Thank you for your patience. Your cat's symptoms are definitely very concerning, and there are quite a number of possible causes for his lethargy and strange behavior this evening. We certainly need to consider everything from a blocked bladder (hopefully he is toileting ok), to early gastroenteritis, or certainly even a toxicity here. If this a toxicity such as by eating a poisoned mouse, then there isn't a lot you can do from home as we don't know what toxin(s) or poison(s) might be involved here. You are definitely going to need to continue to keep a close eye on your boy for now, and if he is particularly distressed or lethargic now, please get him straight down to your local ER vet. Here they can carry out a full physical examination, start him on intravenous fluids, and take some blood to check his internal organ function.
For now, please keep an eye your boy's mucus membranes, capillary refill time and respiratory rate tonight as follows (do be careful that your boy doesn't try to bite you):
Mucus membranes - flip his lip and look at the color of his gums. They should maintain a nice salmon pink color. Get him to the emergency Vet if they appear white or very pale pink, or if they are a dark deep red color.
Capillary Refill time - this measures blood perfusion and test this by putting your thumb on his gum to apply pressure. After you release your thumb you will see the gum blanch. Capillary refill time is the amount of time it takes (in seconds) for the gum to return to a healthy pink color from the blanched white color. If 2 seconds or less don't worry - if it is taking significantly more time, again - off to the emergency Vet.
Respiratory Rate - if he is continuously panting or open mouth breathing at all tonight, this is a sign of shock and or pain and a signal for a trip to the emergency Vet.
Make sure your boy has plenty of fresh water available and do encourage him to drink. If you have seen him trying to urinated and he has had trouble, then this is the sign of a blocked bladder which is a medical emergency, so if this is the case - please get him seen now. I hope all of the above makes sense? If you have more questions or if I can help in any other way, please do not hesitate to ask! If you would like to accept my answer, please press RATE OUR CONVERSATION (I am not compensated in any other way). Bonuses are always welcome. Thanks! I hope to work with you again soon!
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