Heat Injury in Working Dogs;
Article from Police K9 Magazine, written by Janice
Heat injury is a fairly common problem in working dogs and severe cases
can be fatal. Many recommendations by veterinarians or canine
first aid references offer conflicting and complicated recommendations
on the best way to treat an overheated dog. The single most
important factor to survival is
immediate treatment and
rapid cooling to reduce the dog’s core body temperature when the
first signs occur. For the working dog handler and tactical
medical personnel supporting units with canine teams, this means
beginning treatment at the point of injury, long before arrival to
veterinary care. While heat injury is a complex problem that can
have serious complications or outcome, immediate lifesaving treatment is
relatively simple, and does not need to be complicated. Basic,
rapid measures to cool the dog to a more normal body temperature can
greatly increase his chance for survival.
Recognizing Heat Injury
There are many definitions for heat injury, with temperature ranges from
105-107 depending on the source of information. Normal temperature
of dogs is usually between 99-102.5, however their temperature may go
up as high as 106 to 107 during hard work and still be abnormal.
Hyperthermia is the term meaning that the body temperature is elevated
above the normal range. However, hyperthermia
does not mean that there is something wrong with the dog. The time
that it takes the temperature to return to normal after a dog stops
working may be a better indicator of if there is a problem, vs. the high
temperature itself. Different dogs will respond differently and it is
important to know what normal recovery time is for your dog. In general,
all definitions of heat injury include a significantly high body
temperature in combination with clinical signs such as abnormal
behavior, exhaustion, or collapse. With mild cases of heat injury
a dog may only show vague signs such as appearing tired, or slow or
reluctant to follow commands. In more serious cases the dog may
collapse, lose consciousness, and may have seizures. Any
sudden change in behavior, level of energy, or physical actions of a dog
during warm or hot weather should be considered possible heat injury
until proven otherwise.
An affected dog’s heart rate will likely be elevated, possibly at 150
beats per minute or greater for a typical 60 to 80lb dog, and his
respiratory rate and effort will likely also be increased. Like
his body temperature, this could be elevated from hard work and still be
considered normal for him. The heart rate and respiratory
effort of a normal dog should begin to return to normal within a few
minutes of when he stops working and rests.
Heat injury is usually categorized in different degrees of severity.
Mild cases are typically called “heat stress” or “heat exhaustion.”
These cases may resolve with adequate rest in a cool environment and
rehydration by drinking water or administration of IV or subcutaneous
fluids. More severe cases are typically called “heat stroke,” and can
often have serious complications. It is not as important for you
to know the definitions of the types as it is being able to recognize
the conditions in which it’s likely to occur, ways to prevent it, or
treat if when it happens.
Working dogs, with their high drive and desire to please their handlers,
may not show any signs at all of problems, then suddenly stagger for a
few steps and collapse. Any sudden change in behavior, level of
energy, or physical actions of a dog during warm or hot weather should
be considered possible heat injury.
Thermometers and Method of Taking a
Every canine first aid kit should contain a thermometer. Rectal
measurement of temperature is the most practical, accurate
representation of core, or
inner body temperature in dogs. Since many working dogs
don’t like having a thermometer inserted into their rectum, it would be
nice to have a less intrusive method of evaluating their temperature.
Unfortunately, there is currently no better way to do this. Ear
thermometers are generally designed for humans and are not long enough
to reach areas of the ear canal that give an accurate temperature
reading, and a lot of dogs resent those just as much as rectal
thermometers. Flexible digital thermometers, many of which give a
reading within seconds, are probably the best type to use as far as
accuracy, safety, and comfort for your dog.
According to studies in both veterinary and human medicine, the most
important factor in treatment of heat injury is
treatment. The more quickly cooling occurs,
the better chance for survival. Specifically, if aggressive
cooling begins within 10 minutes of collapse, the patient has a
significantly greater chance for survival that if cooling is delayed
longer than this. If you have only one choice at a time between
cooling the dog or transporting the dog, cool him first, then transport
him to a veterinarian. Ideally, you would start rapid cooling
first, then transport to a veterinarian while continuing cooling if
needed. Air conditioning inside a vehicle would not be considered
“aggressive cooling.” Aggressive cooling would include more rapid
measures, such as immersion in cold water or placement several ice packs
around the dog’s body and head.
