Which Pet Medications Fail in a Hot Car: What the Labels Say, What the Studies Measured, and What Nobody Publishes

A go-bag fails on a date. That is the assumption behind every rotation checklist ever written, including ours: you check the expiry printed on the bottle, you swap the old stock for new, and the kit is good again. This page is about the other failure, the one with no date attached. A blister strip that lived in a hot car through July can reach its printed expiry looking exactly the way it looked in June, and the printed expiry describes storage the manufacturer specified, not storage the bag actually got. Temperature is a separate clock, it runs faster than the calendar, and nothing on the package tells you where it is.

So this page does not tell you to throw anything away, and it does not tell you to keep using anything either. FDA’s own page on drug safety after a disaster comes closest to a general instruction, and it is conditional rather than a rule: under its section on drugs exposed to fire, it states that “the effectiveness of drugs can be destroyed by high temperatures from a fire” and that “if you think your medicines have been exposed to excessive heat, consider replacing them.” Consider replacing is not a threshold, and it names no specific product, temperature or duration, so it does not answer whether one pet medication left in one hot car for a known number of hours has failed. Nobody, including a website, can tell you that from a temperature alone. What this page does is separate three things that get collapsed into one sentence online: what your product’s label actually says, what anyone has actually measured about that product under heat, and who is entitled to decide. Those turn out to be three different columns, and for most pet medications the middle one is empty.

Two topics belong to other pages and stay there. Insulin has its own labels, its own temperature range and its own rules, and other pages here carry it: pet insulin outside the fridge is the label-by-label page, reading Vetsulin, ProZinc and the human insulin labels one document at a time and printing where each one is silent, and our pet medication and refrigeration in a power outage guide handles it with the manufacturers quoted directly. Compounded preparations carry a beyond-use date set by the pharmacy that made them, which is a pharmacy determination and not something a general table can restate. Neither appears below.

The 59 to 86 Degree Range Is a Shipping Rule

Start here, because almost every wrong conclusion about pet medication and heat starts with this number being read as something it is not.

Open a pet’s prescription bottle and you will often find a phrase like “excursions permitted between 15° and 30°C (between 59° and 86°F).” It reads like a tolerance. It reads like the drug has been tested and found to survive 86 degrees. It is neither. It is a definition borrowed from a pharmacy and supply-chain standard, and the standard says out loud what it is for.

USP publishes an authorized reprint of General Chapter 1079.2, on the use of mean kinetic temperature in evaluating temperature excursions, stamped “Authorized for reprint on October 28, 2024.” Its Table 1 sets out the controlled room temperature framework in four numbers: a storage range of 20° to 25°, an acceptable excursion range of 15° to 30°, a maximum temperature of 40°, and a maximum excursion time of not more than 24 hours, with mean kinetic temperature not more than 25° calculated over 30 days. Those are the numbers the label phrase comes from.

Now read the chapter’s own scope statement, which is the sentence that changes how the whole page reads:

“This chapter applies to every link in the supply chain from the manufacturer through any entity that transports or stores a finished drug product, with the sole exception of the patient.”

The framework stops at the person holding the bottle. It is written for manufacturers, warehouses, wholesalers, third-party logistics providers, pharmacies and clinics. It is explicitly not written for the last mile, which for our purposes is your car.

The chapter is equally direct about what an excursion is, carve-out included: “It is important to note that an excursion is a nonconforming event (except as previously noted when provided by the manufacturer).” The default is a nonconformance that has to be evaluated. The exception is the manufacturer’s own data, and Table 1’s own footnote a says how to read a number that sits outside the chapter’s default ranges: “Exposure to higher and/or lower temperatures beyond what is recommended in this chapter should be evaluated using monographs, product labels, or stability data provided by the manufacturer.” Put the two together and the number printed on a label is not a universal ceiling every product shares. It is the supply chain’s own default, and the manufacturer’s own labeling is what actually governs a specific product. And on the tempting idea that a cool night undoes a hot afternoon, it states: “This ignores the fact that any degradation due to the higher temperature is not reversible.”

There is one more line worth carrying, footnoted directly to the excursion table: “Some CRT- labeled products may have stability issues with the higher and/or lower excursion limits. These products must be evaluated and shipped within the stability limits provided by the manufacturer.” USP itself is saying the range does not certify any individual product.

