Theophylact of Ohrid

A new sorrow was to see that others enjoyed abundance while he languished in hunger. For he desired to be filled not with luxurious foods, but with the crumbs from them — such as the dogs fed on. No one cared even to treat Lazarus's wounds, for the dogs licked his sores, since no one drove them away.

Commentary on Luke ↗

Ambrose of Milan

But the insolence and pride of the wealthy is manifested afterwards by the clearest tokens, for it follows, and no one gave to him. For so unmindful are they of the condition of mankind, that as if placed above nature they derive from the wretchedness of the poor an incitement to their own pleasure, they laugh at the destitute, they mock the needy, and rob those whom they ought to pity.

Catena Aurea by Aquinas ↗

Gregory the Dialogist

But Lazarus, full of wounds, desired to be fed by the crumbs which fell from the rich man's table, and no one gave to him; because that proud people disdained to admit any Gentile to the knowledge of the Law, and words flowed down to him from knowledge, as the crumbs fell from the table. Sometimes also in the holy Word by dogs are understood preachers; according to that, That the tongue of thy dogs may be red by the very blood of thy enemies; (Ps. 68:23. …

Catena Aurea by Aquinas ↗

Bede

He who lay at his gate full of sores, desiring to be fed with the crumbs which fell from the rich man's table; moreover even the dogs came and licked his sores. The beggar Lazarus, full of sores, lies at the gate of the rich man. Concerning this matter the Lord accomplished two judgments at once. For the rich man might perhaps have had some excuse if the poor and sore-covered Lazarus had not lain at his gate, if he had been removed, if his poverty had not been obtrusive to his eyes. …

On the Gospel of Luke ↗