Heat Stroke in a Boston Terrier
History. At 3 pm on a 95o F (35o C) day in August, you receive a frantic phone call from a client. The client went to a shopping mall and left her car parked in the lot.
She had her Boston terrier with her, but because she thought she would only be a few minutes, she left the dog in the car. While in the mall, she was delayed by an uncooperative clerk when her debit card was rejected. When she returned to the car, her dog was prostrate •with its tongue hanging out of its mouth and was unresponsive. You instruct the owner to bring the dog over to your practice immediately and to drive with the windows open for the half- mile trip.Clinical Examination. On arrival at the clinic, the dog is laid on the examining table, where it fails to respond to its name. Its mouth is open, its tongue is distended, and its mucous membranes are dry. Body temperature is 42.20 C (normal, 38.5o C).
From the history, the animals body temperature, and its lack of response, you diagnose heat stroke. The dog is placed in a bath of cool water, and fluids are administered intravenously. Within 5 to 10 minutes, the dog begins to look around and recognizes its owner. The water bath treatments are continued for 2 hours, at which time the body temperature is close to normal. The dog remains in the hospital overnight and is then discharged to the relieved owner the next day.
Comment. The temperature inside a car parked in the hot sun rises rapidly to above body temperature. At this time, the only mechanism available for losing heat is evaporation of water from the respiratory tract, which the dog attempts by panting and salivating. For a short time this is an effective means of losing heat, but water vapor is transferred to the air in the car and progressively saturates the atmosphere with water. As the percentage saturation of the air increases, the animal has more and more difficulty achieving evaporation and therefore heat loss.
Eventually the animal cannot lose heat, and the body temperature begins to rise. Once the body temperature exceeds 41.5o to 42.5o C, the animal loses consciousness. In addition, the panting results in dehydration and reduces the dog’s ability to deliver heat from the core of the body to the extremities. Brachycephalic dogs, such as Boston terriers, have an added disadvantage in temperature regulation: the short nose and convolutions in the wall of the pharynx increase the work of breathing, especially when the dogs pant. This increased work is an additional source of body heat, and the anatomy of the upper airway probably makes evaporative cooling less effective.Therapy for this condition is to reduce body temperature and to restore circulatory function as rapidly as possible. For this reason, the dog is placed in a cool water bath to reduce body temperature and also receives intravenous fluids to rehydrate it by expanding its circulatory volume and restoring the ability of the circulation to redistribute heat within the body.