A retrieval note, stated plainly. The definitions of controlled room temperature and controlled cold temperature live in USP General Chapter 659, and we could not read the current official text of 659 directly. USP’s DOI landing page for 659 returns a subscriber preview only, and www.usp.org and www.uspnf.com returned HTTP 403 to our requests on August 11, 2026. That is a paywall and a blocked fetch, not an absent document. USP’s own authorized reprint of 1079.2 states that the controlled room temperature and controlled cold temperature definitions sit in 659, and it reproduces the excursion limits that reference them. The warm and excessive-heat figures come from a different source already cited on this page: Ondrak, Jones and Fajt (BMC Veterinary Research, 2015) state that “the U.S. Pharmacopeia defines controlled room temperature as 20–25 °C. Temperatures between 30 and 40 °C are considered warm, while excessive heat is defined by the U.S. Pharmacopeia to be temperatures above 40 °C.”

What Has Actually Been Measured Inside a Vehicle

Four measurement studies matter here, and each one measured something slightly different. Naming the difference is the whole job, because the temptation is to blend them into a single number and then attach that number to a drug.

A passenger cabin, in California, over one hour. McLaren, Null and Quinn published in Pediatrics in 2005 the study most commonly cited for hot cars. They parked a dark-blue 2000 Honda Accord with a medium-gray interior in full sun in Fremont, California on 16 cloud-free days between May 16 and August 8, 2002, at ambient temperatures from 72 to 96°F, and logged the interior every five minutes for an hour. They reported that “The average mean increase was 3.2°F per 5-minute interval, with 80% of the temperature rise occurring during the first 30 minutes”, that “even at the coolest ambient temperature, internal temperatures reached 117°F”, and that an “average 41°F (range: 28–49°F) increase from starting ambient temperature occurred for the ambient temperature range of 72 to 96°F.” They also found that cracking the windows did not help: “cracking open windows is not effective in decreasing either the rate of heat rise or the maximum temperature attained.”

Read the methods before you apply that to a medicine pouch. Their “wireless temperature sensors were placed in the test vehicles in the rear passenger section 15 inches above the seat, in the shade and not in direct contact with any part of the car.” That is cabin air, in shade, in one car, over one hour. It is not a trunk, not a cargo area, and not the inside of a closed bag. It also measured risk to children, which is a different question from whether a tablet held its potency.

Actual veterinary drug storage compartments, in Texas and Nebraska, over a summer. Ondrak, Jones and Fajt published in BMC Veterinary Research in 2015 the study that comes closest to a go-bag. They put temperature loggers in the drug storage units of 24 large-animal practice vehicles in central Texas and south central Nebraska and ran them from May 15 to September 16, 2013. Their findings, in their words:

“The highest temperatures recorded in a storage unit were 54.4 and 47.7 °C in Texas and Nebraska, respectively. The mean temperature recorded across all 24 storage units was 29.1 °C, with a mean of 26.9 °C in Nebraska and 31.4 °C in Texas. In Nebraska, at least one temperature over 25 °C was recorded on a mean of 111/124 days and a mean of 63 % of total logger readings. In Texas, temperatures over 25 °C were recorded on a mean of 123/124 days and a mean of 95 % of total logger readings.”

54.4°C is 129.9°F. And note the shape of the Texas result: not a spike on the worst day, but a mean above the upper limit on most labels, on 123 of 124 days.

They also noticed something about enclosures generally: “the temperatures recorded in the storage units consistently exceeded the environment temperatures suggesting a greenhouse effect in the storage unit which may have been exacerbated by a lack of shade.” Eighteen of the 24 vehicles were routinely unshaded during working hours.

Their own conclusion about the excursion framework, comparing what they logged against USP’s allowances, was blunt: “Temperatures in study vehicles exceed these allowances both in magnitude and duration.”

Four cars, in the UK, over two years. Carter, Hall, Connolly, Russell and Mitchell published in the Open Veterinary Journal in 2020 a study logging four vehicles at 15-minute intervals across a two-year study period, each car for between 7 and 18 months depending on its availability, explicitly framed around both dogs and drugs. They reported that “the internal car temperature ranged from -7.4°C to 54.5°C during the study period,” that “the internal car temperature exceeded typical drug storage recommendations (>25°C) during every month, and exceeded the canine thermoneutral zone (>35°C) from April to September,” and that “peak temperatures occurred between 14:00 and 17:00 hours.” Their recommendation to veterinarians was to keep drugs “within the manufacturer’s temperature range year-round.” Note the year-round part: they recorded temperatures below 8°C in every month except June and July, so a vehicle is a two-directional problem, not only a summer one.

A bag, in different places in a car, in an English spring. Rudland and Jacobs published in the BMJ in 1994 the only study we located that compared storage sites within a car for a bag of medicines. Measuring doctors’ visiting bags in a South Devon coastal town during May and June, they reported: “The bag was coolest in the car boot, but irrespective of storage site, maximum internal temperature of the bag was always over 25 degrees C and reached up to 80 degrees C.” Coolest of the sites tested does not mean cool enough, and the study’s own conclusion was that the bag should be removed from the car to a cooler site when not in use.

