Wow, this is a puzzle!
It is really odd that he was fine before this event, and again after this event. Of course, since you have only had Buddy for 10 days, it`s hard to know if he has ever had this type of event before.
The things that I would be considering if Buddy were on his way in to see me are:
1. Petit mal seizure
What you are describing with Buddy could possible be a partial motor seizure – also called a “petit mal” seizure.
Here are some videos of this type of seizure:
In a dog of this age, if he suddenly started to have seizures, it could be because of epilepsy. This is fairly common in dogs, and sometimes we have to put them on anticonvulsants like phenobarbital if they seizure more often than once a month.
Here is more about epilepsy:
Beagles have a bit of reputation for eating things that they should not eat, and this would be the thing that I think is most likely for Buddy. Things that could cause the type of symptoms you are seeing are eating certain poisonous mushrooms, eating marijuana (which dogs like and will seek out on walks), or even eating compost.
Not all wild mushrooms are poisonous, but some are. the symptoms from eating them can be just drooling, or outright vomiting, and also possibly diarrhea, muscle tremors, and collapse.
Here are some links to more information about mushrooms and dogs:
Pets ingesting marijuana become incoordinated and begin stumbling. Most become quite lethargic. Some may experience hallucinations. The danger with marijuana is that vomiting is common, and if the pet is profoundly lethargic and begins vomiting, aspiration of the vomitus into the lungs can lead to severe breathing problems and even death.
3. Exercise induced collapse
This is a syndrome that I have only ever seen in Labrador retrievers, but it is faintly possible that Buddy could be affected. It comes on after exercise, especially if the dog overheats. The dog seems totally fine one minute, but then has hind end weakness and collapse rather suddenly. Dogs often seem unaware that their back legs are not working and try to keep running. It goes away on its own as the dog rests.
Here is a video of an affected dog:
4. Frog ingestion
What you are describing in your dog with profuse drooling could happen if he picked up a frog. This is because of the really horrible taste from the amphibian’s skin. It is irritating to mucus membranes and causes extreme salivation and sometimes vomiting.
It works well (from the frog’s perspective) at making the dog spit the frog out!
That said, there is a toxic toad in the USA and one in Australia, too. In the USA it is the Bufo Toad, and in Australia, it is the Cane Toad. In the USA the Bufo Toad is found in South Florida and South Texas, and also further south into central and South America.
Here is more about it:
It is unlikely that your Beagle got one of these, however. Probably he might have just picked up a regular frog or toad, and found that they taste horrible!
Those would be the main things I would be concerned about in Buddy as a cause for his odd symptoms. If they happen again, try to take video of it, if you can. That could really help your vet, or one of the experts here, to better identify what is going on. It can also be really helpful during an episode to check how many breaths a minute he is taking and even to check Buddy's temperature if he will let you.
Instructions here: http://www.petplace.com/dogs/how-to-take-your-dog-s-temperature/page1.aspx
I certainly hope that you never see this type of problem again. Given that he is a Beagle, my top concern would be that he ate something he should not have! I had a beagle for 14 years and in that time he ate a LOT of things he should not have!
As he seems fine now, I would simply monitor him for the time being and see if this ever happens again. If you have any way of finding out his previous history to see if he has ever had an episode before, that would also be helpful!
I do hope that this has been useful to you and that you and Buddy never have this problem again!
If you need more information, just click on reply and I will still be here to provide it.