Mighty saber-toothed cats and dire wolves probably had achy joints

The cataclysmic climate changes that ended our last Ice Age wiped out multiple fascinating species, such as, giant beavers, mastodons, and giant ground sloths. Unfortunately, we also lost some early canines and felines. According to a new study, the saber-tooth cats and dire wolves who roamed the Earth as the planet warmed and giant ice sheets melted may have faced an internal foe that still plagues cats and dogs today—bone disease. The findings were published July 12 in the open-access journal PLOS ONE.

[Related: Dire wolves are actually ice age mega-foxes.]

Osteochondrosis is a common developmental bone disease that is known to impact joints in vertebrates, including domesticated species like house pets and humans. However, the condition is not well understood in wild species. 

In this study, the team identified signs of osteochondrosis in over 1,000 limb bones of saber-tooth cats and over 500 limb bones of dire wolves from around 55,000 to 12,000 years ago. These skeletons were dug up in the La Brea Tar Pits in Los Angeles, California. The team found small defects in many bones that are consistent with a specific manifestation of bone disease called osteochondrosis dissecans (OCD). These defects were largely in the knee and shoulder joints, with about six percent of the limb bones of young adult and juvenile saber-tooth cats, specifically knee joints, having divots that were less than seven millimeters. 

Almost three percent of young adult and juvenile dire wolves showed defects in the knee joints, which tended to be a bit bigger at over 12 millimeters. 

The small shoulder joint defects tended to be more common in wolves at a rate of almost 5 percent. Only a few of the adult limbs studied and none of the juvenile limbs had signs of osteoarthritis, which is a degenerative joint disease that can eventually result from OCD.

About 6 percent of the saber-toothed cats femurs and 2.6 percent of the dire-wolf femurs in the study had visible defects. About 4.5 percent of dire-wolf shoulder specimens also had these defects.

The prevalence of OCD among the animals appeared to be more than among modern animals and humans, according to study co-author and veterinary orthopedic surgeon Hugo Schmökel. Schmökel also told The New York Times that while previous paleontologists had noticed these defects, “no one had realized that maybe these were premortem damages to the bone and not post-mortem.”

[Related: Life in Los Angeles was brutal for saber-toothed cats.]

Additional study is needed on other fossil sites to look for patterns in the prevalence of this disease since it is limited to the isolated bones found in one specific location. Seeing patterns of bone disease might shed additional light on other aspects of these animals’ lives, including if these joint difficulties hindered their hunting abilities. 

OCD is also commonly seen in more highly inbred modern domestic dos.The team believes that it is possible that the high incidence of the disease in these fossilized animals may be a sign of population decline as they approached extinction.  

“This study adds to the growing literature on Smilodon and dire wolf paleopathology, made possible by the unparalleled large sample sizes at the La Brea Tar Pits & Museum,” the authors wrote in a statement. “This collaboration between paleontologists and veterinarians confirms that these animals, though they were large predators that lived through tough times and are now extinct, shared common ailments with the cats and dogs in our very homes today.”