From Dogs: Their Management. In this exerpt from his 1854 book, the late Edward Mayhew presented sage advice for those who would attend to a dog as in treatment or crare.  I have copied this snipped from the article posted on Molosserdogs in hopes of sharing some good advice on the general management of the dogs behavior but most importantly our own behaviour towards the dog. A link to the article is presented in the citation at the end of this post.

He who would attend upon the dog must be able to command his feeling, and, whatever fear he may be conscious of, he must have power to conceal his emotion. The hand slowly and cautiously advanced, to be hastily retracted, is nearly certain to be bitten. Whatever therefore is attempted should be done with at least the appearance of confidence, and the determination of the man will, in the generality of cases, check the disposition of the beast. There should be no wrestling or fighting. The practitioner should so prepare his acts as to prevent the dog in the first instance from effectually resisting, and the animal mastered at the commencement is usually afterwards submissive. If, however, from any cause, the primary attempt should not be effective, the attendant, rather than provoke a contest which can be productive of no beneficial result, should for a brief period retire, and after a little time he may with better success renew his purpose.

Strange dogs are not easily examined in their own homes, especially if they be favorites and their indulgent owners are present. Like spoiled children, the beasts seem to be aware of all the advantages which the affections of their master give to their humors. They will assume so much, and play such antics, as renders it impossible to arrive at any just conclusion as to the actual state of their health. Dogs in fact are great impostors, and he who has had much to do with them soon learns how cunningly the pampered "toy" of the drawing-room can "sham." For deception, consequently, it is necessary to be prepared, and practice quickly teaches us to distinguish between what is real and that which is assumed. The exertion, however, required to feign disturbs the system, and the struggle which always accompanies the act renders it frequently impossible to make the necessary observation with requisite nicety. Petted dogs are, therefore, best examined away from their homes, and in the absence of any one who has been in the habit of caressing them. Frequently I have found it of no avail to attempt the examination of these creatures at the residences of their owners; but the same animals brought to my surgery have, without a struggle, allowed me to take what liberties I pleased. I usually carry such dogs into a room by myself, and commence by quickly but gently lifting them off their legs and throwing them upon their backs. This appears to take the creatures by surprise, and a little assurance soon allays any fear which the action may have excited. The dog seldom after resists, but permits itself to be freely handled. Should, however, any disposition to bite be exhibited, the hand ought immediately to grasp the throat, nor should the hold be relinquished until the creature is fully convinced of the inutility of its malice, and thoroughly assured that no injury is intended towards it. A few kind words, and the absence of anything approaching to severity, will generally accomplish the latter object in a short period, and confidence being gained, the brute seldom violates the contract.

Dogs are intelligent and honorable creatures, and no man will have reason to regret who teaches himself to trust in their better qualities. I have hitherto, in a great measure, escaped their teeth, and being slow and infirm, my good fortune certainly cannot be attributed to my activity. Kindness and consideration work upon animals; nor do I believe there are many of the lower creatures that will not appreciate such appeals. It is better, therefore, to work upon the sympathetic nature of the brute, than to compete with it in strength, or endeavor to outvie it in agility. Manual dexterity will often fail, and is seldom employed save when danger is present. Mental supremacy appealing to the source of action ensures safety, by subduing, not the resistance, but the desire to resist.

It is easy to ascertain when the dog has regained that tranquillity which would allow of its being trusted with security. The eye need alone be consulted, and a little observation will speedily instruct any one to read its meaning correctly. When the creature is irritated, the pupil invariably dilates, and by singly marking this circumstance, the temper of the beast may be correctly ascertained. Nor should caution be discarded until the contracted circle assures that the agitation has passed away.

Mayhew, Edward, 1813?-1868: Dogs: their management. Being a new plan of treating the animal, based upon a consideraton of his natural temperament. By Edward Mayhew. (London, G. Routledge, 1854) (page images at HathiTrust)