Effects of Heat Exhaustion in Dogs

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By Katy Fogt, DVM 

Summertime means vacation, sunshine, and beach trips, but it also means high temperatures. When the temperature begins to climb, heat exhaustion (or more commonly known as heat stroke) can be seen in dogs and humans alike and is a medical emergency. However, unlike humans, dogs lack the ability to sweat when they overheat. Our furry friends rely on other methods to cool down, such as: conduction via laying on a cool surface, convection (air blowing over their skin), and evaporation by panting. Heat stroke in dogs occurs when they can no longer get rid of that heat efficiently and their body becomes overwhelmed.

Normal body temperature in dogs ranges from 99.5-102.5°F; however, in dogs with moderate heat stroke, temperatures get as high as 104-106°F. Severe heat stroke is classified by temperatures over 106°F. High core temperatures experienced by dogs with heat stroke cause multiple organs to fail and ultimately death, if not treated. The side effects of heat stroke vary greatly -- depending on how overheated the dog became, as well as, how long the dog has been overheated.

Risk factors

All animals can suffer from heat stroke; however, some cats and dogs are more at risk.   These risk factors include dogs and cats who are:

  • Very young or very old
  • Obese
  • Brachycephalic

These dogs include Bulldogs, Boxers, Pekingese, Shih Tzu, and other smashed nose breeds. Cat breeds include Persian, Himalayan, British Shorthair, and Scottish Fold.

  • Have existing medical conditions

Such as collapsing trachea, laryngeal paralysis, Myasthenia Gravis, and Addison’s

  • History of a previous heat illness
  • Thick or dark hair coats

Signs and Symptoms:

In most cases, animals will have some combination of:

  • Rapid panting and heart rate
  • Bright red gums and tongue
  • Poor pulses
  • Vomiting and diarrhea
  • Weakness and depression
  • Dehydration
  • Hypovolemic shock

Hypovolemic shock occurs when there is a decrease in the dog’s total blood volume due to blood loss internally or externally. Signs of hypovolemic shock are pale gums, weakened but faster heart rate or pulse, and cold feet and ears.

  • Disseminated intravascular coagulation (DIC).

DIC is a disease that affects the ability of blood to clot. Initially small clots form throughout the body, which uses up all the clotting factors; resulting in the uncontrollable bleeding of the dog. Signs of DIC include nosebleeds, bruising, small red dots on the skin (hemorrhages).

  • Acute renal failure (ARF)

Acute renal failure is a sudden failure of the kidneys to remove toxins from the body. Signs of ARF include increased thirst and urination, lethargy, decreased appetite, and vomiting.

Long-term effects could include:

  • Permanent damage to the kidneys, heart, and liver
  • Residual neurological deficits

What should you do if you suspect a problem?

If you suspect your dog is suffering from heat stroke,

  1. Immediately remove him/her from the hot area
  2. Take your dogs temperature rectally with a thermometer
  3. Place your pet under a fan (you can also cover your dog with cool wet towels; however, giving your dog a bath in cool water is not recommended as it can prevent heat loss)
  4. If his/her temperature is 103°F or higher, your pet should see his/her veterinarian as soon as possible to evaluate for dehydration and other complications. DO NOT put your pet in a plastic crate in your car to get him or her to the vet. Airflow is critical at this point. Your veterinarian will lower your pet’s temperature, give intravenous fluids if dehydrated, and monitor for shock, kidney failure, clotting disorders, and other complications. In order to properly monitor the complications of heat stroke, your veterinarian may take a blood sample and urine sample.

Long-term Care

Some dogs may not have any long-term illness; however, dogs with severe heat stroke may require a special diet or medications because of permanent organ damage. Additionally, dogs that get heat stroke once are more likely to get heat stroke again; therefore, prevention is very important for pet parents.

Prevention

Because of the significant side effects associated with heat stroke in dogs and the poor prognosis, the best thing we can do as pet parents is prevent heat stroke from ever occurring in the first place.

There are many things you can do at home to prevent heath stroke including:

  • Keep your animal indoors if possible
  • Your pet should never be left in your car for any length of time
  • Provide cooling contraptions such as a wet towel for him or her to lie on.
  • Take walks in the morning or late evening
  • Provide cool treats (such as ice cubes)
  • Take your pet to swim in a pool or pond during the hot days
  • Provide your dogs with access to water at all times
  • Offer shaded areas when dogs are outside
  • Avoid areas where heat is reflected, such as asphalt or cemented areas

 

 

References:

1) Bosak, J.K. (2004). Heat Stroke in a Great Pyrenees dog. Can Vet J. (45). 513-515.

2) Flournoy, W.S.; Macintire, D.K.; Wohl, J.S. (2003). Heat stroke in Dogs: Clinical Signs, Treatment, Prognosis, and Prevention. Compendium, (25, 6). 422-431.

3) Brashear, M. (n.d.) Heat stroke in dogs. DoveLewis Emergency Animal Hospital, Portland, OR.

4) Bruchim, Y.; Klement, E.; Saragusty, J.; Finkeilstein, E.; Kass, P.; Aroch, I. (2006). Heat Stroke in Dogs: A Retrospective Study of 54 Cases (1999-2004) and Analysis of Risk Factors for Death. J Vet Intern Med, (20). 38-46.

5) Bruchin, Y.; Loeb, E.; Saragusty, J.; Aroch, I. (2009). Pathological Findings in Dogs with Fatal Heat stroke. J Comp Path, (140). 97-104.

 

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