You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

Low white blood cell counts can be caused by a variety of disorders in cats

In cats there are several different types of white blood cells and if they are all low on a blood count (a condition called panleucopenia) it can be due to several possible causes including the following :

Feline infectious enteritis (also called feline panleucopenia) - virus infection
Feline leukaemia virus infection
Acute toxoplasmosis - a coccidian parasite 
Leishmaniasis - a protozoan infection - uncommon in cats
Acute salmonella infection - a bacterium
Drugs side effects eg carbimazole, methimazole

If only some specific types of white blood cell are low , other causes may be :

Auto-immune disease
Tumours
Radiation damage
Stress
Hyperadrenocorticism 
Steroid therapy
Chronic renal failure

Updated October 2013