A former dog breeder from Sydney's north-west has been found guilty of animal cruelty after officers found five dead dogs in freezers on his property and others living in "grotesque" conditions.

RSPCA NSW and police also found the partially burnt remains of a dog in a fire pit near live dog pens, and pools of blood and bodily fluids in a kennel where an animal is believed to have decomposed.

Eighteen dogs of varying breeds were seen to be suffering from potentially life-threatening conditions during the inspection last March of a property in Vineyard that had previously been used by Herizon Kennels to breed dogs, the RSPCA said in a statement on Wednesday.

Todd Baker, 41, was convicted of 15 counts of animal cruelty in Penrith Local Court last week and sentenced to a three-year good behaviour bond, prohibited from owning animals for 10 years and ordered to pay more than $80,000 in costs.

Inspector James Arentz said the state of the animals on Baker's property was hard to comprehend.

"Every single dog had serious health problems - some of them truly grotesque and heartbreaking," he said.

"The mind boggles how someone that has a history of breeding for profit could let so many dogs get in such horrendous conditions."

The RSPCA said the live dogs were found flea-ridden and dehydrated, with injuries such as ulcerated paw pads and severe osteoarthritis, while the concrete floors they slept on were "all heavily laden with faeces and urine".

One of four rottweilers was chained up with no access to food, water or shelter and another dog had burnt testicles "consistent with sitting on hot concrete".

The animal welfare group said Baker was hostile, aggressive and verbally abusive towards inspectors throughout the investigation and once confronted staff face-to-face at a shelter.

He claimed the animals died in dog attacks or of old age and that he intended to use a company to cremate them "but admitted to burning them in his fire-pit once room in the freezers was exhausted".

Seized dogs have been rehomed after extensive veterinary work and behavioural rehabilitation.

AAP