Local authorities should refrain from "panic" cuts to services, charities for disabled children have warned.
The Council for Disabled Children says some families are seeing "lifeline services" stopped with little warning.
Losing services such as a few hours' respite break for parents can have a huge impact on families, it warns.
The charity's director, Christine Lenehan, says councils seem to be making knee-jerk decisions ahead of anticipated spending cuts.
Every Disabled Child Matters - a campaign run by Contact a Family, the Council for Disabled Children, Mencap and the Special Educational Consortium - asked families with disabled children to report on cuts to local services.
'Lack of direction'
It found that some local councils were stopping services at short notice, even before they had received any cuts from central government.
It suggests that financial fears about the future are pushing councils to make "premature" cuts.
"There is panic and uncertainty over cuts... local authorities are worried about a lack of direction," says Ms Lenehan.
"My biggest concern is about knee-jerk reactions. Families have told us that services they rely on have been stopped with only a week's notice."
The report highlights the anxieties of families losing very specialised and localised support services.
These can be clubs for children with mental or physical disabilities, respite opportunities for families, help for voluntary clubs and funding for support staff.
The withdrawal of such services can have a devastating impact on families, says Ms Lenehan.
She says that short breaks - providing somewhere for children to go for an afternoon once a month or so - can be the difference that allows families to keep going.
But she says local authorities in some areas are considering cutting up to 75% of short breaks, as part of their planning for anticipated spending cuts.
The report, Close to Crisis: Frontline Service Cuts for Disabled Children, shows responses from families.
For example, it gives the reaction to the loss of a Saturday club for disabled children: "To lose this would just mean another blow for us in coping with the stress that families deal with on a day-to-day basis."
Ms Lenehan says: "We are deeply concerned that disabled children and their families are losing vital support that they see as a 'lifeline'.
"This report shows that local areas are making the decision to cut services in anticipation that there will be no funding for front-line services when the Aiming High for Disabled Children programme comes to an end in March 2011."
Shadow Education Secretary Ed Balls said: "This is a really worrying report, which suggests local authorities are assuming the worst will happen in the spending review and already cutting back on much-needed services to the most vulnerable children in our community."