With six out of the top ten most popular breeds of dogs in the UK (Lifetime Pet Cover, 2020) being prone to allergic skin disease, it’s no surprise to us as veterinary professionals that we are likely to see more and more of these potentially tricky cases to manage.
Pet parents are unwittingly choosing breeds that are more prone to skin problems, and setting themselves up for the potential need for lifelong veterinary care. Add to this the potential negative impact that chronic pruritic skin disease can have on the quality of life of the patient, together with the additional negative impact on the pet–owner bond, and it’s an unfortunate situation we find ourselves in.
As veterinary professionals we’re all aware of the potential pitfalls in the management of chronic skin disease cases. What may appear to be a simple problem to the pet owner – a dog who is scratching – suddenly becomes a lengthy process of work-up, treatments, revisits, further treatments and so on. So how can we improve the process for owners and patients alike?
Communication from the outset is key
As with any other chronic condition, whether that be osteoarthritis, obesity or diabetes mellitus, effective communication and owner education is essential right from that first consult.
In fact, effective communication prior to purchase may have avoided this situation altogether. Owners should be encouraged to come to you ahead of getting an animal so that you, as their trusted veterinarian, can discuss the common issues associated with certain breeds and the care the animal will require. Pre-purchase consultations are a great first step to build that trust and communication from the outset and it’s a great opportunity to discuss all of the planned new arrival’s needs, from vaccinations and socialisation to exercise requirements and nutrition, and not forgetting insurance.
Nevertheless, when presented with a chronic skin disease case, we must engage and educate the pet owner at the earliest opportunity. A lot of pet owners may have had previous experiences of pruritic pets with relatively simple problems, potentially only requiring appropriate antiparasiticide treatment together with an antipruritic medication. As such, the expectation of a quick fix for what may appear to be a “minor” complaint wouldn’t be unexpected.
Taking time to explain the potential diagnoses, the need for a logical and systematic work-up and the potential therapeutic interventions, all pitched at the appropriate level, is no walk in the park. However, it is essential that the pet owner has realistic expectations as to what may lie ahead and what time and financial implications this may have, as well as understanding the reasoning behind following your intended diagnostic plan.
This is also an opportunity to take full advantage of your team of registered vet nurses. Dermatology nurse clinics are a great addition to the list of services your practice may offer. Engaging your nursing team in the communication and monitoring of chronic skin disease cases can be a great asset, providing opportunities for your nursing team to develop new skills. This also ensures you are providing your clients with the time they need to go on their journey of understanding.
Process of elimination
One of the frustrations pet parents face surrounding the work-up of chronic skin disease lies around the fact there is a need to run through the process of treating and/or eliminating potential causes. In a world where we are so used to getting immediate answers, there is often no answer immediately to hand.
When looking at allergic skin disease, we know the major causes include flea allergic dermatitis, canine atopic dermatitis (CAD) and cutaneous adverse food reactions. Frustratingly, whilst CAD is at least two to three times more common than food allergy, we can’t make a diagnosis of CAD without first ruling out food allergy. In addition, we know that approximately 30 percent of CAD cases also suffer with adverse food reactions, making diagnosis and management all the more difficult.
Ensuring the pet is kept comfortable throughout with appropriate use of antipruritic medications – whether that be with initial corticosteroid therapy for the more severely affected, or medications such as cyclosporine or oclacitinib once under better control – can provide much-needed relief. This does, however, reinforce the need for clear and transparent pet owner communications to ensure they understand that we are treating the symptoms and not the cause, and there is still benefit in making a diagnosis to better target our therapy.
The dreaded diet trials
When it comes to elimination diet trials it is imperative that not only the pet parent is on board but the whole household and visitors to the home are too. Young children dropping food, grandparents ignoring the rules or visitors giving secret treats can always pose a problem to this time in the diagnostic process.
We know that to rule out food as a potential cause of allergic skin disease, we need to ensure a pet is on an elimination diet trial for up to 8 to 12 weeks. Should a pet get hold of something along the way, they need to start all over again. Understandably this not only is frustrating to the owner and to us as the vet healthcare team, but also means a more prolonged period of dietary restriction for the pet. It is a huge commitment on all sides.
If the owner goes through a diet trial with no sign of improvement we are left with our diagnosis of exclusion – CAD. Good news on the one hand – we have a diagnosis – but further frustrations on the other as we continue our investigations and treatment.
At least at this point we are able to target our therapy at the underlying condition more effectively, but this may mean a potential need for serum IgE blood tests if considering allergen-specific immunotherapy (ASIT) or sublingual immunotherapy (SLIT), or ongoing lokivetmab (Cytopoint) therapy. Either way we are embarking on long-term management of a chronic condition which inevitably will have financial implications as well as require an owner’s commitment and compliance throughout.
As such, the relationship between a vet professional and pet parent needs to be built on transparency and trust. Going through this lengthy process is not easy, and should the owner not feel supported or doubt the rationale at any point, they may likely seek advice elsewhere and have to start this process all over again, which not only is costly for the pet owner but could be traumatic for the animal themselves.
The science of skin and dietetic foods
Multiple clinical studies have shown that therapeutic nutrition can play an important role not only in the diagnosis and management of cutaneous adverse food reactions, but also in the management of CAD and those suffering both.
