A newly approved option for managing allergic pruritus in dogs is set to enter UK practice, following VMD authorisation of atinvicitinib (Numelvi, MSD Animal Health). For clinicians already familiar with JAK inhibitors, the key question is not what it is, but where it fits in day-to-day case management.
What has been approved?
Numelvi (atinvicitinib) is newly authorised in Great Britain for the treatment of pruritus associated with allergic dermatitis, including atopic dermatitis, in dogs aged from six months and weighing at least 3kg. It is administered once daily as an oral tablet.
The product is classified as a POM-V and received VMD approval in January 2026.
How does it differ from existing options?
Atinvicitinib is described by the manufacturer as a “second-generation” JAK inhibitor with increased selectivity for JAK1. In practical terms, this is intended to target cytokine pathways associated with itch while minimising broader immunomodulatory effects.
For vets, this positioning will inevitably invite comparisons with oclacitinib and lokivetmab. However, head-to-head clinical data in real-world settings are currently limited in the public domain, so decisions will likely rely on individual case response, tolerability, and client factors rather than clear superiority claims.
What does the evidence suggest so far?
According to MSD Animal Health, atinvicitinib demonstrates:
- Onset of antipruritic effect within hours of the first dose
- Once-daily dosing without a loading phase
- No requirement for routine blood or urine monitoring in the label
These points may be particularly relevant when considering compliance and ease of use for owners, especially in chronic cases.
However, as with any new product, it is worth noting that much of the currently available data originates from company-led studies. Independent, peer-reviewed comparisons and longer-term safety data in general practice populations are still emerging.
Practical considerations for use in clinic
For UK practices, the arrival of another oral JAK inhibitor expands the toolkit rather than replacing existing approaches. Situations where Numelvi may be considered include:
- Dogs with allergic dermatitis where rapid itch control is a priority
- Cases where once-daily dosing may improve owner adherence
- Patients that have not responded as expected to other therapies
- Young patients where other options would be used off-license
As with other immunomodulatory treatments, case selection remains important. Signalment, concurrent disease, parasite control, and underlying diagnosis should all be considered before initiating therapy.
Cost, availability, and client preference will also influence uptake, particularly in practices where oclacitinib or monoclonal antibody therapies are already well established.
The bottom line for practice teams
Numelvi adds another option for managing canine allergic pruritus, with a familiar mechanism of action and a once-daily dosing profile that may appeal to some clients.
Vets can find out more about the drug at MSD's website.
