Managing Canine Allergic Dermatitis With Janus Kinase Inhibitors

Sponsored by Elanco

Dermatitis is a common presenting complaint in small animal veterinary practice. Atopy, which is just one potential cause of canine allergic dermatitis, is estimated to affect 3% to 15% of dogs, with considerable variation among studies.¹ Other conditions such as contact dermatitis, food allergies, and flea-allergic dermatitis further contribute to the prevalence of allergic dermatitis in dogs.

Veterinarians have multiple options available to manage the clinical signs of allergic dermatitis, including oral, injectable, and topical treatments. Each of these treatments comes with its own unique advantages and disadvantages. Individual patient responses may vary, and finding an effective management plan for an individual patient may prove challenging.

In September of 2024, the US FDA approved a medication for the treatment of canine allergic dermatitis: Zenrelia™ (ilunocitinib tablets). This Janus kinase (JAK) inhibitor blocks the signaling pathway involved in cytokine production, reducing skin inflammation and itch. Zenrelia offers veterinarians an additional treatment to add to their toolkit when managing allergic dermatitis in dogs.

Before prescribing this drug, clinicians should read the entire package insert, including the boxed warning regarding fatal vaccine-induced disease and inadequate immune response to vaccines. It is important that dogs are up to date on vaccinations and free from serious infections prior to starting Zenrelia. Explore this case series highlighting dogs that have experienced improved quality of life after treatment with Zenrelia.

Zenrelia Applications: A Case Series

River’s Case

River is a middle-aged German shorthaired pointer. At the time River started receiving Zenrelia, his itch score was determined to be 7.2/10 on the Pruritus Visual Analog Scale (PVAS). This was significantly above the 2/10 PVAS score that is expected for a clinically normal dog.² After just 1 week of receiving Zenrelia, River’s PVAS score decreased to 4/10 and continued to decrease to 1.4/10 in the coming weeks, which is below the 2/10 threshold at which a patient is considered to be in remission.

River did experience a slight increase in itch during the peak of spring allergy season; however, even during this time, his PVAS score peaked at 1.8/10. At the end of peak allergy season, River’s PVAS score decreased to 1.2/10 and remained at that level in the following months.

Hunter’s Case

Hunter is an 8-year-old male Labrador retriever with a history of chronic dermatitis (Figure 1). His dermatitis was first noted at 1 to 2 years of age and gradually progressed over time, eventually causing significant impacts on Hunter’s quality of life. Hunter chewed the fur from his distal hindlimbs, and his front paws were chronically inflamed and crusty. Hunter’s owner tried a variety of treatments; although some treatments offered partial relief, his dermatitis was never well-controlled. Hunter’s owner felt defeated and discouraged by his constant skin issues and lack of response to treatment.

FIGURE 1

Hunter before starting treatment with Zenrelia

Once Zenrelia became available, Hunter’s veterinarian prescribed it for Hunter’s allergic dermatitis. Hunter responded better to Zenrelia than he had to any previous medications. His clinical signs, including pruritus, paw licking/chewing, and secondary infections, improved dramatically with Zenrelia (Figures 2 and 3). Hunter’s overall quality of life also improved, and his owner reported that he was more comfortable and more playful than he was prior to Zenrelia treatment.

FIGURE 2

Hunter 2 weeks after starting treatment with Zenrelia

FIGURE 3

Hunter 2 months after starting treatment with Zenrelia

Scrappy’s Case

Scrappy is a male Yorkshire terrier crossbreed. Since his adoption, Scrappy had a history of chronic itching and hot spots. Scrappy’s owner felt that he was often “miserable” and unable to get comfortable because of his skin issues. This left the client feeling frustrated and hopeless.

A veterinary dermatologist recommended Zenrelia to treat Scrappy’s chronic dermatitis. Scrappy’s owner noticed a difference soon after treatment started. At Scrappy’s 8-week recheck, the veterinary dermatologist noted marked improvement in Scrappy’s dermatitis. He had visible hair regrowth, no visible skin inflammation, and no evidence of secondary infection. Scrappy’s owner was very pleased with his progress, reporting that he was no longer chewing and that Zenrelia had worked better than she expected.

