Dehydration in Dogs

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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. During illness, dehydration may be caused by an inadequate fluid intake. Fever 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.

Dehydration is caused by either a lack of food or water intake or an increase in water loss through illness or injury.

What to Watch For

Signs of dehydration include:

  • Loss of skin elasticity
  • Lethargy
  • Depression
  • Sunken eyes
  • Dry gums
  • Increased heart rate
  • Slow capillary refill time

    Diagnosis

    Physical examination findings can help determine if dehydration is present. A common but inaccurate way to diagnose dehydration is based on skin elasticity. When the skin along the back is gently lifted, it should immediately return to the normal position. In a dehydrated animal, the skin does not return to normal quickly. The speed of return to normal position can help determine the severity of the dehydration.

    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.

    Treatment

    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.

    Home Care and Prevention

    There is no home care for dehydration. If you suspect that your pet is dehydrated, prompt veterinary care is recommended.

    Some animals can be treated with subcutaneous fluids at home, after an initial diagnosis and treatment. Ask your veterinarian if this is an option and have him/her show you how to administer injectable fluids at home.

    Make sure your dog eats and drinks normally. The best way to prevent dehydration is to have your pet examined and treated early if an illness occurs. For sick pets, preventing dehydration may be difficult but if promptly treated, can result in recovery.

  • Dehydration can be caused by numerous illnesses or abnormalities and can be divided into two main categories: reduced fluid intake or increased fluid losses.

    Reduced Fluid Intake

    The body relies on a steady intake of fluid to maintain hydration. When the ingestion does not meet the body demands, dehydration occurs. If your pet is not eating or drinking adequately because of disease or illness, dehydration is likely to occur. Reduced fluid intake can also occur if there is either accidental or deliberate deprivation of food or water. If you leave your pet unattended for several days and he spills his water bowl, he may be without water for several days.

    Increased Fluid Losses

    In some diseases or illnesses, your pet may be able to consume enough fluid to meet body demands. The most common cause of this is vomiting and diarrhea or kidney disease. With vomiting and diarrhea, excess fluids are lost. In kidney disease, the kidneys are unable to conserve fluids and they excrete excess fluid in the urine. Other causes of increased fluid losses include excessive panting, fever, large wounds or burns that ooze fluid or severe prolonged drooling.

    How To Detect Dehydration

    There is no single test that can accurately determine the presence or severity of dehydration. The diagnosis is generally based on history, physical examination findings and laboratory tests.

    The recent history is very important and can determine if dehydration is possible and may help determine the underlying cause. Be prepared to answer questions about:

  • Your pet's eating and drinking habits
  • The presence of vomiting or diarrhea
  • Whether your pet is urinating more frequently
  • The presence of excessive drooling
  • How long the signs have been present

    The severity of dehydration is listed as a percentage. This percentage indicates the amount of fluid the body is lacking. The maximum amount of dehydration that can be present in a live animal is 15 percent. Any dehydration beyond that is incompatible with life.

    Care must be taken on interpreting these results in obese or very thin patients. In obese pets, underestimating the severity of dehydration can occur easily because the skin returns to normal due to excessive skin fat. In emaciated or extremely thin pets, the skin is not as elastic as a normal pet so the degree of dehydration can be overestimated.

    If the pet is less than 5 percent dehydrated, the skin will immediately return to normal. This mild dehydration is rarely detected on physical examination. Pets that are 5 percent dehydrated have a subtle loss of skin elasticity. The skin will return to normal but does so a little slower than a normal pet.

    Pets with 6 to 9 percent dehydration have a noticeable delay in the skin returning to normal. The eyes may also appear sunken and the gums dry.

    Pets with 10 to 12 percent dehydration have skin that does not return to normal position. It will stay in the tented position until it is physically returned to the normal position. The eyes are significantly sunken, the heart rate is elevated and the pulses are weak.

    Pets with 12 to 15 percent dehydration are in a life threatening situation. The pet is typically collapsed, severely depressed and in shock. Death is imminent if aggressive and immediate treatment is not provided.

    In addition to physical exam findings, lab tests are needed to determine the presence and severity of dehydration.

  • A packed cell volume (PCV) and total protein test are the most important tests. The packed cell volume is the percentage of red blood cells currently in circulation. Normal PCV ranges from 35 to 50 percent. In dehydration, the fluid in the blood is inadequate and the blood becomes more concentrated. This results in an increase in the PCV.

  • The total protein is the amount of large protein molecules in the blood. As with red blood cells, in dehydration, the concentration of the protein increases due to a lack of fluid. In a dehydrated animal, both the PCV and total protein are elevated.

  • A urinalysis can also help reveal dehydration and may even help determine an underlying cause. In dehydration, the concentration of the urine is higher than normal. If a known dehydrated animal has dilute urine, kidney disease is the suspected underlying cause of the dehydration.

  • Complete blood counts and biochemistry profiles can help determine the overall health of the animal as well as determine possible underlying causes for dehydration. Unfortunately, these blood tests do not always diagnose dehydration and can be normal even in a severely dehydrated animal.

    Treatment

    The treatment for dehydration is to rehydrate with fluids. Since the animal is unable to meet the fluid demands by consuming sufficient food or water, injectable fluids are used. The fluids may be given subcutaneously or intravenously. Intravenous (IV) fluids are preferred since the rehydration is hastened and can be more appropriately monitored.

    Once your pet is diagnosed with dehydration, the amount of fluid needed must be determined. The volume of fluid that needs to be replaced is based on the percentage of dehydration and the animal's body weight. A rough calculation can be made based on one of the following formulas:

  • The number of liters of fluid required is equal to percentage of dehydration multiplied body weight in kilograms.

  • The number of milliliters of fluid required is equal to 500 multiplied by the percentage of dehydration multiplied by the body weight in pounds.

    In addition to rehydrating, fluids are also needed to maintain hydration and meet ongoing fluid needs if the underlying cause of the dehydration has either not been found or has not been treated.

    There are multiple different types of injectable fluids. The type of fluid used in based on the concentrations of sodium, chloride and potassium as well as any other patient needs.

  • After rehydration, the underlying cause of the dehydration must be addressed. Additional testing as well as examinations may be required to find the underlying cause.

    Make sure your pet eats and drinks normally. If dehydration is suspected, prompt veterinary assistance is essential to prevent further dehydration.

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