What none of these measured. We did not locate a published study that put a logger inside a pet owner’s medication pouch in a passenger vehicle trunk across a summer in the United States. Searches on August 11, 2026 through PubMed, including the queries “veterinary drug stability hot car” and “medication left in car heat stability pet,” returned the Carter 2020 UK vehicle study and nothing matching that specific design. That is a statement about what those searches returned, not a claim that such a study cannot exist or has not been published somewhere we did not look. Where this page needs a vehicle-compartment figure, it uses Ondrak’s veterinary storage units and says so.

The Table: Labeled Storage Versus Published Stability

Every cell in the left half of this table is the product’s own label, quoted, read on DailyMed on August 11, 2026. DailyMed is the National Library of Medicine’s repository of the labeling submitted to FDA, and it carries FDA-approved animal drug labels alongside human ones. Where the label prints its own revision date, that date is in the first column.

The right-hand column is deliberately hard to fill, and most of it is empty. A labeled storage statement is not a failure threshold. “Store at 20° to 25°C” does not mean the product fails at 26°C, and nothing in this table should be read as saying it does. The two columns answer two different questions: what the manufacturer instructed, and what anyone has published about measuring it.

Product, manufacturer, label revision	Labeled storage, in the label’s own words	What the label says about excursions	Published stability data located for this product under heat
APOQUEL (oclacitinib maleate) tablets, Zoetis, revised December 2020	“APOQUEL should be stored at controlled room temperature between 20° to 25°C (68° to 77°F)”	“with excursions between 15° to 40°C (59° to 104°F)”	None located. See the search record below.
APOQUEL CHEWABLE (oclacitinib) chewable tablets, Zoetis, revised July 2025	“APOQUEL CHEWABLE should be stored at controlled room temperature between 20° to 25°C (68° to 77°F)”; also “Remaining half tablets should be stored in the original package and used for the next dose.”	“with excursions between 15° to 40°C (59° to 104°F)”	None located.
CERENIA (maropitant citrate) Tablets, Zoetis, revised January 2020	“CERENIA Tablets should be stored at controlled room temperature 20°–25°C (68°–77°F)”	“with excursions between 15°–30°C (59°–86°F)”	None located.
CERENIA (maropitant citrate) Injectable Solution, Zoetis, revised April 2020	“CERENIA Injectable Solution should be stored at or below 30°C (86°F)”; after first vial puncture, “stored at refrigerated temperature 2-8°C (36-46°F). Use within 90 days of first vial puncture.”	“with excursions permitted up to 40°C (104°F)”	None located.
VETMEDIN (pimobendan) chewable tablets, Boehringer Ingelheim, revised 11/2025	“Store at 20° to 25°C (68° to 77°F)”	“excursions permitted between 15° and 30°C (between 59° and 86°F)”	None located.
VETMEDIN Solution (pimobendan), Boehringer Ingelheim, revised 12/2025	“Store at or below 77°F (25°C)”; “Once the bottle is opened, use the contents within 8 weeks.”	“with excursions permitted up to 86°F (30°C)”	None located.
RIMADYL Caplets (carprofen), Zoetis, revised May 2019	“Store at controlled room temperature 15°–30°C (59°–86°F).”	No separate excursion sentence on this label	None located for the marketed caplet under vehicle heat.
GALLIPRANT (grapiprant) tablets, Elanco	“Store at or below 86° F (30° C)”	No excursion sentence on this label	A laboratory study exists, and it is not about tablets in a car. See below.
NEXGARD (afoxolaner) chewables, Boehringer Ingelheim	“Store at or below 30°C (86°F)”	“with excursions permitted up to 40°C (104°F)”	None located.
HEARTGARD Plus (ivermectin and pyrantel pamoate) chewables, Boehringer Ingelheim	“Store between 68° F - 77° F (20° - 25° C)”; “Protect product from light.”	“Excursions between 59° F - 86° F (15° - 30° C) are permitted.”	None located.
THYRO-TABS CANINE (levothyroxine sodium) tablets, Lloyd, Inc. of Iowa	“Store at controlled room temperature 20°-25°C (68°-77°F)”; “Protect from light and moisture.”	“with excursions allowed between 15° and 30°C (59° and 86°F)”	None located.
CLAVAMOX (amoxicillin and clavulanate potassium) Chewable tablets, Zoetis, revised September 2020	“Store in a dry, cool place at temperatures not above 25°C (77°F). Do not remove from foil strip until ready to use.”	No excursion sentence on this label	Classified as equivocal in a published review. See below.
CLAVAMOX DROPS (oral suspension), Zoetis, revised February 2019	No storage-temperature statement for the unreconstituted powder was located on this label; for the mixed product, “Any unused portion of the reconstituted suspension must be discarded after 10 days. Refrigeration of the reconstituted suspension is required.” Carton: “Do Not Use if Product is Discolored”	None stated	Classified as equivocal in a published review. See below.
Furosemide Tablets, Covetrus North America, approved under ANADA 200-759	“Store at controlled room temperature, 20° to 25°C (68° to 77°F)”; “Use half-tablet within 90 days.”	“Excursions permitted to 40°C (104°F).”	Classified as equivocal in a published review. See below.
NEURONTIN (gabapentin) tablets and capsules, Viatris, revised 4/2025	“Store NEURONTIN Tablets and Capsules at 25°C (77°F)”; the oral solution is separate: “Store NEURONTIN Oral Solution refrigerated, 2°C to 8°C (36°F to 46°F).”	“excursions permitted between 15°C to 30°C (59°F to 86°F) [see USP Controlled Room Temperature]”	None located.
Phenobarbital Tablets USP, Sun Pharmaceutical Industries, revised May 2024	No storage-temperature statement located anywhere on this label	None stated	Listed under “Demonstrated to be stable” in a published review. See below.
Phenobarbital tablet, Coupler LLC	“Store at 20°- 25°C (68°- 77°F) [See USP Controlled Room Temperature]. Protect from light and moisture.”	Refers to USP Controlled Room Temperature	Listed under “Demonstrated to be stable” in a published review.
EpiPen and EpiPen Jr (epinephrine injection, USP) auto-injector, Viatris Specialty, revised 2/2023	“Store at 20°C to 25°C (68°F to 77°F)”; “Protect from light”; patient labeling: “Do not expose to extreme cold or heat. For example, do not store in your vehicle’s glove box or trunk.”	“excursions permitted to 15°C to 30°C (59°F to 86°F) [See USP Controlled Room Temperature]”	Epinephrine is listed under “Demonstrated to be unstable” in a published review. See below.

