Dehydration in Cats

cat drinking water from a pool

It's said that we cat owners should drink around 2 to 2.5 litres of water each day. We don't always manage this and sometimes suffer from headaches and a bad mood in the evenings. But how much fluids do our cats actually have to consume in order to not suffer from dehydration? And how do I recognise whether my cat has drunk enough or if it is dehydrated? We will give you all the important facts and tips on the subject of dehydration in cats.

How much should my cat drink?

You can calculate the amount of water your cat needs based on the following factors:

  • Weight (on average, cats drink 45ml of water per kilogram in body weight)
  • Water content in the food
  • Ambient temperature
  • Activity level of the cat

How do I recognise that my cat is dehydrated?

Many cats have outdoor access and drink water during their day-to-day strolls, sometimes from puddles, bathing pools, paddling pools or other water containers. In this case, they like to leave their drinking bowl untouched and only consume fluids at home should they be fed wet food. This is the reason why we often can't know how much water our cats actually consume.

So how can we, as cat owners, estimate our own cats' water balance? There is a simple trick for this that even works without prior veterinary knowledge.

Water is absorbed by all body cells, including the skin. If there is plenty of water in the body and the cells are bulging nicely, the skin tightens. If the cat is dehydrated and the cells are empty, the skin appears slack and lined.

You can make use of this fact by carefully pulling up one of your cat's neck folds and releasing it suddenly. If the skin is released quickly, you can rule out your cat being dehydrated. However, if it releases very slowly, this is sign of dehydration.

You can also make this same observation regarding the eyes of your beloved feline. The eyeballs fall back into the eye socket with dehydrated cats.

What is dehydration?

The term dehydration is understood by medical professionals as a reduction in the body's water content, i.e. a lack of water. Since this can be triggered by many different causes, it isn't a stand-alone disease but a symptom (sign of illness).

Water balance plays a central role for all living beings, because water gives body cells the required shape and also acts as a cooling agent on hot days. In addition though, it also contains important minerals like sodium.

As an electrolyte, sodium is a key component of common salt and is necessary for the transmission of nervous stimuli, cardiac and muscular activity. Normally sodium from the kidneys is retained in the body, whilst water is excreted in the form of urine. Disruption to kidney function can therefore lead to a disturbed water and electrolyte balance.

Depending on the development, dehydration can be associated with a change in the electrolyte balance, which is why water loss is divided into three forms:

Isotonic dehydration: The term 'iso' originates from Greek and means 'equal', whilst 'tonus' means 'pressure'. With this form of dehydration, the cat's water and sodium levels remain balanced.

Hypertonic dehydration: If there is merely a drop in the quantity of fluids, there is probably too much sodium in the body. A known cause of this form is diabetes insipidus, which involves increased water excretion via urine.

Hypotonic dehydration: Here the loss of sodium is greater than the loss of water. It can result in water retention in the tissue, such as cerebral oedema.

Note: Often using the terms dehydration and dehydrogenation as synonyms isn't entirely correct. In chemistry, dehydrogenation is understood as the removal of hydrogen and the corresponding chemical reaction

Causes of a lack of water

Most cats are dehydrated due to a lack of drinking water. The less they drink, the less fluid is present in their body. This can often be observed in hot summer months in particular.

There are further causes for cats suffering from dehydration, which include, for instance, the following symptoms or underlying diseases:

  • Vomiting and diarrhoea due to infectious diseases or intoxications
  • Severe kidney damage
  • Adrenal insufficiency (Addison's disease)
  • Burn injuries
  • Treatment with diuretic medication
  • Diabetes insipidus
cat drinking water from a bowl

What can happen if my cat is dehydrated?

A lack of water is often underestimated and not just on hot summer days, because cats can suffer from a disturbed water balance in cold temperatures too. Depending on the cause, severe symptoms can emerge. Seeing a vet is essential, especially with major water loss!

Dehydrated cats can suffer from the following severe consequences:

  • Diminished general condition to the point of unconsciousness
  • Reduced or no urination
  • Uraemia: symptoms of intoxication due to the lack of excretion of urinary substances (e.g. urea, uric acid or creatinine)
  • Low blood pressure (hypotension)

A particularly severe lack of water can incidentally lead to exsiccosis (bodily dehydration). This condition can be fatal for cats.

How can we treat dehydration in cats?

If your cat shows signs of severe dehydration, your vet can use a fluid therapy to gently provide your cat with water. The fluid (infusion) can be given under the skin or also intravenously.

The composition of the infusion depends on the type of dehydration:

  • Isotonic dehydration: isotonic infusion solution like Ringer's solution
  • Hypertonic dehydration: isotonic infusion solution plus 5% sugar solution
  • Hypotonic dehydration: isotonic infusion solution plus sodium

Preventing a lack of water in cats

Cats fed dry food tend to suffer from dehydration. Hence, it's advisable to offer cats wet food for an equal water and electrolyte balance. Some types of food are even adapted to increased fluid content. It's also advisable to clean the water bowl on a daily basis and to position several bowls or drinking fountains with fresh water throughout your home.

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