dissenting.
I dissent.1 This is a product liability case involving the five oral polio vaccine Orimune. The case was submitted to the jury on three separate theories: product liability (Count I) and negligent manufacture (Count II) as to Cyanamid; and medical negligence (Count VI) as to Dr. Jawaid. Because the plaintiff did not prove causation and thus failed to make a submissible case on one of its offered theories, and because the trial court erred when it ex-eluded relevant evidence, I would reverse and remand for a new trial.
FACTS
Cortez Strong (Cortez) was born 7 February 1987. When he was two months old, Dr. Georgia Santos-Jawaid (Dr. Jawaid) gave Cortez his first dose of oral polio vaccine (OPV). The OPV given to Cortez was manufactured by American Cyanamid Co. (Cyanamid), and known as Orimune. The history of the development of OPV and the drug’s evolution are discussed thoroughly in the following cases: Graham v. American Cyanamid Co., 350 F.3d 496 (6th Cir.2003); United States v. St. Louis University, 336 F.3d 294 (4th Cir.2003); and In re Sabin Oral Polio Vaccine Prods. Liab. Litig., 743 F.Supp. 410 (D.Md.1990).
Because OPV is made from live polio virus, it will cause polio, even if it is properly manufactured and tested. During the 1980s, when Cortez received Ori-mune, less than twenty-five doses of OPV caused paralytic polio yearly; by the 1990s, the occurrence of vaccine associated paralytic polio dropped to approximately ten per year, or one out of every 2.6 million doses. Graham v. American Cyanamid Co., 350 F.3d 496, 501 (6th Cir.2003). Cortez received his second Ori-mune dose on 5 June 1987. Three or four days later, he developed partial paralysis in his arms, which is permanent.
In 1999, Cortez brought suit against Dr. Jawaid and Cyanamid, and alleged that his second Orimune dose was defective and gave him paralytic polio. In particular, Cortez asserted that Cyanamid failed to test Orimune in accordance with FDA reg*529ulations. After a trial in the Circuit Court for the City of St. Louis, Hon. Michael B. Calvin presiding, a jury found for Cortez and against Cyanamid on theories of product defect and negligent manufacture, and awarded Cortez $8.5 million ($1.5 million past non-economic damages; $2 million future economic damages; and $5 million future non-economic damages). The verdict did not specify which portion of the damages was awarded for the two separate theories submitted. The jury found for Dr. Jawaid on Cortez’s personal injury claim. Cyanamid responded with a Motion for Judgment Notwithstanding the Verdict, which was denied.
DISCUSSION
Cyanamid argues, inter alia, that the Court erred when it denied its Motion for Judgment Notwithstanding the Verdict. Cyanamid claims there was insufficient evidence of causation to support Cortez’s claims of product defect and negligent manufacture. In his cross-appeal, Cortez argues that 1) the Court erred when it denied his motion to amend the judgment to add prejudgment interest under Section 408.040 RSMo (2000); and 2) the Court erred when it excluded the rebuttal testimony of Dr. Elizabeth Diehl.
When reviewing the denial of a motion for judgment notwithstanding the verdict, we review to determine if every fact essential to liability is predicated on legal and sufficient evidence. Uxa ex rel. Uxa v. Marconi, 128 S.W.3d 121, 128 (Mo.App. E.D.2003). We view the evidence and inferences therefrom in the light most favorable to the verdict, and disregard evidence and inferences therefrom that conflict with the verdict. Id. We leave witness credibility to the jury’s determination, and will only reverse the jury’s verdict for insufficient evidence if there is a complete absence of probative fact to support it. Id.
Because I find that the Court erred when it submitted the product defect case to the jury, and when it refused to allow Dr. Diehl’s testimony, I would reverse and remand for a new trial.
Product Defect: Instruction No. 7
Instruction Number 7, based on MAI 25.04, was submitted to the jury on plaintiff Cortez’s product defect claim against Cyanamid. It stated:
On plaintiffs claim based on product defect, your verdict must be for plaintiff against defendant American Cyanamid Company, if you believe:
First, defendant American Cyanamid Company sold the Orimune polio vaccine in the course of defendant’s business, and
Second, the Orimune oral polio vaccine administered to plaintiff was then in a defective condition unreasonably dangerous when put to a reasonably anticipated use, and
Third, the Orimune polio vaccine was used in a manner reasonably anticipated, and
Fourth, plaintiff was damaged as a direct result of such defective condition as existed when the Orimune polio vaccine was sold.
