Shares of veterinary diagnostics maker Heska ($HSKA) have doubled in the past year, as investors have rewarded the company for its efforts to generate higher revenues from recurring sources. It's clearly still a work in progress for the Colorado company though: Heska reported that sales in its first quarter rose just 10% year over year to $22.9 million. Analysts had expected revenues to come in at $24 million. Heska did report that its net income for the quarter was in line with estimates at $598,000, or 9 cents per share. The company has been watching its expenses, said CEO Kevin Wilson in a press release announcing the earnings results, while slowly building awareness of new products such as the Element HT5 5-part hematology analyzer. That focus on improving the bottom line pushed Heska's gross margin to 44% from 40% during the same period a year ago. Release