As dogs age, their nail color often changes from pink to a dark brown or black shade. This is a natural part of the aging process and not necessarily a cause for concern. However, sometimes abnormal nail discoloration can signal an underlying health issue. The purpose of this article is to provide a comprehensive overview of why dogs’ nails may turn black as they get older. We will examine the anatomy of dog nails, what’s normal versus abnormal, causes of dark nail discoloration, breed differences, potential health implications, grooming considerations, and other nail color changes.
Anatomy of Dog Nails
A dog’s nails, also called claws, are complex structures composed primarily of a protein called keratin (https://pawsafe.com/blogs/claw-care/dog-toenail-anatomy). Keratin is the same fibrous structural protein that makes up hair, horns, feathers, hooves, and skin in animals. The nail consists of a visible portion protruding from the fur and an embedded portion within the toe.
The visible part contains several distinct sections. The hard outer layer that makes contact with the ground when the dog walks is called the nail sheath or nail capsule. Underneath this is a softer section called the nail bed which contains blood vessels and nerves. The blood supply in the nail bed is what causes bleeding if the nail is cut too short. At the base where the nail emerges from the toe is the cuticle or quick – the area with the highest concentration of blood vessels and nerves (https://www.dreamstime.com/illustration/dog-nail-anatomy.html).
The embedded inner part of the nail contains the nail root where new keratin is produced and extends into the bone within the toe. This part anchors and supports the visible nail structure above it.
Puppy Nails
The nails of newborn puppies are soft and colored pale white to light pink. This light color is due to the Lack of keratin and pigment in the nail beds of puppies [1]. As puppies grow older and more active, their nails begin to harden and take on pigment from the skin around the paw pads. The nails typically start to darken at 3-8 weeks of age, changing to black, brown, or yellow-tan color depending on the breed [2].
The growth rate of puppy nails is quite rapid, almost 2-3 times as fast as adult dogs. This fast growth is due to the high activity levels and metabolism of puppies as they explore their surroundings. It’s important to trim puppy nails regularly, such as once a week, to keep them neatly trimmed and prevent issues. Overgrown nails in puppies can lead to pain, bad posture, and other orthopedic problems if left untrimmed [3].
Adult Dog Nails
A dog’s nails are typically fully grown and at their darkest color by the time they reach adulthood, which is around 12-18 months old depending on the breed. Adult dogs have thicker, harder nails than puppies. The nail color can range from light to dark, but black or dark brown are the most common healthy adult nail colors.
As a dog ages, their nails may gradually turn more black. This is partly due to thickening of the nail and slower nail growth. The nails lose moisture and become more brittle over time. Exposure to ground surfaces when walking can also make them darker. Thick, black nails are normal in senior dogs. However, severely brittle, splitting, or crumbling nails can indicate an underlying health issue.
Causes of Black Nails in Dogs
There are a few potential causes that can lead to black nails in dogs:
Melanin Deposits
One common reason dogs can develop black nails is from melanin deposits in the nail bed. Melanin is the pigment that gives skin, hair, and nails their color. As dogs age, their bodies can produce more melanin which leads to darkening of the nail over time (Source).
Bruising/Injury
Trauma or injury to a nail can also cause it to turn black. If a dog’s nail gets cracked, broken, caught on something, or injured in another way, it can cause bleeding under the nail. As this blood dries and scabs over, it leaves a black/brown discoloration in the nail (Source).
Nail Bed Disease
Certain nail diseases like nail bed tumors or infections can also lead to blackening of the nails. Fungal infections, in particular, can cause the nail to thicken, crumble, and turn dark in color (Source).
Breed Differences
Certain dog breeds are more prone to having black nails than others. Breeds with predominantly black coats, like the Rottweiler, Great Dane, and Black Russian Terrier, often have black nails as well. The pigment that causes a dog’s black fur also causes black nails in these breeds.
