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KEEPING YOUR DOG SAFE IN WARMER WEATHER
Learn to Recognize and Prevent Hyperthermia (heat stroke) in Dogs
Hyperthermia can lead to vital organ failure and death; or lifelong health problems, even after recovery.
← CLICK THE IMAGE AT LEFT for a HANDOUT SUMMARY OF THIS ESSAY
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| Georgia: spider-woman |
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Heat-stroke (hyperthermia) occurs when a dog's normal heat regulating mechanisms become overwhelmed and cannot keep his body temperature in a normal (safe) range: that is, when heat gain exceeds his ability to dissipate it. When the elevated body temperature is sufficiently high, it is a true medical emergency requiring urgent treatment to prevent disability or death.
During onset of hyperthermia, the dog's body temperature begins to ascend uncontrollably, due to failed thermoregulation. Thermoregulation is the ability of a mammal to maintain its body temperature within certain margins, despite fluctuations in the proximate temperature. This process is one facet of homeostasis, the dynamic process through which the dog regulates his internal environment to maintain a stable, constant condition related to the external environment.[1] Dogs, as warm-blooded animals, are endotherms, and have a high temperature almost constant and independent of that of the surrounding air (homeothermy).
Hyperthermia is different from fever, the mechanism that provokes an elevated constant body temperature. A fever is caused through the action of the pre-optic region of the anterior hypothalamus, which re-sets the body's core (normal) temperature (analogous to re-setting the thermostat) to a higher temperature. It is among the body's immune responses that attempt to neutralize a bacterial or viral infection. Hyperthermia, however, occurs when the dog's body temperature rises without this signal from the his thermoregulation process.
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| Angelica: lost, momentarily... thoughtful yearning |
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Contrary to what we often assume, dogs overheat more quickly than we do. Dogs do not sweat though their skin like humans, but sweat only through their nose and foot pads (you'd notice this on a hot day, if you "shook hands").
Dogs primarily release heat by panting, (blowing out heat), because the lungs have a large surface area and are highly vascularised (endowed with blood vessels, thereby capable of transmitting oxygen). Air is inhaled, cooling the surface of the lungs; then exhaled losing heat (and some water vapor). A dog panting is an example of thermoregulation.
Elevated core body temperature quickly leads to dehydration, and speeds up the metabolism[2] of different tissues to such a rate that their metabolic capital (the ability to integrate and transmit energy through metabolic pathways) becomes exhausted. Blood that is too warm thickens and clots, producing dyspnea (shortness of breath)[3] by debilitating the metabolic capital of the respiratory center. The resulting strain on the heart increases its rate; the beats then become arrhythmic (irregular) and eventually cease. Death to tissues of the central nervous system, brain, and intestinal cells by oxygen deprivation soon begins. The central nervous system is overwhelmed by conflicting signals and delirium (cognitive deficit) and convulsions may set in. Soon after, consciousness may also be lost, propelling the dog into a comatose condition, wherein neurologic injuries such as stroke and asphyxia (severe oxygen deprivation, loss of blood supply, choking) can occur. At this stage, muscle becomes rigid with heat rigormortis, with the sudden rigidity of the whole body and generalized hypoxia (loss of blood supply to the entire body):4] rendering life impossible. Permanent injury to vital organs, and death, soon follow.
Even a dog who “recovers” from overheating can have vital organ damage,
renal failure,[5] and lifelong health complications and challenges.
We cannot judge the comfort or safety level of our dogs through our own standards of “being hot.” This is most especially so for overweight dogs and for certain “flat-nosed” (brachycephalic) breeds (bulldogs, French bulldogs, pugs, & others) who are more at risk because the lack of a snout limits their ability to cool themselves down.
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| Gracie: a boldness, her size notwithstanding |
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The prompt for progression from being hot→ heat stress→ heat exhaustion→ heat stroke is exposure to a trigger, such as inflammation in the body, side effects from drugs, or more commonly, a hot or humid environment. Hyperthermia may be exertional or non-exertional, depending on whether the dog has been exercising in the heat. If a dog cannot effectively expel heat, his internal body temperature begins to rise. Normal body temperature is 100° - 102.5°F, and a rise in body temperature of only 4° above that can cause damage to the body's cellular system and organs, which may become irreversible. Once the process of heat stroke has begun, there is precious little time before serious damage—or even death—can occur.
Walking a dog on hot pavement (especially asphalt surfaces) can initiate this process, or walking in areas without tree cover. Another common scenario that Fairfield Beach Access members have taken effort to remind others about is that heat inside a parked car can build, in just a few short minutes, to as much as 40 degrees above the outside temperature—especially if the car is in the sun—and even with the windows cracked or "open."
Owing to their biological and physiological origins, dogs are stoic, and as a “survival technique” do not communicate discomfort, distress, or pain to their guardians well.[6] As such, too many dogs succumb to heat stroke when it could have been avoided or treated: it is important that the dog guardian be aware and alert to the signs of hyperthermia.
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| Buca: Can you resist, smiling back? |
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Symptoms of heat stroke
...leading to coma and death.
