The RSPCA has seized more than 100 malnourished and distressed horses and ponies from a property in Victoria's west.

It said the rescue came just a fortnight after 13 other horses had to be rescued from the same property after they were found at risk of collapsing.

The animal welfare group said many of the horses seized were very underweight and had protruding hip bones and visible ribs and spines.

They said a majority of the horses appeared to have worms and parasites.

"All of the horses seized today require intensive veterinary care and a careful feeding program if they are to have any chance of being restored to good condition," the RSPCA said in a statement.

"Very few have ever been handled, some of the mares are pregnant, there are some young foals and only a few of the stallions and colts appear to have been gelded.

The RSPCA said some of the horses may not survive the first month, while others may have to spend the rest of their lives at a sanctuary or welfare organisation.

The group said it was working to treat, rehabilitate and rehouse the horses.