Dehydration can quickly become a serious health concern for cats, particularly if it goes unnoticed or is caused by an underlying illness. Because cats naturally have a low thirst drive, it can sometimes be difficult to tell whether they are drinking enough water.

Knowing the signs of dehydration and understanding how to respond can help you protect your cat's health and prevent more serious complications. In this guide, we'll explain how to recognise the symptoms of dehydration, what causes it, and what you can do to help keep your cat properly hydrated.

What is Dehydration in Cats?

When cats don't drink as much water as they lose, it's known as cat dehydration. Sometimes it's just because they don't feel well and aren't drinking much, but other times it could be due to a sickness like diarrhoea or vomiting. 

Cats typically experience changes in multiple electrolytes, including potassium, calcium, and sodium, when they get dehydrated. Maintaining a healthy electrolyte balance and adequate hydration are critical to the correct operation of a cat's organs and tissues. 

What Causes Dehydration in Cats?

A dehydrated cat might have a variety of causes, but the fundamental one is that your pet is losing fluids faster than they are gaining them. 

Every cat loses fluids continuously throughout the day, and anything that throws this equilibrium off is likely to cause dehydration. Typical reasons for dehydration in cats include:

• Not eating or drinking as much: Anything that prevents your cat from eating and drinking adequately is one of the more frequent causes of dehydration. Dehydration occurs quickly if your cat is utilising fluids but not ingesting them. 
• Diarrhoea and vomiting: Your cat may not be feeling well enough to drink or eat to replenish the fluids they are rapidly losing. 
• Diabetes: These two extremely prevalent conditions in cats lead to increased water loss, which can quickly lead to dehydration. 
• Hot weather or dry air: Over time, dehydration can result from both hot weather and dry air. 

Are Certain Cats Prone to Dehydration?

Dehydration is generally more common in elderly cats and cats with a history of other illnesses. For example, discussing healthy and optimal hydration levels with your veterinarian can be beneficial if your cat has cancer, diabetes, hyperthyroidism, or kidney disease.

How Do You Rehydrate a Cat?

Giving cats wet food or low-sodium chicken broth will help them replenish lost electrolytes and stay hydrated. However, you should consult a vet if your cat is ill or losing fluids due to vomiting or diarrhoea.

How is Dehydration in Cats Treated?

During a thorough examination, your vet will search for any indications of general illness as well as any underlying issues that might have caused your cat's dehydration. Generally speaking, to ascertain the degree of dehydration and its underlying cause, your veterinarian might also choose to do certain laboratory tests. A cat that is dehydrated will also require different treatments. 

Fluids administered subcutaneously are frequently used to treat a variety of diseases, including mild dehydration. In order to administer fluids directly into the bloodstream, sick cats who are more delicate or dehydrated may need to be admitted to the hospital and have an IV catheter inserted. 

How Can You Tell if Your Cat is Dehydrated?

Cats can be prone to dehydration, especially if they do not drink enough water or lose fluids due to illness, hot weather, or certain health conditions.

Common signs that your cat may be dehydrated include changes in behaviour, reduced energy levels, and physical symptoms that indicate a lack of fluids. Understanding these signs can help you take action quickly and support your cat's health.

Your Cat’s Skin Does Not Snap Back Quickly

One simple way to check for dehydration is the skin tent test. Gently lift the skin between your cat’s shoulder blades and then release it. In a well-hydrated cat, the skin should quickly return to its normal position. If the skin stays raised or returns slowly, it may indicate dehydration.

However, this test is not always accurate for every cat, especially older cats or cats with certain health conditions, as their skin may naturally lose elasticity. If you notice other signs of dehydration alongside slow skin movement, it is best to contact your vet.

Your Cat Has Dry or Sticky Gums

A healthy cat’s gums should feel moist and appear pink. If your cat is dehydrated, their gums may feel dry, sticky, or less slippery than usual. Checking your cat’s gums can provide another indication that they may not be getting enough fluids.

If your cat’s gums appear pale, unusually dry, or you notice changes in their mouth, this could be a sign of an underlying health issue that requires professional advice.

Your Cat is More Tired Than Usual

Dehydration can affect your cat’s energy levels and overall behaviour. A dehydrated cat may become less active, sleep more than usual, avoid playing, or appear weak. Sudden changes in your cat’s normal behaviour should always be monitored carefully.

If your cat seems unusually tired and is also showing other symptoms such as reduced appetite or decreased drinking, dehydration may be contributing to the problem.

Your Cat Has Reduced Appetite

Water plays an important role in digestion and overall health, so dehydration can sometimes lead to a reduced appetite. If your cat is eating less than usual, it may be a sign that something is wrong, particularly if the change happens suddenly.

A loss of appetite combined with dehydration symptoms should be taken seriously, as cats can develop additional health complications when they do not eat for extended periods.

Your Cat’s Eyes Appear Sunken

In some cases of dehydration, a cat’s eyes may appear slightly sunken or less bright than usual. This can happen when the body does not have enough fluids to maintain normal hydration levels.

Sunken eyes are usually a more concerning sign and may indicate more significant dehydration. If you notice this symptom, especially alongside weakness or other changes, speak with a veterinarian.

What Should You Do if Your Cat is Dehydrated?

Seek immediate assistance from your veterinarian if you think your cat may be dehydrated. To rehydrate your cat in the meantime, consider these home remedies:

• To their water, add a tiny bit of tuna juice or chicken broth.
• Try feeding them wet food instead of dry food.
• Put a few ice cubes in their dish of water.

How Long Can a Cat Go Without Water?

Before a surgical procedure, a brief fast is acceptable (i.e., getting food and drink the night before the procedure is scheduled). If not, fresh, clean water should always be available to cats. 

How Do I Know if My Cat is Drinking Enough Water?

Knowing whether your cat is drinking enough water can be difficult because cats naturally drink smaller amounts compared to many other pets. Monitoring your cat’s habits and looking for changes in their normal routine is one of the best ways to identify whether they are getting enough fluids.

The table below highlights common signs that may indicate your cat is drinking enough water or may need encouragement to drink more.