Dehydration

Dehydration refers to a state in which your dog’s body loses more water than it takes in, an imbalance that can become life-threatening within hours.

The term is often underestimated because the first signs are subtle. A dog may have already lost 5-8% of its body water before you notice obvious symptoms. From 10% water loss, circulatory collapse and organ failure threaten.

What causes dehydration in dogs?

Persistent diarrhoea tops the statistics. A 20-kilo dog can lose 1-2 litres of fluid daily with severe diarrhoea, which corresponds to 5-10% of its body weight.

Vomiting dramatically increases the loss. Each act of vomiting costs about 50-100ml of fluid plus stomach acid. With repeated vomiting, this quickly adds up to critical amounts.

Fever drives up water requirements by 10-15% per degree of temperature increase. A dog with a fever of 40°C (instead of 38°C) already needs a third more water than normal.

Kidney disease creates a vicious circle: The diseased kidneys can no longer concentrate water, the dog constantly loses diluted amounts of urine and cannot keep up with drinking.

How do I recognise dehydration in my dog?

The skin test gives you a reliable answer within 2 seconds. Gently lift the skin between the shoulder blades and let go.

Normal: The skin snaps back immediately, under 1 second.

Mild dehydration: 2-3 seconds return time.

Moderate dehydration: 4-6 seconds.

Severe dehydration: Over 6 seconds or the skin stays in place.

The mucous membranes reveal additional details. Press on the gums with your finger; they should be pink and turn pink again within 1-2 seconds after releasing. If they remain white for longer, circulation is already impaired.

Concentrated urine shows an intense orange-yellow colour, almost like strong black tea. Normal dog urine is pale yellow to straw-coloured.

When does dehydration become dangerous?

From 6-8% water loss, measurable circulatory problems develop. The pulse becomes weaker but faster; over 120 beats per minute in a resting dog is a warning sign.

At 10-12% loss, the critical phase begins: The eyes sink in, the nose becomes dry and cracked, and the dog only responds sluggishly to being spoken to.

Beyond 15% water loss, unconsciousness threatens. Without immediate intensive medical treatment, the dog dies.

What can I do as an owner?

In cases of mild dehydration (skin test 2-3 seconds), small, frequent drinking helps. Offer 50-100ml of water every 15 minutes, not the entire daily amount at once.

You can dilute electrolyte solutions from the pharmacy (for infants) 1:1 with water. Most dogs accept the mild taste.

Never force drinking. A dog that refuses water often has a good reason, such as nausea or stomach pain.

When do I need to go to the vet immediately?

A skin test over 4 seconds means: Now, not later.

Additional emergency signals: Apathy despite being spoken to, unsteady gait, dry nose with simultaneously cold paws, or if the dog has not urinated for over 6 hours.

The vet can replace critical amounts of fluid via infusion within 1-2 hours, an advantage you could never make up at home.

How do I prevent dehydration?

A 20-kilo dog needs 500-700ml of water daily at normal temperature and activity levels. At an outside temperature of 30°C, the requirement rises to 800-1000ml.

Water bowls should be cleaned daily. Stale water often smells unappetising to dog noses, even if we do not notice it.

Take drinking breaks every 2 hours when travelling, especially in the car, where the air dries out quickly.

Older dogs or those with kidney problems need constant access to water. A second bowl in another room can be life-saving if the first one tips over.