Christine Weisheit has been charged with more than 60 animal cruelty offences, brought by the RSPCA, for allegedly mistreating horses on a property near Ararat in western Victoria.

She has pleaded not guilty to all charges, including allegations she starved many of the horses and kept them inside contaminated paddocks.

Veterinarian Paul Owens, who specialises in equine dentistry, was shown photos of underweight horses with visible rib cages as he was cross-examined in a virtual Melbourne Magistrates Court hearing on Thursday.

He visited the Warrak property and was asked about the conditions of the paddocks by prosecutor Amelia Beech, who is acting for the RSPCA.

"There was zero grazing, there was dust and very high faecal contamination of all paddocks, simply because of pressure on those paddocks," Dr Owens told the court.

"Therefore there would be a higher worm burden and, as there is nothing to graze, a higher possible ingestion of faecal material."

During his visit, Dr Owens said he found no evidence that any food was being provided to the horses.

Weisheit's barrister Luke Howson put to Dr Owens that some horses were starving because they escaped to a nearby state park.

"If horses are not getting food they are starving, I cannot make a comment about the state park," Dr Owens replied.

Another veterinary expert, Andrew Stent, who performed post-mortem examinations on two horses, said the animals were emaciated and infected with worms.

He said it appeared both horses had not been treated for worms and were nutritionally deficient for weeks to months before they died.

He reviewed more than 200 horse post-mortems and said the level of worm infestation in one of the horses, named Teddy, was the worst he has ever seen.

"This one stays in mind for me," Dr Stent told the court. "It had severe issues that needed veterinary attention."

The hearing continues before magistrate Rodney Crisp on May 25.

Australian Associated Press