Photo: Кристина Корнеева/Adobe Stock

The FDA has issued an emergency use authorization for lotilaner chewable tablets (Credelio Cat; Elanco Animal Health) for treating New World screwworm (NWS) infestations in cats and kittens. Credelio Cat is the first drug to receive FDA authorization for the treatment of NWS in cats.

The emergency use authorization for Credelio Cat follows the earlier 

FDA authorization of lotilaner (Credelio) for treating NWS infestations in dogs

, which was announced on October 24, 2025.

The FDA determined that, based on available scientific evidence, Credelio Cat may be effective in treating NWS infestations in cats and kittens. Although the product is not officially FDA approved for treating NWS, the federal agency concluded that the known and potential benefits of the product outweigh its known and potential risks, clearing the way for its emergency use in affected animals.

The authorization was based on research evaluating Credelio Cat’s efficacy against naturally acquired Old World screwworm (OWS) myiasis in 2 cats in Malaysia, as well as studies of Credelio’s effectiveness against NWS myiasis in 11 naturally infested dogs in Brazil.

The latter study was the basis for the FDA’s emergency use authorization of Credelio for dogs earlier this fall.

 According to the study on Credelio Cat, the treatment had 100% larvicidal effectiveness against OWS (

) at 24 hours post treatment in the 2 cats.

 Credelio also demonstrated 100% efficacy against the parasite’s larvae within 24 hours of treatment.

“This historic [emergency use authorization] equips veterinarians and cat owners with a treatment solution and provides reassurance that they're prepared to act quickly if New World screwworm crosses into the US,” Ellen de Brabander, PhD, executive vice president of innovation and regulatory affairs at Elanco, said in a news release.

Credelio Cat is approved for flea- and tick-related indications in cats and kittens. The product gained FDA approval for this use in 2019. Specifically, the product is approved for the treatment and prevention of flea infestations (

) for 1 month in cats and kittens 8 weeks of age and older that weigh 2 lb or more. The drug is also indicated for the treatment and control of infestations of 

, commonly known as the black-legged tick, for 1 month in cats and kittens 6 months of age and older that weigh 2 lb or more.

As an isoxazoline, lotilaner use has been linked to neurologic adverse effects, such as muscle tremors, ataxia, and seizures. Veterinarians should take extra caution if using the product on cats with a history of neurologic disorders.

The product is only available through a prescription from a licensed veterinarian, as professional expertise is needed to monitor for and respond to possible adverse reactions.

 Although NWS poses a low risk to most cats in the US, outdoor felines 

 or those that have traveled to countries with active NWS cases face a higher risk of NWS exposure.

On August 18, 2025, the Department of Health and Human Services (HHS) declared NWS a potential for a public health emergency.

 According to an announcement by the FDA, the emergency use authorization for Credelio Cat to treat NWS in cats will be in place until it is revoked or until HHS declares that NWS no longer presents a significant potential for a public health emergency.

“Given [NWS's] aggressive and invasive nature, any minor wounds from grooming, scratching, or outdoor activities can serve as an entry point for these parasites," Casey Locklear, DVM, a Texas-based veterinarian and parasiticide lead at Elanco, said.

 "It's essential to prevent or quickly address any wounds to keep cats safe from [NWS].”

FDA issues emergency use authorization for Credelio Cat to treat New World screwworm in cats. FDA. November 21, 2025. Accessed November 21, 2025. https://content.govdelivery.com/accounts/USFDA/bulletins/3fc7c4b?reqfrom=share

Bautista-Alejandre A. FDA grants emergency use authorization for lotilaner to treat New World screwworm in dogs. 

. October 24, 2025. Accessed November 21, 2025. https://www.dvm360.com/view/fda-grants-emergency-use-authorization-for-lotilaner-to-treat-new-world-screwworm-in-dogs

Fact sheet for veterinarians: emergency use authorization of Credelio Cat (lotilaner). FDA. November 21, 2025. Accessed November 21, 2025. https://www.fda.gov/media/189726/download?attachment=&utm_medium=email&utm_source=govdelivery

Han HS, Yasmin L. Chrysomya bezziana (Diptera: Calliphoridae) infestation in two Malaysian cats treated with oral lotilaner. 

. 2020;31(4):335-e87. doi:10.1111/vde.12855

do Vale TL, Costa AR, Miranda LM, et al. Efficacy of lotilaner against myiasis caused by Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs. 

