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The first ever in-depth investigation of the teeth of captive orca has found them a sorry state, raising serious concerns for the charismatic mammals’ overall health and welfare.
Anyone with a toothache knows how painful and distracting that can be - in orca which have around 48 large teeth, a sore tooth is likely no less painful or debilitating than for a person.
Now, a new study by a team of international researchers, including noted New Zealand orca expert Dr Ingrid Visser and Dr Carolina Loch of the University of Otago's Faculty of Dentistry, revealed how every individual examined had damaged teeth.
The team investigated 29 orca owned by one company and held in the United States and Spain.
“Every whale had some form of damage to its teeth,” said Professor John Jett of Florida’s Stetson University, the first author of the study just published in the journal Archives of Oral Biology.
“We found that the more than 65 percent possessed moderate to extreme tooth wear in their lower jaws, mostly as a result of chewing concrete and steel tank surfaces.”
Further, the researchers found that more than 61% of the orca they studied have “been to the dentist” to have their teeth drilled.
Officially termed a “modified pulpotomy”, a hole is drilled into the tooth to extract the soft pulpy tissue inside.
Dr Loch specialises in the dentition of whales and dolphins, and says that unlike us, the resultant hole is not filled or capped, but rather is left open for the rest of the animal’s life, requiring daily flushing with chemicals to keep the teeth empty of food and bacteria in an attempt to manage resulting infection.
“Once the tooth gets worn to the point where the pulp is exposed this opens up a channel for disease and infection, so the staff then drill the teeth,” she said.
Dr Jeff Ventre, another of the study authors, also an ex-orca trainer and now a medical doctor, said that he had drilled orca teeth in his former work.
“Teeth damage is the most tragic consequence of captivity, as it not only causes morbidity and mortality in captive orcas, but often leads to chronic antibiotic therapy compromising the whale’s immune system, as we saw recently with the orca known as Kasatka.”
Dr Loch added that a drilled tooth is severely weakened and if any other trauma occurs, fractures will happen.
“We have documented more than 60 percent of the second and third teeth of the lower jaws were broken and this high number is likely linked to the drilling.”
During his time as a trainer, Dr Ventre said that he had witnessed “whales breaking their teeth on steel gates while jaw popping”.
“Small tooth fragments were then collected below the gate while diving the pool.”
Dr Visser, who has studied orca in the wild for more than three decades, has long been advocating for an end to orca captivity.
“We know that confining them in tanks is bad for the animals and this research now gives us some hard numbers to illustrate just how their health and welfare is compromised.
“Given how big the root of an orca’s tooth is and that orca have a nervous system similar to ours, these injuries must be extremely painful.
“Compared to free-ranging orca, the teeth of captive orca are incredibly compromised and you just don’t see this type or level of damage in the wild.”
Dr Loch pointed out that dentists had long said that oral health was a measure of general health, as our mouths were the gateway to our body, and this was likely the same for orca.
“We have documented that tooth damage starts at a very early age in captivity and that all the orca in the study have issues with their teeth,” Prof Jett concluded.
“Teeth are incredibly important to the overall health of an animal, and the results of our study should raise serious concerns for the health and welfare of captive orca.”