Skin disease is one of the most common reasons owners bring their pet to see the vet (Nielsen et al., 2014). These conditions can be frustrating for both owner and vet to get to the bottom of but very rewarding when managed correctly. For management to be successful, accurate diagnosis and client compliance play important parts. Determining the cause of the issue is also important to minimise the risk of recurrence and flare-ups. Veterinary practices are lucky to have an array of parenteral medications to help relieve clinical signs like pruritus and inflammation, but for long-term success it is essential to support and maintain the skin barrier. This is done with topical therapy.
The skin is the largest organ of the body. It regulates temperature, provides a barrier against the environment and it keeps moisture in, keeping the skin hydrated.
It can be divided into three barriers: mechanical, immunological and microbiological. To minimise the risk of skin disease developing or flaring up it is important to maintain the health of these three barriers. This is done by incorporating topical products with restorative properties into the treatment plan. Topical therapy is very important when managing allergic, infectious and seborrhoeic disorders (Banović and Lemo, 2019).
Atopic dermatitis
Atopic dermatitis (AD) is a common disease in dogs. It is an inflammatory and pruritic disease with a variety of clinical presentations that can resemble other disease processes. This can make it a difficult disease to diagnose. Diagnosis is based on meeting the clinical criteria for the disease and ruling out other possible causes with similar clinical signs. It is worth noting that allergy testing is not considered a diagnostic tool for atopic dermatitis but can be done once a diagnosis has been made to identify potential causative allergens for the inclusion in allergen-specific immunotherapy (Hensel et al., 2015).
Dogs with AD have an impaired skin barrier with lower proportions of ceramides and cholesterol in the stratum corneum, widening of inter-corneocyte spaces and abnormal filaggrin production (Lam, 2012) leading to dry and more permeable skin and making it more susceptible to external allergens. They have also been shown to have disturbances in their microbiota. This dysbiosis can lead to bacterial or fungal overgrowth that may favour or enhance atopic flares (Gatellet et al., 2020). It is therefore important to include topical therapies in our AD management plan (Figure 1). Topical products will have a soothing effect on the skin, can help rebuild and maintain the skin barrier and rebalance the microbial flora as well as having the potential to reduce flare-ups. Topical therapies should therefore always be part of the multimodal treatment plan for patients with AD.
Pyoderma
Pyoderma has been traditionally divided into three types depending on the depth of infection: surface, superficial and deep. In surface pyodermas there is overgrowth of bacteria on the surface of the skin, for example hot spots. In superficial pyodermas the microorganisms have penetrated the skin, but the infection doesn’t extend past the basement membrane, for example folliculitis. Deep pyodermas are those infections that penetrate below the basement membrane, such as furunculosis or cellulitis. Treatment of pyoderma differs depending on the type present.
Diagnosis of pyoderma should always include cytology to determine what type of organisms (bacteria, yeasts, etc) are involved in the infection. This will give you an indication of what you are dealing with and what treatment to use. Oral antibiotics are not always required when treating pyoderma but if indicated, cytology should be followed up with culture and sensitivity testing to determine the most appropriate antibiotic to use.
Surface pyoderma should never be treated with oral antibiotics but can be managed solely with topical treatment containing an antiseptic agent (Figure 2). Most cases of superficial pyoderma can also be managed successfully with just topical treatment, without the need for oral antibiotics (Jasmin, 2003; Müller, 2012; Borio et al., 2015).
For treatment of deep pyoderma, topical therapies play an important role but need to be accompanied by oral antibiotics. This should be based on culture and sensitivity testing. While waiting for culture and sensitivity results to come back, topical therapies can be used. This will avoid the use of an inappropriate antibiotic, save the client money and also soothe the pet’s skin. In cases of recurrent pyoderma, an underlying cause needs to be investigated and treated.
The use of topical therapies can help reduce the occurrence of resistant bacteria. Chlorhexidine digluconate has been shown to be effective against both sensitive and multi-drug resistant Staphylococcus pseudintermedius and it has been suggested that it is at least as effective as amoxicillin-clavulanate against this organism (Borio, 2015). Chlorhexidine digluconate at 2 to 4 percent concentrations have also been shown to provide residual antibacterial activity on canine skin for at least 10 days (Mesman et al., 2016).
Seborrhoea
Seborrhoea can be either primary or secondary in origin. Primary disorders are usually due to a genetic defect that disrupts the normal keratinisation process causing excessive scaling, whereas for secondary seborrhoea the excessive scaling is caused by an underlying disease. Secondary disorders are most common and account for about 80 percent of cases (Barnard, 2015). For treatment to be successful, it is therefore essential to identify and treat, or rule out, any underlying disease (Mauldin, 2013).
Topical therapy is the mainstay of treatment for keratinisation disorders. Treatment goals include scale and crust removal, and oil, pruritus and inflammation reduction. Some topical therapies, such as tar, can be harsh on the skin so try to avoid these and use moisturising therapies to protect the skin barrier. Topical therapies for seborrhoeic disorders include keratolytic (remove scales and reduce adhesion of keratinocytes) or keratoplastic (normalise keratinisation) ingredients as well as moisturisers and emollients to protect the skin barrier, and topical antimicrobials for the management of secondary infections.
Treatment should be tailored to each individual patient and compliance is essential for success (Mauldin, 2013; Barnard, 2015). Therefore, selecting a topical formulation that will suit the owner is of importance. Shampooing the dog or cat is important to get rid of crusts and scales. This can be followed up by mousse applications or using the mousse in between baths. Spot-ons can also be beneficial in restoring the skin barrier function (Figure 3).
Topical therapy and owner compliance
Topical therapies come in different formulations (eg shampoos, mousses, pads or spot-ons) and choosing the right type can help with client compliance. Bathing the dog or cat is important in order to get rid of allergens and crusts from the skin and it should ideally be done at least once at the start of the treatment. Not all dogs or cats like to be bathed or the owner might not be physically able to get their pet into the bath or shower, so in these cases a mousse may be a more appropriate option.
Ophytrium
Ophytrium is a natural ingredient extracted from the root of the Ophiopogon japonicus plant. It has been shown to reduce the intensity and frequency of flare-ups of atopic dermatitis in humans as well as improving quality of life for patients with this condition (Mainzer et al., 2019). Through innovative in vitro human and canine skin models beneficial effects have been demonstrated on the three skin barriers. It has been shown to strengthen the mechanical skin barrier, limit adhesion of S. pseudintermedius to the canine skin and reduce irritation (Ollivier et al., 2019).