. 2023;16(1):86. doi:10.1186/s13071-023-05661-z

Elanco's Credelio Cat (lotilaner) receives first FDA emergency use authorization (EUA) for treatment of New World screwworm (NWS) in cats. News release. Elanco Animal Health. November 21, 2025. Accessed November 21, 2025. https://investor.elanco.com/press-releases/press-releases-details/2025/Elancos-Credelio-CAT-lotilaner-Receives-First-FDA-Emergency-Use-Authorization-EUA-for-Treatment-of-New-World-Screwworm-NWS-in-Cats/default.aspx 

Freedom of information summary (FOI): original emergency use authorization (EUA). Elanco. November 21, 2025. Accessed November 21, 2025. https://www.fda.gov/media/189728/download?attachment=&utm_medium=email&utm_source=govdelivery

Declaration of emergency pursuant to the Federal Food, Drug, and Cosmetic Act for New World screwworm. Department of Health and Human Services. August 20, 2025. Accessed November 21, 2025. https://www.federalregister.gov/documents/2025/08/20/2025-15918/declaration-of-emergency-pursuant-to-the-federal-food-drug-and-cosmetic-act-for-new-world-screwworm?utm_medium=email&utm_source=govdelivery

Articles

The FDA determined that Credelio Cat may be effective in treating New World screwworm infestations in cats and kittens.

Antiparasitic receives FDA emergency authorization to treat New World screwworm in cats

Jack Teitelman is a retired Drug Enforcement Administration (DEA) supervisory special agent with more than 26 years of experience investigating and dismantling narcotics trafficking organizations in the US and internationally. Following a distinguished DEA career that included leadership roles in electronic surveillance, complex criminal investigations, and the New York Organized Crime Drug Enforcement Strike Force, Teitelman now serves as president and founder of TITAN Group, a regulatory consulting firm specializing in DEA compliance in animal and human health care. Over the past 9 years or so, he has worked as a pharmaceutical expert on the legal side, alongside veterinarians, manufacturers, distributors, and health care professionals to provide regulatory compliance services.

, Teitelman breaks down what veterinarians need to know about DEA compliance. He explains how veterinary practices have now become a formal part of the DEA’s annual work plan, why audits are occurring more frequently than ever before, and what clinics must do to avoid the most common compliance pitfalls.

This interview has been edited and condensed for clarity.

: What are some of the best DEA practices for managing controlled substances in veterinary clinics?

: I [recently] gave a talk to the Connecticut [Veterinary Medical Association]. At the end of the webinar, there’s a slide that says: 

. That is the most important thing you can do: keeping up with your record keeping.

Security [is also important]: if you don’t have an alarm system, get one; if you don’t have cameras covering all pertinent areas where you store controlled substances, get them. These are all pain points the DEA [looks at] when things go wrong—they’re going to ask, “Why didn’t you have this? Why didn’t you have that?” And you should [have it]. It's all in your bible—the [

Reconciling is a little different from counting. Counting is part of it, but [you need to] make sure you have consistent cycle counts—whether you do it on a daily basis, weekly, quarterly, [you must] do it. If you haven’t done a biennial inventory, do it today. These are all things that DEA expects you to have ready and retrievable for them when they walk in the door...so you have to be prepared for them.

Reconciling is [the] No. 1 [best practice.] Being proactive is No. 2. Being proactive means understanding what it is that you're buying and how you manage it. [It’s also knowing] how you balance [substances], what you bought, what used, what you have on hand, and what you sold. It's very simple math, but it gets out of hand as time goes by.

: How should controlled substances be appropriately stored and dispensed?

: According to the DEA, they have to be stored in a substantially constructed device. The easiest way [to do this] if you don't have a large amount of drugs is to go to Home Depot and buy a small gun safe—those are easy to secure; it has to be secured. You can put 2 lag bolts in and you’ve met the standard of a storage.

If you have a larger inventory, you’re better off buying a large, 750-lb safe that can't be carried out. And if you're using a refrigerator to store drugs, make sure the refrigerator is also secure and that you have ancillary storage inside that refrigerator.

