant tissue to develop.”

All of this, says Dias Rosa, “proves [EMA] a viable treatment option, especially because of the preservation method. We can say that during the healing process, the wounds healed better and produced less scar tissue. That is a desirable thing when it comes to horses.”

Reference: “Cryopreserved equine amniotic membrane and its use in cutaneous wounds of horses,” Brazilian Journal of Veterinary Medicine, December 2022