Three things fall out of reading down that table, and each is worth its own section.

The Same Brand Can Give You Two Different Answers

This is the single most useful thing on the page, and it is invisible if you think in drug names instead of products.

Cerenia. Zoetis’s tablet label states storage “at controlled room temperature 20°–25°C (68°–77°F) with excursions between 15°–30°C (59°–86°F).” Zoetis’s injectable label for the same active ingredient states storage “at or below 30°C (86°F), with excursions permitted up to 40°C (104°F).” One brand, one active ingredient, two formulations, and the second one carries an excursion ceiling 18 Fahrenheit degrees higher than the first. Reading the injectable’s number and applying it to the tablets, or the reverse, is a mistake the labels themselves rule out.

Vetmedin. The chewable tablets are labeled “Store at 20° to 25°C (68° to 77°F), excursions permitted between 15° and 30°C.” The solution is labeled “Store at or below 77°F (25°C) with excursions permitted up to 86°F (30°C)”, and it adds an in-use clock the tablets do not have: “Once the bottle is opened, use the contents within 8 weeks.”

Apoquel. Both the coated tablet and the chewable carry the same storage sentence, including an excursion range up to 40°C, and the chewable label adds a half-tablet instruction the tablet label does not: “Remaining half tablets should be stored in the original package and used for the next dose.”

Phenobarbital, which is not one product at all. This one deserves care, because phenobarbital is among the most commonly prescribed long-term medications in canine seizure management, and pet owners fill it as a human-labeled generic. On DailyMed on August 11, 2026, the Phenobarbital Tablets USP label from Sun Pharmaceutical Industries, revised May 2024, carries no storage-temperature statement at all. There is no degree symbol anywhere in it. A different phenobarbital tablet label on the same repository, from Coupler LLC, states: “Store at 20°- 25°C (68°- 77°F) [See USP Controlled Room Temperature]. Protect from light and moisture.”

Two labels, same drug, same dosage form, and one of them gives an owner nothing to check an exposure against. If your pharmacy hands you a bottle whose label is silent on temperature, the silence is not permission. It means the question routes to the pharmacy, which knows which manufacturer’s product it dispensed and can reach that manufacturer’s medical information line.

The practical rule from all four of these: the row is the product. Not the drug, not the class, not the brand across formulations. Two tablets from different manufacturers can carry different sentences, and a tablet and a liquid from the same manufacturer routinely do.

What the Stability Literature Has Actually Found

Now the harder column. A labeled range tells you what the manufacturer instructed. It does not tell you what happens when the instruction is broken. That question has been studied, mostly in emergency medical services, and the results are neither reassuring nor uniformly alarming.

