Almost a third of Susan Harmer's prize-winning flock were left dead or injured at her farm in Offham, near Lewes.
Twenty-five were mauled, including a ram and pregnant ewes, in the overnight attack earlier this month.
"Sheep were strewn everywhere, with a pile of them in one corner where the dogs had trapped them and attacked them," Ms Harmer said.
"These are sheep which we have for their whole breeding lives - about 10 years - and we get very fond of them.
"They're not just a commodity, they're our livelihood. This is a huge emotional loss."
Ms Harmer said the attack was the worst her farm had faced this year.
She appealed to dog owners to put their animals on a lead before entering a field and to not put them out at night.
Sussex Police are investigating the attack, which happened overnight on 4 December, and have urged anyone with information to contact them.
The fourth dog attack in a year on a flock of sheep in Sussex has "wiped out years of work", a farmer has said.