Eclampsia is the sudden onset of clinical signs associated with low blood calcium levels (hypocalcemia) that occur mostly in lactating (nursing) bitches. More commonly known simply as 'milk fever' or more technically as 'puerperal tetany', eclampsia is a fast acting, potentially fatal condition in which there is an imbalance between the impute of calcium in the blood and the loss of calcium from the body. This leads to a decreased amount of calcium in the blood and signs of calcium deficiency begins. The condition is due to underactive parathyroid gland, the gland that is responsible for regulating the parathyroid hormone, which in turn regulates the amount of calcium that is stored in the bones, to be removed as needed for use in the blood. As the parathyroid gland has not being signaled to stimulate the parathyroid hormone to release calcium from the bones into the body, when the bitch's milk comes in and the demand for calcium suddenly increases, the parathyroid gland is unable to respond quickly enough for her needs to be met. The lack of calcium results in tonoclonic contractions of the skeletal muscles, where the muscles in the body contract convulsively, limiting movement.
While eclampsia is most commonly seen in toy-breed bitches within a few weeks of whelping a relatively large litter and in first litters, it can happen to any size or breed of dog with nursing puppies. Chihuahuas, miniature pinschers, shih-tzus, miniature poodles, Mexican hairless dogs and pomeranians are at increased risk for eclampsia, as as toy breeds and bitches with their first litters.
Symptoms occur during first 40 days after giving birth and include
Poor maternal behavior
Clumsy walking, stiff gait
Muscle tremors, tetany (entire body goes stiff), convulsions
Dog lies down with paws rigidly extended (usually seen 8–12 hours after the first onset of symptoms)
High body temperature, fever
Rapid, heavy breathing
Dilated pupils which are slow to contract when exposed to light