Zoetis Inc, formerly the animal health subsidiary of US pharmaceuticals giant Pfizer Inc, posted a better-than-expected quarterly profit, driven by strong growth in sales of pet products in the United States.

Animal health is considered an attractive business for drugmakers as there are fewer worries about patent expiries and regulatory interventions, and a growing middle-class population in emerging markets means more people can afford pets.

However, the worst drought in the United States in more than half a century has hit sales across the industry.

Zoetis said sales of livestock products rose just 2%, compared with a 13% rise in pet products sales.

Zoetis's pet products include Revolution, a heartworm and flea-control medicine for cats and dogs, and Palladia, the first drug to be approved by the FDA for treating cancer in dogs.