Roland Seitre / Tibetan wild ass (Equus kiang) in snow. Captive at Moscow Zoo breeding station. Occurs on the Tibetan plateau..

Kristel Richard / Wild Mongolian mare and her foal trotting, plains at the foot of Dungurukh Uul mountain, near the border with China and Kazakhstan, Bayan-Olgiy aymag, Mongolia. September.

Terry Whittaker / Bay Icelandic horse trotting in the snow, Snaefellsnes Peninsula, Iceland, March.

Kristel Richard / A herd of Retuerta mares trotting, Guadiamar scientific reserve, Donana National Park, Andalusia, Spain. This breed of horse was close to extinction in the 1990s with only 5 individuals left, but now...

Carol Walker / Lusitano horse, grey stallion trotting, Portugal

Carol Walker / Lusitano horse, grey stallion trotting, Portugal

Kristel Richard / A purebred Lusitano colt (with his mane and tail cut to mark his first year) trotting in the arena at the Companhia das Lezírias Stud Farm, Samora Correia, Santarém, Portugal, July 2011

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

Sergey Gorshkov / Aerial view of Caribou / Reindeer (Rangifer tarandus) trotting through shallow water, Kamchatka, Far east Russia, August

Charlie Summers / Mustang (Equus caballus) herd trotting in light snow covered prairie, IRAM Wild Horse Sanctuary south of Hot Springs, South Dakota, USA, May

Kristel Richard / A Khampa warrior leads his Tibetan horse towards the start of the race, during the horse festival, near Huangyan, in the Garze Tibetan Autonomous Prefecture in the Sichuan Province, China, June 2010

Laurent Geslin / Group of Wild Boar (Sus Scrofa) trotting through forest of Rambouillet, near Paris, France. Autumn.

Kristel Richard / A Shagya Arab stallion (Equus caballlus) is shown in hand in the courtyard of the Babolna Arabian Stud, Babolna, Komarom-Esztergom, Hungary.

LYNN M. STONE / Domestic horse, Arabian Horse trotting through brushy meadow, Fort Bragg, California, USA

Carol Walker / Purebred grey Andulasian stallion carriage horse, high trotting, Carriages Exhibition, Seville, Spain

Carol Walker / Purebred leopard appaloosa horse running in snow, Flitner Ranch, Shell, Wyoming, USA

Carol Walker / Purebred black Friesian stallion doing passage, Ojai, California, USA,

Carol Walker / Mustangs / Wild horses, stallion and mare trotting, Return to Freedom Sanctuary, Lompoc, California, USA

Carol Walker / Leopard appaloosa horse running in the snow at Flitner Ranch, Shell, Wyoming, USA

Carol Walker / Wild Horse / Mustang, pinto stallion running, McCullough Peaks Herd Area, Cody, Wyoming, USA

Carol Walker / Purebred Friesian gelding trotting out of the sea, Summerland Beach, Ojai, California, USA

Carol Walker / Bay Azteca stallion (Andalusian and Quarter Horse cross) trotting onto beach from waves, Summerland Beach, Ojai, California, USA

Carol Walker / Cowboy on sorrel Quarter horse trotting in the snow at Flitner Ranch, Shell, Wyoming, USA Model released

Carol Walker / Cowboy on grey Quarter horse trotting in the snow at Flitner Ranch, Shell, Wyoming, USA Model released

Carol Walker / Leopard appaloosa horse running in snow, Flitner Ranch, Shell, Wyoming, USA

Carol Walker / Silhouette of cowboy trotting at sunset, Flitner Ranch, Shell, Wyoming, USA Model released

Carol Walker / Silhouette of cowboy trotting, swinging a loop at sunset, Flitner Ranch, Shell, Wyoming, USA Model released

Carol Walker / Purebred black Friesian stallion trotting, Ojai, California, USA

Carol Walker / Bay Andalusian stallion trotting in paddock, Ojai, California, USA

Carol Walker / Black Friesian gelding trotting in field, Longmont, Colorado, USA

Carol Walker / Black Friesian gelding trotting in field, Longmont, Colorado, USA

Carol Walker / Black Friesian gelding trotting in field, Longmont, Colorado, USA

Anup Shah / Male African lion {Panthera leo} trotting across his territory to see of an intruder, Masai Mara GR, Kenya. Lions can run at speeds of 50mph!