Some recommended methods of immediate cooling include:
Move into a cooler environment (shade, air conditioning, etc)
Immersion in cold or cool water
Wrap in cool or cold wet towels
Provide a strong breeze with fans or other air movement
Place ice packs around the body and head
Administer IV fluids if available
Place rubbing alcohol on wet fur (avoid the face)
Contrary to some recommendations, there are really no “wrong” methods
of cooling down an overheated dog, baring the extreme or obviously
unsafe. For years veterinarians and canine first aid references
have warned against immersion in cold or ice water, claiming that those
methods will actually slow down or prevent cooling. This is based
on the idea that cold or ice water will cause the blood vessels in the
skin to constrict, preventing needed heat loss from the blood.
While the vessels will constrict to some degree, there is no scientific
evidence to show that this slows or prevents cooling overall, and there
is also no scientific evidence to show that this method is actually
harmful to the overheated patient. In fact, many studies confirm
that cold water immersion is the most rapid method for cooling subjects
with exercised-induced heat injury, and is the preferred method of
cooling down humans with heat stroke.
Similarly, some recommendations state not to place wet towels over a dog
to cool them down as the towels will actually “trap” the heat from
escaping. Similar to cold water immersion, there is no
scientific evidence to back up this recommendation either, and it may
come down to common sense on that one: If the water in the towels
is colder than the dog, then heat will be transferred from the dog to
the towels and the dog will cool down. One
study showed that cool water immersion cooled down overheated subjects
twice as fast as wrapping the patient in wet towels, but both methods
were effective in cooling overall.
If you or your teammates have the skills to place IV catheters and
administer fluids, this could also be considered. However, do not
delay cooling efforts in order to place an IV catheter. And along
that same line, once the dog has been cooled, do not delay transport to
veterinary care in order to place an IV catheter. Subcutaneous
fluids (fluids administered under the skin) may not help much in a
severe case of heat injury, but administered in an appropriate dose may
help with mild cases, and probably won’t hurt in more severe cases.
Do not attempt IV or subcutaneous fluid administration unless you have
been properly trained to do so, as serious complications could occur if
not done properly with the right type of fluid solution.
Many scientific studies have been done on dogs and humans to evaluate
which method and speed of cooling is best for survival, and to date the
only practical conclusion from these studies is that the more rapid the
cooling, the greater chances of survival. The method used should
be the one available to you that will cool him most quickly.
Because your goal is to rapidly cool the dog, you
have to be careful not to overcool him and cause his temperature to drop
too low. Overheating can alter the dog’s ability to regulate his
temperature through damage caused to his hypothalamus; a specific part
of the brain that controls temperature regulation. With loss of
his normal temperature regulation mechanisms, and your aggressive
cooling methods, his temperature can drop way below normal. The
general recommendation is to stop aggressive cooling when the dog’s
rectal temperature reaches 103 degrees F. If his temperature
continues to drop below that, you may need to take measures to keep him
warm and prevent even more heat loss. Drying him with a towel and
wrapping him in a dry blanket may be all that is needed, but the most
important part is to continue monitoring his temperature every five to
ten minutes after that until his temperature remains stable and he is in
the care of a veterinarian.
Practical treatment of heat injury in working dogs revolves around the
idea that the more rapid an overheated dog is cooled down after he
reaches a critical temperature, the more likely he is to survive this
potentially fatal condition. Don’t let yourself be hindered by
complicated recommendations of which methods of cooling are the best or
are detrimental to care. The bottom line is that all of the
practical methods seem to be effective and not harmful if done with
common sense and frequent monitoring of the dog’s temperature.
Cool the dog first, then transport to a veterinarian unless aggressive
cooling and transportation can be done at the same time.
Checklist for Treatment: What You
-Cease working the dog, and move him to a cooler environment if possible
(a/c is ideal)
-Remove his muzzle if he is wearing one
-Get him wet all over, with cold water if available. Immerse him in the
water if safe to do so, protecting his head from going under
-If the only water available is room temperature or slightly warmer
(i.e. warmed by the sun) use it anyway but do not immerse him in it—pour
it over him or sponge it on him to wet his fur. Do not use hot water
-Place ice packs around the dog’s head if he is unconscious.
-Provide a strong breeze with fans if available
-Provide oxygen by mask if available
-Take his rectal temperature as soon as possible, and repeat every
5minutes to monitor cooling.
-Stop cooling when his temperature reaches 103 degrees F.
-Be prepared to keep him warm if temperature continues to drop or goes
below 99 degrees F.
-Administer IV or subcutaneous fluids if already trained to do so.
DO NOT delay other methods of cooling or transportation in order to
place an IV or administer fluids.
-Transport to a veterinarian for further
Janice Baker, DVM
Veterinary Tactical Group
Even if you don't have a dog, you might have friends
who do. This is worth passing on to them.