If One-Eyed has Sleipnir, Ingui is said to have a steed named Blóðughófi or Bloody Hooved. The name is listed by Snorri in his Edda, where it is said that the slayer of Beli (i.e. Frey) rode Blóðughófi. It is the only known reference to it and it may be the horse mentioned in the eddic lay För Skirnís, where Skírnir asks Frey for a steed so he could ride to the land of giants. If this is a genuine pre-Christian element, then it adds to Ingui’s warrior side. A more common link, however, is that between the god and sacred horses kept in temples or by devotees, which can be found in different sagas: Hrafnkels saga is one well-known example and another is in Vatnsdæla saga. There have been doubts on how far this represents an actual pre-Christian element, but sacred horses are mentioned by Tacitus in his Germania, so it may be genuine – if not in the connection to Frey, at least in the religious role of the animal apart from sacrifice.
But what is it about a horse that associates it with Ingui? To my mind, there are two things. One is quite obviously fertility: a stallion is still a synonym of sexual prowess, both with regards to vigour and the size of the genitalia (eg. hung as a horse). The other is agricultural work, which until the 19th century made a large-scale use of equines, from grinding and ploughing to pulling carriages.
Any of these links might have been made by pre-Christians in ancient Scandinavia. However, I should point out that we, unlike the old polytheists, do not generally view the horse as they did. For the most part, that animal has lost the sacred nature it held in the past, when it was an almost divine creature with a special connection with the gods. And I’m not talking about being sacred to this or that god: I’m referring to a general sense of living holiness! This may be an old Indo-European thing, dating back to the days of tribes that crossed the fields on horseback; to give a modern analogy, think of the Dothraki in Game of Thrones. It may also be something rooted in the animal’s ability to ride through different types of terrain, which religiously translates into being a vehicle between worlds. Hence its use in sacrifice (it carries messages to the gods), in temples (it is the earthly steed of otherworldly beings) or in graves (it carries the human dead to the other side). This means that several gods may have been connected to the horse for no special reason other than the fact that that animal is an excellent vehicle.
In Ingui’s case, there is a connection to sexuality and fertility that is still alive in modern mentality, while mechanization has largely replaced equine presence in rural life. The memory remains, however, and a few modern heathens keep horses in their farms, so despite the loss of sacredness, the animal remains a valid symbol of Frey. Perhaps it is not out of place to call Him the Great Stallion – in a sexual and not necessarily belligerent sense.