Hill believes water retention under the skin is a result of poor placental development, resulting in calves being much larger than normal.

CNN: Cloning experts to tell House committee pros, cons

The creature that gave rise to all the placental mammals - a huge group that includes whales, elephants, dogs, bats and us - has at last been pinpointed.

BBC: Earliest placental mammal ancestor pinpointed

Their results indicate that all placental mammals arose from a small, furry, insect-eating animal.

BBC: Earliest placental mammal ancestor pinpointed

The normal way of catching the infection, caused by a bacterium called Coxiella burnetii, is breathing in barnyard dust which contains dried placental material, birth fluids, and faeces.

BBC: Cull workers struck by rare fever