Horses have horse teeth. Not human teeth. Not dog teeth. Not cat teeth, or any other kind of commonly studied teeth in veterinary medicine.
As such, they also have their own special, disease-prone gingiva—or gums. Because equine dental anatomy and issues are unique to horses, they deserve special scientific analyses as well as consideration at home, said a German research team.
Brachydonts vs. Hypsodonts
“For a long time it’s been assumed that the anatomy and histology of the equine gingiva and of other periodontal components are similar or even the same as already described in brachydont species like dog and man,” said Saskia Steinfort, DrMedVet, of the Institute of Veterinary-Anatomy, Histology and Embryology in the Faculty of Veterinary Medicine at Justus Liebig University, in Giessen, Germany.
However, the nature of horse teeth as hypsodont rather than brachydont means their surrounding structures are also different, Steinfort explained.
Brachydont teeth have short crowns compared to their roots, said Steinfort’s department director, Prof. Carsten Staszyk, DrMedVet. In humans and dogs, the crown is the part of the tooth you can see above the gum. It’s covered by enamel that stops at the neck of the tooth—the part between the crown and the root.
The opposite of a brachydont tooth is a hypsodont tooth, which is what horses have, Staszyk said. Hypsodont crowns are very long compared to the roots—although it might not appear that way when you look into a horse’s mouth. The part of the tooth you see is called the “clinical crown.” But it’s only the tip of the full crown. The horse’s hypsodont teeth have tall crowns, covered in enamel, that go well below the gum surface. Unlike human (brachydont) teeth, equine teeth don’t stop erupting. That crown keeps pushing out and out—kind of like the lead in a mechanical pencil—over the course of the horse’s life, said Staszyk.
“Only with the development of modern equine dentistry has the question arisen, whether the diagnostic and therapeutic procedures used in man and dogs can be simply transferred to the equine patient,” he said.
Dissecting the Equine Gingiva
To attempt to answer the question above, Steinfort, Staszyk, and their colleagues decided to investigate horses’ teeth and gums in detail, in hand and under microscope. They dissected the jaws of six horses (euthanized for reasons other than dental problems) and developed the first scientific description of healthy equine gingiva.
They said they found significant differences in horse gums compared to what was previously believed. For example, the space between the tooth and the gingiva (where the tooth “fits into” the gum), called the gingival sulcus, isn’t nearly as deep as researchers thought.
“The normal depth is described in several publication as measuring up to 5 millimeters,” Steinfort said. “But when we evaluated the gingival sulcus, it turned out that its depth is less than 1 millimeter, often not even visible in macroscopical (naked eye) evaluations. This is a good example of the importance of not simply transferring anatomical data from brachydont species to the horse.”
However, they also discovered “surprising” similarities with brachydont gingiva, Staszyk added. “Because the equine tooth is continuously erupting, we expected a special attachment apparatus different from what we know in brachydont species,” he said. “Surprisingly, though, we noted the same components here as in the gingiva of the brachydont tooth. This is an issue we would like to investigate in detail in future studies.”
Understanding Gingival Disease in Horses
Horses’ gingiva is susceptible to disease, and the most common pathology is gingivitis, the researchers said. Like in humans, gingivitis causes inflammation of the gingiva. However, it’s a very different disease process in horses. If owners are looking for “human” signs of gingivitis in their horses, they’re likely to miss the signs altogether.
“When we talk about gingiva issues (gingivitis) most people think about redness, swelling, bleeding, and increased gingival sulcus depth causing the formation of periodontal pockets, etc., at the sides of the teeth,” Staszyk said. “These are the gingival problems man and dogs suffer from.
“However, in the horse, gingival inflammation leading to deep pockets and loss of tooth attachment is most often associated with diastema (spaces between teeth) formation and food impaction in the interdental regions,” he continued. “It is very hard for the owners to recognize it, because they can only see a very small part of their horse’s dentition (outer/labial incisor region).”
Only a veterinarian with proper equipment and experience can detect the early stages of the disease in horses, he explained. Because gingivitis creates “pockets” that get progressively deeper, it will eventually affect the periodontal ligament that anchors the tooth to the bony socket. At that stage, the tooth becomes loose and painful, and it will either fall out or have to be removed.
“Owners might realize a bad odor from their horses’ mouth, or they might recognize that the horses suffer from severe pain, and there might be weight loss, etc.” said Steinfort. “However, in these cases, periodontal disease is often well advanced already. Yearly dental checkups are necessary for picking up early signs.”
Finally, a Horse-Specific Gingiva Analysis
Gingival problems aren’t new in horses, said the researchers. In fact, periodontal disease was labeled “the scourge of the horse” as early as 1906 by the former president of the British Society of Dental Surgeons, Sir James Frank Colyer, KBE, FRCS, FDSRCS Eng, they said.
As a result, such a study of equine gingiva has been well overdue. “Indeed, it’s quite surprising that it has never been done before now,” Steinfort said.