Photo by Barbara Schneider
While you may dread your six-month dental check up remember that you’re not the only one that gets dental check-ups. Animals in human care receive dental check-ups sometimes even more frequently than humans. It is just one of the many things that veterinary professionals examine to monitor an animal’s health. Some animals have very unique teeth that require unique treatments. Animals such as elephants have large tusks that are important in digging, lifting objects, stripping bark from trees, and used in defense.
Elephant Molars and Tusks
An elephant’s tusk is a very unique tooth. In fact it has characteristics that separate it from other mammalian teeth. Elephant teeth do not have nerves innervating the pulp. Most mammalian dental pulp contains connective tissue composed of ground substance, fibroblasts, nerves and blood vessels. Additionally, the nerves are associated with the blood vessels and can be myelinated or un-myelinated. When examining dental pulp from elephant teeth, all the components of the pulp can be found except for the nerves. Three of the most commonly seen dental disorders are impacted molars, malposition of the molars and abraded, split, or fractured tusks. While Asian elephants have a greater propensity for impacted molars, damaged tusks are found in both Asian and African species.
Molars are critical for grinding food for digestion. An unusual characteristic of molar dentition in elephants is the way in which individual molars are created from the fusion of twelve or more dental plates. The numbers of plates are predetermined by the embryonic denticles developing from the replicating dental lamina (Fagan et al. 1999). The molars are composed of these parallel plates as well as vertical laminae of enamel, which is surrounded by dentin and cementum. The enamel prevents abrasion during mastication of food, while dentin and cementum are more easily worn down. Each of theses plates are joined together to create the tooth. There is a difference in the shapes of molars between the two species of elephants. African elephants have squashed diamond shape molars, while Asian elephants have squashed ovoid shape molars (Fagan et al. 1999).
Molars impacted with food debris can become infected. Unfortunately the infection may not show up in the blood profile during blood analysis, thus making it difficult for veterinarians to know the severity of the infection. The most common remedy for both infection and malposition is the extraction of the affected molar. If not extracted in a timely manner the animal will have an inability to properly chew their food, which can eventually lead to nutritional deficiencies (monitored by examination of fecal matter), weight loss, and impaction colic. To reduce some of these risks in young animals, animal care experts monitor the animal’s diet and can adjust the abrasiveness of that diet. Plants have cellulose in the cell walls and woody plants are lignified. These are very abrasive on the animal’s molars. Animal care experts will develop a diet for the animal where the abrasive wear rate does not exceed the mineralization rate of teeth calcification. It is even recommended that young animals be provided a non-abrasive diet up to two years of age when molars are fully mineralized. However, abrasive diets are necessary after two years of age to erode away chewing surfaces at a uniform rate so that it will facilitate the growth and replacement associated with normal dental wear (Fagan et al. 1999).
Like molars, tusks are vascularized denticles that lack any nerves (Fagan et al. 1999). Tusks continuously grow throughout an elephant’s life. The tusks are attached to the jaw via the periodontal ligament, similar to the way ligaments hold bones together at a joint. The tusks have two types of tissue; both have a rich blood supply. Pulp tissue is the soft tissue inside the tusk and the tip of the tusks contains the pulp horn, which provides vascular supply to the surrounding bone and periodontal ligament.
The pulp can be exposed during abrasion and allow microbial infection, much like that of a human broken tooth exposing pulp. Because the tusk is well supplied with blood through its vascular network, inflammation responses can occur as a reaction to injury. While this sounds painful, the elephant does not experience pain because they lack the nerves that interact with the bradykinins, prostaglandins, and leukotrienes released from the inflammatory process, thus there is no network of conductive neurons to signal pain or increased temperature. Because the tissue is so well vascularized, the immune system is normally able to mediate infection on its own. Additionally, the tooth can activate a self-repairing mechanism to isolate the injury and infection site from the rest of the tusk by forming a secondary dentin bridge. If the infection or injury is too severe or if there are other health concerns, then veterinary medical treatment is necessary. Treatment can include use of antibiotics, use of composite resins, or tusk removal.
Composite Resin Tusks Repair
The Case of Bulwagi
The health of Bulwagi, a beloved 35-year-old elephant at the Birmingham Zoo, declined due to an infection in his tusk. Despite their best efforts the veterinary staff decided that surgical intervention was required and consulted with a few experts. On May 12, 2016, Bulwagi underwent surgery to remove the infected tusk. Since the surgery, he has made a great recovery.
