Veterinary drug maker Dechra Pharmaceuticals has unveiled a glossy-coated first-half trading update, in line with expectations following a year of expansion in the US.The FTSE 250 group's revenues increased by 6%, impacted by a weaker first half due to adverse weather conditions and supply issues for its dermatology product Animax in the US.Its US Pharmaceuticals division saw an increase of 54% in revenues driven by the acquisition of dog and horse supplement Phycox, the launch of horse lameness treatment Osphos and the relaunch of two ophthalmic products.The European market grew 0.5% offset by a decline in food producing animal products due to a reduction in the rate of vets prescribing antibiotics in Germany and the Netherlands.Chief executive Ian Page said: "The positive momentum experienced during the end of the last financial year has been maintained."On the strength of our recent revenue growth, we will accelerate investment in our sales and marketing infrastructure, particularly in the US as we look to strengthen our market presence."We remain confident that the execution of our strategy will continue to deliver future value."Investec analysts said the update represented a solid underlying performance which was ahead of its original expectations."We see today's announcement as further delivery of the Group strategy; geographic expansion, acquisitions and launch of pipeline assets are all helping to deliver strong revenue growth. We think this trend will only increase from here given the deep pipeline potential and strong balance sheet."Shares were down 0.53% to 845.5p on Wednesday to 10:39.