By Linda Cole
The Greyhound and Whippet are the fastest dog breeds, but other sighthounds aren’t far behind. The environments that sighthounds were originally bred to hunt in were wide open and expansive regions such as deserts which required a hound to have exceptional eyesight, agility and speed. But it’s the extraordinary vision of sighthounds that makes them unique among all other dog breeds.
What are Sighthounds?
Sighthounds are defined as a dog breed that hunts mainly by sight rather than scent. Their amazing speed, stamina and agility enable them to stay with their prey to keep them in sight. These “canine Ferraris” have been around for thousands of years and were selectively bred with a deep chest to support a large heart and lungs, a flexible back, long powerful legs and a lean body. A long slender head gives a sighthound stereoscopic vision for a full range of sight to detect movement. No part of the head interferes with their vision, so they can clearly focus on their prey.
Sighthounds differ in coat type, size and speed depending on the country of origin where they were developed. The terrain, climate and prey in a region were all taken into consideration. Early humans who bred these dogs were not concerned with appearance and focused only on the dog’s ability to see, chase and catch or detain prey until hunters arrived. What is common in all sighthounds is a long, narrow skull that gives them exceptional vision. They essentially have the same type of vision as prey animals. Predators normally have eyes at the front of the head which gives them better depth perception when stalking and pouncing on prey. Herbivores have eyes on the side of the head which gives them a greater field of view and helps them see predators. Sighthounds were developed with a herbivore field of view for a more specialized vision.
What makes the sighthound vision special is an area in the retina called a visual streak that is horizontally aligned with ganglion cells, which are neurons that transport visual information to the brain via the optic nerve. The visual streak has the highest concentration of cones, lowest concentration of rods and a small receptive field size. This area also has the sharpest focus. In humans the area is circular, but in prey animals it’s an elongated region, which allows these animals to detect the slightest movements in their peripheral vision and gives them a panoramic view of the ground. This is called a herbivore field of vision and it’s key to their survival because it helps them spot approaching predators from different directions and clearly see where they are going when fleeing from danger. While running, the elongated visual streak allows them to see out of the corner of their eyes to detect obstacles in their way as they twist and turn quickly over uneven terrain and jump over things as they try to avoid capture.
Because sighthounds have a herbivore field of vision, they can see the same panoramic view as prey animals. During a high-speed pursuit, they can keep their eyes on twisting and turning prey and see obstacles in their peripheral vision while navigating the uneven terrain. Panoramic vision allows sighthounds to search expansive landscapes watching for the slightest movement of prey.
The sighthound breeds were the first dogs developed with an elongated visual streak. They have better peripheral vision than most other dog breeds. Canines with pushed in noses, like Pugs or Bulldogs, have a field of vision of around 220 degrees, but most dog breeds have a field of vision of around 250 degrees. Sighthounds have a field of vision up to 290 degrees. The longer the nose of a dog, the better his field of vision.
Many of the animals that larger sighthounds were developed to hunt are fierce, agile, intelligent and speedy competitors. This includes powerful animals like wolves, lions, bears and wild boar, as well as fast prey such as gazelle, antelope and deer. Smaller sighthounds were used to hunt prey like hare and rabbits. Regardless of what a sighthound has in his sight, his extremely high prey drive kicks in and the dog can be out of view in an instant. Besides their incredible and unique vision, sighthounds also share a stubborn streak and an ability to think on their own. The explosive speed of these dogs quickly took them far away from their hunting owners. They needed to be able to think for themselves to make decisions and find their way back home after a chase.
According to genetic studies, sighthounds and ancient dogs are the first groups of canines most closely related to their wolf ancestors. The Saluki doesn’t look like a wolf, but this sighthound is one of the most ancient – if not the first – domesticated dog breed. Other dogs in the sighthound category include the Afghan Hound, Azawakh, Borzoi, Greyhound, Irish Wolfhound, Italian Greyhound, Scottish Deerhound and Sloughi.
If you have a sighthound, it’s important to provide him with a high quality dog food. CANIDAE makes a wide variety of delicious and nutritious formulas for all ages, breeds and sizes.
Read more articles by Linda Cole