Dehydration in Cats: Symptoms and Treatments

Close-up of a lazy cat
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It is no secret that cats need water. Although their ancestors came from the desert, cats need fluids to survive. Water keeps body tissues healthy and is vital for the kidneys to do their job of flushing toxins out of the system. According to WebMD, water constitutes 80 percent of cats' bodies. Cats who eat raw or canned food get extra moisture from their meals. However, dry cat food only contains an average of 10 percent water. All cats, no matter their diet, need a continual source of fresh water to replace fluids lost through urination, defecation, and respiration. Water not only provides fluids, but also electrolytes, such as sodium, potassium, and chloride, all of which are necessary for proper body function.

Symptoms of Dehydration in Cats

How do you know your cat is dehydrated? Your first indication may be when your veterinarian tells you so. However, a fairly easy test at home can tell you immediately that your cat is suffering from the loss of fluids: the scruff area between the shoulders of cats is normally smooth and flexible. Therefore if you grasp it with your fingers and gently life up, the scruff will almost immediately fall back into place. However, if a cat is dehydrated when you lift the scruff of skin, it will form a tent, and when you release it, it will either slowly return or remain upright in its tent shape. Other symptoms of dehydration, depending on the stage of fluid loss, include sunken eyes, dry gums, drooling, or panting.

Risk Factors

Dehydration can be caused by either fluid loss, inadequate processing of fluids due to disease or too little fluid intake. Here are several things that can be associated with dehydration in cats, though this is not an extensive list. They include:

  • Heatstroke: Loss of Fluids During Hot Weather: A cat's temperature can climb quickly when outside, or worse, left in a vehicle on a hot summer day, especially if they concurrently lack extra fluids. Keep a rectal thermometer handy, and learn how to use it. A temperature of 103°F or higher should be considered a veterinary emergency.
  • Renal or kidney failure: Whether sudden or chronic, can quickly fill the bloodstream with those toxins the kidneys normally handle. Replacing the lost fluid and electrolytes plays a vital role in treatment. Fluid replacement may be recommended by your veterinary clinic staff with IV (intravenous) fluids or subcutaneous fluids depending on the severity of the disease. In some situations, your vet may recommend teaching you how to give sub-q fluids at home. Although it may sound frightening at first, done properly, giving Sub-Q fluids isn't all that bad, and your cat will feel so much better afterward that it's well worth learning how. 
  • Feline Hyperthyroid Disease: Symptoms of Hyperthyroidism in cats include frequent vomiting, diarrhea, and polydipsia (increased) thirst, clues that Hyperthyroid cats may be dehydrated.
  • Feline Diabetes: As with Hyperthyroidism, symptoms of Feline Diabetes include frequent urination, excess thirst, which could also be a sign of dehydration. One of the most serious side effects of untreated feline diabetes is Diabetic Ketoacidosis, which can be life-threatening. An important part of the treatment for that condition is hospitalization for intravenous fluid therapy. Diabetic Nephropathy (Renal or Kidney Failure) is also a serious potential side effect when high levels of glucose damage the filtering function of the kidneys. As with Diabetic Ketoacidosis, the treatment includes veterinary IV fluid replacements.
  • Liver Disease or Hepatic Lipidosis: Hepatic Lipidosis, commonly known as "Fatty Liver Disease," is a life-threatening disease, however, it can be reversed in many cases if treated in time. Simply put, the liver starts shutting down if a cat stops eating. Treatment consists of feeding through a tube in a veterinary hospital, along with IV fluids to keep the kidneys working. Once stabilized, your veterinarian might suggest syringe feeding a watery mix of food, along with Sub-Q fluids. Other liver diseases can cause dehydration as well.
  • Lack of Drinking: Cats may not drink for a lot of reasons. Clean, fresh water needs to be accessible to cats at all times and is necessary for their survival. Illness may cause cats not to drink. If you are concerned your cat is not drinking or you know your cat went a period of time without access to water, call your vet right away.

The information found herein underscores the critical need to know your cat's normal condition so that any deviation from the normal is a strong indication that it is time to call your veterinarian. You are your cat's lifeline to good health, and he is depending on you to help keep him healthy and well-hydrated. You'll both be much happier if you respect that trust.

Disclaimer: The author is not a veterinarian. This article is not intended to be a definitive answer to any questions you might have about dehydration in cats, but is meant to give you a starting place to do your own research so you can make an informed decision, should it ever become necessary. Above all, your own veterinarian should always be your primary source of information and advice about your cats.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.