African wild dogs will soon have own sperm bank

Scientists from the Institute for Breeding Rare and Endangered African Mammals have been working in Southern Africa for more than 15 years to protect endangered African wild dogs.

They have now decided to freeze sperm from as many genetically diverse African wild dogs as possible and use this to artificially inseminate females for the first time.

Wild dogs are a native species to Sub-Saharan Africa.

They are highly efficient pack hunters, but need large home ranges to survive and avoid competitors like lions.

The problem is that most of the remaining habitats are so small and fragmented that they can’t support large populations any more.

Usually, when wild dogs are subadults (about two years old) they move far away and form their own pack.

But being stuck in small reserves, they cannot do this. Instead they interbreed, reducing their genetic diversity.

Human encroachment makes habitats smaller for almost every species, pushing many reserves to the limit of their carrying capacity.

Today, wild dogs occupy only 7% of their former range.

According to our best estimates, there are about 550 dogs remaining in SA, scattered across 14 highly fragmented populations.

Genetic diversity helps build resilience to disease. Outbreaks of rabies and canine distemper virus are frequent either spread from domestic dogs nearby, or from viruses already present in reserves.

Those diseases can spread rapidly among wild dogs and decimate a pack, which is about five to 20 dogs.

In 2017, canine distemper virus wiped out 21 out of 22 packs of wild dogs in Laikipia County, Kenya, in four weeks.

Using sperm freezing and artificial insemination to help distribute genetic diversity among isolated populations will give wild dogs a better chance of surviving disease.

We can take sperm from dogs in a region with resistance to canine distemper virus and mix those valuable genes into many other packs quickly.

The next time there is a disease outbreak, a large number of their offspring will survive.

To increase genetic diversity, African wild dogs have been translocated across SA since 1998.

Young dogs that are ready to leave their pack are artificially grouped in a boma (temporary enclosure in the wild) with dogs of the opposite sex from a different part of the country.

They form a new genetically mixed pack that is released into the wild.

But the drawback is that the new pack is junior and only able to colonise the limited habitat on the periphery of an established pack’s territory.

So it can take about 150 generations (about 300 years) for genes from the new pack to spread through the existing population via the formation of subsequent packs and natural breeding.

It’s also not possible to simply introduce a genetically valuable dog directly into an established pack to breed it would be killed due to the pack’s social hierarchy.

We can’t afford to wait that long. Most of the challenges facing wild dogs have occurred in the last 200 years.

A whole population of wild dogs could be lost with the next disease outbreak.

Our research shows that a hybrid approach combining natural and artificial breeding during translocation will bring in new genes much faster.

We could even directly introduce valuable genes into established packs by moving sperm rather than animals.

To do this, we plan to monitor the alpha female for signs she is in heat, while the pack is in the translocation boma.

We can then artificially inseminate her with frozen sperm from a valuable male.

This has the potential to produce new, genetically diverse, disease-resistant pups every year.

Our backup plan against disease outbreaks is to create a bank of African wild dog sperm from multiple males.

Sperm frozen in liquid nitrogen tanks can last 50-100 years, a method which is very successful in livestock breeding.

We were not able to do this until now because African wild dog sperm lived for only 30 minutes after it was thawed, but to inseminate a female dog, the sperm has to survive for at least four to six hours.

We recently improved the freezing technique so African wild dog sperm are now able to swim and survive for eight hours after being thawed.

We can now set up an African wild dog sperm bank for the first time.

The frozen sperm will be taken into the field in portable liquid nitrogen tanks.

Our partners, the University of Pretoria Mammal Research

Institute and Embryo Plus, will help develop the sperm bank.

We plan to build a consortium so that we can have multiple sperm banks throughout SA as backups.

Some recent modelling in other species found that the hybrid approach was between seven and 84 times cheaper than natural breeding.

This is because it needed 13100 times fewer animals to maintain 90% genetic diversity in the population over a 100year period.

With fewer animals needed, the total cost to conserve the species is lower.