Ernie Janes / Domestic dog, Pointer on guard in cottage garden, Norfolk, UK, July 2008

Ernie Janes / Domestic dog, Pointer on guard in cottage garden, Norfolk, UK, July 2008

LYNN M. STONE / Portrait of female Doberman Pinscher sitting in yellow maple leaves, Illinois, USA

Nick Upton / Spanish mastiff guard dog (Canis domesticus) wearing a metal spiked carlanca collar to protect it from wolves, protecting a herd of sheep on pastureland above the Lakes of Covadonga, Asturias, Spain,...

Axel Gomille / Farmer with sheep dogs which guard the herd from wolves. Saxony, Germany, June 2015.

Ashley Cooper / Sheep dog wearing nail studded collar for protection from wolves. Picos de Europa National Park, Spain, June 2005

Florian Möllers / Malinois or Belgian Shepherd dog 'Floyd', an 18 months male, a future guard dog with the German police, playing in the snow. Germany

Florian Möllers / Malinois or Belgian Shepherd dog 'Floyd', an 18 months male, a future guard dog with the German police, playing in the snow. Germany

Philippe Clement / Military attack dog, Belgian Shepherd Dog / Malinois (Canis familiaris) biting man in protective clothing during training session of the Belgian army, Belgium

Florian Möllers / Guard Dog (Canis familiaris) in front of a farm in Zhouzhi Nature Reserve. Shaanxi, China, October.

LYNN M. STONE / Doberman Pinscher leaping over agility fences, Illinois, USA

LYNN M. STONE / Head portrait of Doberman Pinscher, with cropped ears, sitting on grassy stream bank, Illinois, USA

LYNN M. STONE / Head portrait of Doberman Pinscher, with cropped ears, sitting on grassy stream bank, Illinois, USA

LYNN M. STONE / Two female Doberman Pinschers, with cropped ears, sitting on grassy stream bank, Illinois, USA

LYNN M. STONE / Portrait of Doberman Pinscher lying in fallen maple leaves, Illinois, USA

Wild Wonders of Europe / Widstrand / Domestic sheep grazing with dog keeping guard, Parque Natural Hoces del Rio Riaza, Monejo de la Vega, Segovia, Spain, March 2009

Mark Taylor / Border Collie bitch, Bliss, snarling in a car.

Nick Upton / Domestic Dog (Canis familiaris) with feral pigs (Sus scrofa domestica), helping to guard and round up piglets, NE Greece.

Colin Seddon / Man training Belgian shepherd / Malinois dog to attack, trainer wearing padded protective clothing, UK

Colin Seddon / Man training Belgian shepherd / Malinois dog; trainer wearing padded protective suit, UK

Colin Seddon / Man training Belgian shepherd / Malinois dog to attack, trainer wearing padded protective suit, UK

Colin Seddon / Doberman dog peering over kennel fence {Canis familiaris} Scotland, UK

Shattil & Rozinski / Black tailed prairie dog standing on guard near burrow {Cynomys ludovicianus} Colorado, USA

Pete Cairns / Shepherd with Cuvac breed sheepdog to guard sheep, Slovakia.

Tom Vezo / Black tailed prairie dog on guard {Cynomys ludovicianus} Mexico

Mitsuaki Iwago / Domestic Dog (Canis familiaris) with security guard

Yves Lanceau / Domestic dog, Rottweiler, man training two dogs to attack

Doug Gimesy / Member of Cheetah Conservation Botswana (Phale Seele) chatting with local goat farmers and guard dog recipients from Cheetah Conservation Botswana, Mr Andrew Molatole (middle) and Mr Ofeletse Thaushe...