Milk Fever in Cats: Symptoms, Causes, and When to Call a Vet
By Dr. Zubair Khalid, DVM, MS, PhD ·
Can cats get milk fever? Yes. A nursing mother cat can develop a sudden, dangerous drop in blood calcium, and the first signs are often tremors, wobbling, and weakness. This condition is a medical emergency, so a cat with these signs needs a veterinarian right away.
This article is educational and is not a substitute for veterinary diagnosis or treatment.
Quick Answer
- Milk fever (eclampsia) is a sudden drop in blood calcium in a mother cat who is nursing, most often in the first weeks after birth.
- Early signs include restlessness, panting, a stiff or wobbly walk, muscle twitching, and a glazed look.
- Later signs include tremors, weakness, inability to stand, seizures, and a high body temperature.
- Call an emergency veterinarian immediately if you see tremors, collapse, or seizures. Do not wait for a regular appointment.
- Do not give your cat calcium supplements or human calcium products on your own. Treatment needs a veterinarian who can calculate the correct dose for your cat's weight and health.
What Is Milk Fever in Cats?
Milk fever is the common name for postpartum hypocalcemia, which means low blood calcium after giving birth. It is also called eclampsia in nursing cats. When a queen (an unspayed female cat) nurses a litter, her body pulls calcium from her blood into her milk. If her calcium intake or her body's calcium regulation cannot keep up, blood calcium falls.
Calcium does more than build bones. It helps muscles contract and nerves send signals. When blood calcium drops, muscles and nerves become overactive at first, then start to fail. That is why a cat with milk fever may twitch, tremble, and then become too weak to stand.
Calcium disorders are common in small animals. In one large review of cats and dogs at a referral hospital, hypocalcemia was found in a meaningful share of cats, and the severity of the calcium problem was linked to its cause [1]. Low ionized calcium is the form that matters most for nerve and muscle function, and it can appear in many different illnesses [1][2].
Milk fever is different from most of those cases because it has a clear trigger: nursing. It usually happens in the first two to three weeks after birth, when milk production is highest. It can also happen later if the kittens are nursing heavily or the mother is not eating well.
Cat Milk Fever Symptoms: What Owners Notice First
The signs of milk fever in cats often come on fast, sometimes within hours. Owners usually notice changes in movement and behavior before anything else.
Early signs
- Restlessness, pacing, or an unusual amount of panting
- A stiff, unsteady, or wobbly walk
- Muscle twitching, especially in the face, ears, or legs
- A glazed or anxious expression
- Hiding from the kittens or refusing to settle with them
- Pacing and then lying down, over and over
Later signs
- Visible tremors or shaking
- Weakness and trouble standing
- Lying flat and unable to lift her head
- Heavy breathing or open-mouth breathing
- Seizures
- A body temperature that is higher than normal
Some cats also vomit or stop eating. If your cat is vomiting and you are not sure why, see What to Do If Your Cat's Medication Is Causing Vomiting: Home Care and When to Call the Vet for guidance on sorting out causes, but remember that a nursing mother with tremors needs emergency care first.
A simple table of signs and urgency
| Sign you see | What it may mean | What to do |
|---|---|---|
| Restless, panting, pacing | Early milk fever or another problem | Call your vet today |
| Stiff walk, twitching face or ears | Low blood calcium affecting nerves | Emergency visit now |
| Tremors, cannot stand | Serious hypocalcemia | Emergency visit now |
| Seizure, collapse, high temperature | Life-threatening emergency | Go to an emergency hospital now |
Causes and Risk Factors for Eclampsia in Nursing Cats
Milk fever happens when the calcium leaving the mother's body in milk is greater than the calcium going in from food and from her bones. Several things raise the risk.
- A large litter. More kittens means more milk and more calcium lost each day.
- A first litter. The body's calcium regulation may not adapt as smoothly the first time.
- Small body size. A small queen nursing a big litter has less reserve to draw on.
- Poor diet during pregnancy and nursing. A mother cat needs a complete and balanced diet made for growth or nursing.
- Heavy milk production. Milk fever is most common in the first weeks after birth, when output peaks.
- Not eating well after birth. A queen who is stressed or not eating loses her main source of calcium.
Low calcium is not the only reason a cat can have low blood calcium. In sick cats, low ionized calcium is seen with serious conditions such as sepsis and kidney problems, and it is linked to heart rhythm problems, low blood pressure, gut slowdown, and bleeding problems in people and animals [3]. In cats with kidney disease, low calcium is common and is usually mild, though it can be moderate or severe in some cats [2]. These are different situations from milk fever, but they show why a veterinarian needs to find the cause instead of guessing.
On the other side of the coin, some cats have too much calcium. One cat was found to have high calcium during a routine wellness exam and turned out to have a parathyroid problem [4]. That is the opposite problem from milk fever, but it is a reminder that calcium levels in cats can go wrong in both directions and need testing to sort out.
How Veterinarians Diagnose Milk Fever
Diagnosis starts with the story. If you tell your vet that your cat recently gave birth and is nursing, and she is trembling or weak, milk fever moves to the top of the list.
Your vet will do a physical exam and check your cat's temperature, heart rate, breathing, and reflexes. They will look at how she stands and walks and whether she responds normally.
Blood testing confirms the diagnosis. The most useful test measures ionized calcium, the active form in the blood. A low ionized calcium level in a nursing queen with matching signs supports milk fever. Your vet may also check total calcium, glucose, electrolytes, and kidney values to rule out other causes of weakness and tremors.
Other tests depend on how sick your cat is. A cat who is breathing hard may need oxygen and imaging before more tests. Dyspnea (trouble breathing) is common in feline emergencies, and in one study of severely dyspneic cats, respiratory causes made up about a third of cases, followed by heart disease, trauma, and cancer [5]. A nursing mother who is panting could have milk fever, but she could also have a heart or lung problem, so your vet will sort that out.
