Before setting out the signs of feline leukemia a little background information may help. I am also making the presumption that people searching for information about feline leukemia are in fact searching for information about the feline leukemia virus, which causes cancer and it is referred to as an oncogenic RNA virus. An RNA virus is a virus that has RNA (ribonucleic acid) as its genetic material1. Oncogenesis is the process of malignant transformation leading to the formation of a cancer or tumor (tumorigenesis). It is characterized by a progression of changes on cellular and genetic level that ultimately reprogram a cell to undergo uncontrolled cell division, thus forming a malignant mass1.
Above: the feline leukemia virus (Wikipedia Commons file)
The cancer caused is lymphosarcoma. 90% of cats with this cancer carry this virus. However only a small percentage of cats with persistent viremia develop a virus related cancer3. Viremia means: a medical condition where viruses enter the bloodstream and hence have access to the rest of the body1.
The virus is known as FeLV. FeLV infects cats throughout the world including small wildcat species.
The virus survives for only minutes to hours outside the body. This means that infection is by direct contact between cats is necessary to transmit the disease (or in utero transmission – leads to fetal death 80% of time). This also means that the highest infection rates are in crowded colonies or groups (e.g. colonies of urban feral cats).
Infected cats become carriers as they are unable to rid themselves completely of the infected cells2. Cats that are viremic (have the infection in their blood stream) spread the virus through:
- saliva – e.g mutual grooming, licking, biting, sharing feeding bowls
- respiratory secretions
- faeces – sharing litter boxes
Most infected adults are less than 3 years old. Older infected cats have either died or combated the disease.
There are four outcomes following infection2:
|All cats||Virus infects lymphatic tissue (lymph nodes). Virus present in blood stream. Cat sheds virus.|
|1. 30% cats successfully fight of disease||Cats develop immune response. Disease does not progress. Virus eliminated.|
|2. Unknown number of cats develop immunity but carry disease||Virus remains in body of cat but it is not shed to other cats. Most of these cats eventually eliminate disease.|
|3. 30 – 40% of cats latently infected||Late immune reaction. Virus does not spread in body. No shedding of virus to other cats. Mothers transmit disease to kittens via milk.|
|4. 30 –40% of cats actively infected||Infection progresses. Poor prognosis. Most die within 3 years|
Signs of Feline Leukemia2|3
|Stage||Signs of Feline Leukemia|
|Stage 2: Peristent infection||
As can be seen the signs of feline leukemia are wide because FeLV leads to a wide range of other diseases.
Related pages – further information
FeLV infected cats can live for a relatively long time and therefore need homes. These are adoptable FeLV cats. This page: Adoptable FeLV cats also covers information about testing for FeLV and has an input page for people to advertise FeLV cats for adoption.
Signs of Feline Leukemia – Notes:
1. Wikipedia authors
2. The Cat, Its Behaviour, Nutrition & Health by Lind P Case pages 198 – 202.
3. Cat Owner’s Home Veterinary Handbook by Drs Carlson and Giffin pages 62 – 64.