A veterinary review classified the drugs. The Ondrak 2015 paper did not stop at logging temperatures. It also reviewed published stability data for drugs common on large-animal practice vehicles and grouped them three ways: demonstrated to be stable outside manufacturers’ storage recommendations, equivocal data, and demonstrated to be unstable. Reading its Table 3 as printed:

• Demonstrated to be stable included atropine, diazepam, midazolam, morphine sulfate and phenobarbital; amikacin, gentamicin and neomycin; ciprofloxacin, difloxacin, enrofloxacin, marbofloxacin, norfloxacin and ofloxacin; clindamycin, lincomycin, tilmicosin, tulathromycin and tylosin; oxacillin and cloxacillin; sulfadimethoxine and sulfamethoxazole with trimethoprim; chlortetracycline and oxytetracycline; and calcium chloride, dexamethasone, diphenhydramine, sodium bicarbonate and thiamine.
• Equivocal data about stability included lidocaine and naloxone; erythromycin; amoxicillin with or without clavulanate, ampicillin and penicillin G; sulfamethoxazole; doxycycline and tetracycline; and dopamine and furosemide.
• Demonstrated to be unstable included cefazolin and cephalothin; and epinephrine, heparin and oxytocin.

Four cautions travel with that list, and dropping any of them turns a useful classification into a false one. First, the paper’s own note on the table states its exclusions: “Excluded drugs include extemporaneous solutions, temperature ranges significantly different than those encountered in veterinary practice, and drugs in tissues such as urine or meat.” Second, it is a classification of whether published data exist and what they showed, not a temperature and not a time; the paper attaches no threshold to any name. Third, the underlying studies are largely human and emergency-medicine studies, and the paper is about a large-animal practice truck, so applying a row to a specific dog’s prescription is a domain extension this site is naming out loud rather than performing silently. Fourth, “demonstrated to be stable” in that table refers to particular tested conditions in particular studies, and it is not a statement that the drug in your bag is fine.

The same paper is careful about what its own temperature data prove, and so should we be: “More research is needed to determine whether these excursions alter efficacy of stored drugs or lead to degradation products which may pose a health risk to the patient or eventually the consumer.”

A year in an actual response vehicle. De Winter and colleagues published in Annals of Emergency Medicine in 2013 a study storing five emergency drugs for one year at refrigerated temperature, at room temperature, and in an emergency physician transport vehicle in real working conditions, treating a drug as stable “if its content was above 90%.” They found that “adrenaline hydrochloride and methylergonovine maleate remained stable for 1 year at room temperature and in the emergency physician transport vehicle,” while “at room temperature and in the emergency physician transport vehicle, lorazepam became unstable within 4 weeks,” and succinylcholine and cisatracurium became unstable within months. Two things worth holding: a real vehicle did not destroy everything in it, and the drug that failed fastest failed in weeks, not in an afternoon.

Sixty days of American EMS summer. McMullan and colleagues published in Prehospital Emergency Care in 2013 a study collecting benzodiazepine samples before and after 60 days of EMS deployment during spring and summer months in 14 metropolitan areas, with temperature logged every minute. They reported that “after 60 days, midazolam showed no degradation” and was stable across temperature exposures, while “lorazepam experiences small but statistically significant temperature-dependent degradation after 60 days in the EMS environment.” Their conclusion added a limit worth respecting: “Additional study is needed to evaluate whether clinically significant deterioration occurs after 60 days.”

Deliberate thermal cycling to the temperature a vehicle actually hits. Gammon and colleagues published in the American Journal of Emergency Medicine in 2008 a study of 23 commonly carried EMS medications in which “pharmaceuticals were thermally cycled (-6 degrees C and 54 degrees C) every 12 hours” for a month. The upper bound there, 54°C, is essentially the 54.4°C Ondrak later logged in a Texas veterinary truck and the 54.5°C Carter logged in a UK car. The result: “Eight (35%) of 23 prehospital pharmaceuticals revealed ending concentrations of less than 90% with strong correlation to thermal exposure time. These included lidocaine, diltiazem, dopamine, nitroglycerin, ipratropium, succinylcholine, haloperidol, and naloxone.”

Two thirds of the tested drugs held above 90% through a month of that cycling. One third did not. That is the honest shape of the evidence: heat is not a universal solvent for medication, and it is not harmless either, and which side a given product lands on is a product-specific empirical question rather than something you can reason out from the drug’s name.