Remi & Missy: 2 Housemates

Remi, a Dalmatian, and Missy, a crossbreed dog, live in the same household. Remi had a long-term history of allergic dermatitis, beginning when she was 1 to 2 years of age. Her owner tried a variety of prescription and over-the-counter treatments, but they typically resulted in minimal improvement. Missy’s itch started ≈1 year prior to presentation. She was itching and chewing constantly, especially on her legs and tail. Like Remi, Missy was diagnosed with allergic dermatitis.

A veterinary dermatologist recommended starting both Remi and Missy on Zenrelia to treat their allergic dermatitis. At their 2-month recheck, both Remi and Missy showed significant improvement. The client reported that both dogs were responding well to the medication, with no signs of itch observed between doses. Missy did not have any visible skin lesions on recheck examination, and the veterinary dermatologist found no evidence of itch or inflammation. Remi’s dermatitis also improved dramatically on Zenrelia. This was especially remarkable to both the veterinary dermatologist and the client, given Remi’s long history of previous treatment failures.

Zenrelia: A Treatment for Canine Allergic Dermatitis

Zenrelia is approved to manage itch caused by atopic dermatitis, contact allergies, food allergies, and flea-allergic dermatitis in dogs ≥12 months of age. In a study of 268 client-owned dogs across 25 veterinary clinics, 83% of dogs achieved treatment success (defined as a ≥50% decrease in client-reported PVAS scores or ≥50% decrease in veterinarian-documented skin lesions) by day 28 of treatment.³

Unlike the other currently available JAK inhibitor, Zenrelia is designed for once-daily administration from onset of treatment, which can help improve client compliance.⁴ Once-daily administration from the outset also helps avoid rebound pruritus that can occur with medications that require an initial loading dose followed by a dose reduction.⁵ Zenrelia’s safety has been demonstrated in a margin of safety study.⁶ Healthy dogs treated with up to 5× the label dose for 6 months demonstrated no serious adverse effects. However, Zenrelia should not be used in dogs with serious underlying infections, and its use has not been established in pregnant, breeding, or lactating dogs. In addition, Zenrelia should be discontinued for at least 28 days to 3 months prior to vaccination and withheld for at least 28 days after vaccination.

Conclusion

Zenrelia is a JAK inhibitor that has been proven to be safe and beneficial for many canine patients with allergic dermatitis. It can be used to manage multiple types of allergic dermatitis, including atopy, contact allergies, food allergies, and flea-allergic dermatitis. In addition, Zenrelia’s convenient, once-daily administration from the start makes treatment straightforward for clients, helping to improve compliance.

Although treatment outcomes are inherently variable and influenced by numerous factors, the case studies presented^a illustrate how Zenrelia can significantly impact the lives of dogs with allergic dermatitis and their owners. Because dogs can have varying clinical responses to different JAK inhibitors, having multiple options available allows veterinarians to address the needs of a broader range of canine patients suffering from allergic disease.

^aAll cases discussed in this article are based on real case presentations and have been shared with permission from their respective owners.

IMPORTANT SAFETY INFORMATION

Read the entire package insert before using this drug, including the boxed warning. For full prescribing information, call 1-888-545-5973 or visit http://www.elancolabels.com/us/zenrelia

WARNING: VACCINE-INDUCED DISEASE AND INADEQUATE IMMUNE RESPONSE TO VACCINES. Based on results of the vaccine response study, dogs receiving Zenrelia are at risk of fatal vaccine-induced disease from modified live virus vaccines and inadequate immune response to any vaccine. Discontinue Zenrelia for at least 28 days to 3 months prior to vaccination and withhold Zenrelia for at least 28 days after vaccination. Dogs should be up to date on vaccinations prior to starting Zenrelia. Do not use in dogs less than 12 months old or dogs with a serious infection. Monitor dogs for infections because Zenrelia may increase susceptibility to opportunistic infections. Neoplastic conditions (benign and malignant) were observed during clinical studies. Consider the risks and benefits of treatment in dogs with a history of recurrence of these conditions. The most common adverse reactions were vomiting, diarrhea, and lethargy. Zenrelia has not been evaluated in breeding, pregnant, or lactating dogs and concurrent use with glucocorticoids, cyclosporine, or other systemic immunosuppressive agents has not been tested.

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