We offer a diversified portfolio of products which allows us to capitalize on local and regional customer needs. Generally, our products are promoted to veterinarians and livestock producers by our sales organization which includes sales representatives and technical and veterinary operations specialists, and then sold directly by us or through distributors, retailers or e-commerce outlets. The depth of our product portfolio enables us to address the varying needs of customers in different species and geographies. Many of our top-selling product lines are distributed across both of our operating segments, leveraging our R&D operations and manufacturing and supply chain network.

Over the course of our history, we have focused on developing a diverse portfolio of animal health products, including medicines, vaccines and diagnostics, complemented by biodevices, genetic tests and a range of services. We refer to all different brands of a particular product, or its dosage forms for all species, as a product line. We have approximately 300 comprehensive product lines, including products for both companion animals and livestock within each of our major product categories.

•vaccines: biological preparations that help prevent diseases of the respiratory, gastrointestinal and reproductive tracts or induce a specific immune response;

•animal health diagnostics: testing and analysis of blood, urine and other animal samples and related products and services, including point-of-care diagnostic products, instruments and reagents, rapid immunoassay tests, reference laboratory kits and services and blood glucose monitors; and

Our remaining revenue is derived from other non-pharmaceutical product categories, such as nutritionals, as well as products and services in biodevices, genetic tests and precision animal health.

Our companion animal products help extend and improve the quality of life for pets; increase convenience and compliance for pet owners; and help veterinarians improve the quality of their care and the efficiency of their businesses. Growth in the companion animal medicines, vaccines and diagnostics sector is driven by economic development, related increases in disposable income and increases in pet ownership and spending on pet care. Companion animals are also living longer, deepening the human-animal bond, receiving increased medical treatment and benefiting from advances in animal health medicine, vaccines and diagnostics.

Our livestock products primarily help prevent or treat diseases and conditions to allow veterinarians and producers to care for their animals and to enable the cost-effective production of safe, high-quality animal protein. Human population growth and increasing standards of living are important long-term growth drivers for our livestock products in three major ways. First, population growth and increasing standards of living drive demand for improved nutrition, particularly through increased consumption of animal protein. Second, population growth leads to greater natural resource constraints driving a need for enhanced productivity. Finally, as standards of living improve and the global chain faces increased scrutiny, there is more focus on food quality, safety, and reliability of supply.

Revenue by geographic area


	Year Ended December 31,
(MILLIONS OF DOLLARS)	2023		2022		2021
United States	$	4,555	$	4,313	$	4,042
Australia	323		289		259
Brazil	393		330		312
Canada	255		238		232
Chile	140		141		136
China	320		382		357
France	142		126		132
Germany	202		176		183
Italy	121		111		115
Japan	158		173		186
Mexico	162		136		133
Spain	122		118		128
United Kingdom	277		235		234
Other developed markets	512		468		467
Other emerging markets	784		758		778
	8,466		7,994		7,694
Contract manufacturing & human health	78		86		82
Total Revenue	$	8,544	$	8,080	$	7,776

Revenue exceeded $100 million in twelve countries outside the U.S. in 2023, 2022 and 2021. The U.S. was the only country to contribute more than 10% of total revenue in each year.

Revenue by major species


	Year Ended December 31,
(MILLIONS OF DOLLARS)	2023		2022		2021
U.S.
Companion animal	$	3,529	$	3,341	$	2,990
Livestock	1,026		972		1,052
	4,555		4,313		4,042
International
Companion animal	2,047		1,862		1,699
Livestock	1,864		1,819		1,953
	3,911		3,681		3,652
Total
Companion animal	5,576		5,203		4,689
Livestock	2,890		2,791		3,005
Contract manufacturing & human health	78		86		82
Total Revenue	$	8,544	$	8,080	$	7,776

Revenue by species


	Year Ended December 31,
(MILLIONS OF DOLLARS)	2023		2022		2021
Companion Animal:
Dogs and Cats	$	5,291	$	4,939	$	4,426
Horses	285		264		263
	5,576		5,203		4,689
Livestock:
Cattle	1,503		1,440		1,557
Swine	543		565		659
Poultry	524		476		507
Fish	220		212		187
Sheep and other	100		98		95
	2,890		2,791		3,005
Contract manufacturing & human health	78		86		82
Total Revenue	$	8,544	$	8,080	$	7,776

Revenue by product category


	Year Ended December 31,
(MILLIONS OF DOLLARS)	2023		2022		2021
Parasiticides	$	1,947	$	1,860	$	1,635
Vaccines	1,771		1,718		1,673
Dermatology	1,427		1,329		1,180
Other pharmaceuticals	1,280		1,043		966
Anti-infectives	1,057		1,081		1,215
Animal health diagnostics	376		353		374
Medicated feed additives	354		360		420
Other non-pharmaceuticals	254		250		231
	8,466		7,994		7,694
Contract manufacturing & human health	78		86		82
Total Revenue	$	8,544	$	8,080	$	7,776

We primarily sell our companion animal products to veterinarians or to third-party veterinary distributors that typically then sell our products to veterinarians, and in each case, veterinarians then typically sell our products to pet owners. In certain markets, we also sell certain companion animal products through retail and e-commerce outlets. We sell our livestock products primarily to veterinarians and livestock producers, including beef and dairy farmers as well as pork and poultry operations, in addition to third-party veterinary distributors and retail outlets who then typically sell the products to livestock producers. Sales to our largest customer, a U.S. veterinary distributor, represented approximately 15% of total revenue for 2023, and 14% of total revenue for 2022 and 2021.