Summer brings better weather, more activities with our pets and, with it, more danger of their becoming dehydrated. We would not plan a family hike or picnic without packing along water and possibly a sports drink or juice. It is equally important to take your dogs' replacement requirements into consideration.

Any type of stress, including "good stress" like family fun leads to increased fluid loss through panting. When the ambient temperature rises, bodily fluid loss increases as well. We don't see the loss as graphically as in species that sweat, but anyone who has mopped up after a panting, drooling, overexcited dog has some idea how fast and copious the loss can be.

Heat, exercise or anxiety can cause the dog to increase their respiratory rate. This allows evaporation from the tongue and respiratory tract to increase. During exercise water loss can increase ten to twenty times over the resting rate. Even mild dehydration has been shown to produce circulatory instability, reduced physical work capacity, threat of kidney compromise and contribute to the possibility of heat stroke.
For any dog, adequate water intake is the most important dietary consideration. The definition of adequate varies from dog to dog and with environmental factors. Heat exhaustion can occur in working dogs when water and electrolytes become depleted. The dog may exhibit fatigue, weakness, tremors and mild temperature elevation. At the first sign of distress the dog's temperature should be checked as the metabolic cascade happens very quickly resulting in thermal damage to tissues. With increased thermoregulatory strain the duration over which maximum work can be maintained is significantly reduced.

We should also keep in mind the "special needs" dogs that require extra attention. The geriatric dog with kidneys that have been performing adequately will probably not be able to tolerate even brief dehydration without losing precious kidney tissue. Dogs on medications that are metabolized through the kidney must have constant good urine flow to insure safe handling of the drugs. Pregnant and nursing bitches have greatly increased fluid needs. Especially in the first few weeks of lactation, drinking extra fluids is one of the surest and safest ways to encourage adequate milk production. Dogs who are recovering from surgery or illness often neglect to drink adequately and need to maintain normal fluid balance to speed their recovery.
Measures can be taken in advance to ward off dehydration. It is preferable to encourage hydration or even mildly over-hydrate your dog prior to a stressful event rather than deal with the consequences later. When under-hydration is allowed to develop, the sensation of thirst may be reduced, thus making the animal reluctant to drink at a time when it may be critical.

If exercise continues, the animal's condition will deteriorate. Travel, showing, performing or even boarding can result in increased fluid and electrolyte needs. When traveling, dogs often reduce water consumption because they are not accustomed to the flavor of water in a new environment. When excited in competitive situations, they are often too distracted to drink in the amounts that their body requires. Unfortunately, we cannot explain to them the importance of hydrating prior to an event. Hot weather means more consideration for the dogs' needs, attention to their condition (and conditioning) and plans to maintain hydration needs.

Robin Truelove Stronk D.V.M. is a 1975 graduate of the veterinary college at Cornell University. After 5 years in mixed practice and teaching veterinary technicians at Quinnipiac University she purchased Windham Veterinary Clinic in Brattleboro, VT with her husband, John. She has written a health column for Spaniels in the Field magazine for 10 years and has had many articles published in similar publications in this country and England. She is a member of the American Canine Sports Medicine Association and works closely with agility, field trial, hunting, tracking and assistance dogs.