Category Archives: animal attack

Komodo dragons: Myth vs Reality

The Komodo dragon is a creature that inspires fear and mysticism in many. It’s got all the characteristics of a good monster movie: only found on rare tropical islands, large, and possessing magical saliva that can kill. First identified by the west in 1910 by Dutch sailors, they reported the lizards could spit fire and reached 7m in length. In reality the lizard can only get up to 3m and can weigh 70kg, and none have been identified as either breathing or spitting fire.

Komodo dragon (Varanus komodoensis), Komodo National Park, Indonesia

This review comes after a zoo worker was bitten on the hand by a small Komodo dragon. She had transient hypotension, and a retained tooth on xray. This was not removed, and after loose approximation (Ed. note: never do this), she was discharged on antibiotics. Thankfully the tooth came out on its own, and she did not develop a deep space infection. After this case report, the authors decided to do a literature review, knowing that it would help them get published.

Many of us are taught in school that Komodo dragon saliva is a possibly venomous, potentially fatal concoction of particularly virulent bacteria, including E. Coli, Staphylococcus, Streptococcus, and Pasteurella. These bacteria live in the rotting flesh that they leave in their mouth. But what is that based on?

It turns out, not much. The “facts” we have in textbooks, zoos, and medical literature are based on one guy’s book written in 1981. While Walter Auffenberg was the Jane Goodall of Komodo dragons, moving to the island and studying them in their natural habitat, his results haven’t been widely reproducible. And, more importantly, komodos don’t carry rotting flesh in their mouth. They fastidiously clean their teeth and gums. Now, perhaps the water buffalo does die of sepsis after being bitten, but if it does, it’s because it runs into murky water with fresh wounds, and not from bacteria in the mouth of the lizard. So, the “bacteria as venom” concept is just as dead in the water as the buffaloes.

So what about the venom aspect? The author of that study (Fry) was able to identify glands in the lower jaw that could potentially be venom glands. Furthermore, the extract of those glands does in fact contain proteins that inhibit blood clotting similar to snake venom. However, there isn’t any evidence that the venom actually affects the prey or is secreted in any significant amount during bites. The teeth lack venom grooves present in every other venomous animal (including the shrew). On the plus side, the author did come up with the “grip, rip, and drip” model of lethality from komodos.

Then why do animals die after being bitten by a large, reptilian predator? For the same reasons they die after being bitten by any large animal. Direct trauma, blood loss, and hypovolemic shock (and by eating).

Our findings are also in accord with the view that the killing technique of V. komodoensis is broadly similar to that of some sharks and Smilodon fatalis (saber cat). Despite obvious anatomical differences, these unrelated predators kill or are thought to have killed (respectively) large prey by using relatively weak bite forces amplified by sharp teeth and postcranial input.

They have strong neck muscles and serrated teeth, so after they bite they pull away, tearing holes in the prey that then bleeds to death. Is it possible that venom can increase this bleeding? Sure, but it’s also possible that it doesn’t.

So then why did this patient become hypotensive? Likely a vasovagal response. And given that the bite was on the hand, it’s appropriate to put the patient on antibiotics. But maybe we can finally stop propagating the magical thinking associated with komodo dragons.

Bitten by a Dragon
http://www.wemjournal.org/article/S1080-6032(16)00100-9/abstract

Further enjoyable reading
National Geographic
http://phenomena.nationalgeographic.com/2013/06/27/the-myth-of-the-komodo-dragons-dirty-mouth/
A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus (Megalania) priscus
http://www.pnas.org/content/106/22/8969.full

Animals attacks aren’t really that bad, after all

At least, not according to the CDC WONDER database. When you take 9 years of data from said database, you get a whopping 1802 deaths. That comes out to just a hair over 200 deaths per year. Now, the article says they used ICD-10 codes W53-59 and X20-29 as their inclusion criteria, so take from that what you will.