In the UK, nutrition often isn’t considered until the later stages of our diagnostic work-up when we are looking to embark on an elimination diet trial. Given that CAD is a far more common diagnosis than adverse food reactions, and given the benefits that nutrition brings, the fact that nutrition is a late-stage consideration is a real shame as we are inadvertently withholding the potential beneficial effects that nutrition may bring in terms of relief of inflammation and pruritus.
Asking a pet owner to change the diet they are feeding their canine companion may be perceived to be a “big ask” as it involves a change in habit and behaviour. As such we may reserve this “ask” should we need to perform an elimination diet trial. However, if a pet owner understands the reasoning behind a recommendation and the potential benefits this may bring (much in the same way we would do with a pharmaceutical), then this recommendation becomes part of the therapeutic plan for their pet. In addition, pet parents may prefer nutrition to pharmaceutical intervention in many cases – or be happy if it were to allow lower doses/less frequent need for pharmaceutical intervention.
The use of a skin supplement may be seen to be an easier option and one easier to swallow by the pet owner (given the wide availability of supplements in human nutrition). However, the majority of supplements lack any clinical evidence to support their efficacy. If using any supplement, it would seem pertinent to look at what is being included, the doses/levels and potentially the ratios being used (see omega fatty acids below), and then consider the effect of adding this to an unknown food with its own nutrient profile. Finally, ask the manufacturer for any clinical evidence they have backing its efficacy – where possible our decisions should be built on evidence-based veterinary medicine.
Cutaneous adverse food reactions are relatively rare – equating for around 10 to 20 percent of cases of canine allergic skin disease and only 1 to 2 percent of the general population (Olivry and Mueller, 2017). Allergen avoidance may seem somewhat straightforward to a pet owner, with the three most common food allergens including beef (34 percent), dairy (17 percent) and chicken (15 percent) (Mueller et al., 2016), and a whole host of pet foods claiming to be “hypoallergenic” (a term derived from the cosmetic industry, with no legal definition). However, cross-contamination within pet foods is very common and diets frequently contain undisclosed protein sources (Ricci et al., 2018, 2021).
Hydrolysed diets are not a new innovation, but are still central to helping make an elimination diet trial less arduous to those owners who are keen to avoid home cooking for their dog over the coming 8 to 12 weeks. Enzymatic hydrolysis breaks down the protein used in these diets into small peptide units which are then too small to trigger an immune response within the bowel, meaning they avoid triggering the cutaneous immune response. Treats incorporating these same proteins are also available – ensuring pet parents have the ability to easily treat their dogs too.
But how can nutrition help with canine atopic dermatitis, a far more common cause of canine allergic skin disease?
Both omega-3 and omega-6 fatty acids play a key role, as can polyphenols, vitamin E and the use of egg protein. Omega-3 fatty acids have anti-inflammatory effects when used at appropriate levels through their suppressive effect on the formation of arachidonic acid-derived prostaglandins and leukotrienes. In fact, when omega-3 fatty acids enter the inflammatory pathway (COX and LOX initiated) they produce inflammation-dampening and resolution-promoting mediators called resolvins and protectins. Omega-6 fatty acids are pro-inflammatory but are a key component of the ceramide which helps “glue” the cells together within the stratum corneum. Inclusion of omega-6 fatty acids can help to reinforce the skin barrier, and in doing so helps to reduce trans-epidermal water loss and reduce allergen penetration. Research suggests inclusion of 125mg/kg0.75 of omega-3 fatty acids eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), with a low omega-6:omega-3 ratio below 5.5:1 being effective (Bauer, 2011).
Polyphenols are plant-based bioactive molecules shown to have anti-inflammatory and/or antioxidant effects within the body (Manach et al., 2004). In humans, this is similar to nutrients found in red wine, chocolate, blueberries and other “superfoods”. Some of these nutrients, such as quercetin, have been shown in humans to impact the immune response associated with environmental allergens – with reduction in cytokine production and histamine release (Singh et al., 2011).
Egg white and yolk components have been shown to have antioxidant and immunomodulatory effects (Mine, 2008), and studies performed in-house at Hill’s Pet Nutrition demonstrated that the inclusion of egg in a diet can impact both immediate and delayed hypersensitivity reactions (unpublished data).
When it comes to selecting a therapeutic diet and determining when to intervene, we want to consider a diet which includes the appropriate nutrients to impact clinical disease, which has clinical evidence backing its efficacy, that will manage as many of the causes of allergic skin disease as possible and which tastes great.
Summary
Canine allergic skin disease is a complex multifactorial disease process requiring a logical and systematic diagnostic plan. Excellent client communication is key to ensuring the pet parent fully understands all potential diagnoses, the step-by-step plan and the costs and time involved.
Multimodal therapy is the key to help ensure the most effective management plan for your patient, combining pharmaceutical therapy with shampoos and topicals together with nutrition for best effect. Communication is again key to ensuring pet parents understand the role each component plays and the reason for its inclusion.
Making use of the whole vet healthcare team, with vet and vet nurse working together, will often ensure the best result for the pet and the pet parent, and ultimately for you and your practice.
