Eighty-six dogs, including 23 puppies, were removed by ISPCA Inspectors from an unlicensed dog breeder in Co Roscommon.
It followed a visit by an inspector and the county dog warden last Friday.
The dogs were being kept in "very poor conditions" and had only one person to care for them all.
Nineteen of the dogs were suffering from health issues - including mange, eye conditions and ear infections.
They are now receiving veterinary treatment, the ISPCA says.
A further 17 puppies were removed from a house on Thursday - where the owner had allowed his dogs to breed without consideration for the consequences.
All of the dogs will need to be vaccinated, neutered and microchipped before being re-homed.
The ISPCA is appealing to the public for donations, after taking in over 100 dogs in just three days.
The dogs - including Shih Tzu’s, Cocker Spaniels, Jack Russell terriers, Pugs, French bulldogs - are being cared for at the ISPCA’s animal centres in Longford and Donegal
Twenty-five of the dogs have been transferred to the Dogs Trust.
The ISPCA is asking the public to report their suspicions about unlicensed dog breeders to its National Animal Cruelty Helpline on 1890-515-515 or to their local authority.