Of the 1802 deaths, 1088 (60%) were from nonvenomous species, and specifically, 655 (36% of the total) were from farm animals. Thus, farm animals account for nearly as many deaths as venomous animals. Guess which one we spend more time on with teaching. When’s the last time you saw a board question that involved cattle?

The authors also break down the statistics by gender, race, age, and regional geography. The gender and race of the most commonly injured shouldn’t surprise anyone (white, male), but the ages might. We are taught that often it is young, intoxicated men are on the receiving end of most bites, but this data shows the overwhelming majority of those killed are >35 years old. The only group with more deaths at a young age(<9) is those killed by dogs, sadly. Children under 9 make up 46% of dog related deaths, despite making up only 10% of the total deaths.

Now, the question is, is this an example of the problems with ICD-10, or just a problem with reporting in general? Clearly more than 200 people are killed per year by animals, so how do we accurately assess the true risks? Based on this data we should put as much emphasis on agricultural education as we do on venomous species. Now, a significant majority of the farm animal injuries occur in rural areas, but so do most of the venomous animal injuries that don’t involve hymenoptera (~28% of the total). And yet we clearly devote a larger proportion of our teaching towards exotic, venomous animals. This even differs from the perceived over-emphasis on critical care, as knowing the exact thing to do in a time stressed situation can have a mortality benefit. Rarely is that true in the case of a venomous species, apart from anaphylaxis.

As the authors propose, we should as a specialty spend more effort on teaching agricultural safety as well as dog safety in homes with children. We already do a fair amount of teaching and community outreach with regards to anaphylaxis and hymenoptera, which is another significant cause of mortality. However, we could always do more with regards to preventable deaths.

Fatalities from venomous and nonvenomous animals in the United States (1999-2007)
http://www.ncbi.nlm.nih.gov/pubmed/22656661

What do you do if a puma attacks?

Puma face.jpg
Licensed under CC BY 2.0 via Wikimedia Commons.

Pumas (Puma concolor) are large feline predators that have been known to attack humans. Slightly more concerning is that most attacks on humans are as prey, not as defense. Thus, there are often signs to warn people going into areas where pumas are common. Doing a google image search will bring up comical parodies of said sign. But do the signs give good advice?

MountainLionAttackProtocol.jpg
Licensed under CC BY 2.0 via Wikimedia Commons

That was what the authors of this article set to find out. They looked at puma attacks in North America from 1890 to 2000, and found 185 attacks with injury, and 155 more close encounters with no injury. They then analysed the data to see if historically anecdotal risk factors for puma attacks were associated with higher likelihood of injury or death. The variables they analysed were:

  • Age (<13 vs older)
  • Group size (alone, two, or 3 or more)
  • Movement (stationary, quickly, or slowly)
  • Posture (crouching, upright, or on horseback/bicycle)
  • Separation from group, and
  • Noise making

As you can see, the sign above involves 5 of these classic variables. Age, separation from group, posture, noise-making, and movement. An argument can be made for saying that group size is inferred by the number of stick figures in the bottom left pictogram. Interestingly, a couple of those make little or no difference in an attack. There was no association with age or group size.

However, moving quickly did decrease likelihood of severe injury or death in proportion to no injury, while moving slowly or being stationary did not. Crouching versus upright posture did not differ in severity of attack, but being elevated (ie on horseback or bicycle) drastically reduced likelihood of injury or death. Being separated from a group has the highest relative risk, with no uninjured people. Not straying from your group gives you a 40% chance of being uninjured. Last, shouting does help a little over being quiet with regards to escaping uninjured. Doing something even louder (specifically in this article, shooting a gun) makes a larger difference, with a nearly 3:1 odds of escaping uninjured.

So what does this mean if you meet a puma in the wild? Mainly, you need to run away quickly(on a horse if possible). You should probably also carry an air horn, whistle, or some other loud noise-making device for an extra bit of safety. Also, stick with the rest of your party, as there is strength in numbers. Running away flies in the face of what the sign (and classic teaching) tells you, which is to slowly back away. Observations of predatory animals in the wild shows that they often stalk the slower moving members of the herd, as these are easy targets. The article even talks of observed predatory behavior captive cats have towards toddlers and those with unsteady gaits, so it makes sense not to appear weak or infirm to an animal trying to eat you.

