Dogs and cats do not tolerate high environmental temperatures as well as humans.  Dogs depend on panting to cool blood vessels in their tongue and dissipate the heat in the blood coming from other parts of the body.  Cats depend on inactivity, licking their hair coat, and eventually panting.  When the air temperature is close to the normal body temperature (101.5o F) or humidity is high preventing evaporation, cooling by panting is not effective.  Impaired blood circulation or airway disorders compound the risk of being unable to cool the body. 

Causes
Being left in a car in warm and/or humid weather Being confined on concrete runs or tethered outside in warm weather without constant shade Having a short-nose, such as bulldog, pugs, or Persian cats Wearing a muzzle during warm weather Having an airway disease, any condition that impairs breathing, or heart disease

Signs
Heat stroke begins with rapid, frantic, noisy panting.  The tongue and mucous membranes become bright red.  The saliva thickens and becomes sticky.  Vomiting occurs next.  If the condition is not corrected quickly, the animal becomes unsteady and staggers, has diarrhea that is frequently bloody, and develops extreme weakness leading to complete collapse.  Coma and death soon follow.

Diagnosis
The cause of the problem is usually evident by the typical appearance of the animal, but it can be confirmed by getting a body temperature.  The body temperature will be high, sometimes in excess of 106o F.  (Normal is 101.5o F)

Treatment
If signs have begun and the body temperature is elevated, emergency measures must be begun on-site and at once.  A trip to a veterinarian’s office without any immediate assistance could result in the animal’s death.

Mild cases respond to cooler surroundings, such as an air-conditioned building or car.  When the signs are more severe or the body temperature is above 104o F, the animal should be cooled by immersion in a tub or play pool of cool water.  If this is not possible, it should be rinsed from a garden hose.  

After providing immediate assistance, the animal should be taken to a veterinarian for examination and possible continued care.  Shock and/or permanent damage to the heart, kidneys, or brain can result in survivors of severe heat stroke.  Treatment with intravenous fluids and cool water enema may be needed.

Prevention Measures
Do not expose pets to prolonged heat, especially if they have short-noses, heart disease, or respiratory problems Restrict exercise during the heat of the day in summer Never leave a muzzled dog alone Crate dogs in open wire cages if exposure to warm environmental temperature is likely Provide shade and cool water to animals kept outdoors in warm weather

For more information, contact your local veterinarian or the MU Veterinary Medical Teaching Hospital 573-882-7821 or visit <http://www.vmth.missouri.edu/>