Nail Diseases in Dogs and Cats

Just like your nails, a dog or cat’s claws can break or become infected.

They can also be affected by internal issues, such as nutritional deficiencies or autoimmune diseases.

There are a lot of different kinds of nail problems in dogs and cats, but we’ve summarized some of the most common issues for you here.

Important Note: Because a lot of nail diseases look alike, it is very important to have your veterinarian check your pet’s feet to make sure you know exactly what the cause of their problem is and can treat it appropriately.

Nail Structure and Function

Claws in dogs and cats grow from the outermost segment (known as the third phalanx) of the toe. They are made of keratin, a type of protein, with a central core that contains blood vessels and nerves (also known as the quick).

Nail growth originates from a deep area of the claw called the coronary band, and damage to the coronary band can affect claw growth permanently. Claws are important for movement, gripping with the feet, and for self-defense.

Keeping your pet’s nails trimmed properly is important for good paw health and normal movement. They grow fairly slowly at around 0.7 to 2.1mm per week, so it can take up to 6–8 months after any damage for the nail to return to normal.

We use the terms "nail" and "claw" interchangeably. Essentially, they are the same thing, but in veterinary medicine the "claw" refers to the entire nail and bone structure. Usually, the nail refers to the part that we see extending out from the paw pad.

Common Pet Nail Issues and Diseases

Trauma and Injuries

Trauma is the most common cause of claw disease in dogs and the second most common in cats.

It can occur by running into or kicking a hard surface, catching the claw and pulling it partially or entirely off, or breaking part of it. Usually, when this happens, only one or two toes are affected. When the quick of the nail (visible in white nails as per the photo below) is involved in an injury, your pet’s toe can bleed a lot.

If your pet’s nail is damaged in an injury, this can be quite painful and you should bring them to a veterinarian as soon as possible.

Your veterinarian may want to remove some portions of the damaged nail for your pet’s comfort, and they could recommend X-rays of your pet’s foot if they think that parts of their toes have also been injured.

If only the nail was involved, your pet may go home with pain medications and a bandage to protect the area, and potentially antibiotics if your veterinarian is worried about infection. They will likely recommend that your pet not walk around too much for a few days to help with healing, and your pet will usually be back to normal within a week or so. If your pet’s claw needs to be completely removed, it will grow back over time, but your pet may be sensitive when that toe is touched for several weeks until the quick is protected again.

Read more on how to keep your dog occupied if they need crate rest during the healing phase.

As the nail grows back, it may be twisted or thickened for a time due to damage to the base of the nail. It will often return to normal over time, but keeping any twisted nails short by regular trimming will stop them from catching on each other or the environment while they heal.

Bacterial and Yeast Infections

Dogs and cats can develop bacterial and yeast infections that affect the skin on the base of their nails. This leads to redness and swelling of the nail base tissue, crusting at the base of the nail, red-brown staining on the nails themselves, and sometimes the affected nail can fall off.

Most often, multiple nails are affected on the same paw, and usually, multiple paws are affected. The affected paws can be uncomfortable and itchy, and your pet may try to lick or chew the area.

Usually, bacterial and yeast infections of the feet occur due to an underlying problem making the skin abnormal and less able to fight off infections. This can happen for lots of reasons, like injuries, allergies, or hormonal diseases that suppress the immune system (such as diabetes, low thyroid levels, or Cushing’s disease).

Bacteria and yeast are present on your pet’s skin all the time in small amounts, but they can multiply and develop into an infection when the skin is abnormal. However, bacteria and yeast will not infect the claws themselves, just the skin around them.

If you notice signs of a possible infection on your pet’s paws, you should bring them to a veterinarian so they can check for an infection using a cytology. A cytology is a sample collected from your pet’s skin surface that is put onto a slide and examined under the microscope.

If your pet has bacteria or yeast on their skin, your veterinarian will be able to see it on a cytology. If an infection is present, your pet will likely be sent home with oral antibiotics or antifungal medications and potentially topical wipes or sprays.

It can take several weeks to resolve a surface infection and up to 4–6 months to treat a very deep infection in the claw base tissue. Once the infection is gone, any brown staining on your pet’s claws will slowly grow out, and you will be able to see normal colored claw tissue near the claw base.

Ringworm Infections

Ringworm is a fungal infection (called dermatophytosis) in dogs and cats that can invade the claws, causing them to become brittle, flaky, and break easily. It is rare that only your pet’s claws will be infected, so a pet with ringworm will usually also have crusting and hair loss in other areas of their body.

Your veterinarian will be able to check for a ringworm infection at your appointment with a Wood’s lamp, a special light that can detect strains of ringworm fungi. They can also send out samples for a genetic material test (called a PCR) and culture to confirm or rule out ringworm as the cause of your pet’s symptoms.

