109 Hi Dave but I thought I’d share from experience…..
Defiantly Agree with Mike and Judy, food for thought also is depending on the dogs fitness level, breed, situation and acclimatisation period.
Specifically for MWD’s, CAD’s, EDD’s and SAR Dogs, here is some info from a 3 day hands on course i recently completed called TCCC (tactical care of the canine casualty) through http://www.k9hardcase.com, the instructors advocated strongly Rapid cooling for heat injuries coupled with fluid intervention should the dog be suffering from a heat injury, when heat stress signs are first apparent they are subtle to most but easily recognisable, shade seeking, distracted, tongue lolled out to the side, puff eyes, intense heavy breathing, mouth wide open teeth exposed…ect these are the first signs that you as the handler need to identify early and rest the dog.
Obviously in the shade somewhere cool, give small drinks, beyond that the dogs health can go from anywhere to having immediate severe diarrhoea (straight up heat injury), to drunkedness/ listless, cardiac arrest.
The big take away from the course was core body temp which relates to heat stress then heat injury are totally independent from dog to dog and there is no actual definitive core temp range that you should abide by as the guidelines are mostly inaccurate, this is because of the differences in dogs through breed, fitness level, work rate, the list goes on in variables….the best advice was (get data) measure the dogs temp prior to training, at rest. Then measure it during the activity, then after the activity. Note any changes in behaviour that relate to heat stress, that will give you a figure you can work off as well as looking for earlier signs.
For instance my English Springer completed a 600m route search, measured core temp prior to task in his kennel 39* celsius, the day temp and humidity was 32* and 92% humidity Darwin wet season(think super tropical sauna), during the task measured core temp again he was 43*, shade seeking, puffy eyes, wide mouth breathing, but still searching relentlessly we completed task in a time of 55min, rested 4 times throughout for between 3-7mins this includes shade and water and core temp measurements. measured temp on completion and he was 44*, we rapid cooled him in the shade in a kids bath filled with water and his temp dropped 3* in around 7-8min. the physical changes for him were immediate no puffy eyes, breathing slowed, and his physical recovery was amazing as he was ready to go again 2 hours later.
Another team completed the same task, same time/atmospherics this time with a Kelpie (2 years older) measured prior to task 40*, during task 42* similar rest periods however minimal heat stress indicators because the dog took care of itself, worked at a steady pace the whole way through task time was 1hour and 10mins, measured core temp at end of task 42*, the dog maintained self preservation, again we rapid cooled the kelpie in the same manner temp dropped to 41* in around the same time as the springer and was keen to go after 2 hours, the springer was faster but the draw back was temp increased fast and caused changes which i had to be aware of and maintain, the kelpie just cruised along but spent longer on the task which has other implications.
We are taught at rest a dogs temp is between 38-39.5*, so technically both dogs were suffering from heat stress just sitting in their kennel. but did not show any signs.
These examples are of very athletic EDD’s, who train daily, PT daily, who now eat a very healthy balanced diet specific to their requirements and performances which have been measured individually in terms of output.
Hope this is of some help mate. hit me up if you have any other heat related stuff i work with it and in it everyday.