Until the last day of 2025 there was one anti-IL-31 monoclonal antibody for canine allergic and atopic dermatitis. Now there are two, and the question veterinary teams keep typing into a search box is the obvious one: what is the actual difference.
Here is the honest version, including the parts nobody can answer yet.
They work the same way
Both Cytopoint (lokivetmab, Zoetis) and Befrena (tirnovetmab, Elanco) are monoclonal antibodies given by injection in the clinic. Both target interleukin-31, the cytokine most closely associated with the itch signal in canine atopic dermatitis. Neither is a tablet, neither is given at home, and neither suppresses the immune system the way a steroid or an oral JAK inhibitor does.
That shared mechanism matters more than it sounds. It means the clinical conversation is not "which drug class" but "which product, on what schedule, at what price, from which company".
Where the labels differ
Cytopoint has been the category for years. Its label directs a minimum dose of 2 mg/kg, repeated at intervals of four to eight weeks as needed for each patient. Field studies behind that label show pruritus and skin lesion scores reduced for four to eight weeks after a single injection.
Befrena received USDA approval on December 31, 2025, with Elanco planning a United States launch in the first half of 2026. Trade coverage of the approval reports a dosing interval of six to eight weeks, and use in dogs of any age.
So the headline difference is the floor, not the ceiling. Both reach eight weeks. One starts its window at four, the other at six. For a dog that genuinely needs redosing at four weeks, that is a difference. For the large group of dogs comfortably held for eight, it is not.
What nobody can tell you yet
There is no head-to-head trial. No published study has given one group of dogs Befrena and another Cytopoint and compared them. Any claim that one controls itch better than the other is, today, an inference from separate studies run under different protocols.
Befrena's price is not public. Cost per injection, and cost per year of control, is the variable most likely to decide this in practice, and it is the one nobody outside the two companies can see yet.
Real-world duration varies by dog more than any label conveys. A 2025 cohort following long-term lokivetmab use found 87 percent of dogs maintained an owner-assessed itch score below their own baseline across twelve months. That is a useful signal and a small, uncontrolled one. Your own patients' redosing intervals are better evidence than either label.
What will actually decide it
Three things, none of them mechanism.
The redosing interval decides the visit. A product reliably holding eight weeks is six visits a year; one needing four is thirteen. That changes the owner's annual cost, the clinic's appointment load, and compliance, which is the thing that quietly determines whether any chronic therapy works.
The relationship decides the default. Cytopoint has years of prescriber habit, reorder history and client familiarity behind it. Befrena arrives as the challenger into a category where the incumbent has already been through a difficult year commercially.
The portfolio decides the conversation. Befrena is Elanco's second dermatology approval in under eighteen months, after Zenrelia, its oral JAK inhibitor. A company with both an oral and an injectable can offer a practice a dermatology conversation rather than a product, and Elanco has sized the United States canine dermatology market it is arguing about at roughly 1.3 billion dollars.
What to watch
Watch the redosing interval your own clinics actually achieve once Befrena has been in use for two seasons, because that is where the label difference either becomes real or disappears. Watch for a published head-to-head, which the challenger has more incentive to fund than the incumbent. And watch pricing at launch, because in a category where two products share a mechanism, price and dosing cadence do the work that efficacy claims cannot.
If either changes materially, the answer to the question in the title changes with it.
Use it this week
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