As indicated in the fourth paragraph of this instruction, a strict product liability case may not be submitted to the jury unless the plaintiff proves causation. Grover v. Grover, 972 S.W.2d 568, 573 (Mo.App. E.D.1998). Missouri requires both proximate and “but for” causation. Callahan v. Cardinal Glennon Hosp., 863 S.W.2d 852, 860-61 (Mo. banc 1993). “But for” causation is satisfied if the plaintiffs injury would not have occurred “but for” the defendant’s conduct. Id. In other words, Cortez was required to prove that, but for some action by Cyanamid, he *530would not have contracted polio. In addition to “but for” causation, a plaintiff must prove that an injury is a reasonable and probable consequence of the defendant’s act or omission. Id. at 865.
In United States v. St. Louis University, infra, St. Louis University brought a contribution action to recover damages from the United States in an Orimune case. In the judgment below, a jury had found for the plaintiff in a suit to recover for paralysis caused by Orimune administered by St. Louis University Hospital. United States v. St. Louis University, 336 F.3d 294, 295 (4th Cir.2003). The Fourth Circuit sets out what must be shown to establish proximate cause in a strict liability case against Cyanamid:
As to proximate cause, we note that all OPV, including OPV that satisfied all regulatory requirements, carried the risk that the recipient would actually contract polio. Therefore, to show that [plaintiff’s] polio was caused by the government’s regulatory violations, we conclude that SLU was required to establish that [plaintiff] likely would not have contacted [sic] polio (or would have contracted a less severe case of polio) from a vaccine that satisfied the government’s neurovirulence requirements.
Id. at 304. Shortly thereafter, the Sixth Circuit confirmed St. Louis University’s holding regarding causation in another oral polio vaccine case:
All vaccines produced from live viruses, as this one is, carry the paradoxical risk of inducing the very disease that the vaccine strives to prevent. In the absence of expert testimony showing that these alleged regulatory violations made Orimune more unsafe than it otherwise would have been, a rational trier of fact could rule for plaintiffs only on the basis of conjecture, not a legitimate set of inferences drawn from admissible evidence. On this record, it remains unknowable whether plaintiffs’ injuries stemmed from an avoidable defect in the product or unavoidable bad luck.
Graham v. American Cyanamid Co., 350 F.3d 496, 512 (6th Cir.2003). I conclude that the analysis set out by the Fourth Circuit and Sixth Circuit is correct as to the proof necessary for the submission of Instruction No. 7, under the Missouri cases cited supra.
Cortez, however, did present expert testimony, discussed in detail later in this opinion, which indicated that the Orimune given to Cortez had not been properly tested and was therefore more likely to cause polio. However, that is not what Instruction No. 7 required. Rather, Instruction No. 7 required the jury to find that Orimune was “in a defective condition unreasonably dangerous,” and that this defective condition caused Cortez’s polio.
Orimune, a live polio vaccine, is inherently dangerous. St. Louis University at 296. Without further proof that the improperly tested Orimune carried a defect and was therefore additionally “in a defective condition unreasonably dangerous,” there was insufficient evidence from which a jury could determine that Orimune caused Cortez’s polio. On the evidence submitted, it is just as likely that Cortez’s condition was caused by the callously described “unavoidable bad luck.” Graham at 512. As such, Instruction No. 7 was not supported by the evidence and should not have been submitted to the jury.
Negligent Manufacture: Instruction No. 9
The difference between the jury instructions for Cortez’s product defect and negligent manufacture claims is subtle — but it is a difference that demands disparate results. Instruction Number 9, based on MAI 25.09, was submitted to the jury on *531Cortez’s negligent manufacture claim against Cyanamid. The instruction stated:
On plaintiffs claim based on negligent manufacture, your verdict must be for plaintiff against defendant American Cyanamid Company, if you believe:
First, defendant American Cyanamid Company manufactured the Orimune oral polio vaccine administered to plaintiff, and
Second, the Orimune oral polio vaccine was not tested for neurovirulence in Orimune oral polio vaccine seeds SOM Type 1, SOM Type 2, SOM Type 3, 45B157, 45B158, 45B164, 701S, or 801S, and
Third, defendant American Cyanamid failed to use ordinary care to manufacture the Orimune oral polio vaccine administered to plaintiff to be reasonably safe, and
Fourth, as a direct result of such failure, plaintiff sustained damage.
