Feline leukaemia virus (FELV)

Disease overview

Feline leukaemia virus (FeLV) is an important viral infection of cats which causes a wide variety of secondary problems including immunosuppression, anaemia, and cancer. Most persistently infected cats will die as a result of their infection. The virus is mostly spread through social contact e.g. mutual grooming, sharing of food bowls, litter trays. The virus can also be transmitted through fighting.

Feline leukaemia virus (FeLV)

How is it diagnosed?

  • Diagnosis is confirmed by a blood test for feline leukaemia virus.

Clinical signs

  • The clinical signs associated with progressive feline leukaemia virus infections are variable and are related to the type of secondary problem which the cat develops e.g. immunosuppression, anaemia, and cancers such as leukaemia
  • Signs may include weight loss, poor coat condition, decreased appetite, lethargy, pale gums, persistent diarrhoea, fever.

Risk factors

  • Younger cats are at higher risk although cats of all ages can be infected
  • Cats with outdoor access
  • Cats in multi-cat households living with infected cats or cats of unknown feline leukaemia virus status.


  • Treatment involves management of any secondary diseases which develop e.g. anaemia, secondary bacterial or viral infections, cancer
  • There is no cure for feline leukaemia virus.


  • Vaccination is very effective at preventing disease caused by feline leukaemia virus.
  • Keeping cats strictly indoors can reduce the risk of infection
  • Testing all new kittens or adult cats for feline leukaemia virus before bringing them into the household.

Feline allergic dermatitis

Disease overview

An allergy occurs when the immune system reacts or over reacts to substances that are usually harmless. Allergic dermatitis involves allergies which result in skin problems and can be caused by many different allergens including environmental substances, food ingredients and parasites e.g. fleas. It can sometimes be very difficult to confirm the exact cause of the allergy.

Feline Allergic Dermatitis

Possible causes include:

  • Fleas – cats can become allergic to flea saliva from flea bites
  • Food ingredients
  • Environmental allergens that the cat breathes in or absorbs through the skin, such as dust mites, pollen or moulds.

How is it diagnosed?

  • Confirmation of the exact cause may not always be possible and other potential causes need to be ruled out
  • Your vet will examine any skin lesions to assess for any secondary problems or potential causes e.g. bacterial infections or parasites.
  • Samples may be taken from the skin/hair for microscopic examination to look for evidence of infection (e.g. bacterial, fungal) or parasites
  • An elimination diet may be recommended by your vet if a food allergy is suspected
  • Intradermal skin testing may be used where allergens are injected into the skin to assess for a hypersensitivity reaction.

Clinical signs may include

  • Itchiness (pruritus) leading to scratching and/or over grooming
  • Inflamed, irritated areas of skin
  • Scabs or crusts on the surface of the skin
  • Thickened areas of skin with pigment changes
  • Thinning hair or hair loss
  • Inflammation or infection of the ears.

Risk factors

  • There may be a genetic susceptibility to certain allergens in some cats
  • Cats not on regular (year round) and effective flea control are at risk of flea allergies.

Treatment options

  • Treatment will be dependent on your vet’s assessment of the skin lesions and likely causes
  • Eradicating fleas on the cat and in the home is very important as flea allergies are common
  • Feeding an elimination diet may be recommended if a food allergy is suspected
  • Medications to treat fungal and/or bacterial infections may be required
  • Medications to reduce itchiness and scratching may be required.


  • Prevention may not be possible as not all allergens can be avoided
  • Optimal flea control is very important as fleas may be the cause of the allergy or make other skin problems worse
  • Reducing levels of dust mites and moulds in the home if environmental allergens are suspected
  • If a food allergy is confirmed then feeding a diet without the food ingredient should prevent the signs (with veterinary advice).