What 90% is doing in all of those sentences. It is the potency floor those studies used, and it is not arbitrary. FDA’s Center for Veterinary Medicine, in Guidance for Industry #5, Drug Stability Guidelines, dated December 9, 2008, prints it as a quotation with attribution: “Although there are exceptions, 90% of the labeled potency is generally recognized as the minimum acceptable potency level.” The guidance credits that line to Remington’s Pharmaceutical Sciences, sixteenth edition, page 284, 1985. The same guidance defines instability in a way worth keeping in mind: “A drug product is considered unstable when the drug substance (active ingredient) loses sufficient potency to adversely affect the safety or efficacy of the drug or falls outside labeled specifications as shown by stability-indicating methods.”

What We Searched For and Did Not Find

This site’s most common failure mode is writing that something does not exist when it does. So here is the search record for the empty cells, in enough detail that you can repeat it or beat it.

For each active ingredient in the table with an empty stability cell, we searched PubMed through the NCBI E-utilities interface on August 11, 2026, and we searched the product’s own label on DailyMed the same day. The PubMed queries were, verbatim: “oclacitinib stability”, “oclacitinib stability temperature”, “maropitant stability”, “maropitant stability temperature”, “pimobendan stability”, “pimobendan stability temperature tablet”, “afoxolaner stability”, “grapiprant stability”, “levothyroxine stability temperature”, “levothyroxine tablet stability elevated temperature”, “carprofen stability temperature”, “carprofen tablet thermal stability storage”, “ivermectin stability temperature storage” and “ivermectin chewable stability temperature”.

What those returned:

• Oclacitinib. One indexed record, a 2025 spectroscopy study of oclacitinib binding to bovine serum albumin. Not a storage-stability study.
• Maropitant. Five records, all clinical or pharmacological, including an anesthesia case report and a cyclodextrin applications review. None a storage-stability study of the marketed product.
• Pimobendan. Eighteen records, the closest being a 2025 study of three-dimensional printed inks and their preparations. None a storage-stability study of the marketed tablet or solution.
• Afoxolaner. One record, a 2021 reversed-phase assay of afoxolaner and its related substances in commercial bulk batches. That is a bulk-substance analytical paper, not a study of chewables held at vehicle temperatures.
• Levothyroxine. The temperature query returned a large, mostly irrelevant set, the top records being about whole-blood sample stability, protein complexes and endocrine analytes in serum. The narrower query about tablet stability at elevated temperature returned nothing.
• Carprofen. Eight records including polymorph characterization, a validated stability-indicating analytical method with degradation-product characterization, and dilution studies of the injectable in laboratory-animal settings. The narrower tablet-storage query returned nothing.
• Ivermectin. Six records, none of them a storage-stability study of the marketed chewable.

Grapiprant is the one exception, and it is worth being precise about. Gumulka, Tarsa, Dabrowska and Starek published in Biomedicines in 2022 a paper titled “Quantification of Grapiprant and Its Stability Testing under Changing Environmental Conditions.” They did test a Galliprant tablet, finding 20.29 mg of active substance against the 20 mg declared. But the stability work was done on grapiprant solutions at varying pH held at room temperature and at 70°C, and they reported that degradation was much faster at 70°C and in acidic media, and identified probable degradation products. That is a laboratory forced-degradation study of the substance in solution. It is not a measurement of a Galliprant tablet in a glove box, and it does not supply a threshold for one.

So: for most of the products in the table, we did not locate a published study of that marketed product under heat. That is a statement about what those searches returned on that date, from those databases, and it is not a claim that no such data exist. Manufacturers hold stability data that is not published, and the label itself is the public face of it. Which is exactly why the routing below is the answer instead of a number.

The Go-Bag Problem, Which Is Different From the Errand Problem

An hour of errands and a summer in a trunk are two different exposures, and only one of them has been measured well.

The errand case is what the Pediatrics study describes: a fast rise, 80% of it inside the first 30 minutes, to a cabin temperature that reached 117°F on a 72-degree day. It is a short, sharp excursion, and USP’s own framework caps a permitted excursion at not more than 24 hours.

The go-bag case is the one that matters more here and is discussed less. A kit packed in April and left in a vehicle through hurricane season is not experiencing an excursion. It is experiencing a storage condition. Ondrak’s numbers are the ones to sit with: in Texas, a mean storage-unit temperature of 31.4°C across the whole logging period, with at least one reading over 25°C on a mean of 123 of 124 days. In Nebraska, a mean of 26.9°C and readings over 25°C on 111 of 124 days. Carter’s UK cars exceeded 25°C in every month of a two-year study period, with each car logged for between 7 and 18 months.

Rudland and Jacobs is the study that speaks directly to the bag rather than the air, and their finding is the one to take into the garage: the boot was the coolest of the sites they tested, and the bag’s maximum internal temperature was still, in their words, “always over 25 degrees C and reached up to 80 degrees C.” Their own recommendation was to take the bag out of the car when it was not needed there.