Unlike the verdict director for Cortez’s product claim, Instruction No. 9 did not require the jury to find that the Orimune administered to Cortez was defective. Rather, the jury was only required to find that Cyanamid failed to test Orimune for neurovirulence, and that this failure caused Cortez’s injuries.
At trial, Dr. Burris, a pediatric neurologist, testified that Cortez contracted polio from the Orimune vaccine administered. Cortez also provided the testimony of Thomas Bozzo, a former FDA compliance officer with degrees in pharmacy and public health. Mr. Bozzo testified that, while there were records indicating that Cyan-amid tested Orimune in accordance with FDA regulations, these records were “con-clusionary” and did not include actual test records. Tr. 744. Mr. Bozzo also testified that a failure to properly test Orimune increased the risk that Orimune was unsafe:
A. Safety testing should be done to assure that the product is safe, safe, pure, and potent.
Q. What happens if you don’t do the test?
A. Well, if you omit safety tests, then you raise the possibility of a product being unsafe.
Q. When you say you raise the possibility of a product being unsafe, what do you mean in regard to the general public, who is going to receive that vaccine?
A. Well, the general public is then exposed to product that is at higher risk or higher danger for an untoward effect. And if you’re talking about a neurovir-ulence test, it’s virulent polio virus being given to them.
Tr. 686.
In Graham, supra, the Sixth Circuit established what evidence a plaintiff must produce in order to show that Cyanamid’s regulatory noncompliance caused polio. Graham, 350 F.3d at 508. The plaintiffs in Graham, individuals who contracted polio after receiving Orimune or coming in contact with someone who received Orimune, sued Cyanamid on theories of product liability and negligence, et al. Graham at 503-05. The plaintiffs alleged that Cyan-amid failed to comply with the FDA’s “tissue culture passage” and “consistency of manufacture” neurovirulence regulations. Id. The Court affirmed the lower court’s grant of summary judgment to Cyanamid, finding that the plaintiffs “did not show ... that American Cyanamid’s alleged regulatory noncompliance increased the risk that the Orimune vaccine would cause polio in recipients or those in close contact with recipients beyond the inherent risk long known to be associated with OPV.” Id. at 508.
As stated earlier in Graham, the Court went on to say: “[i]n the absence of expert *532testimony showing that these alleged regulatory violations made Orimune more unsafe than it otherwise would have been, a rational trier of fact could rule for plaintiffs only on the basis of conjecture, not a legitimate set of inferences drawn from admissible evidence.” Id. at 512. Unlike the plaintiffs in Graham, Cortez presented expert testimony that Cyanamid’s failure to test Orimune as required by FDA regulations, and failure to exercise ordinary care to ensure Orimune is reasonably safe, increased the risk that Orimune would cause polio, thereby making it more unsafe. Mr. Bozzo testified that, as a result of Cyanamid’s failure to test, “the general public is then exposed to product that is at higher risk or higher danger” of causing polio. Tr. 686. Mr. Bozzo’s testimony was sufficient to establish causation and make a submissible case on Cortez’s negligent manufacture claim.
Verdict Form
However, because of the way the case was submitted to the jury, I am not confident that this jury rendered this verdict without confusing the instructions on the two claims. On the verdict form, the jury awarded Cortez $8.5 million. The verdict form submitted directed the jury to award a single damages award, and this the jury did. As such, we cannot tell whether the damages were allocated with respect to Instruction No. 7 or Instruction 9, and thus a new trial is required.2
Rebuttal Testimony
Additionally, as to Cyanamid’s rebuttal expert, Dr. Diehl, I would hold that it was an abuse of discretion not to allow Dr. Diehl’s testimony or deposition into evidence.
Because the admission or exclusion of evidence, especially expert testimony, is within the trial court’s discretion, we review for an abuse of discretion. Twin Chimneys Homeowners Ass’n v. J.E. Jones Const. Co., 168 S.W.3d 488, 504 (Mo.App. E.D.2005).
At trial, Dr. Jawaid was questioned about her routine when discussing Ori-mune’s risks and benefits with patients. Dr. Jawaid testified that she did not recall advising Cortez’s mother about the risks of oral polio vaccine, but she followed her usual routine, which is based on the “Red Book,” a pediatrics reference book:
Q. With regard to the routine you had in discussing OPV and other vaccines with patients, did you derive that routine ... from the Red Book ... ?
