what could have cause my healthy 8 month pupy to pass on

[kitkat1983]

yesterday my friend took my bulldog out for a walk it was about 70-72 degrees out during the walk she just stopped walking so my friend carried her home when she was getting close to the house lola(dog) went limp when she got to the house i thought maybe she over heated so i put her in the tub to cool her down put some leamon jucie down her throat to break up any mucose when i picked her up she felt normal temp and her tounge and gums were normal colour i called the vet she told me things to watch for and call back if things got worst or if her tounge went blue about 1.5hr-2hr after she stopped panting her tounge truned blue she had diarrea and she had vomited once i called the vet when she called me back i had lifted lolas head and her tounge colour went back to normal  after she started moving her head looking around and pushing her self up on to her bed i had been checking on her about 20 min before she stop breathing her tounge and gums were normal colour she was making her normal noise and looking around she stopped breathing i did cpr on her for about 20 as a friend drove me to the vet. any ideas what could have caused this

[Dan Sims, DVM]

I would suspect a heart disease first and respiratory
disease second as English Bulldogs all have  breathing issues.
The only way to find out for sure is a necropsy which your veterinarian can
provide.
I am very sorry for your loss

[kitkat1983]

thank you so much