That is the honest conclusion for a pet go-bag, and it is a storage decision rather than a discard decision. If the medication compartment of your kit lives in a vehicle year-round, it is being stored outside most of the ranges printed on the labels above for a large share of the year, and that is knowable in advance rather than after the fact. Our rotation checklist handles the calendar half of kit maintenance. The temperature half is a placement question: which parts of the kit have to be grab-and-go in the car, and which parts can live indoors and be added on the way out.

A useful split many owners land on: the bag lives in the car, the medication pouch lives inside the house next to the door with a written note in the bag naming what is missing and where it is. Our go-bag checklist is where the rest of that packing decision lives, and the pet emergency binder is where the note belongs so it does not get separated from the kit.

Can You See It?

Short answer: only where the label says so, and only for that product.

Some labels do publish an appearance rule. The FDA-approved patient labeling for EpiPen and EpiPen Jr states that “When exposed to air or light epinephrine changes quickly to a pinkish or brown color and should not be used”, and instructs patients to inspect the solution through the window and replace the device if it “appears discolored (pinkish or brown color), cloudy, or contains particles.” Zoetis’s CLAVAMOX Drops carton carries “Do Not Use if Product is Discolored.” Heartgard Plus and Thyro-Tabs Canine both carry protect-from-light instructions, and Thyro-Tabs adds moisture.

What this page will not tell you is that a normal-looking tablet is undamaged. No source we read supports that as a general proposition, and the products whose labels say nothing about appearance say nothing about appearance in both directions. FDA’s disaster guidance splits the difference in a way that is honest about the limits: it states that “After a natural disaster, it is important to inspect all drugs”, and in the specific case of a lifesaving drug exposed to fire or unsafe water where no replacement is available, that “If the drug looks unchanged”, giving the example of pills in a wet container that appear dry, “the drugs can be used until a replacement is available.” That permission does not stand alone. The same guidance immediately adds the hard stop it depends on: “If the pills are wet, then they are contaminated and need to be discarded.” Read the whole thing in context, not the middle clause alone. It is written by the Center for Drug Evaluation and Research for human patients and their own medicines, which matters for what a pet owner can borrow from it and what they cannot, and no stability finding in it transfers to a veterinary product. It is written about fire and flood, it is written for the case where the alternative is going without a lifesaving drug, and it is written alongside the instruction to replace the product as soon as possible.

The Call You Actually Make

Most of the veterinary labels above print the route, in the same place, under a Contact Information heading, and several offer technical assistance by name. Zoetis’s APOQUEL label states it this way:

“To report suspected adverse events, for technical assistance or to obtain a copy of the Safety Data Sheet, contact Zoetis Inc. at 1-888-963-8471 or www.zoetis.com.”

Boehringer’s VETMEDIN label carries the equivalent sentence: “To report suspected adverse reactions, to obtain a Safety Data Sheet (SDS), or for technical assistance, contact Boehringer Ingelheim Animal Health USA Inc. at 1-888-637-4251.” Both also point to FDA at 1-888-FDA-VETS for adverse event reporting. The number on your label is the number that matters, since manufacturers change and contact lines change, and the label in your hand is the current record.

For a human-labeled generic dispensed for your pet, the pharmacy is the first call, because the pharmacy knows which manufacturer’s product it handed you and can reach that manufacturer’s medical information line. FDA’s own instruction covers both cases: “If you are concerned about the efficacy or safety of a particular product, contact your pharmacist, healthcare provider, or the manufacturer’s customer service department.”

What to have written down before you call. Nothing on this page and nothing in the sources tells you to prepare these, so this list is ours. It exists because a technical services line can only evaluate an exposure it can see:

• The product name, strength and dosage form exactly as printed on the label, including whether it is the tablet, the chewable, the solution or the injectable.
• The manufacturer’s name from the label, and the lot number and expiry date.
• Roughly how long the product was in the vehicle, and whether that was one afternoon or a season.
• The highest temperature you can actually document, and how you know it. A minimum and maximum recording thermometer left in the compartment turns a guess into a number, and it costs nothing to add to a kit you are already maintaining.
• Where in the vehicle it sat, and whether the vehicle was shaded.
• Whether the product changed in any visible way, and whether its own label says anything about appearance.

Then let them decide. The decision to keep using, to replace, or to substitute belongs to the veterinarian who prescribed it, the pharmacist who dispensed it, or the manufacturer who set the label, and this site is not a party to it.

If the answer is replace, and the prescription is one your animal cannot go without, the refill timing question is its own problem. Our medication refill calculator works the dates, and the hurricane season prep calendar is where a pre-season refill belongs so that a heat question in August is not also a supply question.