If you are familiar with how quickly and deeply your dog breathes when he is comfortable and after a walk on a cool day you can use that information to judge when he is breathing harder than normal on a hot day.
• Rapid, frantic panting;
• Dilated pupils/"wide-eyed" look, or "startled expression";
• Thickened saliva, drooling;
• Bright red tongue;
• Hot, dry skin;[7]
• Dark red gums, then:
• Tacky or dry mucus membranes (specifically, the gums)
as dehydration advances; eventually gums become
pale, then grey;
• Vomiting; • Diarrhea; • Dizziness or disorientation; • Lethargy, staggering;
• Recumbancy (lying down & refusing or unable to rise);
• Shock; Collapse and/or loss of consciousness; seizures.
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| Coco: shaking off some mirth |
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What To Do if You Suspect Heat Stroke.
If you have even the smallest question that your dog is suffering from heat stoke, you must take immediate action. Don’t be hesitant to ask others—even passersby—for assistance, or to call your vet as you work without delay,
as time is of the essence.
1. Move your dog out of the heat and away from the sun
immediately (ectothermic cooling).
2. Begin cooling your dog by placing cool, wet rags or
washcloths on the body - especially the foot pads and
around the head. Use a fan to blow air over him if one
is available (ectothermic cooling).
3. Important! DO NOT use ice or very cold water:
intense cold can cause the blood vessels to constrict,
(vasoconstriction) preventing the body's core from
cooling—and cause the internal temperature to rise even further. Additionally, over-cooling can cause hypothermia
(metabolic reduction: slowing of internal body processes), which introduces other problems and is also a medical
emergency requiring immediate treatment. Rectal body temperature should be checked every 5 minutes:
when it reaches 103°, stop cooling.
4. Offer your dog cool water, but do not force water into his mouth: he may inhale it or choke.
5. Even if your dog seems recovered: call or visit your veterinarian immediately for advice: internal damage may not be
evident to you; further testing may be important. Dogs who suffer from heat stroke can develop serious delayed
complications that can lead to death, if they are not properly monitored.
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| Izabelle: in-supressable charm |
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Follow-up & Aftercare. Dogs with moderate heatstroke often recover without complicating health problems. Severe heatstroke can cause organ damage that might need ongoing care (a veterinarian-prescribed special diet), and are at increased susceptibility to succumb to hyperthermia in the future: exceptional care must be taken on hot, humid days.
What will Your Veterinarian Do? If you have been unable to, your vet will lower your dog's body temperature to a safe range, and continue to monitor his condition. He will be hydrated, and possibly be given oxygen. The vet will monitor for shock, respiratory distress, kidney failure, heart abnormalities, and other complications: and treat accordingly. Blood samples may be taken before and during the treatment, so that your vet can evaluate and
supervise his clotting time.
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| Riley: quiet grace & distinction |
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Preventing Hyperthermia
Any dog that cannot cool himself is at risk. What you can do to prevent heat stroke from happening:
• NEVER leave your dog alone in the car
on a warm day, regardless of whether
the windows are open.
Even if the weather does not seem extremely hot, the
inside of the car acts like an oven: temperatures
can rise to dangerously high levels—even 140 degrees
—in a matter of minutes. "Cracking" or partly
opening the windows will NOT alleviate this
danger. Neither will parking "in the shade." This
past year saw a dramatic increase in the number of
of dogs nationwide injured or killed after being left alone
in cars for "just a moment or two." And regardless of lack of intent, guardians are subject to prosecution pursuant to
animal cruelty laws.
• Dogs outside for any period of time need access to shade: chaining is dangerous, and illegal in many municipalities,
pursuant to animal cruelty laws: (Alabama, Arkansas, Florida, Georgia, Missouri, North Carolina, Oaklahoma, Texas:
(CLICK HERE for information); restricted in some states (California, Washington, DC, Florida, Georgia, Indiana, Kansas,
Louisiana, Maryland, Massachusetts, Michigan, Missisippi, Missouri, New Jersey, New Mexico, New York,
North Carolina, Ohio, Oaklahoma, Oregon, Tennessee, Texas, Virginia, Wisconsin: (CLICK HERE for information);
and addressed state-wide, in California, Connecticut, Nevada, Texas, and Virginia: (CLICK HERE for information).
• Avoid vigorous exercise on warm days. When outside, as you would for yourself, seek shady areas.
• On a hot day, do not muzzle your dog; (it can impair his ability to pant/exhale heat).
• Dogs with predisposing conditions (heart disease, obesity, elderly dogs, or those with breathing problems): need extra
supervision: even so-called “normal activity” for these dogs can be harmful.
• Don’t jog with your dog on a day that is even moderately hot.
• Avoid hot surfaces (sand), and areas lacking shade—particularly asphalt—where heat is reflected upwards.
• Keep fresh cool water available at all times, encourage your dog to drink frequently.
• Wetting down your dog with cool water, or allowing him to swim, can be beneficial. However, do not assume that a dog
playing in water cannot overheat: when water temperature gets above 75°, vigorous play can lead to hyperthermia.