According to The Labrador Site, “Dogs with dark coats and black nails such as Rottweilers, Giant Schnauzers, and Black Russian Terriers are disproportionately more affected than light coated dogs like Labradors and Golden Retrievers.”
Lighter coated breeds like Labrador Retrievers, Golden Retrievers, German Shepherds, and Siberian Huskies usually have lighter nails. However, they may still get black nails as they age due to internal pigmentation changes.
According to Quality Dog Resources, other breeds prone to black nails include:1
- Great Danes
- Saint Bernards
- Dalmatians
- Chow Chows
- Poodles
- Cocker Spaniels
- Portuguese Water Dogs
Health Implications
There can sometimes be a link between black nails and underlying disease in dogs. According to PawSafe, dark nail discoloration is often caused by bruising, internal bleeding, or trauma under the nail. This bruising usually occurs due to injury, but it can also be a sign of health conditions like thyroid disease, diabetes, Cushing’s disease, or autoimmune diseases.
If your dog develops black nails suddenly, especially if the discoloration is accompanied by other symptoms like limping or licking at the paws, it’s a good idea to get them checked out by a vet. A veterinarian can rule out underlying illness as the cause of the nail discoloration through a physical exam, bloodwork, urinalysis, and other diagnostic tests. According to Southwest Journal, you should contact your vet promptly if your dog develops unexplained black nails to get proper diagnosis and treatment if needed.
Grooming Considerations
Trimming black dog nails requires extra care and attention. The quick, which contains the blood vessels and nerves, is difficult to see in black nails. Going too short can cause pain and bleeding. When trimming black nails, go slowly and look for clues:
- Trim off smaller amounts at a time.
- Watch for a gray oval shape in the center, which may indicate the quick.
- Feel for a bumpy or rough texture, signaling the start of the quick.
- Notice when the nail gets moist, suggesting close proximity to the quick.[1]
If bleeding occurs from cutting the quick, use styptic powder or cornstarch to stop it. It’s better to trim little by little, cautiously avoiding going too short.
For overall nail health, trim nails regularly every 2-3 weeks. Provide scratching posts and textured surfaces to help wear down nails. Daily walks on pavement also help keep nails short. Avoid letting nails get too long, which can cause injury and pain. With patience and practice, black nails can be trimmed safely and kept healthy.[2]
Other Nail Color Changes
In addition to black nails, there are other nail color changes that can occur in dogs:
White Nails
Some dogs naturally have white or light-colored nails. Breeds like the Samoyed and West Highland White Terrier typically have white nails. A dog can also develop white nails as a result of aging, which causes the nails to thicken and become opaque over time. Vitamin and mineral deficiencies may also cause nails to turn white.
Splitting/Cracking
As a dog ages, their nails may start to crack or split. This happens as the nails become more brittle. Injury or trauma to the nails can also cause splitting and cracking. Keeping the nails trimmed regularly can help prevent cracking from getting worse. See a vet if the splitting causes pain or bleeding.
Summary
In summary, dogs’ nail color can change naturally as they age. Puppy nails start out transparent or pinkish and gradually darken over their first year, eventually turning black or dark brown in adulthood. This darkening is caused by increased melanin production and keratin buildup in the nail. Certain breeds such as Poodles and terriers tend to retain lighter nail colors throughout life. While some blackening is normal, reddish-brown, yellow, or brittle nails may indicate underlying health issues like infections, inflammation, or nutritional deficiencies. Make sure to regularly trim and inspect your dog’s nails, and consult your vet if you notice any abnormal changes. Providing proper nutrition with vitamins and minerals can help maintain healthy nail color. With good care, nail discoloration is usually harmless in aging dogs.
In summary, while darkening nails are a normal part of aging, abnormal color changes may warrant a veterinary exam. Dog owners should regularly inspect and trim their pet’s nails, providing a nutritious diet to help keep the nails strong and healthy. Though nail darkening is mostly an aesthetic concern, it can also clue owners into potential health issues that need veterinary attention.