A. Yes, I did.
Q. Do you have any reason to believe as you sit here today that on June 5, 1987, you didn’t follow your regular routine in discussing the risks and complications of polio?
A. No, I followed the Red Book.
Q. And you do that regularly?
A. Yes, because I was trained to follow the Red Book as my guideline.
Tr. 1987.
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Q. So if there is a — if you will, a standard of care by this Red Book, you think you’ve complied with that standard of care?
A. I followed their guidelines, so I guess I did it.
Tr. 1995.
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*533Q. ... “it’s your interpretation of the Red Book that you don’t need to also advise them of the availability of the IPV,3 is that correct?”
A. You’re right.
Tr. 1996.
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Q. ... With regard to how you determine to do things, like giving advice to patients or getting their consent ... you are relying on the Red Book as the standard of how you do that, correct?
A. That is correct.
Q. Okay. And it is your understanding that that is the standard for physicians to do that, correct, pediatricians?
A. Yeah, that’s the guideline.
Tr. 2013-14.
Dr. Jawaid testified that the Red Book is the “standard” or “guideline” for pediatricians, and that it did not require her to discuss the availability of IPV with Cortez’s mother. Cortez then attempted to call Dr. Elizabeth Diehl, one of Dr. Ja-waid’s named experts, to offer rebuttal testimony regarding the standard of care for physicians administering polio vaccine. Dr. Diehl was prepared to testify that the standard of care required a pediatrician to advise potential Orimune recipients of the availability of IPV in addition to OPV. L.F. 4107-09. However, the Court prohibited Cortez from calling Dr. Diehl.
Dr. Jawaid argues that the testimony of Dr. Diehl should have been offered in the plaintiffs case-in-chief. “[R]ebuttal testimony is not necessarily inadmissible simply because ... it would have been better procedure to offer it as part of the state’s evidence-in-chief instead of rebuttal.” Aliff at 316; quoting State v. Petty, 967 S.W.2d 127, 141 (Mo.App. E.D.1998).
In Cortez’s case-in-chief, he offered the testimony of Cortez’s mother, Alesia Allen, who testified that Dr. Jawaid did not inform her of the risks associated with OPV. Tr. 484-85. One cannot read this transcript and but conclude that Dr. Jawaid did not inform Ms. Allen of the availability of IPV, and that Ms. Allen would have chosen IPV if she had known it was an option. Tr. 485-86. Simply, Cortez was not allowed to present evidence as to the standard of care applicable to doctors administering OPV. While it is true that the trial court has considerable discretion when deciding whether to admit rebuttal evidence, this discretion is not limitless.
When Ms. Allen took Cortez to Dr. Ja-waid in 1987, she did not possess medical knowledge of the available polio vaccines and their risks. Consequently, she was in a position of total reliance on Dr. Jawaid, and trusted Dr. Jawaid with her infant son’s safety. Given the disparity in the parties’ knowledge, the severity of the resulting injury, and the availability of rebuttal testimony from a designated defense witness — thus no surprise, I find that Dr. Jawaid’s testimony should not have gone un-countered. The Court’s decision to exclude Dr. Diehl’s rebuttal testimony was arbitrary and unreasonable and thus constituted an abuse of discretion.4
*534Prejudgment Interest
In his cross-appeal, Cortez also argues that the Court erred when it denied his motion to amend the judgment to add prejudgment interest under Section 408.040 RSMo (2000). I agree that Cortez complied with Section 408.040 RSMo (2000).
I would reverse and remand for a new trial.
. As we would remand for a disjunctive instruction, a portion of which is without factual basis. Stacy v. Truman Medical Center, 836 S.W.2d 911, 925 (Mo. banc 1992); Knox v. Simmons, 838 S.W.2d 21, 24 (Mo.App. E.D.1992).
. IPV, or Inactivated Polio Virus, is an alternative to OPV that does not carry the risk of causing vaccine associated polio.
. Dr. Jawaid also argues that the "standard of care” was not raised in her testimony and, as such, rebuttal testimony was inappropriate. I find no merit in this argument. "Standard of care” is defined as "... the degree of care that a reasonable person should exercise.” Black’s Law Dictionary (8th ed.2004). While Dr. Jawaid did not use the precise term "standard of care” in her testimony, she testified that the Red Book is the "standard” or "guideline” used by pediatricians. This language constitutes testimony regarding the “standard of care," as does the question of Dr. Jawaid’s counsel.