The goal of this study was to follow a cohort of dogs with CAD who received Cytopoint for an additional 9–11 months after they had achieved treatment success after an initial 1, 2 or 3 injections of Cytopoint, and characterize the ongoing benefit of this treatment. While the primary outcome, reduction in PVAS < 36 was selected based on the available COSCAD recommendations [23], previous research has suggested many (88% of 314 dogs) apparently healthy dogs have a PVAS ≤ 19 mm [26]; thus, the authors felt it relevant to include analysis of PVAS < 20 mm in the study outcomes (Table 4). In addition, this study was designed to include all dogs on a given therapy. Accordingly intention to treat analysis, which requires a control and treatment group for those dogs who either had poor compliance or protocol deviations, was by the very definition not available.
Given that chronic CAD requires lifelong treatment often with a combination of products to control pruritus and treat skin lesions [28], it is to be expected that a population of dogs in the study exhibited atopic flares when exposed to allergens during the course of the year. Recent studies have highlighted the importance of the “proactive approach when managing CAD” versus the “reactive approach”[29]. Ideally, when using Cytopoint, proactive management prior to a flare allows ongoing neutralization of IL-31 providing the best response [8, 29]. In this study, pet owners determined their own schedule for reinjection (within the 4–8 week parameters) based on initial duration of effect, which, at times was more about convenience or impacted by other family or personal factors. For example, many pet owners should have returned prior to their Day 180 and Day 365 visits for an injection but instead received an injection at the visit. This represents a very real-world picture of CAD in practice and the importance convenience plays for pet owners and how easy it is to move away from proactive management of CAD. This also underscores the benefit of using Cytopoint in a prescriptive and preemptive manner for dogs diagnosed with CAD by forward booking the next Cytopoint injection before the pet owner leaves the practice.
In this study, Cytopoint was intended to act as an anchor therapy, with the majority of dogs utilizing treatment with Cytopoint alone. This allowed the veterinarian to add short-term supplementary therapies only when needed. During the 12-month study, none of the dogs required rescue treatment with products like Apoquel or steroids. All of the dogs in this study achieved periods of pruritus reduction below a PVAS of 36, thus even dogs whose mean PVAS appear > 36 mm (12%; Table 4) received appreciable relief from the pruritus associated with their atopic disease during the study. In addition, the reduction of CADESI-04 and VetVAS scores show a resolution of, and ongoing protection from, inflammation and lesions associated with pruritus over time.
Management of pruritic skin disease often presents challenges for both pet owners and veterinarians including increased caregiver burden [21]. Caregiver burden has been defined as a reaction of strain caused by providing care for a loved one with an illness and has been associated with depression and reduced quality of life in studies involving companion animal owners [30, 31]. Greater caregiver burden is associated with a lower quality of life and both caregiver burden and quality of life have a distinct link to a pet’s chronic disease [21].
Recent studies have shown the importance of starting with the simplest effective treatment when treating a dog with CAD, as it may reduce owner strain and the transfer of caregiver burden onto veterinary staff [31, 32]. When complex treatments can be reduced, clients view a veterinarian as more compassionate and trustworthy, thus improving the working relationship between a veterinarian and pet owner [20]. In addition, a pet owner’s belief that there is good control of chronic disease reduces caregiver burden [31].
In our study, pet owners were able to reduce the use of topical and oral medications during the study and reported a “very good” quality of life (Fig. 4). Pet owners reported consistent duration and improvement in their pet’s CAD over the course of the study (Fig. 4) confirming their belief that Cytopoint was controlling their pet’s CAD and ultimately leading to an improved quality of life. As we impacted the pet owner’s view of their pet’s chronic disease through reduction of additional products and simplifying treatment options, we assisted in the reduction of the caregiver burden. At the same time, pet owners felt their pet’s CAD was well controlled, also aiding in the reduction of the pet owner’s caregiver burden. Prior work has described the relationship between high caregiver burden and low pet/pet owner QOL [21]. If we can support the overall wellbeing of pets and their owners and ultimately, decrease caregiver burden, everyone involved benefits.
CAD is a lifelong disease, therefore, setting reasonable pet owner expectations at the start and throughout the life of the pet is critical. It is not uncommon for pet owners to expect complete resolution of a pet’s atopic disease, since skin disease may not be perceived as a “true” chronic disease. Some owners may struggle to understand the perpetual waxing and waning of clinical signs and while a long-term outcome may be achieved with regular veterinary visits and treatment, the financial cost may be prohibitive. In addition, for some dogs, control of 100% of a pet’s clinical signs may not be possible. Dogs receiving Cytopoint did not require a static number of injections, but instead, this study found treatment can be tailored to the response of the dog. The Fear Free movement has suggested setting pet owner expectations that controlling 80% of clinical signs is achievable for most dogs [33] and will help pet owners understand the importance of regular preemptive therapy with Cytopoint.
Our study design presents limitations in that neither the owners nor the veterinarians were blinded to the treatment group and we lacked the of comparison with a control placebo group or other antipruritic therapy. In addition, the variable nature of reinjection frequency allowed pet owners flexibility, but added a level of challenge in consistent management of pruritus. Despite these limitations, because of the ease of administration and the lack of restrictions for age, breed, chronicity or type of allergy, this real world study provides support to include Cytopoint in the canine toolbox of choices to combat allergic skin disease.