It all depends on the underlying cause; poisoning would be a concern for the sudden onset of these symptoms in a short time frame in a young cat, however without examining Buffy I cannot be certain of the underlying cause. You should try to rinse out her mouth with plain water and try to keep her still, if you have an Emergency Veterinarian open near you, you should visit regardless of distance and cost. Regards Dr Callum Turner DVM
Care: Russian Blue cats are fairly easy to care for. Their coats simply need to be brushed once a week so that they stay can show off their beautiful blue color. They may require more brushing when they are going through a season of shedding. Trim their nails and clean their ears as needed to keep them looking lovely. And, as with any cat, it is important to regularly brush their teeth to prevent periodontal disease. If you are looking for a hypoallergenic cat then the Russian Blue cat is a great candidate. They produce less of the Fel D1 protein which is the true cause for your allergic reaction. There is no cat that is 100% allergy free so increasing the frequency of grooming and bathing your furry friend will also help.
Rapid breathing (tachypnea) is a respiratory disorder characterised by abnormal breathing that is rapid and shallow. It is caused by a reduced level of oxygen, mechanical disorders (where the lungs aren’t able to expand as they should, usually due to a build-up of fluid in or around the lungs), and physiological disorders in which the cat’s respiratory centre in the brain is over stimulated.