Summer Heat Study

In my article about keeping dogs safe from the summer heat, I mentioned that I'm doing a study to show how different types of cooling products can help keep our pet dogs safe in summer. I have gotten a number of emails with questions about my study, so I thought I would write a post explaining what I'm doing, how I'm doing it, and why I'm doing it.


Disclaimer

Please bear in mind that this is by no means a University-level study about the effects of heat on dogs. I am not a veterinarian. I'm not a working dog handler who has to be out in 110 degree heat with her dog. I'm a pet owner and this study is designed for pet owners to help them make smart decisions about keeping their dogs safe from the summer heat.

No dogs were harmed in the making of this study!


Why are you doing the Heat Study?

I'll explain why I'm doing this study first, since it's the simplest part of the explanation. It's because I own a wonderful dog and I want her to stay healthy and be safe from heat-related injuries.

It's also because I want other dog owners to know how dangerous heat and humidity can be for their dogs and just how quickly a dog's body temperature can raise to a dangerous level, even with only moderate exercise.


About my test subject, Abby

Since I'm using my own dog, Abby, as the subject for my study, I need to say a little bit about her. I'll explain why a little further down.

Abby is 4 years old at the time of my study. She's a purebred German Shepherd dog and red and tan in color. She's 23.8 inches at the withers and a lean 60 pounds. She is physically in good condition. One thing that is important to note is that she is acclimated to the warmer temperatures. We do not use the air conditioning at home unless the outside temperatures go above 100 degrees.

These things are important to note because the way a dog deals with the heat is not just dependent on external factors such as the temperature and humidity, but also on the individual dog.

The following are susceptible to heat-related injuries:

• short-muzzled breeds
• young puppies
• senior dogs
• overweight dogs
• dogs with medical conditions
• dogs that spend most of their time indoors

Establishing a Base Line Temperature

In order to establish how the heat affects Abby and how well the cooling products work, I needed to first establish what Abby's normal temperature is so that I could see how her temperature changed with exercise and wearing the different types of products.

I established her Base Line Temperature (BLT) over the course of one week. This was done by taking her temperature each morning when I first took her out of the crate before her morning walk. The temperature was taken rectally with a digital thermometer. The same thermometer was used for each reading.

Abby's BLT fluctuated between 97.9 degrees and 100.4 degrees, with the average temperature being 99.5 degrees, just a little below normal.

The normal body temperature of a healthy adult dog ranges between 100 and 102.5 degrees, depending on when in the day the temperature is taken. Just like the body temperature of humans, the body temperature reading of a dog is generally lower in the morning and higher in the evening. It also fluctuates to a certain extent based on outside temperatures as well as physical factors.

Therefore, if you're planning to monitor your dog's body temperature in the summer heat, you need to make sure to establish the BLT for your individual dog and your individual circumstances and go from there.



Measuring the difference Exercise Makes

In order to get a good idea of how exercise affects Abby's body temperature, I needed to set some guidelines for the exercise. It would be unfair to one day measure exercise as 15 minutes of playing ball and on another day measure exercise as a 45 minute walk. I therefore used two kinds of exercise that best describe what most people do with their pet dogs: playtime and walks.

Playtime Parameters

For the purposes of this study, playtime was kept down to 15 minute sessions.

The game of choice was "soccer" using a half-deflated basketball since that's what Abby likes to chase. The premise of the game is me kicking the ball and Abby chasing it, repeating as necessary. Playtime took place in the grassy field behind the house, which is not quite level, and in the late afternoon / early evening between 4 and 6 pm.

Abby's temperature was taken immediately after coming back inside from playtime, prior to giving water.

Walking Parameters

For the purposes of my study, going for a walk was limited to a 1 mile course around the neighborhood, with me walking on the sidewalk and Abby walking on the grass next to me. Walks took place in the late afternoon, in the 4 to 6 o'clock time-frame.

Our course takes us briefly across level ground, then uphill for approximately two quarters of the way, then level again, then down a long wooden staircase, and then back across level ground to the house. No stops were made on the walk with the exception of one stop for peeing or pooping, generally lasting less than 30 seconds.

The walking pace was fairly quick and set by me. My normal "marching" pace (fast walk) is a slow gait (trot) for Abby. I realize that most people walking with their dogs go at a slower pace and take stops during their walks - however, this was the best way for me to be consistent with the level of exercise for the study.

Abby's temperature was taken immediately after coming back inside from the walk, prior to giving water.



How humidity figures into the Study

You probably know the saying that "It's not the heat that kills you, it's the humidity." Humans cool down through evaporation - when we sweat, the water on our skin evaporates, which helps cool the body. On humid days, less evaporation takes place because the air is already saturated with moisture. This means that less cooling takes place - which is why it feels hotter on humid days that it actually is.

You might wonder why this is important in my study - particularly since dogs don't sweat and the amount of evaporation is limited to the moisture coming off the dog's tongue.

It's important because many cooling products are based on the concept of evaporation. If you have to soak it in water for it to work, the cooling takes place through evaporation. So what does this mean if you use such a product on a day that is both hot and humid?

• In a climate that is hot and humid, the products will work less well than they do in a climate that is just hot. Less evaporation takes place = less cooling takes place.
  
  
• If it is very hot and humid, these products can become dangerous. Now they're not only not cooling, but they are also another layer of material that is trapping heat around your dog. Particularly in the case of vests that cover a large area of the dog's body, this is a serious consideration.

Because humidity makes such a big difference in how well these cooling products work, I have tested each product on days that were hot and dry, as well as on days that were hot and humid. That means each product was tested at least four times: twice on walks and twice during playtime. A "control group" of walks and playtime using no products whatsoever was also done in low and high humidity conditions.

My temperature and humidity readings were taken immediately prior to a test phase and provided based on my local zip code through The Weather Channel's website.



How the cooling products are scored

Rather than just giving a thumbs up or thumbs down on the products I've reviewed for this study without any explanation, I'm giving each product an individual score based on the following:

• its performance in hot, dry weather
• its performance in hot, humid weather
• its fit and adjustability on my dog
• its construction and durability

Fit is a factor because different dog breeds are built differently. I'm not talking about buying the "right size" for the weight and height of dog, but rather about how the "right size" product can be adjusted for fit to take into account the difference in fit needed to make a product work as well on a narrow-chested dog as on a wide-chested dog, for example.

I will give an overall verdict as well as an explanation of what features I like and don't like when I post the individual study test results.