Chapter 31 — Further Reading

A note before the list. This chapter argues that evidence belongs to the population it was gathered in, so it would be poor form to hand you a reading list that blurs the same distinction. Each entry below says what kind of source it is and what question it answers. Where an entry points at a body of work rather than a single document, it says so.

Tier 1 — Start here

The FDA Center for Veterinary Medicine's public materials on extra-label drug use. The agency maintains plain-language explanations of what extra-label use is, the conditions the Animal Medicinal Drug Use Clarification Act imposes, and the list of drugs prohibited from extra-label use in food-producing animals. This is the primary-source version of §31.7, and reading it does more than any argument to make the point that veterinary regulation is a real system with real requirements.

The same agency's materials on withdrawal periods and drug residues. How a withdrawal period is derived from residue depletion data and a tolerance, and how compliance is monitored. Short, technical, and genuinely interesting once you understand that its whole purpose is to protect a person who never met the animal.

The World Anti-Doping Agency Prohibited List, current edition. Read it as a document with a purpose. Notice how many entries are class-based, how prominent the "non-approved substances" category is, and how little of the document reads like a claim about efficacy. It is the fastest cure for "they wouldn't ban it if it didn't work."

The FDA guidance on estimating the maximum safe starting dose in initial clinical trials in adult healthy volunteers (2005). This is where the species conversion factors used in §31.5 and Case Study 2 come from. Read the section on body-surface-area normalization, and then read the sections on safety factors — the second half is what makes clear that the whole document is about floors, not effective doses.

The American Veterinary Medical Association's policy resources on extra-label use and on therapeutic medication in performance animals. Professional-body positions, written by practitioners for practitioners. Useful for §31.8 in particular, because they take the welfare question seriously without rhetoric.

Tier 2 — Go deeper

Reagan-Shaw, Nihal, and Ahmad, "Dose translation from animal to human studies revisited," FASEB Journal (2008). A short, widely cited paper that walks through the body-surface-area conversion explicitly and works examples. If you want the arithmetic of Case Study 2 in its primary form, this is the most efficient route to it. Read it alongside the FDA guidance rather than instead of it.

Kleiber, "Body size and metabolism," Hilgardia (1932). The origin of the three-quarters-power scaling relationship. Historically interesting and shorter than you expect. The modern literature debating the exponent is large; the original is where to see the observation before it became a controversy.

Eng and colleagues, "Isolation and characterization of exendin-4… from Heloderma suspectum venom," Journal of Biological Chemistry (1992). The lizard paper. This is comparative physiology producing a drug class, and it is worth reading the original to see how unglamorous and specific the observation was at the time.

Zhang and colleagues, "Positional cloning of the mouse obese gene and its human homologue," Nature (1994). The leptin discovery. Read it as the triumph it was, then read Chapter 13 for what happened when the molecule met common human obesity. The pair together is the best available lesson in a model being right about mechanism and wrong about application.

Bjerre Knudsen and colleagues on GLP-1 receptor agonists and rodent thyroid C-cells, Endocrinology (2010). The primary literature behind the C-cell finding and the species-difference argument in §31.5. Chapter 8 covers the clinical interpretation; this is where the receptor-expression data lives.

Willner's framework for evaluating animal models — face, construct, and predictive validity. Introduced in the context of models of depression in the 1980s and since adopted across fields. The vocabulary in §31.5 comes from here, and seeing it in its original setting makes clear that the problem this chapter describes is not specific to peptides.

The ARRIVE guidelines for reporting animal research (Percie du Sert and colleagues, PLOS Biology, 2020). What a well-reported animal study is supposed to contain: species, strain, sex, housing, randomization, blinding, sample size justification. Read it and then go look at how many of the studies cited on vendor websites report any of it. This is one of the most efficient bad-citation detectors available.

Tier 3 — For the committed

The Journal of Animal Science and the production-animal literature generally. Read three or four growth-performance papers end to end. Do not skim to the conclusions — read the methods and the endpoint definitions. The purpose of the exercise is to develop a feel for how competent the work is and how completely it fails to bear on a human question. Case Study 1 is a summary; this is the experience.

The Journal of Veterinary Pharmacology and Therapeutics. Species-comparative pharmacokinetics as a working discipline. This is where you see, in detail, that "different species clear this differently" is not a hedge but a measured quantity with a literature behind it.

The Journal of Veterinary Internal Medicine and the Equine Veterinary Journal. Clinical veterinary evidence, including consensus statements and controlled trials. Useful correction for anyone who arrived at this chapter believing veterinary research is anecdote.

Codex Alimentarius and the JECFA evaluations of veterinary drug residues. The international residue and maximum-residue-limit framework. Dense, and worth an hour if you want to see how much toxicological machinery sits behind the phrase "withdrawal period."

The European Medicines Agency's Committee for Medicinal Products for Veterinary Use guidelines. The non-U.S. version of the regulatory story, useful for seeing which requirements are universal and which are jurisdictional.

The horseracing integrity literature and the international agreements governing prohibited substances. The International Federation of Horseracing Authorities' international agreement and the U.S. anti-doping and medication control program documents. Read them for the stated rationales, which are the substance of the §31.2 argument.

If you only do one thing

Read the FDA's 2005 starting-dose guidance and Case Study 2 side by side, then find a rodent study of any compound that interests you and do both calculations yourself — the naive one and the corrected one.

Fifteen minutes. You will get a factor of six or twelve, depending on the species, and the number will be much smaller than you expected. Then close the guidance and answer this from memory: what was that number for?

If the answer arrives immediately — a maximum safe starting dose for a first-in-human safety study, with an additional safety factor still to be applied — you have the whole chapter. The arithmetic is the easy half. Knowing what a calculation is for is the half that keeps people out of trouble.