Pete Oxford / Warthog (Phacoecerus aethiopicus) running at sunset, Savuti channel, Botswana, Southern-Africa

Anup Shah / Two Simien jackals / Ethiopian wolf {Canis simensis} Bale Mountains, Bale NP, Ethiopia

LYNN M. STONE / Appaloosa horse trotting through snow {Equus caballus} USA.

Anup Shah / Common zebra running {Equus quagga} Masai Mara, Kenya East Africa.

Tony Heald / Chestnut Arabian horse trotting. Namibia.

Tony Heald / Arabian horse, female and foal trotting one behind the other. Namibia.

Tony Heald / Arabian horse, foal trottting. Namibia.

Tony Heald / Arabian horse, foal trotting. Namibia.

Carol Walker / Percheron draft horse, four trotting through snow. February.

Cyril Ruoso / Przewalski horse (Equus ferus przewalskii), three including female and foal silhouetted at sunset. Great Gobi B Strictly Protected Area, Mongolia. August.

Cyril Ruoso / Przewalski horse (Equus ferus przewalskii). Reintroduced in 1992, Great Gobi B Strictly Protected Area, Mongolia. August.

Kristel Richard / 6 month old UVM Morgan horse foals trotting in a paddock, at the historical stud University of Vermont Morgan Horse Farm, Weybridge, Vermont, USA

Nick Upton / Red fox (Vulpes vulpes) cub exploring woodland. Near Bath, England, UK. May.

Mark Taylor / Black Labrador dog, age 6 months, trotting.

Tony Heald / African wild dog (Lycaon pictus) walking through grassland with radio collar showing. Mana Pools National Park, Zimbabwe.

Kristel Richard / Rare semi-wild Hmong horse, stallion, trotting in dry rice field, Xieng Khuang, Laos.

Kristel Richard / Wild rare Eriskay horse, stallion, trotting on Holy Isle, Scotland, UK. Critical status by Rare Breeds Survival Trust.

Kristel Richard / Man riding a Trocha mare in trot, Rionegro, Antioquia, Colombia.

Mark Hamblin / Red Deer stag (Cervus elaphus) trotting through snow-covered pine forest , Cairngorms National Park, Scotland, UK. December.

Kristel Richard / Canadian Horse mare and her colt / foal trotting in a field, at Upper Canada Village Museum, Morrisburg, Ontario, Canada. Critically Endangered horse breed.

Kristel Richard / Two Canadian Horse mares and theircolt/foal trotting in front of 18th century buildings, at Upper Canada Village Museum, Morrisburg, Ontario, Canada. Critically Endangered horse breed

Carol Walker / Wild bay roan Mustang stallion trotting in Adobe Town Herd Area, Wyoming, USA. October.

Carol Walker / Wild bay Mustang stallion trotting in Adobe Town Herd Area, Wyoming, USA. October.

Carol Walker / Wild Mustang chestnut bachelor stallion trotting in Adobe Town Herd Area, Wyoming, USA. June.

Roland Seitre / Tibetan wild ass (Equus kiang) two walking side by side in snow. Captive at Moscow Zoo breeding station. Occurs on the Tibetan plateau..

Roland Seitre / Tibetan wild ass (Equus kiang) mother and baby trotting. Captive, occurs on the Tibetan Plateau.

Orsolya Haarberg / Man training horse on trotting track. Klaebu, Sor-Trondelag, Norway. October 2013.

Orsolya Haarberg / Man training horse on trotting track. Klaebu, Sor-Trondelag, Norway. October 2013.

Orsolya Haarberg / Man training horse on trotting track. Klaebu, Sor-Trondelag, Norway. October 2013.

Will Watson / Grey coloured Welsh Pony (Equus caballus) trotting, Herefordshire, England. July 2014.

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

Kristel Richard / A pure Arab mare and her foal trotting. Marbach National Stud, Swabian Alps, near Reutlingen, in Baden-Wurttemberg, Germany, May.

Kristel Richard / A member of Marbach's Quadrille team in traditional uniform, mounted on a Wurttemberg horse, performing during the stud's 500th anniversary celebrations. Marbach National Stud, Swabian Alps, near Reut...

Kristel Richard / Marbach riders in traditional uniform, riding Wurttemberg stallions during the stud's 500th anniversary celebrations. Marbach National Stud, Swabian Alps, near Reutlingen, in Baden-Wurttemberg, German...

