A cat’s claws are an amazing part of the anatomy which performs a number of important functions. Located at the end of each toe, these scythe-shaped appendages are used to help the cat climb trees, balance, gripping prey, defend against attacks from other animals, and assist with grooming and protects the toes (digits).
The claws are continually growing, with the outermost layer sloughing off every few weeks to make way for a newer, sharper claw.
Cats have five digits on each front foot and four digits on the hind feet. The claws on the front feet are retractable. Some cats have extra toes, usually on the front feet. This is known as polydactyly.
Epidermis – The tough outer layer of the claw made up of a protective protein called keratin. This outer layer of the claw is known as the coronary horn, nail plate or shell.
Dermis – Also known as the ‘quick‘, this soft inner layer of the claw which is made up of capillaries, glands, and nerves. You may be able to see the pink dermis through the epidermis.
Unguicular pleat – Surrounding the claw is a modified skin known as the unguicular pleat. This fold of cornified skin circles the upper claw.
The Greek word for nail is ‘onyx’, and you will see in this article that many claw disorders start with the letters onych to reflect this. Claw disorders are thankfully quite rare in cats.
What are the causes of claw disorders in cats?
There are a number of causes, ranging from mild (improperly trimmed claw) to cutaneous manifestations of serious systemic disorders. Thankfully most nail disorders are more painful than serious.
Trauma – This is the most common nail disorder seen in cats and can occur in a number of ways. Torn claws are common in cats, which can be caused by nail trimming, accidents, a claw becoming caught while stropping, car accidents, scrambling away from and tri predator.
Signs of trauma may include shortened or jagged claws, bleeding, swelling, pain, reluctance to put weight on one leg.
Treatment depends on the severity of the trauma but may include cleaning and trimming the affected area, bandaging and possibly antibiotics to prevent a secondary bacterial infection.
Bacterial infection – This is the most common claw disorder seen in cats and has a multitude of causes including declawing complications, the nail becoming trapped and pulled as the cat tries to free it. As trauma often exposes the underlying tissue, bacteria can invade and cause infection. Single nails are most commonly affected.
Symptoms of bacterial infection include inflammation of the matrix of the nail (onchyitis), pain, swelling, and discharge.
Bacterial infections are treated with long-term antibiotics.
Onychocryptosis – This is the medical term for ingrown nails and can develop in older cats, particularly those who live indoors. As cats age and become less active, there is less wear and tear on the claws. Arthritis is common among older cats too, which can sometimes make grooming and stropping, which strips off the outer layer of the claw difficult due to painful joints. The claws become thickened and curl in on themselves. The front claws are most commonly affected.
Treatment is aimed at keeping the claws at a reasonable length by regular trimming. If you are unable to trim your cat’s claws yourself, see a veterinarian, it should only take him 5 minutes to do in-house at minimal cost.
Onychorrhexis – Brittle claws are another complaint seen in older cats often in conjunction with overgrown claws. As cats age, their circulation isn’t as good as it once was and fewer nutrients reach the claw. Brittle and overgrown claws can eventually grow into the paw pad causing pain and infection.
Brittle claws can split when they are cut, so very sharp nail cutters should be used when trimming claws as thick and brittle nails are more prone to being crushed and splintering when trimmed.
Onychomycosis(fungal infection) – Dermatophytosis or ‘ringworm‘, is a highly infectious fungus can affect any part of the body including the claws. Dermatophytosis can affect any cat, although it is seen more often in kittens, senior cats, and immunocompromised cats.
Multiple areas can be affected, producing circular patches of hair loss with a slight reddening of the affected skin. The claws may become weak, crusty, malformed (onychodystrophy) or soft (onychomalacia). The adjacent skin may also be affected.
There are a number of medications which can be used to treat ringworm, including Itraconazole, Griseofulvin, and Terbinafine, which are all tablets. Your veterinarian may also recommend lime sulfur dips.
Malassezia is another fungus which lives on the skin of many cats without causing a problem. In some cats who are immunocompromised, the fungus may no longer be kept in check and can produce symptoms of infection such as areas of hair loss, swelling of the chin and if the claws are affected, greasy exudate around the claws, paronychia.
Treatment of Malassezia may include weekly baths in Malaseb, or in more stubborn cases topical or oral therapy with ketoconazole, itraconazole or fluconazole. Finding and treating the underlying condition should also be carried out.
Demodicosis – Is a skin disease caused by the Demodex mite. It is seen more often in dogs but can affect cats too, especially malnourished or immunocompromised animals.
Symptoms of demodicosis include single or multiple lesions of alopecia, hyperpigmentation of the skin on the toes, and a thickening and curvature of the claws (onychogryphosis).
Demodicosis often resolves on its own without treatment. However, your veterinarian may decide to treat your cat with lime sulfur dips or Ivermectin to kill the mites.
Pemphigus – An autoimmune disorder where the cat’s own immune system attacks epidermal adhesion molecules causing them to separate. This condition has a number of clinical presentations and can affect multiple parts of the body including the claws and surrounding tissue.
Symptoms of pemphigus affecting the claws include small red spots and areas of hair loss around the claws followed by fluid-filled blisters which rupture to form a yellowing crusting erosion.
