Hello again, and thanks for your reply with additional information about your cat.
Older cats are more prone to develop certain medical conditions like diabetes, hyperthyroidism, and kidney issues. The symptoms you describe could be indicative of any one of these, or another medical problem.http://www.sniksnak.com/cathealth/hyperthyroidism.html http://www.sniksnak.com/cathealth/diabetes.html http://www.sniksnak.com/cathealth/renal.html
It's possible she might have ingested something she shouldn't have, or accidentally became injured when playing/fighting with your dog, or perhaps jumping down from a height. When you mentioned she was stumbling/could barely walk, this could be a symptom of toxic ingestion or blood sugar that is too high or too low. Although she's an indoor only cat, if anyone brought antifreeze in on their shoes, etc., cats are attracted to this very toxic substance and a symptom is a drunken walk.
Check her gum color to see if they are light pearly pink, as usual. If they are paler, like white or bluish, this may indicate a cardiac or respiratory problem.
When a cat who is normally active, suddenly has no energy, barely moves, is breathing more rapidly than usual and prefers to stay in one place all day, there is no doubt that she needs to be evaluated by a vet, immediately, for diagnosis and treatment. If it's after hours for you now, it would be advisable to have her assessed by an ER vet center so you can find out what's bothering and she can be treated, then feeling more comfortable.
Wrap her in a blanket, pick her up very gently, and bring her to the vet now.
Please let me know how she's doing and what the vet's findings are? Thanks!
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