Chapter 31 — Exercises

Thirty-six items. Work them in any order. Items marked † are harder: they ask you to hold two compatible ideas at once, reason quantitatively, or defend a position you may not hold.

No answers are given here. Several items have more than one defensible response, and the ones that do are the ones worth arguing about with somebody.

Standing rule for every item in this set: nothing here asks for a dose, a regimen, or a source, and no acceptable answer contains one. Where an item involves numbers, the numbers are about study design and arithmetic, not about what anyone should take.

Part A — The frame (§31.1)

A. In two sentences, state what veterinary drug approval requires that human drug approval does not. Explain why that extra requirement exists.

B. Name four peptide or peptide-adjacent drugs in genuine veterinary use, and for each, give the species and the indication. Then say which of the four is a diagnostic rather than a therapeutic agent.

C. The chapter claims that "veterinary evidence answers veterinary questions" is a statement about scope rather than about quality. Rewrite that claim as a single sentence that a person who thinks the chapter is dismissing veterinary medicine would find impossible to misread.

D. † The chapter includes a ✅ rating for GnRH agonists in veterinary species. Explain what would be wrong with the chapter's overall argument if that rating had been left out. Your answer should reference at least one of the six rating rules from Chapter 5.

E. A veterinarian and a physician are both described as prescribing "insulin." Name two ways in which the molecule, product, or practice may differ between them.

Part B — TB-500, horses, and bans (§31.2)

F. State, in one sentence each, the two distinct errors contained in the argument "TB-500 works in horses, so it works in people." Label which is a species error and which is a molecule error.

G. List five reasons a racing or sporting authority might prohibit a substance. For each, say whether it implies anything about whether the substance is effective.

H. Rewrite the sentence "they wouldn't ban it if it didn't work" so that it says only what the evidence supports. Your rewrite should be one sentence and should not be sarcastic.

I. † The chapter says a prohibition tells you "less than nothing" about whether a compound works in a human. Defend or attack that phrasing. If you attack it, propose a more precise formulation that preserves the intended point.

J. Explain why "the horse improved" is a weaker observation than it sounds, listing at least three things other than the compound that changed for that animal over the same period.

K. † Construct the strongest honest case for paying attention to equine practice when thinking about a compound's plausibility. Then state precisely where that case stops.

Part C — Livestock and endpoints (§31.3)

L. List the primary and secondary endpoints of a typical livestock growth study. Then list four outcomes a human user cares about that appear nowhere on it.

M. Define endpoint mismatch in your own words, and give one example from outside peptide science entirely.

N. Explain why the safety data in the livestock growth literature is not human safety data. Your answer must name the party that safety data is protecting and the route by which that party is exposed.

O. † A person argues: "The livestock literature is enormous and rigorous, so at minimum it establishes that these compounds are safe." Identify every step of that argument that fails, and say which failure is the most serious.

P. Why is a large sample size in a production-animal study not evidence that the study answers a human question? Answer in a way that does not disparage the study.

Part D — Provenance (§31.4)

R. State the difference between "used in animals" and "used in laboratory animals," and explain why the difference matters rhetorically.

S. Chapter 1 pointed out that a compound still known by a laboratory code has told you something about its regulatory history. Restate that observation and apply it to BPC-157 in one sentence.

T. † Write a short paragraph defending preclinical animal research against the charge that this chapter treats it as inferior. Use at least one example from §31.9.

Part E — Species differences (§31.5)

U. Name the five mechanisms by which animal-to-human inference breaks, and give one concrete example of each drawn from this book.

V. Explain the rodent thyroid C-cell finding from Chapter 8 in three sentences: what was observed, why it may not transfer, and why the warning nonetheless remains.

W. Define face validity, construct validity, and predictive validity. Then rank them by how often you would expect each to be demonstrated in a paper cited on a vendor's website, and explain your ranking.

X. Using the transected-tendon example, explain how a model can have high face validity and low construct validity at the same time.

Y. State, in one sentence, the direction of the error produced by naive milligram-per-kilogram conversion from a rodent study, and the reason it runs in that direction rather than the other.

Z. † The standard conversion divides a mouse dose by roughly 12 and a rat dose by roughly 6. Explain qualitatively why the divisor is smaller for the larger animal, and predict — without looking it up — whether the divisor for a dog would be larger or smaller than the one for a rat.

AA. † The chapter says the surface-area method is "a floor-finding tool with a safety factor built in." Explain what goes wrong when a floor-finding tool is used to target an effect, and why that error is worse than the arithmetic one.

AB. Explain why the ob/ob mouse was simultaneously a triumph of model-organism research and a misleading guide to a therapeutic market.

AC. Give two reasons a two-year rodent study is long-term evidence and two reasons it is short-term evidence.

Part F — "Used for years" (§31.6)

AD. Write out the four questions. For each, give a one-line example of a claim it defeats.

AE. † Apply all four questions, in writing, to this claim: "Growth-hormone-releasing peptides have been fed to livestock for decades, so we know a great deal about their long-term safety."

AF. † The chapter adds a fifth question — compared to what? Explain why it is placed as an addendum to the fourth rather than as an independent question, and argue for or against promoting it to the main list.

AG. Explain the sentence "a track record is not a dataset unless somebody was recording" to someone with no scientific training, using an example that has nothing to do with medicine.

Part G — Regulation, welfare, and the two-way street (§§31.7–31.9)

AH. Name the conditions required for lawful extra-label use in a veterinary patient. Then state which of them a person purchasing a compound online satisfies.

AI. Explain what a withdrawal period is, how it is set, and who it protects. Then explain why human medicine has no equivalent.

AK. In three sentences, state the welfare argument in §31.8 without moralizing and without implying that people who work with performance animals are indifferent to them.

AL. Give three examples of legitimate animal-to-human traffic in drug development, and one example of legitimate human-to-animal traffic.

AM. † The chapter's closing claim is that "preclinical work earns a compound the right to be tested in people; it does not earn it a conclusion." Write the strongest counterargument you can, then answer it.