An aerial survey in east Texas days after Hurricane Harvey has found thousands of cattle stranded on small patches of dry land, still surrounded by deep water. Video footage shows these cow islands, where cattle are at risk of dying due to the lack of food and fresh water.

"Cattle can go without food for a number of days, but they cannot go without fresh water," Dickie Vest, the senior medical director of the Cleveland Amory Black Beauty Ranch, a Texas-based animal sanctuary, said in a press release. "In areas where there was an ocean surge, the water that they are surrounded by or standing in may be too brackish, and that creates a life-threatening crisis for them."

The Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) has committed to providing emergency assistance for animals, both pets and livestock, and have veterinarians on the ground to help assess the risk to livestock.

The video footage, captured by the Humane Society of the United States, also shows many dead cattle, and cows swimming in search of dry land. Though cows are better swimmers than you might expect, they can't tread water indefinitely, and they are in desperate need of food and water.

The HSUS and Texas cattle producers are working together to create a strategy to rescue cows, and bring supplies to those that can't be rescued, in an effort to curb the loss. It is possible to move large animals, but it takes special equipment and careful expertise to prevent further stress to the cows. Texas farmers raise more cattle than any other state, and some of the state's most productive ranch lands were among the areas hardest-hit by the storm.

Image: USDA

Though many farmers have tried to rescue livestock from the floods, with hundreds of millions of cows to account for, it's been impossible to save them all.

"We know that thousands of pets and the people who care about them have been dealt a terrible blow by Hurricane Harvey," Vest said. "[But] cattle are also suffering, and substantially so."