(WSJ) - THE FIRST TIME I saw a draft horse in a Bordeaux vineyard I thought it was a PR stunt. Call me a cynic, but I was convinced that when the journalists left, the horses would be sent straight back to whichever farm they came from. I hate to admit it, but in the case ofChâteau Pontet-Canet I was wrong.

Every April I visit this small corner of Pauillac, just south of Château Mouton-Rothschild, to taste the latest vintage. The tasting takes place in the winery, where, up a short flight of wooden steps, a large platform sits above the fermentation tanks. Here, you get a clear view of the vineyards and, sure enough, if you look closely, there’s a Postier Breton horse working Pontet-Canet’s vines in place of a tractor.

The theory is that tractors compact the soil too much; horses are significantly lighter and cause less stress to the vines’ roots. At Pontet-Canet, the horses, of which there are eight, are part of a bigger picture—since 2010 the estate has been certified both organic and biodynamic.

For those unfamiliar with biodynamics, it is a farming philosophy based on a series of lectures given by the Austrian philosopherRudolf Steiner in 1924. At its heart is the theory that a farm is a living system that is influenced by planets, lunar cycles and “cosmic forces.” The wine is made without chemicals, pesticides or synthetic additives. Instead, the vines are treated with a series of mineral, animal and plant preparations, made from anything from oak bark to stinging nettles. The aim is to create better soils and healthier vines that produce better wine.

If this all seems at odds with a region known for its love of formality, grand tradition and commerce, that’s because it is. Pontet-Canet is the only certified biodynamic estate in the Médoc cru classé.

“It has definitely been a risk for us,” says co-owner Mélanie Tesseron. “A lot of people thought we were silly for trying, because the climate can be turbulent in the Médoc—we are between two waters [the Atlantic and the Gironde river] and compared to other regions we have relatively high rainfall.”

It was Ms. Tesseron’s co-owner uncle, Alfred Tesseron, and his technical director, Jean-Michel Comme, who made the bold decision to go biodynamic in 2005, after Mr. Comme had tried it on his own estate in Bordeaux.

I recently had the opportunity to taste 10 back vintages of the wine and track its development. There is no doubt that from 2005 there is a noticeable step-up in quality. The ’05 has lively aromatics with lots of lush, ripe fruit. I also enjoyed the ’07 and ’08; the former has a silky, pure texture, and the latter is more refined.