If your cat has ear problems along with her other signs, that is usually a separate issue. See Cat Ear Infection: Signs and When to See a Vet or Ear Infections In Cats Symptoms for those topics.
Treatment Options
Milk fever treatment is urgent and is done by a veterinarian. The main treatment is calcium given into a vein, slowly, while the cat is monitored. Giving calcium too fast can cause heart rhythm problems, so this is not something to try at home.
Your vet will calculate the dose from your cat's weight and health. There is no safe home dose for milk fever, and human calcium pills are not a substitute. Do not give your cat calcium on your own.
Other care may include:
- Fluids to support circulation
- Oxygen if breathing is labored
- Treatment for seizures if they are happening
- Warming or cooling as needed
- Separating the kittens from the mother for a short time so she can rest and recover
The kittens will need to be fed during this time. Your vet can advise on kitten milk replacer and a feeding schedule. Do not put the kittens back with the mother until your vet says it is safe.
After the emergency is under control, your vet may prescribe oral calcium and vitamin D support. The exact product and amount depend on your cat, so follow your vet's instructions closely.
Recovery, Outlook, and Long-Term Management
Most cats with milk fever improve quickly once calcium is replaced. Many start to look better within hours, though full recovery can take a day or more. The outlook is good when treatment starts early. It is much worse when seizures or collapse have already happened.
Long-term management depends on whether your cat will keep nursing.
- If she continues nursing, she needs a high-quality diet for nursing mothers, free access to food, and regular checkups.
- If the litter is weaned or hand-fed, her calcium needs drop and the risk falls.
- If she has another litter in the future, milk fever can happen again. Talk with your vet before breeding her again.
- Some cats need a follow-up calcium check to make sure levels stay normal.
If your cat has diarrhea during recovery, that can be from stress, diet changes, or medication. See Cat Diarrhea: When Should You Call the Vet? for help deciding how urgent it is.
Prevention
You cannot always prevent milk fever, but you can lower the risk.
- Feed a complete and balanced diet for pregnancy and nursing. These diets have the right calcium and phosphorus levels.
- Do not add calcium supplements during pregnancy unless your vet tells you to. Extra calcium at the wrong time can actually make the body less able to regulate calcium after birth.
- Make sure the mother cat eats well after giving birth. Offer small, frequent meals and keep food available.
- Limit litter size if your cat is small or has had milk fever before. Talk with your vet about spaying.
- Watch closely during the first two to three weeks after birth, when risk is highest.
- Call your vet at the first sign of restlessness, twitching, or a wobbly walk.
Limitations and When to Contact a Veterinarian
This article cannot tell you whether your cat has milk fever. Only a veterinarian who examines your cat and runs tests can do that. Every cat is different, and the right treatment depends on her weight, her litter, and her overall health.
Call an emergency veterinarian right now if your cat:
- Has tremors or shaking
- Cannot stand or keeps falling
- Has a seizure
- Is breathing hard or with an open mouth
- Has a body temperature that feels very high
- Is limp, unresponsive, or hard to wake
Call your regular veterinarian the same day if your cat:
- Is a nursing mother and seems restless, anxious, or off
- Has a stiff or wobbly walk
- Is twitching around the face or ears
- Is panting more than usual
- Is not eating well or is hiding from her kittens
Schedule a routine visit if your cat had milk fever before and you are planning another litter, or if you want to talk about spaying. If you notice ear discharge, head shaking, or ear odor in your cat, that is a separate concern and is covered in Cat Ear Infection with Fever: When to Rush to the Vet.
Frequently Asked Questions
Can a cat die from milk fever?
Yes, milk fever can be fatal if it is not treated. Seizures, collapse, and heart problems can develop as calcium falls. Early treatment with intravenous calcium saves most cats.
How soon after giving birth does milk fever start?
It usually starts in the first two to three weeks after birth, when milk production is highest. It can start earlier or later depending on the litter and the mother's diet.
Can I just give my cat calcium pills at home?
No. Home calcium treatment is not safe for milk fever. The dose must be calculated by a veterinarian, and intravenous calcium has to be given slowly with heart monitoring.
Will the kittens be okay if the mother is sick?
The kittens need to be fed while the mother recovers. Your vet can guide you on kitten milk replacer and how often to feed. Do not let them nurse again until your vet says it is safe.
Should I spay my cat after milk fever?
Spaying prevents future pregnancies and future milk fever. Talk with your vet about timing, since it is usually best to wait until your cat has fully recovered.
Related Articles
- Cat Diarrhea: When Should You Call the Vet?
- Ear Infections In Cats Symptoms
- Cat Ear Infection with Fever: When to Rush to the Vet
- Cat Ear Infection: Signs and When to See a Vet
- What to Do If Your Cat's Medication Is Causing Vomiting: Home Care and When to Call the Vet
- Cat Vomiting Bile: Causes and When to Call the Vet
References
- Severity of Ionized Hypercalcemia and Hypocalcemia Is Associated With Etiology in Dogs and Cats. Frontiers in veterinary science, 2019.
- Severity, etiology and outcomes of ionized hypocalcemia in azotemic cats and dogs. Frontiers in veterinary science, 2026.
- Ionized calcium and ionized magnesium disturbances in dogs and cats with septic peritonitis. Frontiers in veterinary science, 2025.
- Hyperparathyroidism secondary to parathyroid hyperplasia in a cat. The Canadian veterinary journal = La revue veterinaire canadienne, 2026.
- Emergency Dyspnea in 258 Cats: Insights from the French RAPID CAT Study. Veterinary sciences, 2025.