• Be aware that certain types of dogs are more sensitive to heat: especially obese dogs[8] and short-nosed breeds (Pugs,
Bulldogs, others) that cannot expel heat efficiently.
• Keep your dog active year-round, to ensure for his general health; build up his tolerance for heat slowly: when anticipating
a heat wave, act accordingly. Move your dog to a cool area of the house; if you do not have access to air conditioning,
keep him in the path of a safe and efficient fan, or, to provide a cooler environment, freeze water in soda bottles, or place
ice and a small amount of water in several re-sealable food storage bags, then wrap them in a towel: place them on the
floor for the dog to lay on.
• Prevention IS the best remedy.
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| Biscuit: dozy contentment in a warm October sun |
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ENDNOTES:
[1] The processes in zoology has been called ecophysiology or physiological ecology.
[2] Metabolism is two categories of chemical reaction in living organisms that maintain life, allowing them to grow and reproduce, maintain their structures, and respond to environmental influences. Catabolism breaks down organic matter to harvest energy (example: cellular respiration); while anabolism uses energy to build components of cells (examples: proteins and nucleic acids). These chemical reactions are structured into metabolic pathways, in which chemicals are successively transformed into different chemicals by a sequence of enzymes. Enzymes regulate these metabolic pathways to respond to changes in the cell’s environment (or signals from other cells), and act as catalysts, coupling spontaneous reactions to quickly and efficiently release energy which would not otherwise occur.
[3] Dyspnea is caused by problems with central information processing in the brain that compares signals from afferent (lymphatic vessels in the lymph nodes) and efferent (found in the thymus and spleen) sources. A conflict or mismatch of these signals results in need for ventilation (afferent signaling) is not being met by the physical breathing that is occurring.
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| Louie: relentlessly sparkling |
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[4] Multiple organ dysfunction syndrome (MODS), in an acutely ill patient, defined when the function multiple organs makes maintaining homeostasis (dynamic equilibrium: maintaining a stable, constant condition) impossible without medical intervention.
[5] Renal failure (or kidney failure) describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood: in hypothermia, resulting from acute kidney injury when the blood supply to the kidneys is suddenly interrupted. Even dogs that "recover" from hyperthermia face an elevated likelihood of developing this condition later in life.
[6] Regarded as a facet of “pack mentality,” an injured dog communicating stress or pain would be threatened with loss of leadership status, or, becoming attractive to predators, impact the ability of the group to travel; and thereby be threatened with ejection from the group.
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| Blue: irresistibly cheerful... |
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[7] The dog’s skin may become red and hot as blood vessels dilate in an attempt to increase heat dissipation, sometimes leading to swollen lips. Dehydration produces subsequent effects as noted above. The decrease in blood pressure can then cause blood vessels to contract (vasoconstriction), resulting in a pale or bluish skin color in advanced cases of heat stroke.
[8] It is worthwhile to examine your feeding protocols, to ensure that the food you use is nutritionally sufficient. There is no better time to commit to the work of keeping your dog’s weight under control (with veterinary supervision), by reducing the levels of grains and needless carbohydrates in his diet, and with a quality food that does not merely rely on exaggerated levels of indigestible fiber to achieve restricted caloric goals, as many “diet” formulations do. You may be able to significantly reduce your overall guardianship costs with better food. Our essay, “The Nutrition Connection," might be a useful springboard to discussion.
N.B.: This essay is written for informational purposes only. Our goal is to build awareness of concepts and define common terminology to stimulate discussion. We draw your attention to issues and concepts that are or may be important to the subject at hand, but do not consider that our interpretation is necessarily complete. Mutually respectful and open relationships with physicians, veterinarians, and shelter/rescue organizations are all essential to productive dialog on this issue. We would welcome your comments or suggestions! We do not specifically endorse any of the organizations discussed here, but interpret that they may be of interest, and have provided links and/or PDF's to stimulate creative thinking so that you may conduct your own research (links are in blue & will illuminate when you pass your mouse over them: click to be directed to a site or to print a PDF). Animal welfare laws may change, and we will endeavor to keep those citations current; we welcome suggestions in that regard.
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| Charly: earnest reflection... |
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“One morning the sky was grey and
it was raining so hard that the sound of
the drops hitting the roof filled the house.
Out of nowhere,
Catalina heard a bird singing.
The sound was so bright and clear she felt as if the bird was singing to directly to her.
As she listened the song reminded her
of the one she used to sing:
On the day that Jasmine was born /
The angels sang a beautiful song...
Catalina believed in the connectedness of things and in the power of their instincts to guide them. Likewise she believed that Jasmine had been sent to her for a purpose. She felt as though Jasmine had a mission
in this life, and having achieved
what she set out to do, she had been freed to move on . Jasmine was off to do something else, somewhere else,
while the rest of us were left to follow our own path.
This is Jasmine's purpose. This is the story she tells.”
Jim Gorant—The Lost Dogs (Michael Vick's Dogs and Their Tale of Rescue and Redemption)
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