And if and animal does attack you, fight back with every means possible.

The Effects of Human Age,Group Composition, and Behavior on the Likelihood of Being Injured by Attacking Pumas
http://www.ingentaconnect.com/content/bloomsbury/azoos/2009/00000022/00000001/art00008

Of note, while pumas carry multiple other names, such as mountain lion, catamount, and others, I specifically did not refer to the animal as a cougar, nor did I refer to the attacks as cougar attacks. I don’t need that kind of traffic coming from google searches.

Big Cats and You

Many people own pets. Somewhere around 30% of US households have dogs, and nearly the same amount have cats. There is certainly some overlap. However, these are the normal people. There are also between 5000 and 7000 tigers in captivity, and only 400 are kept at accredited zoos. Las Vegas shows only account for a small amount of the rest. This creates a problem, as in the US alone there were >300 incidents involving large felines between 1990 and 2011, with 20 fatalities. The likelihood of an escape or attack from an unaccredited facility is higher than that from a zoo. The literature on these attacks is also sparse, with mostly case reports or case series. Media reports are pretty common, since these are sensational events.

Enter this paper, which combed through articles and book chapters (groan) from 1950 to 2013 looking for pretty much everything related to big cats. This was then of course reviewed and narrowed down to ostensibly useful medical information, which was then written up in the review.

A few interesting tidbits:

  •  Tigers are the most frequent killers of humans worldwide, killing 600-800 per year in Asia
  • Man eating lions are much less common
  • The fabled lion pair that the movie “The Ghost and the Darkness” was based on was reported to have killed 130, but actual analysis shows has only found 3 deaths
  • Cheetahs rarely attack people. As in, almost never.
  • In some locales in India, leopards kill more humans than all other cats combined
  • Jaguars attack people more in captivity than in the wild
  • Perhaps you shouldn’t just stand still when a mountain lion attacks, but more on that in a future post.

The good news is that you don’t have to memorize a whole bunch of species specific treatment plans. Basically you want ATLS, and for significant wounds, broad spectrum antibiotics. Big cats are just that, big, and their teeth and claws do a number on our fleshy, unprotected bodies. If a tiger, jaguar, or mountain lion wants you dead (as opposed to just wanting you to leave it alone), it’s probably big enough and smart enough to do it right, by biting your neck so hard that your spinal cord is severed. They typically bite from the back. Conversely, cheetahs, leopards, and lions often bite from the front and crush the larynx. You’re still dead, but it’s a different kind of dead. Even getting swiped with a paw is enough to fracture your skull. So image most injuries, to look for fractures, pneumothoraces, or retained foreign bodies. Angiography is a good idea as well if you’re concerned for vascular injury. Since the animals typically go after Zone 2 of the neck, remember your workup for those injuries.

Data for the use of broad spectrum antibiotics isn’t as good, but since these are rare events, it’s likely less harmful here than for, say, household cat bites. Reports of purulent meningitis after head bites, septic joints, mycotic aneurysms, and other serious suppurative complications gives one pause, even without strong evidence for their use. So use pip/tazo, cefepime, or whatever gram negative/anaerobe combo antibiotic you use at your institution. And yes, people have gotten tetanus from big cat bites, so once again the lifesaving Tdap is recommended. Of note, rabies has been detected in mountain lions, but there isn’t data for the other big cats. The CDC says go ahead and treat unless no potential for being a vector. Also, don’t forget about cat scratch disease, as zoo workers have developed this after contact with big cats.

Finally, the psychiatric component is addressed. Survivors often have PTSD symptoms, and will likely need counseling.  There’s quite a bit more in the 11 page review article, so it’s worth a look.

Human Attacks by Large Felid Carnivores in Captivity and in the Wild
http://www.ncbi.nlm.nih.gov/pubmed/24864068