Kristel Richard / Marbach's Quadrille in traditional uniform, mounted on Wurttemberg horses, performing during the stud's 500th anniversary celebrations. Marbach National Stud, Swabian Alps, near Reutlingen, in Baden-W...

Kristel Richard / Marbach's Quadrille in traditional uniform, mounted on Wurttemberg horses, performing during the stud's 500th anniversary celebrations. Marbach National Stud, Swabian Alps, near Reutlingen, in Baden-W...

Kristel Richard / Marbach's Quadrille in traditional uniform, mounted on Wurttemberg horses, performing during the stud's 500th anniversary celebrations. Marbach National Stud, Swabian Alps, near Reutlingen, in Baden-W...

Kristel Richard / Marbach's Quadrille in traditional uniform, mounted on Wurttemberg horses, performing during the stud's 500th anniversary celebrations. Marbach National Stud, Swabian Alps, near Reutlingen, in Baden-W...

Kristel Richard / Members of Marbach's Quadrille team in traditional uniform, mounted on Wurttemberg horses during the stud's 500th anniversary celebrations. Marbach National Stud, Swabian Alps, near Reutlingen, in Bad...

Kristel Richard / Marbach staff in traditional uniform driving four Wurttemberg stallions during the stud's 500th anniversary celebrations. Marbach National Stud, Swabian Alps, near Reutlingen, in Baden-Wurttemberg, Ge...

Roland Seitre / Pale fox / African sand fox (Vulpes pallida) trotting at night, Mali.

Roland Seitre / Dingo (Canis lupus dingo) Birdsville, Queensland.

Mark Taylor / Yellow Labrador Retriever pup, age 3 months, trotting forward.

Nick Garbutt / African wild dog / Painted hunting dog (Lycaon pictus). South Luangwa National Park, Zambia.

Kristel Richard / Wild, rare Cumberland foal trotting on the beach, Cumberland Island, Georgia, USA. November.

Lou Coetzer / Young Sable antelope (Hippotragus niger) bull trotting, Chobe River, Botswana, October.

Kristel Richard / Noriker filly / foal trotting in a mountain pasture, St Oswald, Carynthia, Austria, September.

Tom Gilks / Pony pulling couple on a trotting cart, Appleby, Yorkshire

Kristel Richard / Four Franches Montagnes / Freiberger (Equus caballus) stallions trotting in heavy rain at the National Stud of Avenches, Vaud, Switzerland, July.

Kristel Richard / A Franches Montagnes / Freiberger (Equus caballus) stallion trotting in heavy rain at the National Stud of Avenches, Vaud, Switzerland, July.

Laurent Geslin / Roe deer {Capreolus capreolus} male trotting across snow, Switzerland, February

Laurent Geslin / Roe deer {Capreolus capreolus} female trotting across snow, Switzerland, February

Laurent Geslin / Trotting horses, France

Laurent Geslin / Simien jackal running {Canis simensis} Bale Mts NP, Ethiopia, 2004 Ethiopian wolf

Igor Shpilenok / Female Reindeer (Rangifer tarandus) with her calf, trotting by water. Kronotsky Zapovednik Nature Reserve, Kamchatka Peninsula, Russian Far East, June.

Carol Walker / Wild horse / mustang called Cremosso, rounded up from McCullough Peak herd in Wyoming and adopted by photographer Carol Walker. Trotting in his corral, Colorado, USA.

Carol Walker / Wild horse / mustang called Mica, rounded up from Adobe Town Herd Management Area in Wyoming and adopted by photographer Carol Walker. Walking in pasture, Colorado, USA.

Tony Heald / African Wild Dog (Lycaon pictus) trotting profile, Mana Pools National Park, Zimbabwe, October 2012

Will Watson / Herd of Fallow deer (Dama dama) fawns trotting with a backdrop of English oaks (Quercus robur), Attingham Park, Shropshire, England, UK, November

Will Watson / Herd of Fallow deer (Dama dama) fawns trotting with a backdrop of English oaks (Quercus robur), Attingham Park, Shropshire, England, UK, November

Will Watson / Male Fallow deer (Dama dama) trotting, with mature Oak (Quercus robur) woodland in the background, captive, Attingham Park, Shropshire, England, UK, November

Will Watson / Male Fallow deer (Dama dama) trotting, with mature Oak (Quercus robur) woodland in the background, captive, Attingham Park, Shropshire, England, UK, November