Just be cognizant of how easy it would be to break into it. That used to be my job at the DEA when I was in a group that did break-ins and put bugs in people's houses and cameras. Some were easy to get into because people didn't secure [properly]. [Proper] hardware, Medeco-type locks, [and] technology like automated dispensing systems [can help].

: What are some common mistakes veterinary professionals make with controlled substances?

: [One major mistake is failing to document the “life story” of a pill.] The DEA is following the life story of one pill. Let’s use tramadol, for example. [DEA] is at the manufacturing facility that makes tramadol. They're stress-testing that manufacturer to make sure what it bought to synthetically make that [pill] is being managed correctly. Then they follow that one pill to the drug distributor—one of the big drug suppliers that you're buying from. Again, they [get] stress-tested by the DEA [questioning], “[How many tramadol pills] did you buy?”

And they're going to go through the same test when that one pill now gets sold to you as the veterinarian. What [often] goes wrong there is the story ends there. There’s no documentation about when that one pill came in, who signed for it. What did you do with that one pill when it came in? Was it put in backstop? Was it immediately given to a patient because you owed the patient pills? Failing to negotiate and complete the basic purchase records the DEA expects you to have is the biggest failure we see. Without this, the DEA can’t verify your inventory.

Accurate tracking of those purchases [and] keeping a perpetual inventory of all of your purchases is vital to passing a DEA inspection. So, if you don't have a logbook of what you bought and then where that went from the beginning, you’re going to fail DEA’s accountability audit when they come in.

: How often are veterinary clinics audited by the DEA?

: .... Your chances of [the DEA] coming are so much higher now than ever before. Audits are happening more often now than ever. DEA investigators’ fiscal year starts October 1, and...veterinarians are now part of the work plan for every DEA investigator.

Why is DEA showing up more than they've ever done before? Well, (a) it's their job, and (b) veterinarians are challenging in the sense that you use controlled substances unlike anybody else. You're using human drugs off label. You're using them for different purposes. You're putting them into compounds. You're making [constant rate infusion] mixtures that sometimes get used across multiple patients. So there are lots of things that need to be addressed when we're in a veterinary clinic that aren't addressed on the human side.

[TITAN Group] understands the challenges of dealing with injectable medications. That is something that the DEA is not used to dealing with. They're used to dealing with the unit doses that they see in a hospital: pills. Pills are easy to count, right? When you have liquid, have injectables, that becomes different. Then you don't know what you started with.

And then there are all the different uses of various needle-size gauge needles that are used. It [messes] things up when we try to track hub loss [and] can make it look like we're missing stuff when we're really not. And so we have to be able to explain that to the DEA agents: No, we're not missing a bottle—it’s because of 

. When we track all of that and we see variances, [we] can prove why it looks like we have a loss when we really don’t. That’s why we haven’t reported it.

Being consistent in how you do your recordkeeping goes a long way. Even if your recordkeeping [isn’t great], if you're consistent, sometimes that gives us a shot at finding where the issues are.

The Drug Enforcement Administration is auditing veterinary clinics more frequently than before, explains Jack Teitelman, CEO of a DEA regulatory consulting firm, in this Q&A.

A former DEA agent on what veterinarians need to know about DEA compliance

 readers! We are now officially 2 weeks away from Fetch Long Beach, our last Fetch dvm360 Conference of 2026. There is still time to join the educational experience, our amazing faculty, incredible exhibitors, and your wonderful fellow veterinary professionals for a conference full of networking, learning, and fun! There is still time to secure your spot, so register 

 today! If you cannot attend, be sure to follow along on dvm360.com for our 

 content team covered on dvm360.com this week:

 a reminder to pet food industry earlier this fall to consider highly pathogenic avian influenza in their food safety plans due to cases tending to increase during the fall migratory season, and comes after several raw cat and dog foods tested positive for avian influenza the past few months.

’s Strategic Alliance Partner Florida Veterinary Advisors, Tom Seeko, CExP, shares a practical guide for veterinary professionals on how they can get “financially married.”

, Kelly Chappell, DVM, DACVM (Small Animal), joined host Adam Christman, DVM, MBA, to talk more on feline infectious peritonitis, including the struggles to diagnosis it in clinical practice, treatment, and alternative options currently available on the market.

