Scabs and sores can be extremely uncomfortable to your cat, itching often accompanies sores, leading to further damage and the potential to develop a secondary bacterial infection. So it is important you have your cat seen by a veterinarian to determine the underlying cause and a treatment plan.
Initially, some irritations may be minor and the cat himself causes further damage due to itching, other disorders may cause large lesions. Scabs may be small and numerous, large and singular or a combination of both. The neck may be the only affected area or scabs and crusting may be more widespread. Itching is common but not always present.
Below are the most common causes of scabs on your cat's neck.
Flea allergy dermatitis
Probably the most common cause of scabs and sores on the cat is caused by a flea allergy. Many cats can develop a sensitivity to the proteins in the flea's saliva. It is quite commonly believed that if you don't see fleas on your cat he doesn't have them, but just one flea can be enough to cause an immune reaction.
Symptoms of flea allergy dermatitis include crusty lesions particularly around the neck and on the back, close to the tail. Itching and scratching accompany sores and scabs. Scratching can damage the skin resulting in the formation of coin-sized scabs.
Treatment of flea allergy dermatitis is diligent flea control as well as treating the environment.
Flea collar allergy
Some cats can develop a sensitivity or allergy (known as contact allergy, see below) to the chemicals found in flea collars or the plastics themselves. Typical symptoms include itching, lesions, sores and hair loss around the neck.
If your cat has a sensitivity/reaction to a flea collar it should be removed immediately and an alternate flea product should be used. If your cat has redness or sores, speak to your veterinarian before applying any topical or shampoo flea products to your cat. Only use flea collars for cats as dog flea collars can contain chemicals toxic to cats and never combine flea collars with other flea treatments unless your veterinarian has told you it is safe to do so.
I'm not a huge fan of flea collars, there are more effective flea products on the market which do a better job with fewer side effects.
Topical flea treatments
Some cats can have an adverse reaction to flea treatments resulting in itching, redness, blistering and sores and hair loss where the product has been placed.
If you notice symptoms shortly after administering the flea treatment, rinse it off the skin with lukewarm water for 20 minutes. If a severe reaction has developed including redness, pain and loss of skin, your cat will need to see a veterinarian. Bring along the packaging of the treatment you applied to your cat.
Allergies come in four forms. Contact, food, inhaled and insect with a huge number of triggers including dust mites, insect bites and stings (flea allergy dermatitis is a form of insect allergy but is so common it gets its own paragraph), medications, pollens, household chemicals, flea collars (see above). Allergies may be seasonal or year round depending on the underlying cause.
Common allergy symptoms may include itching, especially around the head, neck and back, miliary dermatitis (crusty papules), open sores or scabby lesions. These may wax and wane.
Your veterinarian will perform a physical examination and obtain a medical history from you including onset of symptoms, if they are all the time or seasonal. Depending on the suspected cause, your veterinarian may perform a skin prick test which injects a small amount of many common allergens onto the skin to see if there is a localised reaction. If food allergy is suspected, your cat will be put on a new type of cat food (usually a novel source of protein your cat hasn't been exposed to such as duck or lamb), to see if symptoms go away. If they do, your cat will then be put back on his normal diet to see if symptoms return.
Treatment of allergies includes avoidance of the allergen if possible. Food allergy is treated by switching your cat to a hypoallergenic diet. Diligent flea control for FAD. Insect bites and stings should resolve quickly. Benadryl may be administered to help control itching.
Insect bite or sting
Bites and stings can cause localised inflammation or in some cats, an allergic response. Ants, wasps and bees are the most common insects to bite or sting cats and the incidence increases in summer, outdoor cats are more commonly at risk.
Symptoms of insect bites or stings can vary but include a small raised bump at the site of the injury, localised swelling, hives, itching, pain and redness. Itching can lead to damage to the skin and secondary infection.
Most insect bites and stings are self-limiting and will resolve in a day or so. Bee or wasp stings should be carefully removed. Applying an ice pack or cortisone cream can help to reduce swelling. If itching continues to be a problem, you can give your cat some Benadryl to relieve symptoms.
Any cats experiencing severe swelling and/or breathing difficulty should be taken to the veterinarian immediately. Have somebody phone ahead to alert the veterinarian you are bringing in a cat who may be experiencing anaphylaxis.
There are several types of mites which can affect cats. Scabies, Demodex and Sarcoptes.
Common symptoms include itching, hair loss and thickened/crusty like appearance to the skin. Ear margins, head and neck are most commonly affected although other parts of the body can be infected. Itching can be so intense that self-mutilation occurs, causing damage to the skin and running the risk of secondary bacterial infections.
Diagnosis is made by skin scraping and observing the mites or their eggs under a microscope.
Treatment of feline scabies is with dips such as lime sulfur or Revolution which is a topical flea/worming medication. Long-haired cats may need to be clipped prior to treatment. All bedding should be thoroughly washed or disposed of at the time of treatment.
Caused by a fungus which lives on the skin and fur of infected cats. Ringworm can develop on any part of the body, with raised, circular lesions and hair loss. Most affected cats aren't itchy. Kittens and cats in crowded environments such as shelters are more commonly affected. Ringworm is highly contagious and can be passed on from cat to cat, cat to human or human to cat.
If your veterinarian suspects your cat has ringworm he will check the coat with a UV lamp, which may show up as blue on affected cats. A definitive diagnosis is made with cultures of samples from the cat.
Treatment of ringworm is lime sulfur dips to kill the fungus or medications such as Itraconazole or Griseofulvin. Long-haired cats may need to be clipped prior to treatment.
An autoimmune skin disorder caused by the production of antibodies towards certain proteins in the skin and mucus membranes which cause separation of the epidermal cells. This results in areas of hair loss and fluid filled blisters which break open and form a dry crust. Blisters typically begin around the eyes and the bridge of the nose before spreading to the ears, neck, feet and belly. Affected areas are painful and itchy.
Diagnosis is made by taking a biopsy of a blister, direct immunofluorescence to look for antibodies, cytological examination of a pustule as well as routine screening such as biochemical profile, complete blood count and urinalysis.
Treatment of pemphigus involves immunosuppressive therapy to stop the cat's own immune system attacking the tissues. Corticosteroids are the first choice, if symptoms haven't improved within 7-14 days, low dose chemotherapy drugs may be added. Antibiotics may also be prescribed if your cat has developed a secondary skin infection.