HORSE PREGNANCIES MADE BY ICSI AND WHAT IT COULD MEAN FOR RHINOS

A team at Onderstepoort, working with Hemmersbach Rhino Force, has produced South Africa’s first horse pregnancies through ICSI and frozen embryo transfer. The technique is well established overseas, but the significance lies in having the capability here in the country, and what that could do one day for the rhino population.

In November 2025, researchers in Pretoria announced the country’s first horse pregnancies created through a laboratory technique called intracytoplasmic sperm injection, or ICSI, followed by the transfer of frozen embryos. The work was a joint effort between the University of Pretoria’s Faculty of Veterinary Science at Onderstepoort and the Cryovault section of Hemmersbach Rhino Force, led by Dr Janine Meuffels-Barkas, a lecturer at the university and a vet with Rhino Force.

This is not a scientific breakthrough in the sense of proving the technique works. ICSI in horses is roughly thirty years old, the first foal having been born in 1996, and it is now routine in commercial sporthorse breeding across Europe and North America. What is new here is the fact we are performing it ourselves here in South Africa. For the first time, the full sequence, from egg collection through laboratory fertilisation to a frozen embryo and an established pregnancy, has been completed on South African soil, in local laboratories and with local teams. The project was funded by Hemmersbach Rhino Force together with the university’s in vitro fertilisation laboratory, and carried out by a team of vets, embryologists and researchers. The resulting foals are expected later in 2026.

How this differs from ordinary breeding

In conventional breeding, whether natural cover or artificial insemination, large numbers of sperm are introduced and fertilisation happens inside the mare. ICSI works the other way around. A single egg is collected from a mare, and in the laboratory a technician injects one selected sperm directly into it. The fertilised egg is grown in an incubator for several days, and the resulting embryo is then either transferred to a recipient mare or vitrified, a form of rapid freezing, and stored for transfer at a later date.

The practical advantage is that only one viable sperm is needed per egg. That changes what is possible with difficult cases, for instance in stallions with poor or limited semen, for situations where there are only small volumes of frozen semen that would never stretch across a conventional breeding season, or for passing on the genetics from animals that are old, injured or no longer alive. Freezing the embryos adds a second layer of flexibility, because breeders can bank them and match them to a suitable recipient mare whenever the timing is right, rather than racing against a single cycle.

The rhino

Horses and rhinos are close relatives among the odd-toed ungulates, and they share several reproductive features, including a similar pattern of early embryonic development and the same broad type of placenta. This makes the horse a useful working model for techniques that are far harder, riskier and more expensive to attempt directly on a rhino.

Dr Meuffels-Barkas and colleagues set out the rationale in a peer-reviewed paper, arguing that procedures already well established in the horse, including egg collection, ICSI, in vitro fertilisation and embryo transfer, can serve as a foundation for developing the same protocols in rhinos and elephants. ICSI and egg collection have been attempted in rhinos, but the methods are not yet reliable. Refining the entire sequence in horses, where eggs and recipient females are easier to work with, builds laboratory skills and embryo-banking capability locally. The local part really matters, because the rhinos themselves, and the genetic material worth preserving, are here in South Africa rather than in a lab on another continent.

Conservation at Onderstepoort

The pregnancies sit within a broader run of wildlife milestones at the faculty. Onderstepoort has also reported South Africa’s first CT scan on a live adult rhino, carried out through its Wildlife Clinic in partnership with a rhino sanctuary, giving conservationists diagnostic detail that was not previously available. It’s clear from both the horse work and this CT story that Onderstepoort is a veterinary faculty deliberately turning its equine and clinical expertise towards a species under threat.

What next?

The immediate thing to watch is the foaling later this year. Healthy foals would show that the local pipeline holds up from start to finish, which is the point on which everything else in this research depends. The bigger question is whether the equine protocol genuinely applies to rhinos, which remain slower, larger, and far more challenging to breed.

For South African breeders, there is a closer-to-home point too. The same toolkit, ICSI paired with frozen embryos, is already reshaping sporthorse breeding internationally. Having it proven in local laboratories, with local mares, brings that capability within reach here, whatever its eventual role in saving rhinos.

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Sources

Announcement of South Africa’s first ICSI horse pregnancies, University of Pretoria Faculty of Veterinary Science and Hemmersbach Rhino Force, 21 November 2025.

Meuffels-Barkas J, Wilsher S, Allen WR, Ververs C, Lueders I. Comparative reproduction of the female horse, elephant and rhinoceros: implications for advancing assisted reproductive technologies. Reproduction and Fertility, 2023. DOI: 10.1530/RAF-23-0020.

University of Pretoria, Faculty of Veterinary Science, reported clinical and research milestones, including the first CT scan on a live adult rhino through the Onderstepoort Wildlife Clinic.