Cynthia M. Otto reports research showing the benefits of a trained head dunk to prevent heat stroke in dogs

In this dvm360 interview, Cynthia M. Otto, DVM, PhD, DACVECC, DACVSMR, discusses research conducted at the Penn Vet Working Dog Center. Her team developed voluntary head dunk procedure for dogs, a low-resource cooling technique that study results showed can block the typical five-minute post-exercise temperature spike in working dogs. That work has made Otto and her team a finalist for the American Kennel Club’s Canine Health Discovery of the Year Award for the technique’s real-world potential to reduce heat-stroke risk.

RELATED: A simple, trained 30-second head dunk rapidly cools overheated dogs

Learn how to perform this technique by watching the video below:

Transcript

Cynthia M. Otto, DVM, PhD, DACVECC, DACVSMR: I mean, the start of the story goes way back. I have clinical expertise in emergency and critical care as well as sports medicine, and in the emergency room we would see way too many cases of heat stroke. What we know from the research and the literature is that heat stroke is one of those preventable causes of morbidity, mortality, and injury in our working dogs, but also across the board. So, we’ve been really thinking about how to address this heat-stroke risk in dogs when they’re in environments where they are potentially at risk and they have to keep doing things.

Over the years we’ve looked at hydration and different cooling mechanisms, and it came to the point where we know that jumping in a pool of water is great—it’s been shown, that’s fantastic—but that can’t always happen. I was working with some conservation detection dogs in Zambia, and we were like, okay, here we are in a really hot environment. We can’t just take a break. We have to keep working. Is there a way to cool…we can’t carry enough water to fill a pool. The rivers are dangerous because there are crocodiles and hippopotami and things that would potentially put the dogs at huge risk. How do we try and cool these dogs?

We wanted to look at field-relevant cooling, things that you could take with you to do in a place where you might not have the resources. We had previously done a couple of studies. We know that dogs get really hot within 10 minutes of just running back and forth about 25 yards between two people to catch a ball or a toy, and they get really hot. It might surprise a lot of veterinarians. It certainly surprised me. The first time we looked at the temperatures of these dogs after they’d either been working in an actual search-and-rescue training or even this little exercise, their temperatures got up to about 105–106°F, which in our books is considered heat stroke, but these dogs weren’t having heat stroke. They were still able to function fine.

To try and reframe that and figure that if they might be closer to risk of heat stroke, how do we prevent that? How do we prevent that from progressing? In this particular study we tested field-ready approaches. One of them was using those cold chemical ice packs you might carry while hiking; you snap them and they get cold, and we put those under the collars on the dogs. We didn’t shave the dogs or anything. We just relied on what would naturally happen.

A second approach was to take a towel and wet it with cold water—this was 72°F water, basically room temperature—but when you’re in 90 °F, 72 °F is cold. We wet those towels and tried one under their armpits because we discussed wetting dogs on their bottom half where there’s less fur; that might be a better place to cool them. We tried one wrapped around their neck because we also know that cooling blood going to the head can be effective. Then we tried a technique we’d been using at the Working Dog Center for quite a while to help dogs flush out their eyes and noses: having them voluntarily dunk their head into a little pool or bucket of water to get a treat or a toy. We call that the head dunk. It’s a voluntary head dunk because we train the dogs to do it, and they actually think it’s a fun game.

We didn’t have much confidence it would work, but it turned out that by dunking their head into this cold water—again, the water was 72°F, not freezing, just room temperature—the usual pattern after you stop exercising is that your temperature continues to rise for about five minutes. That blocked that rise in temperature and it really dropped their temperatures. Part of our cooling mechanism in dogs is panting, but panting requires evaporation of saliva and fluids in the respiratory tract. When it’s too hot and too humid, you can’t evaporate well. There’s a lot of blood flow to the head that allows for some cooling by heat exchange through breathing: you breathe out hot air, and heat moves from the oral cavity and the head to the environment. When we cool the head, they might drink a little bit during this but not much. We actually measured how many times they lapped the water. It cooled their mouth, the roof of their mouth, their head, and their face.

We didn’t have them dunk far enough to get their ears wet because we didn’t want to fill their ears with water. Thermal cameras showed their ears as bright red—a lot of heat is being lost through the ears—but mostly we were looking at what was happening in their face and mouth, and the impact was quite remarkable. It can be done in a limited environment; it doesn’t require a huge amount of water, and it doesn’t take much training. Often, we’ve had a couple of puppies in demonstrations like this—a puppy who had never done this before, literally within 5 minutes was dunking its head. Some dogs take a little longer; they’re less excited about it, but it’s a really great technique not only for cooling but also for flushing eyes and noses.

We’re big advocates of low-stress handling and cooperative care, so anything that helps with cooperative veterinary care is fantastic. Cooling is really important in the field; flushing eyes and noses can be important in the field and in the veterinary clinic environment. We published a video—I don’t know if you can share the link—it is in JAAHA/JAFFMA (video tutorials), open access, freely available, and it goes step by step: how to train this and when it’s appropriate to use it and when not to use it. Certainly, if a dog is already in heat stroke, that’s too late. We want to do this before they reach that point. We want dogs that are mentally appropriate and showing signs of heat stress, which—again—it’s worth reminding everybody that there are physical signs of heat stress regardless of what their temperature is. Their eyes narrow, their tongue gets long, sometimes there’s more ropey saliva; they pant excessively, the commissures of the mouth are retracted, their ears may be retracted, they may be less motivated to return on a retrieve, or they might be seeking shade. All of those signs tell us the dog is feeling the effects and we need to stop activity and actively cool them. We also looked at what happens if we just stop activity and let them rest in the shade: it doesn’t do much, and it takes a long time for them to come back down. So we want to actively intervene and actively cool them.