Thank you for your patience. Rory's symptoms are very concerning this afternoon, and there are quite a number of possible causes for his lethargy and reluctance to get up. Given his age and breed, we need to consider everything from a musculoskeletal issue (and pain), to an internal organ issue, a toxicity (hopefully there isn't anything he could have gotten into), or even an endocrine problem. Don't give him any antibiotics, as there is no sign this is an infection here, and this may end up making him feel more sick if they cause a stomach upset. Likewise, don't be tempted to try any other human medication, including pain relief, as this is mostly toxic to dogs.
The best next step here is to continue to keep a very close eye on Rory. Keep him inside and warm and encourage him to have a good drink of fresh water. Over the next few hours, you are going to have to monitor him closely. In particular, please keep a close eye on his mucus membranes, capillary refill time and respiratory rate as follows:
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 throughout the night, this is a sign of shock and or pain and a signal for a trip to the emergency Vet.
Hopefully he improves soon, but if he is still just as lethargic in another hour or two, or if any of his parameters aren't right when you check them now, you really do need to play it safe and get Rory checked at your local vet or ER vet. Here they will carry out a full physical exam, as well as carry out a blood test to ensure his internal organ function and blood parameter are all normal. 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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