The University of Denver's Institute for Human-Animal Connection recently received a 

 from the Human Animal Bond Research Institute. Led by Kevin Morris, PhD, the funding will support a new study assessing how effective housing rental deposit programs for low-income tenants with pets are at increasing housing security.

 at the 2025 New York Vet Show, Monica Tarantino, DVM, MBA, cofounder of the Senior Dog Veterinary Society, explains the importance of understanding the point of view of the senior pets caregiver when talking to them about quality of life as well as end-of-life decisions.

Wrap up: FDA urges pet food manufacturers to address avian influenza in food safety plans, and other news

A pair of avian influenza vaccines targeting the H5 strain of the virus in birds have received positive opinions from the European Medicines Agency's Committee for Veterinary Medicinal Products (CVMP). The CVMP has also recommended European Union marketing authorization under exceptional circumstances for these immunizations, known as Vaxxitek HVT+IBD+H5 and Vaxxinact H5, by Boehringer Ingelheim.

Avian influenza has caused outbreaks in wildlife and commercial flocks around the world, including Antarctica. The H5 virus strain is common in avian influenza cases.

The Vaxxitek HVT+IBD+H5 and Vaxxinact H5 vaccines could be important for monitoring disease outbreaks, according to Boehringer Ingelheim. These preventive therapies include a biomarker for distinguishing the immune response to vaccination from infection antibodies that, when combined with surveillance, can play a role in reducing the risk of trade restrictions for animal products.

A new vaccine for swine is launched in the US

“By continuously monitoring the efficacy of our vaccines and advancing our technologies, we ensure the right protection against the evolving avian influenza virus,” Taoufik Rawi, head of franchise and poultry for Boehringer Ingelheim, said in a news release.

 “The positive opinions for Vaxxitek HVT+IBD+H5 and Vaxxinact H5 are critical to increase preparedness against avian influenza outbreaks in Europe.”

The European Commission will ultimately decide on whether marketing authorizations under exceptional circumstances for Vaxxitek HVT+IBD+H5 and Vaxxinact H5 will be granted. These decisions are expected in the coming months, according to Boehringer Ingelheim.

The World Organisation for Animal Health has advised that vaccination for avian influenza may be recommended under certain conditions. This international organization, based in Paris, France, suggests that vaccination for avian influenza should be integrated into comprehensive disease control strategies. However, decisions on vaccination against avian influenza rest with each country’s veterinary authority.

“Transboundary animal diseases like avian influenza will continue to be a threat, so new approaches to control these infectious diseases in animals, especially livestock, are increasingly important,” Armin Wiesler, head of the animal health business unit and member of the board of managing directors for Boehringer Ingelheim, said in the release. Wiesler added that the company is ready to support governments, health authorities, and producers with its vaccines and provide expertise for monitoring and setting up disease control plans.

Highly pathogenic avian influenza was detected in Europe and Canada in 2021, and reached the US through seasonal migration of wild birds, including waterfowl. Millions of poultry have since been affected throughout the US.

New outbreaks of the virus have been recently reported in poultry on commercial farms in Iowa, Minnesota, and Wisconsin. Additionally, Nebraska recently reported its first case of H5N1 in dairy cattle after the virus was detected in milk samples.

Researchers find avian influenza in New York bobcats

Boehringer Ingelheim obtains two EU CVMP positive opinions for avian influenza vaccines Vaxxitek HVT+IBD+H5 and Vaxxinact H5. News release. Boehringer Ingelheim. November 20, 2025. Accessed November 20, 2025. 

https://www.boehringer-ingelheim.com/animal-health/veterinary-public-health/boehringer-ingelheim-obtains-two-eu-cvmp-positive-opinions-avian-influenza-vaccines

Avian influenza. World Organisation for Animal Health. Accessed November 20, 2025. 

https://www.woah.org/en/disease/avian-influenza/#ui-id-3

Poultry. Cornell University College of Veterinary Medicine. Updated May 20, 2025. Accessed November 20, 2025. 

https://www.vet.cornell.edu/highly-pathogenic-avian-influenza-bird-flu-resource-center/poultry

Bautista-Alejandre A. New bird flu outbreaks reported in poultry across 3 Midwestern states. 

. October 6, 2025. Accessed November 20, 2025. 

https://www.dvm360.com/view/new-bird-flu-outbreaks-reported-in-poultry-across-3-midwestern-states

Boehringer Ingelheim earned positive opinions for 2 immunization therapies in the pipeline. 

