What are the common causes of hypernatremia in dogs and cats?

Hypernatremia is commonly associated with inadequate water intake, dehydration, kidney dysfunction, or fluid loss; it may also result from the administration of hypertonic solutions or metabolic abnormalities. The specific cause should be determined by your vet.

What tests will the vet perform to confirm hypernatremia?

Routine tests include a blood draw to measure serum sodium and other electrolytes, along with a biochemistry panel and urinalysis. Imaging studies or repeat blood tests may be arranged when needed.

When should I bring my pet to the vet if hypernatremia is suspected?

Seek emergency care immediately if your pet has seizures, loss of consciousness, severe breathing difficulty, or is unable to stand. If abnormal drinking or changes in alertness persist, arrange a clinic visit as soon as possible.

How much do the tests and treatment usually cost?

Costs vary by clinic and region — ask your vet for an estimate before proceeding.

Disease Guide

Hypernatremia in Dogs & Cats: Symptoms, Electrolyte Testing & Care Guide [2025]

Hypernatremia can result from dehydration, kidney disease, or endocrine dysfunction, leading to neurological signs such as seizures. Sodium levels must be corrected slowly — too rapid correction risks cerebral oedema.

Take 1 minute to check the symptoms first

Last updated: 2026/01/05

Pethealthmap Editorial Team

Sources: AVMA, ACVIM, National Taiwan University Veterinary Hospital

When to See a Vet

Seek Emergency Care Immediately

•Continuous or repeated generalized seizures
•Sudden loss of consciousness or prolonged unresponsiveness
•Rapid breathing or inability to stand independently

Schedule a Clinic Visit Soon (within 24–72 hours)

•Markedly increased or decreased water intake that persists abnormally
•Persistent lethargy or reduced responsiveness
•Noticeably decreased appetite or short-term weight change

01What symptoms indicate a problem?

Hypernatremia in dogs and cats often presents as systemic or neurological signs — watch for changes in drinking behaviour, alertness, and mobility.

Noticeably increased or decreased water intake, or unusually frequent drinking
Repeatedly seeking water or the water bowl, with obvious behavioural change
Seizures or involuntary muscle twitching
Lethargy, dullness, or reduced response to external stimuli
Decreased appetite or refusal to eat
Noticeable weight change over a short period, including signs of dehydration or weight loss

Seek emergency care immediately if you notice the following symptoms:

⚠️ Seek emergency care immediately if seizures are continuous or generalised
⚠️ Sudden loss of consciousness or inability to rouse the pet requires emergency treatment
⚠️ Seek immediate veterinary care if the pet has obvious difficulty breathing or cannot stand unaided

02How to assess the situation at home — key observations and when to go to emergency

Observe and record key changes at home first — this information helps your vet quickly assess the progression of the condition.

Record daily water intake and the number of drinking episodes, measuring as accurately as possible
Monitor mental alertness, responsiveness, and any changes in consciousness
Weigh your pet at the same time each day and note any differences
Track urination frequency and volume (or bring a urine sample to the clinic)
Write down when symptoms first appeared and how they have developed
If seizures or unusual behaviour occur, record a video on your phone for the vet
Bring your pet's usual water bowl or other relevant items to help describe daily habits

03How will the vet make a diagnosis? Common diagnostic tests

The vet will use a physical examination along with laboratory and imaging tests to assess electrolyte imbalance and identify the underlying cause.

Full physical examination and neurological assessment, including reflexes and level of consciousness

Blood and biochemistry panels

focusing on serum sodium and other electrolytes

Urinalysis

assessing kidney function and urine-concentrating ability

CT or MRI when necessary to rule out central nervous system disease

Serial blood draws may be needed to monitor sodium levels and treatment response

04What treatment and care are needed after diagnosis? Medications, dietary adjustments, and care guide

Treatment focuses on correcting fluid and electrolyte imbalances, and must be carried out slowly under close veterinary supervision with regular monitoring.

In acute cases, intravenous fluids are used to correct electrolyte imbalances under close monitoring
Hospitalisation for monitoring of neurological signs and electrolyte levels
Medications or dietary management may be adjusted depending on the underlying cause
Regular blood tests to track serum sodium, kidney function, and other electrolytes
Schedule follow-up appointments after discharge and adjust home care according to veterinary instructions
If symptoms recur or worsen, referral to a specialist centre is recommended

05What should you prepare before the vet visit? Key information to help the vet identify the cause quickly

Note and bring a record of when symptoms started and how they have changed

List all current medications, supplements, and feeding habits

Bring a record of water intake and urination/defecation from the past few days (written or photographed)

If you have a urine sample, bring a small amount to the clinic for testing

If you have recorded a video of seizures or unusual behaviour, bring it to show the vet

Choose a clinic that can perform blood electrolyte testing

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.

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Unconsciousness

Confusion

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