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Our History

Merial was established in August 1997 when Rhône Mérieux, the animal health division of Rhône-Poulenc (later became Sanofi), and Merck AgVet, the animal health division of Merck & Co. Inc., combined their animal health assets into a 50:50 joint venture.  The new company was a stand-alone enterprise with the industry’s broadest line of products and services for the prevention and treatment of animal diseases. 
In September 2009, Sanofi acquired Merck’s 50% stake. Merial is now the animal health division of Sanofi, a diversified global healthcare leader.

The beginnings

Merial can trace its roots to the late-19th century and the great scientist Louis Pasteur. Merial’s forefather, Marcel Mérieux, who worked in Pasteur’s Paris laboratory founded the Institut Biologique Mérieux in 1897. This was the starting point for Merial’s animal health endeavors.

Mérieux’s son Charles, who had become the head of the Institut, drove the development of the first-ever industrial-scale production of any vaccine in 1947. He also created the Institut Français de la Fièvre Aphteuse specifically to make this foot-and-mouth disease vaccine. Another biological milestone was the rabies vaccine in 1968. Merck’s animal health legacy included a major advance in 1940 with sulfaquinoxiline - the first efficient anticoccidial. Coccidiosis was then wiping out 10 percent of US chickens every year making chicken meat as expensive as beef. In 1962, thiabendazole was launched - the first broad-spectrum endoparasitic agent for sheep, cattle and horses.


In the 1970s, researchers isolated a novel micro-organism (S. avermitilis) from a fungus found on a Japanese golf course. This led to the avermectin family of antiparasitics and, in particular, ivermectin. Introduced in 1981 as IVOMEC® (ivermectin) for cattle and EQVALAN® (ivermectin) for horses, ivermectin took the animal health market by storm. It is effective in controlling parasites in a vast array of species from cattle and pigs to horses and companion animals to camels and other wild life. New ivermectin products were produced virtually every year thereafter, with HEARTGARD® (ivermectin) (heartworm in dogs, 1987) being especially successful. By the second half of the 1980s ivermectin had become the largest selling animal health product in the world.


Observations in the late 1970s concerning why insects died on plants that had been treated with candidate herbicides led to Rhône Mérieux’s greatest commercial animal health contribution – FRONTLINE® Brand Products. In 1922, Rhône Poulenc (Rhône Mérieux’s parent) had acquired the British firm of May & Baker. And it was at May & Baker’s Ongar laboratory that the potential of the fipronil molecule to control fleas and ticks on pets was recognized, with FRONTLINE® Brand Products being the resulting veterinary product. This ectoparasiticide, launched in 1994, was eventually to take ivermectin’s crown as the world’s best-selling animal health product. More than 2 billion doses have now been used around the world.

An Immediate Global Enterprise

At the start of its corporate life, Merial’s portfolio contained what remains to this day the only two block busters the animal health sector has produced. The new company was poised to compete on the world market, continuing the tradition of innovation and building for the future. While its global headquarters were in London, Merial’s major sites were mostly in the U.S. and France, with significant investment in Brazil and well-established production facilities in China. At its launch, its annual sales were estimated at $1.7 billion, R&D investment was around $120 million. The new enterprise was able to hit the ground running with the first of several vaccines based on modern biotechnology - the canary pox ALVAC platform. The innovative canary pox platform has been complemented by other biotechnologies including the vector vaccines TROVAC® (avian influenza, 1998) and VAXXITEK® HVT+IBD (Marek’s disease and IBD, 2005). On the pharmaceutical side too, Merial was quick to the market with a new offering. Within three months of the company’s formation, the company was able to launch EPRINEX®(eprinomectin), for the control of internal and external parasites in cattle. Over the years that followed, Merial continued to strengthen its franchise in anti-parasitics, both for production and companion animals. Merial also moved into other therapeutic areas with GASTROGARD® (omeprazole) (equine stomach ulcers, 2000) and PREVICOX® (firocoxib), a COX2 osteoarthritis pain reliever developed specially for dogs (2005). A first, both in human and veterinary medicine, is the therapeutic vaccine, ONCEPT® for the treatment of melanoma in dogs (2009).

Building on Success

Infrastructure investment was already underway in 1997, with the opening of a major clinical research center in France that same year.  Two years later, a new pharmaceuticals research center was opened at New Brunswick, N.J. In 2001, a new poultry vaccines plant was underway in Nanjing, China with an up-grade to the existing Nanchang plant being completed in the same year. In Brazil, the FMD factory at Paulinia became the largest in South America in 2002. Since then expansions and process improvements have taken place at all Merial sites. A major project has seen vaccine manufacturing move from Lyon to neighboring Porte des Alpes.  Lyon and the FRONTLINE Brand Products site at Toulouse ready themselves for future demands.  In 2009, a $70 million expansion of the Nanchang avian vaccines plant was announced, while in 2010, Merial acquired FMD manufacturing and R&D facilities at Lelystad, Netherlands. Today, Merial operates in over 150 countries with its global headquarters in Lyon, France.



EQVALAN Paste 1.87% Warning: Not for use in humans. Keep this and all drugs out of reach of children. Do not use in other animal species as severe adverse reactions, including fatalities in dogs, may result.

Safety of GASTROGARD in pregnant or lactating mares has not been determined

HEARTGARD is well tolerated. All dogs should be tested for heartworm infection before starting a preventive program. Following the use of HEARTGARD, digestive and neurological side effects have rarely been reported. For more information, contact your veterinarian or click here for important safety information and full prescribing information.

IVOMEC EPRINEX (eprinomectin): No meat or milk withdrawal is required when used according to label.

IVOMEC Plus (ivermectin/clorsulon): Do not treat cattle within 49 days of slaughter.

IVOMEC (ivermectin) Pour-On: Do not treat cattle within 48 days of slaughter.

IVOMEC 1%: Do not treat cattle within 35 days of slaughter or swine within 18 days of slaughter.

All IVOMEC and EPRINEX products: Do not use in calves intended for veal. Do not use in other animal species not on the label as severe adverse reactions, including fatalities in dogs, may result.

All IVOMEC products: Do not use in female dairy cattle 20 months or older or in dry dairy cows.