European agency recommends marketing authorization for avian flu vaccines

Several organizations are working together to implement a national animal emergency response program in Canada. The initiative, a collaboration between Mars, Inc, and Humane Canada, aims to improve the preparedness and capabilities for humane societies, Society for the Prevention of Cruelty to Animals (SPCA) organizations, and other animal welfare groups across the country during emergencies and disaster relief efforts.

Through the program, Mars and Humane Canada aim to establish a unified and integrated response network between animal care providers and first responders, ensuring pets have access to essential care and protection during emergencies, the organizations stated in a joint news release.

 The program will also provide first responders with training on dealing with emergency scenarios.

"Humane Canada is proud to collaborate with Mars to build a national framework that strengthens how animals are protected during emergencies," Kathy Duncan, director of national programs at Humane Canada, said in the news release.

 "Every year, our member humane societies and SPCAs respond to wildfires, floods, and other crises, often working alongside first responders under difficult conditions. This program will give them the tools, training, and coordination they need to act faster and more effectively so animals and their families receive the care and support they deserve when disaster strikes."

Mars and Humane Canada are also advocating for the inclusion of animals in national and provincial emergency response plans, arguing that their implementation is essential to ensure pets receive adequate care during emergencies. Without the program, approximately 16 million cats and dogs throughout Canada

 could be left vulnerable during emergencies, especially amid a rise in wildfires and other natural disasters.

"This program marks a meaningful milestone for pets and pet parents in Canada,” Romain Dumas, general manager at Mars Pet Nutrition Canada, said in the release.

“With a rise in natural disasters, specifically wildfires within Canada, there has never been a more critical time for ensuring pets are responsibly cared for and supported during emergencies.”

VCA Canada and Royal Canin Canada will also be assisting in the development and maintenance of the program, as subsidiaries of Mars. "Royal Canin Canada is proud to tangibly support emergency response efforts in partnership with Humane Canada," Rob Lunn, general manager of Royal Canin Canada, said in the release.

"From assisting veterinarians and technicians as boots on the ground to both a financial and nutritional investment, we're excited to do our part to provide assistance for cats and dogs in need across Canada."

VCA Canada noted that a national support system and education for shelter partners, first responders, and hospital teams will have a “meaningful and measurable impact” on supporting pets and their caregivers in times of emergency.

Mars and Humane Canada team up to implement national animal emergency response program in Canada. News release. Vicar Operating Inc. November 19, 2025. Accessed November 20, 2025. 

https://prnmedia.prnewswire.com/news-releases/mars-and-humane-canada-team-up-to-implement-national-animal-emergency-response-program-in-canada-813634396.html

State of the Pet Homelessness Project report. State of the Pet Homelessness Project. Accessed November 20, 2025. 

https://www.stateofpethomelessness.com/latest-report/?Country=Canada

The initiative comes as wildfires and other disasters pose an increasing risk to pets in Canada.

National animal emergency response program is under development in Canada

This content is sponsored by PRN Pharmacal.

Last June, my colleagues at PRN Pharmacal launched sirolimus delayed-release tablets (Felycin-CA1) a new therapy for the management of ventricular hypertrophy in cats with subclinical hypertrophic cardiomyopathy (HCM).

 As the first product conditionally approved by the FDA for use in cats with HCM, Felycin-CA1 marked an industrywide turning point for feline HCM care, offering hope for cats—and owners—affected by this life-threatening disease.

Feline HCM is a progressive, often irreversible condition that causes the heart’s muscular walls to thicken, impairing its ability to pump blood effectively.

 It can lead to congestive heart failure, arterial thromboembolism, or even sudden death, among other complications.

 Althoughthe causes of HCM aren’t entirely clear, some research has shown higher prevalence in certain breeds—such as Maine Coon, Ragdoll, Persian, and British Shorthair breeds—as well as identified cardiac gene mutations in those most commonly affected, suggesting genetic implications.

Despite being the most common cardiovascular disease in cats—affecting 1 in 7 domestic cats—and the No. 1 cause of mortality in adult cats (>9 years of age), feline HCM can be extremely difficult to detect, let alone manage.

In fact, it’s often referred to as a silent disease, since cats with HCM are typically subclinical, progressing without showing any outward signs or symptoms, and if they do show signs, it’s sometimes not until later stages of the disease.

