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
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. Dogs, as warm-blooded animals, are endotherms, and have a high temperature almost constant and independent of that of the surrounding
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. The hypothalamus is a portion of the brain that links the nervous system to the endocrine (hormonal) system via the pituitary gland. 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 his
Princess: divergent thoughts...
How Do Dogs CoolThemselves?
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.
On very warm days or in a hot car, however,
cool air is not available for the dog to inhale
and undertake this process.
SO, ONCE THE AMBIENT (OUTSIDE) TEMPERATURE RISES ABOVE 89°F (32°C):
A DOG CANNOT SHED BODY HEAT.
Elevated core body temperature quickly leads to dehydration, and speeds up the metabolism of different tissues such that their metabolic capital (the ability to integrate and transmit energy through metabolic pathways of radiation and convection) becomes exhausted. Blood that is too warm thickens and clots (coagulates), producing dyspnea (shortness of breath) 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 from
oxygen deprivation soon begins.
Buca: can you resist... smiling back?
Thermal injury to muscle tissue or the endothelium (lining of organs and cavities of the body: particularly the blood vessels, heart, and lymphatic vessels) causes widespread vascular damage, the excretion of high levels of myoglobin, and initiates coagulation to help repair the injured vessels.
Due to peripheral vasodilatation and the corresponding decline in vascular resistance, splanchnic blood pools within visceral abdominal organs. As the volume of circulating blood decreases (hypovolemia), cardiac output declines as vascular resistance (blood pressure) drops (hypotension). The process is known as disseminated intravascular coagulation.
The resulting strain on the heart increases its rate; the beats then become arrhythmic (irregular) and eventually cease. Global thermal injury causes multisystem organ dysfunction: as uncoupling of oxidative phosphorylation (energy transfer) occurs, enzymes are denatured, and cell membrane (epithelial) functions are distrupted. Damage to normal operations of kidney (renal), liver (hepatic), gastrointestinal, brain and central nervous systems begins and may impart irreversible widespread cellular injury or necrosis (death) to tissues from the resulting deprivation of oxygen.
The ordinary barriers of the gastrointestinal system (enterocyte cells) are breached. Hypotension and thermal injury contribute to severe gastrointestinal epithelial damage and necrosis, resulting in hemorrhagic diarrhea, hematemesis, gastric ulceration, and potential for bacterial translocation of already present pathogens into the bloodstream. Thus: the risk for onset of potentially fatal sepsis is dramatic.
As blood flow to the brain declines, low cerebral perfusion, cerebral edema, or neuronal degeneration sets in: 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):  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, 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.
Gracie: the (little) bold one
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 initiate heat exhaustion and cause damage to the body's cellular system and organs, which may become irreversible. Once the process of heat stroke has begun, there is little time before serious damage—or even death—
Walking a dog on hot pavement (especially asphalt surfaces) can initiate this process (he cannot “sweat” through his foot pads), 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—despite that the windows may be “cracked” or even “open.”
The windows in a car act as an insulator, effectively turning the cabin (the greenhouse) into an “oven,” as heat from the dashboard, door panels, plastics and seats is reflected back. Assuming “it just not that hot out” is a mistake: with an outside air temperature of just 75°F, it takes only 10 minutes for the interior to reach 100°F; in just 30 minutes, the same car can rise to 120°F.
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.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.
Sadie: cautious observer
Visible 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" or “startled expression”; • Thickened saliva, drooling; • Bright red tongue; • Hot, dry skin; • Dark red gums, then: • Tacky or dry mucus membranes (specifically:
the gums) as dehydration advances;
eventually gums become pale, then grey; • Vomiting; • Diarrhea;
• Seeming Dizziness or disorientation; • Lethargy, staggering; •Recumbancy (lying down & refusing or unable to rise); • Shock; Collapse and/or loss of consciousness; seizures.
Ceril: quiescent, after a long run
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). Move
to an air-conditioned car.
3.Important! DO NOTuse ice or very cold water:intense cold can cause the blood vessels to constrict,
(vasoconstriction) preventing the body's core from cooling:and cause 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.
Izabelle: in-supressable charm
Follow-up& Aftercare. Dogs with moderate heatstroke often recover without complicating health problems. Severe heatstroke can cause organ damage that may necessitate 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.
Murphy: quiet grace & distinction
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,"
because certain light waves cannot pass
through the windshield.
Recent years have seen a dramatic increase in the number 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 state or local 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).
•Realize that above 89°F, your dog cannot shed body 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 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.
•If you see a dog left in a running vehicle with the air-conditioning running, you should intervene immediately: the air-
conditioning compressor will turn off if the engine gets too hot, and instead of cold air flowing from the vents, hot air
will flow into the car, quickly overwhelming the animal. •Prevention IS the best remedy!
