The Magpies return to action following the two-week international break with a game against the unbeaten Bees at St. James' Park, with Howe's side seeking to end a run of three straight defeats.
Centre back Botman missed the loss at Brighton a fortnight ago after suffering an injury at Manchester City the previous week, while midfielder Tonali missed Italy's win over Ukraine with a minor complaint.
Head coach Howe would like to be able to call upon the influential pair this weekend - along with Elliot Anderson, who withdrew from the Scotland squad with injury - but indicated he will have to make a late call ahead of Saturday's contest.
Here are some of the other talking points from Howe's pre-match media briefing at United's Benton training centre on Friday:
On the prospect of Botman making his return against the Bees...
"Possibly, yeah. He's trained this week, so fingers crossed for Sven - we'll see how he feels today."
On the possibility of Italian international Tonali recovering in time for the weekend...
"I think he felt his thigh in training, so he's come back in and he's had a scan. There's a slight injury there - it's nothing serious or too long - but we'll wait and see whether he's available this weekend."
On the two-week wait for a fixture after the defeat at Brighton last time out...
"I think said afterwards that my preference would always be to play again after a disappointing result. But it wasn't to be, so we've come back here and worked well, I think, with the players that we had left with us - around about 12 players, initially. The lads have been good, training has been good, and now we're ready for the next game."
On midfielder Joe Willock, who is working towards a comeback...
"He's been away - he's been in Spain I believe the last week, a change of environment for him, a change of focus for him. He's been pretty good. There's obviously been a bit of disappointment there, because he's had a couple of setbacks.
"This injury's an achilles injury, the one he sustained originally was a hamstring injury, and the achilles came out of nowhere. Disappointment for him - and he's such a key player for us, so disappointment for us. But our aim is just to get him back as quickly as possible and back to his best form."
On the keys to Brentford's success and the job Thomas Frank has done there...
"Probably a mixture of a lot of things really - shrewd recruitment would be one, (and) a brilliant coach who's done amazing things on a consistent basis with the team. They continue to innovate as well - they're always moving the team forward and changing things, and Thomas deserves a lot of credit for the job that he's done."
On the importance of Saturday's game...
"I think it's a game we obviously want to do well in. We know, and we understand, the game that we're in. I don't want to build it up any more than it is, really.
"It's a game that we have to approach in the right way, it's a difficult game, a very dangerous opponent. They've got good skills and a good way of playing, got their obvious threats, but for us, we have to return to our highest level of performance. I think if we do, then I'd back us to get the job done."
