Nothing like the Daily Mail for raising an eyebrow:

The bizarre requests to use CT scanners, normally intended for four-legged animals, at the UK’s leading veterinary college in north London were revealed as hospitals face pressure to adapt beds and wards for an increasingly obese population.


The practice of referring patients to zoos is commonplace in America where obesity has reached epidemic levels.

Is there more systematic evidence or at least coming from non-tabloid sources on the common use of animal CT scanners for obese patients in the US? (I'm pretty sure that's what the newspaper meant by "America" because the US tops the obesity charts, although apparently Brazil and Mexico are not that far behind.)

A reason to doubt the newspaper statement is that simple supply and demand theory suggests that in a country with a high number of obese people equipment manufacturers would make suitable equipment. On the other hand, it's possible for demand to outstrip supply for any number of reasons, including a more rapid change in demand (rapid obesity increase).

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    "The practice of referring patients to zoos is commonplace in America where obesity has reached epidemic levels." Wow, I live in America and I usually don't see many people that obese. I think its true they may have referred extremely obese people to the zoo, but that is a small fraction of the total population. Exaggerations probably make pretty good clickbait. Commented Dec 26, 2017 at 2:16
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    @JavaScriptCoder The very obese people are usually at home because they don't move around easily anymore. Which is why you can't see them in the public. Unless there is something that bothers them which makes them consult the EMS or a doctor.
    – jjack
    Commented Dec 26, 2017 at 7:34
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    This happened in House M.D. and Scrubs. That almost certainly contributed to the idea that it's commonplace.
    – Richard
    Commented Dec 26, 2017 at 11:44
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    Yes, "America" means the USA. This is completely standard usage of English. Commented Dec 26, 2017 at 19:26
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    What's the reputation of the Daily Mail? Would gross exaggeration or outright fabrication be unprecedented? Commented Dec 26, 2017 at 21:12

2 Answers 2


A 2011 literature review looked at the problem as it related to one particular condition: Difficulties in diagnosing pulmonary embolism in the obese patient: A literature review.

They conclude that there is a problem - not only are many CT scanners unable to handle morbidly obese patients (although this is improving), there are no guidelines for when this poses a problem:

With the increasing prevalence of morbidly obese patients, clinicians will more frequently be faced with obese patients with signs and symptoms suggestive of PE who either cannot receive thoracic imaging at their hospital because of their size or the imaging is inconclusive [...]. The clinician in this situation must first decide whether they should transfer the patient to another facility with a ‘heavyweight’ CT scanner. There are no guidelines to aid the physician in this situation. Locating these facilities is difficult since there is no website or national registry cataloging these CT scanners. In addition, risks are involved with such transfers, especially the risk of re-embolization during travel. Often there are questions about whether third party payors will provide reimbursement for these transfers. Finally, even though the patient may be transferred for the study, there is no guarantee that the study will be diagnostic since image quality may be poor, as described previously.

So, there is no protocol to contact local zoos.

Further, they reference another paper that considered the zoo angle for CTPA. ( CT pulmonary angiography is a particular subset of CT (computer tomography) diagnostic test.

In 2008, Ginde et al. published a study in which they surveyed 136 US academic hospitals and a random sampling of all non-federal USA hospitals with emergency departments to determine the availability of CT scanners capable of imaging obese patients. They located two 500 lb (227 kg) weight capacity scanners in their sample of hospitals and eight in the 136 academic centers they contacted. In addition, they contacted 145 zoos and 28 veterinary schools to see if any of these facilities had scanners used for large animal studies which could be used for obese humans. Only two zoos had CT scanners; both would not image humans. Sixteen of the veterinary schools had large weight capacity scanners but only four would consider scanning humans. Most of the veterinary schools had policies specifically prohibiting imaging human patients. Therefore, the rumor that zoos and veterinary schools will perform CTPA on very obese patients with suspected PE is false.

I checked the abstract of the cited 2008 paper and it concurred, on an even broader scale - all CT and MRI imaging:

Animal facilities are not a viable alternative for diagnostic imaging of human patients.

This is not evidence that it never happens - anecdotes would counter that - but merely that, as of 2008, it wasn't a common occurrence and wasn't a recommended practice.

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    Like @ventsyv, I had doubted there was any serious research on the topic. One of those "pleased to be proved wrong" moments.
    – Oddthinking
    Commented Dec 26, 2017 at 4:22
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    To quantify the affair a little better, the 2nd paper says "Typically, CT and MRI equipment have table weight limits of 350–450 lb to avoid equipment damage and are additionally limited by gantry/bore diameter." And another paper, which sets the limit more conservatively at 300 lbs, tells us how many US residents exceeded this: "The percentage of US adults, >or=20 years, weighing>or=300 pounds was 0.10%, 0.79%, and 1.50% in 1976 to 1980, 1988 to 1994, and 1999 to 2004, respectively (p trend<0.001)." Commented Dec 26, 2017 at 14:16
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    This answer is well-researched but seems rather out of date. It wouldn't be surprising if generally increasing levels of technology had led to more zoos having higher-quality CT scanners since 2011, which could be more suitable for human use than the ones present most of a decade ago. Commented Dec 26, 2017 at 15:58
  • Maybe there has also been a decrease in funding for zoos since 2011?
    – jjack
    Commented Dec 26, 2017 at 17:44
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    @DavidRicherby: I concede the data is 10 years old now; I was careful to mention it. Don't forget that hospitals, too, benefit from advances, and I would like to think high-capacity scanners have improved there too, following the trend the first paper identified in 2011. Note also the non-technological aspects identified in the papers that are unlikely to improve as fast - zoo policies (presumably protecting from legal risk), insurance policies (who pays for travel/procedures?), travel risks, etc.
    – Oddthinking
    Commented Dec 26, 2017 at 21:37

There is anecdotal evidence to support the notion that some obese patients might have been referred to a zoo. Here is a recent NY Times article that explores the standard of care obese patients are receiving. From the article:

When an obese patient cannot fit in a scanner, doctors may just give up. Some use X-rays to scan, hoping for the best. Others resort to more extreme measures. Dr. Kahan said another doctor had sent one of his patients to a zoo for a scan. She was so humiliated that she declined requests for an interview.

I read another article (I can not find it at the moment) in which told a similar story. That article pointed out that the obese patient was turned down by the zoo as they are not trained to work on people.

That makes me believe obese people being treated at the zoo is not a regular occurrence but I doubt there is any serious research on the topic.

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    "She was so humiliated"..... the main reason why I seriously doubt there is anything to the idea this is anything but obscure and rare. Commented Dec 26, 2017 at 15:11
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    No one would make this up...
    – jjack
    Commented Dec 26, 2017 at 17:43
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    @jjack it's demeaning to a poorly-defined and yet largely unpopular segment of the populace in a manner that a fair number of people would find amusing, and that can be used to win internet arguments or make political points. There are absolutely people out there who would make this up.
    – Ben Barden
    Commented Dec 26, 2017 at 22:34
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    @BenBarden I agree, this goes under "social engineering" (I'm not happy with this term).
    – jjack
    Commented Dec 26, 2017 at 22:37
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    "I haven't done it, but another doctor I know of has" sounds like a classic urban legend. (And if the patient was too humiliated to discuss the case, there ought to be zero chance that the reporter actually confirmed the case, as medical confidentiality would preclude putting the reporter in touch with the patient without the patient's consent.)
    – 1006a
    Commented Dec 27, 2017 at 6:17

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