About Coolers and Insulated Cases

The flag on this page’s plan says gear, so here is the gear section, written the way the evidence allows.

We will not tell you that any cooler, insulated case or phase-change product holds a temperature. Manufacturers publish performance claims for their own products, those claims belong to the manufacturers who make them, and restating one as a fact is how a marketing number becomes a safety statement. If you are shopping, read the claim on the manufacturer’s own page, notice the conditions it was measured under, and treat it as a claim.

Two pieces of kit are worth naming because they change what you know rather than what you assume:

A minimum and maximum recording thermometer. It converts the single most important input to the phone call, the highest temperature reached, from a guess into a reading. Put it in the compartment with the medication, not in the cabin.

An opaque, closed container inside the bag. Several of the labels above carry protect-from-light instructions in their own words, including Heartgard Plus and Thyro-Tabs Canine, and Clavamox Chewable adds “Store in a dry, cool place” plus “Do not remove from foil strip until ready to use.” Those are label instructions you can follow for free, and following them is different from claiming a container fixed a temperature problem.

The cooler question in its full form, for the one category of medication where true refrigeration is the labeled requirement, is worked through on our insulin cooler travel case guide and the medication refrigeration in an outage guide, which quote what the manufacturers say and separate a cooling wallet from a refrigerator. That is deliberately not restated here.

Your Hot-Car Medication Checklist

• Read the storage sentence on every medication in your pet’s kit, one product at a time, and write it on the outside of the pouch. Two products from the same brand can carry different numbers.
• If a label carries no storage-temperature statement at all, note that too. Silence is a reason to ask the pharmacy which manufacturer’s product you were dispensed, not a reason to assume the product is unbothered.
• Stop reading the excursion range as a tolerance. USP’s own chapter treats an excursion as a nonconforming event by default, except where the manufacturer’s own label and stability data already allow for it, caps a default excursion at not more than 24 hours, and states its framework covers everyone in the supply chain “with the sole exception of the patient.”
• Decide which parts of the kit live in the vehicle and which live indoors. A season in a car is a storage condition, not an excursion, and it is a decision you can make before anything happens.
• Put a minimum and maximum recording thermometer in the medication compartment now, so a future phone call has a number in it.
• Follow the label’s non-temperature instructions too. Protect from light, protect from moisture, keep it in the original foil, keep the original container with the label legible, which FDA’s own pet medication storage page asks for in these words: “Keep pet medications in their original containers with intact labels.”
• If an exposure has already happened, collect the six items in the section above and call. The prescriber, the pharmacy and the manufacturer are the parties who decide.
• Do not apply anything on this page to insulin or to a compounded preparation. Insulin has its own labeled range and its own page here: pet insulin outside the fridge prints those labels one product at a time. A beyond-use date on a compounded product is set by the pharmacy that compounded it, and that pharmacy is the one to ask.
• Note the cold half of the problem as well. The UK vehicle study recorded internal temperatures below 8°C in every month except June and July, and at least one product label above rules out extreme cold by name alongside extreme heat.
• Keep the medication list itself somewhere the heat cannot reach, and somewhere you can produce it if the bottles are gone. Our records pages cover that: paper versus digital pet medical records and reconstructing pet records when the clinic is gone.

Where to Go Next

This page is the temperature spoke of our pet evacuation kits hub. The rest of the medication problem splits four ways.

If the medication needs a refrigerator. Pet insulin outside the fridge is the label-by-label page for insulin itself, reporting what each Vetsulin, ProZinc and human insulin label states about time out of the refrigerator and where each one states nothing. The medication refrigeration in a power outage guide is the deep dive, including what the veterinary insulin manufacturers publish, and the insulin cooler travel case guide covers the gear side of carrying a refrigerated product out the door.

If the problem is the calendar rather than the thermometer. The pet emergency kit rotation checklist works expiry dates and swap intervals, and the medication refill calculator works out when a refill has to land.

If the animal is the one in the hot car. That is a different emergency with a different clock, and it is covered on our heat and hot cars page for pets and on leaving a pet in the car at an evacuation stop.

If the prescription is one a missed dose actually threatens. The seizure dog emergency kit and the senior dog emergency kit work the supply and continuity question for the animals where the answer to “can we skip a day” is no.

Then do the one thing this page is really asking for, and do it on a quiet afternoon rather than in an evacuation. Take every medication in the kit out of the bag, read its storage sentence off the actual label, and write those sentences down in one place. Half of them will not say what you expected. That list, in your handwriting, is what turns a panicked search for a number into a two-minute phone call with the only people who can answer.