Low platelet count with no other symptoms

My 18 year old cat has an extremely low platelet count but she doesn't really have symptoms to back this up. The blood test was done because she has signs of kidney failure and occasional incontinence but otherwise she eats normally, scratches, runs about and joins in, even though she does sleep a lot (nothing new). The vet says she could haemorrhage at any minute. We could have a steroid injection but that might aggravate the incontinence and it will make her feel worse than she does now. In 4 weeks time we go on holiday, leaving her with my sister who has never had any of her own animals (she is staying in our house). If she has a bleed while we are away it could be nasty for all concerned. Do we put her down before we go or do we risk it that she might live for many months more?

I have not heard of a steroid injection being used to treat low platelet count. A blood transfusion is usual to treat the more severe cases. It's tough to answer your question without knowing all the specifics, but IMO I would not euthanize if she does not seem in pain and her quality of life is good.

I would think that your sister could handle taking her to the vet at the first sign of a problem?

Has she been tested for the feline viruses?  I had a kitten come to me with a very low platelet count and we ran the Feline Parvo Virus snap test and all the other viruses and it came out negative.  Eventually her platelet count came up but all the vets she saw were worried it was either a form of blood cancer stemming from the bone marrow or it was a virus that caused this.  How is the white and red blood count doing?