Ringworm is a zoonotic disease that can be transmitted from animals to humans.

Treating ringworm infections in the claws requires oral antifungal medication because topical sprays or soaks do not penetrate through the keratin well enough to kill the fungus in this area.

It can take several months for treatment to be complete, and your veterinarian will need to recheck samples at least twice to confirm that your pet’s treatment is successful. Their nails will likely take several months to return to normal even after they are finished with treatment, but ringworm infections generally do not cause lasting damage to your pet’s nails.

Autoimmune Diseases That Cause Nail Issues

Symmetric Lupoid Onychodystrophy in Dogs

Symmetric Lupoid Onychodystrophy, or SLO, is an autoimmune disease that attacks a dog’s claws specifically. It has no identified cause, though Gorden Setters and German Shepherds are more likely to develop this condition. It can occur in any dog breed and most often affects young to middle-aged pets.

Aside from their feet, dogs will be healthy — SLO does not affect internal organs or cause illness in other parts of the body. Often, SLO will cause nails to break easily or start to flake off in pieces.

Pets can become lame (limp) and lick their affected toes due to discomfort from nail breakage. When the nails regrow after breaking, they will be short, brittle, thickened, and discolored. Over time, SLO will affect all four paws in most pets, and pets can develop secondary bacterial infections because their nail structures are abnormal and their nail bases are inflamed. If an infection develops, dogs will often have pus, crusting, and swelling at the base of their claws.

SLO is generally diagnosed by a veterinary dermatologist or your primary veterinarian based on your pet’s history and physical exam. The only way to confirm that your pet has SLO is to remove the end of one of their toes and biopsy it, but this is a major surgery, so it usually isn’t viewed as necessary by most veterinarians to diagnose this condition.

If your dog is diagnosed with Symmetric Lupoid Onychodystrophy, they will need medication for the rest of their lives. Most often, veterinarians prescribe pentoxifylline, a drug that improves blood flow, and sometimes stronger immunosuppressive medications are necessary.

Your vet may add fatty acid supplements to help with nail strength and reduce inflammation. They will also need to treat any bacterial infections to help your pet’s nails heal. The goal in successful treatment is that your dog’s nails will slowly grow back normally, and they won’t break off easily. Your pet will often start to show improvement within 2–3 months, but it can take a year or more for their nails to heal completely.

Pemphigus Foliaceus in Cats

Pemphigus foliaceus is an autoimmune disease that affects the cells on the upper layers of the skin. In cats, especially, it can cause crusting, pus, swelling, and redness at the bases of the claws and, in some cases, can even cause the claws to fall off.

Cats with pemphigus foliaceus usually have crusting on other parts of their bodies as well, including the nose, ears, and belly. They can also sometimes have lower energy or a fever due to the amount of inflammation in their bodies from this condition.

Your veterinarian can diagnose pemphigus foliaceus by collecting tissue samples for a biopsy evaluation. Once your cat has been diagnosed, they will need to start immune suppressive drugs to control their inflammation. Your cat will likely need medication for the rest of their lives to control this condition, but pemphigus foliaceus is generally successfully controllable with treatment.

Nutritional Deficiencies in Dogs and Cats

Dogs and cats that eat AAFCO-approved diets are rarely affected by nutritional deficiencies because these diets are balanced in the vitamins and minerals that your pet needs. However, home-cooked diets require additional supplementation to prevent deficiencies.

Sometimes, pets also don’t absorb nutrients correctly from their diets, which can lead to deficiencies even when eating a balanced diet.

Most commonly, claws can become brittle and fragile due to a lack of fatty acids, protein in the diet, or minerals involved in keratin formation (including copper, zinc, biotin, calcium, and selenium). Your veterinarian will be able to help you determine if this is the case with your dog or cat and may recommend a consultation with a veterinary nutritionist if your pet is eating a home-cooked diet.

How the nutritional deficiency is treated depends upon what is missing from your pet’s foods. Fatty acid deficiencies are usually treated with a fatty acid supplement, such as Welactin from Nutramax (fish oil for dogs and for cats).

A diet that is too low in protein can be fixed by adding additional protein sources (lean meat, beans, or eggs) into your pet’s diet. If your pet’s diet is too low in essential minerals, your veterinarian can recommend an appropriate vitamin supplement to add to your pet’s daily routine.

In summary, there are a lot of different causes for your pet’s claws to change colors, break off, or become crusted, red, or swollen. Your veterinarian can assist you in finding out the cause of your pet’s nail issues and help them feel better as soon as possible.