Dehydration occurs when the total body water is less than normal. Usually it involves loss of both water and electrolytes, which are minerals such as sodium, chloride and potassium. Dehydration is caused by either a lack of food or water intake or an increase in water loss through illness or injury. A fever further increases the loss of water.
When there is not enough body water, fluid shifts out of the body cells to compensate, leaving the cells deficient in necessary water. This leads to dehydration. The severity of the dehydration is based on the magnitude of these body water shifts. Dogs lose fluid through: breathing, panting, elimination, diarrhea, vomiting, fever and evaporation through the feet and other body surfaces. Dogs replenish fluid by drinking water or other liquids and by eating moist foods.
A good general guideline is that a healthy dog should drink between ½ and 1 ounce of water per pound of body weight each day.
One way to assess hydration in an animal is to lift the skin over the animal’s shoulder and watch how fast it goes back to its normal position. In a normal, healthy animal, if the skin between the shoulders is lifted up and then released, the skin will pop back to its normal position immediately.
In dehydrated animals, there is less fluid in the skin and it is less elastic. When lifted off the back, the skin of a dehydrated animal will not immediately fall back to its normal position. If a pet has lost 6-8% of its normal fluid, there will be a definite delay in the skin returning to its normal position. If the pet is 10-12% dehydrated, the skin will actually look like a tent and not go back to its normal position. Signs of shock may be evident. If a pet is over 12% dehydrated, it is an extreme emergency.
Other ways to assess dehydration are to examine the mucous membranes (gums); they should be moist. In a dehydrated animal, the eyes may appear sunken in. In very dehydrated animals the heart rate may be increased, but the pulse would be weak.
Maintaining a constant fluid level is as important in dogs as it is in humans.
Blood tests such as a complete blood count and biochemistry profile are important to try to find the underlying cause of the dehydration but may not reveal if dehydration is present.
The most important tests are a packed cell volume and total blood protein test. These tests are done on a blood sample and can help reveal if dehydration is present. If the packed cell volume and total protein are elevated, dehydration is present.
Determining the concentration of the urine can also help determine if the pet is dehydrated and if the kidneys are affected.
The treatment for dehydration is to supplement the body with fluids. It is often not possible for an ill pet to ingest sufficient water to correct dehydration. Fluids are typically administered as an injection. The most efficient method of rehydration is through intravenous fluids. This requires hospitalization as well as an intravenous catheter.
Fluid replacement is done slowly to allow the body to compensate and slowly replenish tissues starved of fluid.
This document is reprinted from the Humane Society of Harrisburg area and is being provided for informational purposes only and is not intended as veterinary counsel. If you think your dog is dehydrated, seek veterinary counsel immediately.