On the Practise of Animal Experimentation and Vivisection

While it may not be the same for everyone, there comes a time in the average person’s life when they are sitting on a bench in a park eating a double cheeseburger when a stray dog walks up with the saddest eyes every seen, staring deep into the person’s soul begging them to find an ounce of compassion. There are also times when we are bitten by mosquitoes, shat on by birds, or climbed on by ants; yet for some reason we do not feel emotion in these cases. What is the difference between the two? Why is it that the dog appears to have emotions while the ant, bee, or fruit fly does not?
Animals have been our test dummies for years. We use them to test new drugs, test cosmetics, experiment with new surgical procedures, etc. Many people have no problem with this; while many others, most notably members of organisations such as PETA, oppose such testing. Is our justification of animal testing linked to some concept of sentience and consciousness that separates man from beast? How do we decide what is ethical and what is not. Is it ethical to test a new cancer drug on a rat? How about a new shampoo? If a person opposes testing on canines, yet supports testing on insects and small mammals, from whence do they formulate their position?

Additionally: I have included a translated version for those readers who avoid standardised spellings:

On th Praktis ov Animl Ixperimentaeshn and Vivisekshn

Whiel it mae not bee th saem fr evrywun, thair kumz a tiem in th av'rij peursn'z lief when thae aar siting on a bench in a paark eeting a dubl cheeseburger when a strae dog wauks up with th sadist iez evry seen, stairing deep in t th peursn'z soel beging them t fiend an ouns ov kmpashn. Thair aar aulsoe tiemz when wee aar bitn bie mskeetoez, shat on bie beurdz, aur kliemd on bie ants; yet fr sum reezn wee doo not feel imoeshn in theez kaesiz. Whot iz th difr'ns bitween th too? Wie iz it that th dog apeerz t hav imoeshnz whiel th ant, bee, aur froot flie {duzdoez} not? Animlz hav bin our test dumyz fr yeerz. Wee {uesuez} them t test nue drugz, test kozmetiks, ixperimnt with nue seurjikl preuseejrz, etc. Meny peepl hav noe probl'm with this; whiel meny uthrz, moest noeteubly membrz ov aurg'niezaeshnz such az PETA, apoez such testing. Iz our justifikaeshn ov animl testing linkt t sum konsept ov sentience and konshsnes that {sep'reutssep'raets} man from beest? Hou doo wee disied whot iz ethikl and whot iz not. Iz it ethikl t test a nue kansr drug on a rat? Hou about a nue shampoo? If a peursn apoeziz testing on kaenienz, yet s'paurts testing on insekts and smaul mamlz, from whens doo thae faurmuelaet thair pzishn?