The FDA’s conditional approval of Felycin-CA1

The active ingredient in Felycin-CA1, sirolimus (also known as rapamycin), was first FDA approved in 1999 as a human immunosuppressant for organ transplants.

 Now formulated as a delayed-release tablet specifically designed for cats, Felycin-CA1 has been proven to help slow the progression of subclinical HCM, via results from the RAPACAT trial, a well-controlled pilot field study that led to its conditional approval, in March 2025.

To receive conditional approval from the FDA, a drug must meet several requirements. Most notably, it must address a serious or life-threatening disease, or an unmet animal or human health need; meet certain manufacturing, safety, and quality standards; and demonstrate a reasonable expectation of effectiveness.

 Through the RAPACAT trial, in addition to the data already established from the use of sirolimus in other species, Felycin-CA1 met the FDA’s conditional approval requirements.

 Although the FDA’s efficacy requirements differ between full approval and conditional approval, the safety standards are the same.

Addressing the unmet need in feline HCM care

Prior to Felycin-CA1, we’ve had very few options to help manage HCM, particularly beyond palliative care.

 In fact, the therapies that were available weren’t managing HCM at all; they were managing the symptoms.

For example, if a cat was diagnosed with HCM and experienced congestive heart failure as a result, a diuretic might be used to help clear fluid from the lungs. Or, in more severe cases, if a blood clot had entered the bloodstream, an antithrombotic might be administered. But ultimately, we had no other choice but to explain to these cat owners that the best they could do was manage the symptoms as the disease progressed.

Hence why Felycin-CA1 is considered so groundbreaking.

 Previous available therapies in this space had failed to slow disease progression, improve quality of life, or show survival benefit in the subclinical setting.

 The RAPACAT trial demonstrated that the left ventricular wall had reduced in those cats with subclinical HCM receiving prolonged administration of Felycin-CA1, suggesting that it may help slow or delay disease progression.

 Consequently, with Felycin-CA1, veterinarians finally have an option that may help manage the pathology associated with subclinical HCM—vs merely what happens to the patient when the heart muscle is failing.

Felycin-CA1 is given to cats at a target dose of 0.3 mg/kg orally once weekly, in conjunction with a meal.

The tablets are available in 3 strengths—0.4 mg, 1.2 mg, and 2.4 mg—and are quite small, about the size of a Tic Tac, making Felycin-CA1 both convenient and easy to administer across a range of patient sizes.

But most importantly, owners of cats with subclinical HCM can breathe a little easier knowing that we veterinarians now have something to start their pet on, instead of waiting for the cat to progress and then supporting them as their heart fails.

As a reminder, Felycin-CA1 is only available by prescription from a licensed veterinarian. Cats should be screened for preexisting liver disease before starting Felycin-CA1, and it should not be used in cats with preexisting liver disease or diabetes mellitus.

Now that we have the first-ever approved disease-modifying agent for subclinical HCM, how do we determine whether a patient is an appropriate candidate? For a cat to be eligible for Felycin-CA1, they must be diagnosed with subclinical HCM.

 Although no single, standardized screening protocol exists for feline HCM—subclinical or not—there are recommendations and best practices.

As work continues to find an ideal diagnostic pathway for screening cats for subclinical HCM, echocardiography is currently considered the gold standard.

 Additionally, a comprehensive physical examination, along with blood pressure measurement, should always be performed.

 This should involve auscultation, as heart murmurs or gallop sounds have been linked to the condition.

 It is also recommended that other tests and imaging, like bloodwork and radiographs, be done to help confirm the diagnosis and rule out other causes, such as dehydration and hyperthyroidism.

 Biomarker and/or genetic testing may be used as well—not in isolation, however, but as a supplement to the entire diagnostic workup, and with caution, as results have been found to be inaccurate.

On a more fundamental level, most of this relies on cat owners bringing their pets into the clinic for examination in the first place (which has its own separate challenges). That’s why it’s critical for practitioners not only to encourage cat owners to bring their pet in but also, when they do come in, to have conversations about the importance of screening and early intervention for conditions like HCM, especially with those who have predisposed breeds.

A couple of small tips that can make a big difference:

That practitioners kindly (and firmly) express to cat owners that it is in their cat’s best interest that they be (and stay) quiet during auscultation, so that practitioners can listen more closely and discern a heart murmur. For some reason, in my experience, I’ve always found that pet owners become most talkative as soon as the stethoscope goes on.