Treatment of pemphigus includes immunosuppressive therapy such as cortisone, if this doesn’t relieve symptoms other medications may be added. Oral antibiotics may also be prescribed to treat secondary bacterial infections.
Systemic Lupus Erythematosus – Another autoimmune disorder in which antibodies are formed against certain tissues in the cat’s own body. Normally antibodies are produced in response to antigens such as bacteria or viruses. The cause isn’t known but it is thought it could be genetic, environmental, due to medications or exposure to sunlight. Any part of the body can become affected including the claws and surrounding tissues.
Symptoms of SLE include yellow exudate around the claw folds, paronychia (inflammation of the soft tissue around the claw) and areas of hair loss.
There is no cure for SLE, treatment includes immunosuppressive therapy such as corticosteroids. These will initially be given at a high dose and once the condition is under control the dosage will be tapered down. Non-steroidal anti-inflammatory drugs may be given to reduce inflammation and treat pain. Antibiotics may also be prescribed to treat secondary infection. Limiting sunlight exposure may also be necessary.
Acromegaly – Also known as ‘pituitary gigantism’, acromegaly is a disease caused by a benign tumour of the pituitary gland, which results in excess growth hormone being produced. Middle-aged to older cats are most at risk of developing this disease.
There are a number of symptoms of acromegaly, all relating to the excess growth hormone which leads to enlargement of the extremities, particularly the head, organ enlargement, heart failure, diabetes and a hardening and thickening of the claws.
Treatment for acromegaly is aimed at slowing down the progression of the disease which may include radiation therapy to shrink the tumour, medications to inhibit or reduce levels of growth hormone, controlling diabetes with insulin and managing heart failure.
Hyperthyroidism – This endocrine disorder is usually caused by a benign tumour of the thyroid gland which is responsible for the secretion of thyroid hormone, responsible for controlling metabolism. Cats 10 years and older are most often affected. Typical symptoms include weight loss despite an increased appetite, diarrhea, vomiting, poor coat condition, increased heart rate and in some cases a thickening of the claws.
Treatment of hyperthyroidism may involve surgery to remove the tumour, radioactive iodine treatment to kill the tumour or medications to control the disease.
Leishmaniasis – A zoonotic protozoal infection found in the Mediterranean and the Americas which causes skin or visceral organs. When the skin is affected, skin nodules develop on the face and extend along the rest of the body, including the feet, the claws may be overgrown, deeply curved (onychogryphosis) and brittle.
Treatment of leishmaniasis may include surgical removal of nodules or medication such as allopurinol.
Tumour – There are a number of tumours which can affect the digits and claws of cats including squamous cell carcinoma, fibrosarcoma, adenocarcinoma, melanoma, and hemangiosarcoma. The forelimb is more commonly affected than the hindlimb. Symptoms of tumours include swelling, pain, discolouration of the claw or toe, separation, sloughing of the claw or splitting of the claw and paronychia. Usually, only one digit or claw is affected.
Treatment of tumours is surgical removal, in some cases, the entire digit or foot may need to be amputated. Radiation or chemotherapy may be necessary after surgery.
Other less common causes of claw disorders include a food allergy, Cushing’s disease, hypothyroidism and vasculitis (inflammation of the blood vessels).
As you can see, there are a number of causes of claw disorders in cats. A single claw is usually due to trauma, or less frequently a tumour. If multiple claws are affected then a more systemic disease may be the cause.
What are the symptoms of claw disorders in cats?
I have made an attempt to summarise symptoms of the disorders listed, however, will include a brief summary here. Symptoms may vary depending on the cause of the nail disorder.
Paronychia – Inflammation of the tissue surrounding the claw.
Claw pain (onychalgia)
Licking at the feet
Swelling and/or redness
Torn shredded or damaged claws
Thickening of the claw(s)
Deformity on one or more nails
Sloughing off of one or more nails
How are claw disorders diagnosed?
Your veterinarian will perform a physical examination of your cat and obtain a medical history from you. He will carefully check the affected claw and surrounding tissue. The number of claws and feet involved can help your veterinarian to narrow down a cause. When one claw is affected, trauma is a likely cause, multiple claws and feet may indicate a systemic disease.
He may need to perform some diagnostic tests to determine the cause. This may include:
Bacterial and/or fungal culture
Further testing may be necessary to determine an underlying cause such as blood tests.
Caring for your cat’s claws:
Cats are fairly easy to care for, but a regular routine once a week can prevent some nail conditions developing, especially in older cats. Check the claws for signs of breakage and/or overgrowth and trim if necessary. Most cats only need to lose 1-2mm of the nail and be careful not to cut the quick, which contains blood vessels and nerves, making it extremely painful if it is cut into. I have always used human nail clippers on my cats which seem to work fine, but you can also purchase nail clippers designed for cats. Some have a circle which you place the tip of the claw inside and cut, this helps to reduce the chances of accidentally cutting into the quick.
Cats may benefit from the addition of omega-3 fatty acids to their food. These essential acids can help reduce inflammation and are great for skin nail and coat condition.
Provide your cat with a scratching post so that he can regularly strop his nails, which helps to remove the outer layer.