Cat Dehydration – Causes, Symptoms & Treatment

Causes   How to check for signs of dehydration   Symptoms   Diagnosis   Treatment   Prevention   Getting more fluids into your cat


At a glance:

About: Dehydration is a serious condition which is the result of a reduction in water in the cat’s body.

Causes: There are many causes including vomiting, diarrhea, increased urination, sickness, heatstroke and no access to drinking water.

Symptoms vary depending on the severity of dehydration but can include sunken eyes, dry gums, poor skin elasticity, lethargy, and constipation.

Treatment: Address the underlying cause as well as fluid replacement therapy.

dehydration in cats

Dehydration (hypohydration) is a serious and potentially life-threatening condition which is defined as excessive loss of water and electrolytes (minerals such as sodium, chloride, and potassium) from the body.

Most animals are made up of around 60% water. When the water ratio falls 5% below normal, cats will start to show signs of dehydration.

Kittens, senior cats and cats with underlying medical conditions are at increased risk from dehydration.


Dehydration can develop due to decreased water intake and/or increased output (urine, vomiting, diarrhea). Dehydration requires veterinary attention immediately. Failure to do so may result in death.

  • Sickness – Any sickness which results in a loss of appetite and thirst can lead to dehydration
  • Increased urination – Medical conditions such as diabetes and kidney disease in which the cat urinates more often, leading to excess fluid loss
  • Vomiting and/or diarrhea
  • Blood loss
  • Shock
  • Fever
  • Heatstroke
  • Lack of available, fresh drinking water


Dehydration has three classes:

  • Mild dehydration: up to 5%
    Moderate dehydration: 5 – 10%
    Severe dehydration: 10% or more

Signs of dehydration include:

  • Sunken eyes
  • Dry, tacky gums
  • Poor skin elasticity
  • Lethargy
  • Increased heart rate
  • Poor capillary refill time
  • Loss of appetite
  • Increased or decreased water intake
  • Constipation. Water is reabsorbed from the colon and if the cat is dehydrated, the body will try to conserve water by removing additional water from the stool

How to check for dehydration in cats:

Skin turgor test (skin tenting):

Grasp some skin at the scruff of the neck and gently pull it up to form a tent. The skin will spring back immediately (as you can see in the video) in a cat who is well hydrated. The skin will be slower to retract if the cat is dehydrated. The more severe the dehydration the slower the skin will take to retract. The skin will remain in the tent shape in a severely dehydrated cat. This requires immediate veterinary attention.

Capillary refill time:

This helps you to test your cat’s blood circulation and can indicate dehydration, heart failure or shock. To test capillary refill time life your cat’s upper lip and press the flat of your finger against the gum tissue. Remove the pressure and you will see a white mark on the gum where your finger was placed. Using a watch with a second hand, time how long it takes for the pink colour to return to the white spot.

  • 1-2 seconds is normal
  • 2-4 seconds is moderate to poor
  • > more than 4 seconds is an emergency
  • < less than 1 second is an emergency


Diagnosis of dehydration is relatively easy to diagnose based on symptoms and performing the skin turgor test. However, your veterinarian may wish to determine what has caused your cat to become dehydrated and perform the following tests:

  • Complete blood count, biochemical profile and urinalysis to check electrolyte levels and kidney function.
  • Additional tests such to further investigate kidney and liver function as well as checking for diabetes.


The goal is to treat the underlying cause as well as replace fluids. This may include:

  • Medications to treat vomiting and/or diarrhea.
  • Fluid replacement therapy either intravenous or subcutaneous.

In some cases, you may be asked to give your cat fluids subcutaneously at home. This is a relatively straightforward procedure. Your veterinarian will supply with needles and syringes as well as fluids. To give fluids, you lift up the loose skin at the back of the neck insert the needle under the skin and slowly administer the fluids.  It is useful to be able to administer fluids to a cat who has an underlying medical condition such as diabetes.


  • Ensure there is a constant supply of fresh, clean drinking water available at all times.
  • Provide your cat with a cool, sheltered area if it has access to the outdoors.
  • If your cat is sick, monitor it closely for signs of dehydration.
  • Seek veterinary attention if your cat has vomiting or diarrhea.
  • Seek immediate veterinary attention if your cat displays signs of increased thirst or urination.

How to get more fluids into your cat: 

Some cats can be fussy when it comes to water, if you need to get more fluids into him you can try the following:

Switch to wet food: Domestic cats are descendants of desert-dwelling animals who obtained most of their water via their food. Dry food only contains 10% water, compared to 70% of canned or raw. Many cats don’t make up the shortfall.

Encourage the cat to eat: If he is reluctant to eat, try feeding him strong smelling foods such as tuna. Warm it slightly in the microwave which can make it smell stronger.

Provide fresh drinking water: Make sure you change your cat’s water at least once a day and wash the cat’s bowl which can develop smells. If you have multiple cats, think about adding additional water bowls.

Buy a cat water fountain: Some cats prefer running water.

For more information on how to get cats to drink more water, read here.


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