The windows in a car act as an insulator, effectively turning the cabin (the greenhouse) into an “oven,” especially in the sun as heat from the dashboard, door panels, plastics and seats is reflected inward. With an outside air temperature of just 75°F, it takes only 10 minutes for the interior to reach 94°; in just 30 minutes, to nearly 110°; and in an hour, that same car can rise to 120°F.
Biscuit: dozy contentment in a warm October sun
ENDNOTES:  The processes in zoology has been called ecophysiology or physiological ecology.
 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.
 Dyspnea (disordered breathing) 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 leads to demand for ventilation: (afferent signaling) is not being met by the physical breathing that is underway.
Ziggy: windswept warrior
 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.
 Renal failure (kidney failure): a life-threatening 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 (similar to massive/sudden blood loss). Even dogs that “recover” from hyperthermia face an elevated likelihood of developing this condition
later in life.
 Regarded as a facet of “pack mentality,” an injured dog communicating stress or pain would be threatened with loss of leadership status; or, risk becoming targeted by predators, thereby impacting the ability of the group to travel, and thus be threatened with ejection from the group.
Blue: irresistibly cheerful...
 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.
 It may be of benefit to carefully examine your feeding protocols, to ensure that the food you use is nutritionally sufficient. Committing to the work of keeping your dog’s weight under control (with veterinary supervision and appropriate exercise), is a goal you may both enjoy. An important consideration should be 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. Note also, that many so-called “diet” formulas may in fact be higher in calories than other “regular” foods (the designation as “diet” or “reduced calorie” may merely be descriptive of its relation to another of the manufacturer's own foods). 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; see also: How To Read Dog Food Labels (2 part essay).
 Recent studies include: Heat Stress From Enclosed Vehicles: Moderate Ambient Temperatures Cause Significant Temperature Rise in Enclosed Vehicles; Catherine McLaren, MD; Jan Null, CCM; and James Quinn, MD: Pediatrics Vol. 116 No. 1 July 1, 2005 pp. e109 -e112 (doi: 10.1542/peds.2004-2368); also: Heatstroke Deaths of Children in Vehicles, Jan Null, CCM; Department of Geosciences, San Francisco State University; also: Heat Exposure in an Enclosed Automobile, Lynn I. Gibbs, MPH, David W. Lawrence, MPH, RN, CS; Mel A. Kohn, MD., 1995 Journal of the Louisina State Medical Society.
 Solar radiation energy which has reached the surface of the earth is composed of a broad spectrum of energy wavelengths, from approximately 200 to nearly 3000 nanometers (nm). Energy that we see as visible light (“photons,” or “visible light particles”) are distributed between 450-700 nm wavelengths. They comprise only a minority of the total spectrum. Most of the spectrum lies in the infrared wavelengths above 700nm—energy we feel as heat. The remainder of the spectrum is short wavelength ultraviolet, below 450nm. The absorption and transmission coefficients for glass are a function of the wavelength of light: blue indicates ultraviolet, yellow visible light, and red indicates infrared or heat energy. This represents the spectrum of solar radiation (sunlight) that may penetrate a car windshield or windows. However, the “transparent” glass is actually transparent only to what we consider “visible” light.
This leads to the seeming paradox where the equilibrium situation reached by the inside of the car is not represented by the external temperature; but why?
Because most of the solar radiation enters as heat. Since glass robustly absorbs heat, this leads to the glass re-radiating heat energy in all directions; some of it enters the car, the rest returns to the environment. The shorter wavelength visible solar radiation is readily transmitted through the glass; this is absorbed by the materials in the car. While some of this energy is reflected as visible light (the colors that we see), most is re-radiated as heat (infared) energy.This energy is a different (longer) wavelength that the glass will not pass. Some of this energy reaches the glass and is again largely absorbed rather than transmitted. The glass then re-radiates the heat energy in all directions, some re-entering the car and some leaving the car: but there is more heat energy trapped in the car than would be without the physical and chemical tendency of glass to absorb and trap heat energy: the essence of the “greenhouse effect.”
This is why we cannot expect the inside of the car to come into thermal equilibrium with the outside air temperature, even on what we may describe as a “cool” day.
N.B.: This essay is written for informational purposes. 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.
“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)
You can brighten the long, lonely day of a needy dog:consider volunteering at a shelter. Your used but servicable linens, towels, bathmats, or cushions can provide comfort while he waits. Need help affording veterinary care? click HERE • Find low-cost spay neuter services: click HERE
Food & Safety Recalls/FDA Advisories for Dog Foods: click HERE
To think about: American taxpayers spend more than $1 billion annually to fund municipal animal shelters.
In those facilities, 14,000 animals are killed each day, often brutally: even in archaic gas chambers...
many within merely hours of their arrival: why are they called shelters?