Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry for this concern for your dog. More than likely, he's injured a toenail rather than broken a toe since the former is far more common than the latter.
I'll provide treatment options for his broken or injured nail but if he's actually broken a toe, it might help to know that we rarely treat this injuries per se with pins or wires but rather let them heal on their own, usually with a splint or bandage.
1. You can gently clean the toe twice a day with over the counter dilute Betadine or Iodine (to the color of weak tea).
I'd avoid peroxide which can retard healing; even warm water will be preferable.
2. You could even soak the toe/foot in a warm Epsom Salt bath but this isn't usually necessary in my experience.
3. If he's not too uncomfortable, you can apply a small amount of over the counter antibiotic ointment on the raw area...if there appears to be a raw area, that it.
4. An even better product for this problem would be Vetericyn Spray which can improve healing time. It's often available at most local pet or grain stores or online.
Since it's a spray, it will be easy to apply; it's also non-toxic so won't be harmful if ingested.
5. It's going to be important to prevent him from licking the toe since he can make it worse. Either he'll need to wear a cone although I know he won't thank me for suggesting it or you can put a sock on the foot or a light bandage.
I don't usually advise the latter since it's often difficult to get them to stay on without making them too tight. Then circulation is compromised and the foot swells up.
6. As long as he's not vomiting nor taking any steroid or non-steroidal anti-inflammatory medication, Aspirin can be given at a dose of 10 mgs per pound of body weight twice a day with food to avoid stomach upset.
In most cases, these toenail injuries will heal just fine and most patients rarely even limp or pay much attention to the toe after a day or so. The nail will regrow although it may take several weeks to do so.
Even if the toe is broken, you might be surprised how well this sort of injury will heal although it will take longer...usually 4-6 weeks or thereabouts.
I hope this helps. Deb