To extend feline HCM care beyond the clinic by showing cat owners how to monitor their cat’s sleeping respiratory rate at home. While their cat’s asleep, they can simply watch their chest rise and fall to count the number of breaths per minute. It should be fewer than 30 breaths, but if it’s more, advise cat owners to schedule a veterinarian appointment immediately, as increased respiratory rate has been linked to the progression of feline HCM.

The HALT Study and the path to full approval

Right now, the HALT Study is underway to provide the substantial evidence of effectiveness necessary for the full FDA approval of Felycin-CA1 (referred to as TRIV202 in HALT) for the management of ventricular hypertrophy in cats with subclinical HCM.

Launched in June 2025 by TriviumVet, in partnership with Pegasus Laboratories, the HALT Study is a multisite, blinded, randomized, placebo-controlled clinical field study conducted across various clinical sites experienced in treating cats with HCM.

 It will be both considerably larger than the RAPACAT trial, aiming to enroll 300 cats (vs 43 cats enrolled at baseline in RAPACAT), and longer, examining cats with subclinical HCM over a 12-month dosing period (vs the 6-month period in the RAPACAT trial), with 5 postenrollment study visits.

The size and duration of the HALT Study highlight our hope for greater insights into the efficacy as well as safety of Felycin-CA1—and our commitment to better understanding its long-term implications.

For more information on the HALT Study, including current study sites and enrollment criteria, or to register your cat or a patient, visit 

More hope on the horizon for feline HCM care

Felycin-CA1 represents a big step forward in feline HCM care—and we’re not stopping there. Through the RAPACAT trial, ongoing patient cases, and now the HALT Study, we will continue to learn more about the effects of Felycin-CA1 on managing this complicated condition and push the boundaries of what’s possible in feline heart care.

For full prescribing information, please visit 

FDA conditionally approves drug for management of ventricular hypertrophy in cats. FDA. March 14, 2025. Accessed October 9, 2025. 

https://www.fda.gov/animal-veterinary/cvm-updates/fda-conditionally-approves-drug-management-ventricular-hypertrophy-cats

Crossley KC. Novel cardiology therapy for cats is launched. 

. June 18, 2025. Accessed October 9, 2025. 

https://www.dvm360.com/view/novel-cardiology-therapy-for-cats-is-launched

Kaplan JL, Rivas VN, Walker AL, et al. Delayed-release rapamycin halts progression of left ventricular hypertrophy in subclinical feline hypertrophic cardiomyopathy: results of the RAPACAT trial. 

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McCafferty C. FDA conditionally approves first drug for feline subclinical hypertrophic cardiomyopathy. 

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https://www.dvm360.com/view/fda-conditionally-approves-first-drug-for-feline-subclinical-hypertrophic-cardiomyopathy

Beck L. First drug OK’d for most common heart condition in cats. VIN News Service. April 24, 2025. Accessed October 9, 2025. 

https://news.vin.com/vinnews.aspx?articleId=86835

Conditional approval explained: a resource for veterinarians. FDA. Updated September 17, 2020. Accessed November 3, 2025. 

https://www.fda.gov/animal-veterinary/resources-you/conditional-approval-explained-resource-veterinarians

Felycin-CA1. Prescribing information. PRN Pharmacal; 2025. Accessed October 23, 2025. 

https://www.triviumvet.com/hubfs/Felycin-PI-Detailer_PRN_02JUN2025.pdf

Häggström J, Luis Fuentes V, Wess G. Screening for hypertrophic cardiomyopathy in cats. 

 2015;17(suppl 1):S134-S149. doi:10.1016/j.jvc.2015.07.003

The HALT HCM Study. HCMinCats.com. Accessed October 23, 2025. 

TriviumVet launch the HALT HCM Study recruiting 300 cats with diagnosed subclinical hypertrophic cardiomyopathy (HCM). TriviumVet. June 25, 2024. Accessed October 23, 2025. 

https://www.triviumvet.com/blog/triviumvet-launch-the-halt-hcm-study-recruiting-300-cats-with-diagnosed-subclinical-hypertrophic-cardiomyopathy-hcm

At last, with Felycin-CA1, veterinary professionals finally have a therapy that extends beyond palliative care for feline HCM.