Get Your Cat Care Questions Answered By Cat Vets ASAP
Yes, the symptoms you describe could be signs of posioning. Heavy breathing is also symptomatic of respiratory problems, or fluid in the pleural cavity. Please get your cat to the vet as soon as possible. Some poisonings don't act immediately, they take time to work through the system, so the faster treatment is given, the better the outcome. If she is acting "off", I would get her in immediately.