Eclampsia in Dogs (Milk Fever): Recognising a Breeding Emergency

Eclampsia — also called milk fever or puerperal tetany — is a life-threatening emergency that can strike nursing dams with little warning. It is caused by dangerously low blood calcium levels (hypocalcaemia) as the body fails to keep up with the calcium demands of milk production. Without rapid veterinary treatment, an affected dam can die within hours.

What Is Eclampsia?

During lactation, the dam's body draws calcium from her blood to produce milk. If the demand outpaces her ability to absorb calcium from food or mobilise it from bones, blood calcium levels crash. The result — hypocalcaemia — disrupts muscle and nerve function throughout the body, causing the characteristic neurological signs.

Which Dogs Are at Highest Risk?

Small and toy breeds are disproportionately affected — especially Yorkshire Terriers, Chihuahuas, Pomeranians, Miniature Pinschers, Shih Tzus, and similar dogs. This is partly because their small body mass means less calcium reserve relative to the demands of even a small litter.

Dams with large litters relative to body size face higher calcium drain.

First-time dams are at higher risk, possibly because they have not adapted to the physiological demands of lactation.

Dams supplemented with calcium during pregnancy paradoxically have higher risk — external calcium supplementation suppresses the parathyroid gland's ability to regulate calcium mobilisation, leaving the dam less able to compensate when milk production peaks.

Signs of Eclampsia

Eclampsia typically appears 1–4 weeks after whelping, most commonly during peak milk demand at 2–3 weeks. Signs progress rapidly:

Early signs:

• Restlessness, panting, whining
• Stiffness or difficulty walking
• Muscle tremors
• Reluctance to care for puppies

Progressive signs:

• Muscle rigidity, spasms
• Stumbling, ataxia (inability to coordinate movement)
• Pawing at the face
• Glassy, wide eyes

Severe/life-threatening:

• Seizures
• High body temperature (hyperthermia from muscle activity)
• Inability to stand
• Coma

What to Do

This is a veterinary emergency — do not wait. If your dam shows any of the signs above:

1. Remove puppies from the dam immediately (she cannot care for them safely and continued nursing worsens the calcium loss)
2. Call your emergency vet
3. Keep the dam calm and cool — muscle activity generates heat and worsens hyperthermia

Your vet will administer intravenous or subcutaneous calcium gluconate, which typically produces dramatic improvement within 15–30 minutes. Following treatment, puppies are gradually returned (or hand-fed if dam's milk is insufficient), and oral calcium supplementation is prescribed for the remainder of lactation.

Prevention

Do not supplement calcium during pregnancy — this suppresses the parathyroid gland response. Feed a high-quality, balanced diet formulated for pregnancy and lactation. Post-whelp, monitor small-breed dams closely during weeks 2–4 of lactation, when risk peaks. Oral calcium supplements after whelping (post-delivery, not pre) can be used preventatively in high-risk breeds under veterinary guidance.