Bulwagi arrived at the Birmingham Zoo with only one tusk due to an injury at a young age. The tusk that Bulwagi had left developed a crack that worsened over the years. He received special media attention last November when the zoo partnered with the University of Alabama at Birmingham to develop a revolutionary procedure to attempt to prevent the crack from spreading further. A composite wrap was placed on his tusk to keep the crack from spreading. Unfortunately the crack spread and became infected.
University of Alabama Development of Innovative Procedure
Bulwagi Tusk Repair
Prior to surgical intervention, the veterinary staff at the Birmingham Zoo made many attempts to treat the infection with antibiotics without success. Such an infection could have quickly become life threatening, since it could have entered Bulwagi’s bloodstream and spread to other organs such as the heart. The only way to prevent the spread of infection was to remove the tusk.
The zoo consulted with experts from the Colyer Institute and Veterinary experts from across the country to help with the removal procedure, which takes many hours to complete. Researchers at the Colyer Institute study oral disease and nutrition in exotic animals. During the extraction they were not seeing the results that they hoped for. “We had a great team in place that made the procedure go very smoothly. While we were hoping to remove the whole tusk, after working for three hours on the extraction without seeing the results we needed, we did not want to keep Bulwagi under anesthesia any longer. We fortunately had planned for a variety of scenarios, and were able to go with the plan to partially remove the tusk. This will allow us to have better access to manage the infection than before the procedure,” says the zoo’s Director of Animal Health, Dr. Stephanie McCain, DVM, Dipl ACZM.
Bulwagi did well under anesthesia and is drinking and eating normally and will receive daily care of the surgical site until it heals. He will also continue treatment for the infection. The zoo’s staff does not anticipate that the partial extraction will affect the social structure of its resident elephants, and believe Bulwagi will remain the dominant male of the zoo’s bachelor herd.
Saving Elephants from Illegal Poaching
Elephant populations have decreased by 50% since 1979 because of many factors, one of which is ivory poaching. It is estimated that over 35,000 elephants are killed in Africa for their tusks each year. Additionally, 12,000 rhinos were killed last year for their horns. Once these are harvested, the carcass of the animal is often left to decay. Illegal poaching and the ivory trade are huge problems, but some conservationists have come up with a possible solution to diminish the chance that an animal will be killed.
Conservationists from the Rhino Rescue Project in Johannesburg, South Africa, have recently gained media attention with a newly developed tactic, but it is expensive. The conservation team has developed an animal friendly compound made of indelible dye and ectoparasiticides that render the rhino’s horn useless for both ornamental use and medicinal purposes, thus making the horn worthless to poachers. The rhino has to be darted with a tranquilizer gun from the air and, once the animal is immobilized, a ground crew performs the procedure. They also microchip the animal for security measures and tracking purposes, and take a sample of DNA for storage for many reasons including the preservation of genetic diversity (see Frozen Zoo).
While the practicality and expense of such a procedure has been called into question by many organizations, it is still a positive step in the right direction. Conservationists at the International Conservation Fund of Canada believe that this method is impractical to impossible in the wild, compared to a reserve, due to both the logistics and costs associated with implementing this program on a larger scale. “ Darting and applying dye to elephants would involve huge costs and stress and risk to the elephants. Even if achieved on a small-enclosed population, poaching pressure would be diverted elsewhere”, stated Ann Lambert. The World Wildlife Federation, who also does not endorse the method of infusing horns with dye due to its impracticality, echoes this sentiment. Dr. Coleman O’ Ciodain stated that, “the reason we didn’t endorse this method is because simply in order to do that you have to dart and anesthetize the rhino. Most of the poaching is happening in Kruger National Park and that’s the size of Wales and it’s just not practical. Not to mention the fact that in a matter of time they would have babies and you’d have to do it again.” These organizations believe that the only way to save elephants and rhinos is to devalue the horns and tusks from a consumer perspective. While this is also needed, the bravery and ingenuity of the conservationists at The Rhino Rescue Project have led to the consideration of this method even if it is not projected to take place on a larger scale. The fact of the matter is that this group took action, and that is a breath of fresh air, after all actions often speak louder than words in today’s society.
Fagan, D.A., Oosterhuis, J.E. and Roocroft, A., Significant dental disease in elephants. Colyer Institute.
Fagan D.A., Benirschke K, Simon J.H.S., and Roocroft A. 1999. Elephant dental pulp tissue: where are the nerves? Journal of veterinary dentistry, 16(4) 169-172.
Please visit the Colyer Institute (http://www.colyerinstitute.org) for more information about elephant dentistry as well as dentistry in other animals.