If your pet should become dehydrated it will make any medical problem worse. This is especially true if the dehydration occurs rapidly and thus does not give the body enough time to shift fluids from other compartments to compensate. The very young and the old don’t have a large fluid reserve to draw from and are therefore are more greatly affected.
As is the case with humans, our pets are mostly made up of water. Body fluids are lost primarily through the urinary system and the digestive system and secondarily through the respiratory system by evaporation. When a disease or metabolic condition is present sometimes the thirst mechanism is not able to keep up with the loss of body fluids. The blood vessel compartment is usually affected first, followed by the intercellular (between the cells) compartment and lastly by the intracellular (inside the cell wall) compartments.
Clinically, the earliest state of dehydration that can be readily detected is when the body has lost 8% of its normal fluid state. This is usually determined by pulling the skin over the shoulder area away from the body and letting it drop. If the skin snaps back quickly then the state of hydration is probably normal. If it takes a little longer to return to the body then your pet is probably dehydrated. Another, less reliable, state of hydration test is to stick your finger into the pet’s mouth and feel for saliva. A dehydrated pet will often have a dry mouth. The most reliable way to determine the state of hydration is to take a sample of your pet’s blood and measure the hematocrit, total protein and sodium levels.
Once dehydration has been confirmed your veterinarian can give you several options to correct this problem. The most common means to reestablish normal hydration is to give a balanced electrolyte solution intravenously (in the vein) or subcutaneously (under the skin). Identifying the underlying cause of dehydration is important in order to make the best selection of fluids and get the best response.
Although it is more expense to deliver the fluids by the intravenous route because it requires a cathater be placed in the vein, it is the quickest way to correct any degree of dehydration. Many medications can be added to the bag of fluids to speed recovery. In most case the volume and rate of administration of the fluids is control by an infusion pump that delivers a measured amount over a specific amount of time.
I am often amazed at what a difference it makes to the recovery process when the state of dehydration is corrected. Once the body has the proper balance of fluids the time needed to heal seems to be less. Your veterinarian can guide you by making recommendations for home management of pets that may be prone to periods of dehydration.