Gestational Pathology: Hydrallantois (Bloated Bull Frog) vs Hydramnios (Bulldog Calf)

• Clinical Presentation of Hydroallantois (Hydrallantois): Hydroallantois (dropsy of the allantoic sac) in dairy cows is characterized by sudden, rapid, massive transudation of fluid into the allantoic cavity ($100\text{--}200\text{ liters}$ over $5\text{--}20\text{ days}$) during the last trimester.
• 'Bloated Bullfrog' Sign: The cow develops immense, symmetrical, rounded bilateral distension of the lower abdomen that gives the animal the pathognomonic 'bloated bullfrog' or barrel-shaped appearance.
• Contrasting Hydroamnion: Hydroamnion develops slowly over months, involves the amniotic sac (amniotic fluid accumulation of $20\text{--}50\text{ L}$), and is associated with fetal craniofacial anomalies ('bull-dog calf').

Correct option: (2) Hydroallantois