One of my labs had gastroenteritis last week but only had sickness with it. I stopped feeding for 24 hours and then offered her some id diet, just a teaspoonful. Within an hour she was being sick again and this time every 5 minutes. It was 5.30pm but the vets agreed to see her and gave her antibiotics and an anti vomiting injection. The next day (Tuesday) she was fine.
Wednesday introduced a little fluid and food, it came back up! Phoned vets and they saw us again and gave anti vomiting injection and antibiotics injection. I took her home and was told to start fluid by syringe on Thursday morning, this I did, but once again it came straight back up. She was admitted to the vets and put on a drip. They took some blood.
The vets said they had had quite a few cases in in the last few days that weren't responding to treatment and that one of the dogs had died.
Brooke stayed in the vets until Sunday, she is fine in herself and is now keeping down a little food. She will see the vets again on Tuesday and Friday and hopefully then will be fine.
The vets have said that in the South West this illness is killing dogs at present so please be careful. Brooke's blood test results were normal.

I am from the North East and one of my labs went through similar last weekend. She has had blood taken twice now as the first results indicated a liver problem, but were inconclusive. I am now awaiting the results of the second test. It would seem as if this problem is not confined to the South. I hope your dog is feeling better soon. My Tara appears to be on the mend....