Carol Walker / Andalusian horsea, two stallions coming together in arena one dappled grey and one pure white. Spain.

Carol Walker / RF - Percheron horse trotting through snow. Alberta, Canada. Febraury. (This image may be licensed either as rights managed or royalty free.)

Carol Walker / RF - Knabstrupper stallion with leopard spotting colouration, running in pasture. Germany. May. (This image may be licensed either as rights managed or royalty free.)

Klein & Hubert / Mustang stallion kicking out after winning fight. Rocky Mountains, USA, June.

Carol Walker / Two wild pinto Mustang stallions battle for dominance in Sand Wash Basin, Colorado, USA.

Carol Walker / Head portrait of grey Arabian stallion running in desert dunes near Dubai, United Arab Emirates.

Carol Walker / Two wild Mustang stallions fighting in the White Mountain Herd Area, Wyoming, USA. August.

Kristel Richard / Two cowboys mounted on a Pantaneiro stallion, round up a band of wild Pantaneiro horses, Pantanal, Mato Grosso do Sul, Brazil. August 2015.

Klein & Hubert / Young Haflinger stallion in alpine meadow, Austria.

Klein & Hubert / Two young Haflinger stallions grooming each other in alpine meadow, Austria..

Kristel Richard / Two wild Przewalski / Takhi Horse (Equus ferus przewalskii) stallions play fighting Hustai National Park, Tuv Province, Mongolia. Endangered species. September.

Kristel Richard / Przewalski / Takhi Horse (Equus ferus przewalskii) breeding stallion stands alert, Hustai National Park, Tuv Province, Mongolia. Endangered species. September.

Kristel Richard / Two Cambodian Pony stallions play fighting, rearing on back legs, Siem Reap, Cambodia. March 2013

Kristel Richard / Lady riding a black Menorquin stallion, performing the bot or walking courbette of the Doma Menorquina, during the festival Mare de Deu de Gracia, in Mahon, Menorca, Spain 2012. Tourists are trying t...

Kristel Richard / Portrait of a grey Andalusian stallion, in Ciutadella, Menorca, Spain.

Carol Walker / Andulasian bay stallion running in snow storm, Longmont, Colorado, USA

Carol Walker / Friesian horse, black stallion running in field, Livingston, Montana, USA

Carol Walker / Lusitano horse, bull fighter mounted on grey stallion, in this type of bull fighting neither horse nor bull are injured, Portugal, May 2011, model released

Carol Walker / Lusitano horse, grey stallion trotting, Portugal

Carol Walker / Lusitano horse, grey stallion trotting, Portugal

Carol Walker / Lusitano horse, dun stallion pawing the ground, Portugal, May 2011

Carol Walker / Lusitano horse, man training stallion in dressage steps, the high leap, Royal Riding School, Lisbon, Portugal, May 2011, model released

Carol Walker / Lusitano horse, man training stallion in dressage steps, standing up on hind legs and then jumping in the air, Royal Riding School, Lisbon, Portugal, May 2011, model released

Carol Walker / Lusitano horse, man training stallion in dressage steps, the high leap, Royal Riding School, Lisbon, Portugal, May 2011. No release available.

Carol Walker / Black Friesian stallion, head neck portrait, Ojai, California, USA

Carol Walker / Arabian stallion, chestnut, portrait, Ojai, California, USA

Carol Walker / Andalusian stallion running out of the sea on beach, Ojai, California, USA

Kristel Richard / A rare East Bulgarian stallion cantering at the Kabiuk National Stud, Shumen, Bulgaria, February 2012

Kristel Richard / A purebred Lusitano stallion galloping in the arena at the Companhia das Lez?as Stud Farm, Samora Correia, Santar? Portugal, July 2011

Kristel Richard / During the Festa do Colete Encarnado (Red Waistcoat Festival), a bull running festival, a traditionally dressed 'cavalheiro' delivers the 'banderilla' mounted on his Lusitano stallion in the bullring...

Kristel Richard / Portrait of a traditionally dressed estancia owner mounted on his stallion, during the Festa do Colete Encarnado (Red Waistcoat Festival), a bull running festival, in Vila Franca de Xira, District of...

Terry Whittaker / 2020VISION / Konik horse (Equus caballus) stallion and juvenile on Wicken Fen, Cambridgeshire, UK, June 2011

Kristel Richard / A rare Sorraia stallion cantering, Coudelaria Nacional (National Stud Farm), in Alter do Chao, District of Portalegre, Alentejo, Portugal.

Kristel Richard / Portrait of a rare Sorria stallion, Reserva Natural do Cavalo do Sorraia, Alpiarca, District Santarem, Alentejo, Portugal.

Terry Whittaker / 2020VISION / Konik horse (Equus caballus) two stallions fighting, wild herd in rewilding project, Wicken Fen, Cambridgeshire, UK, June 2011. Photographer quote: "Koniks are a rare Polish horse used as surrogate gr...

Charlie Summers / Two Wild Horse Stallions (Equus caballus) fighting in mist. Montana, USA, June.

Carol Walker / Chestnut arabian stallion running, California, USA

Carol Walker / Grey Andalusian / Spanish stallion running, California, USA

Carol Walker / Grey Andalusian / Spanish stallion running, California, USA

Carol Walker / Grey Andalusian / Spanish stallion running, California, USA

Carol Walker / Grey Andalusian / Spanish stallion running, California, USA

Carol Walker / Chestnut Paso peruvian stallion running, California, USA

Carol Walker / Spanish / Andalusian stallion performing Alta Escuela moves, rearing up, Andalucia, Spain

Carol Walker / Wild Horses / mustangs, two stallions rearing up fighting, Pryor Mountains, Montana, USA, June

Diane McAllister / Wild stallion (Equus caballus) lying down in the sagebrush and yawning. The foothills south of Reno, Nevada, USA, May.

Kristel Richard / Close-up of the eye of a tobiano Kathiawari stallion, Gujarat, India.

Carol Walker / Summerland Beach, Ojai, CA, horse, purebred bay Azteca stallion running in water