Intertrigo or skin fold dermatitis is commonly encountered in primary care practice. Inflammation in skin folds is created by friction as skin rubs on closely apposed skin. Although any area where intimate skin-to-skin contact occurs can be affected, the rise in popularity of brachycephalic breeds such as the French Bulldog, Pug and English Bulldog has meant more dogs are presenting with intertrigo. Typically these breeds develop facial, neck and body fold intertrigo. Other forms of intertrigo can affect lip folds, vulval folds and mammary and scrotal folds (Miller et al, 2013; Paterson, 2017).
Cytological assessment of lesions is easily achieved and important in the selection of therapy. Early recognition of intertrigo allows management with topical cleansers and protectants (Paterson, 2017). However, if the disease goes unnoticed, it can develop into a painful, ulcerated dermatitis that is difficult to manage as a result of both owner and pet resistance (Paterson, 2017). Where severe disease is present and medical therapy impossible, surgical intervention may be necessary to remove the excess skin (Paterson, 2017). The practice nurse can play an invaluable role in checking puppies of susceptible breeds when they come in for their first check-ups and advising owners on the management of skin folds to prevent disease.
Aetiology of intertrigo
Bacterial or yeast overgrowth is seen in skin fold areas because of the localised inflammation that occurs with skin fold abrasion. Microtrauma to the skin can occur purely through skin-to-skin contact in poorly ventilated areas because of anatomical factors such as prominent facial folds. However, if excretions such as tears, saliva or urine are present, additional maceration of the skin can occur leading to the creation of a micro-environment that favours the development of overgrowth of bacteria and/or yeast.
Clinical signs
The most common sites of intertrigo and predisposing factors, summarised in Table 1, will now be examined.
| Site | Breed incidence |
|---|---|
| Facial folds | Brachycephalic breeds, French bulldog, English bulldog, Pugs, |
| Tail folds | Dogs with corkscrew tails — English Bulldogs, Boston terriers |
| Body folds | Shar Peis, Basset hounds, Blood hounds |
| Lip folds | Gundogs — especially spaniels (cocker, springer, Clumber) |
| Neck folds | Breeds with pendulous dewlaps, e.g. Basset hounds, Bloodhounds, |
| Vulval folds | Dogs with juvenile vulvas speyed before their first season, mature bitches after whelping, older bitches due to urinary tract disease (infection, urolithiasis, incontinence) |
| Scrotal folds | Entire male dogs |
Facial folds
Facial fold intertrigo is seen most commonly in the increasingly popular brachycephalic breeds such as the French Bulldog, Pug and English Bulldog, as well as the Pekingese. The skin-to-skin contact and abrasion of the closely apposed skin folds over the bridge of the nose in these breeds leads to the development of moist erythematous skin changes which can lead to superficial erosion (Figure 1). Where animals suffer from concurrent ocular disease such as trichiasis, distichiasis, ectopic cilia or entropion, the resulting epiphora exacerbates skin maceration and leads to secondary overgrowth of both bacteria and yeast.
Any brachycephalic dog with facial fold dermatitis should be assessed for ocular disease, as failure to identify and manage it will inevitably lead to a poor response to therapy for the skin problem (Paterson, 2017). Although brachycephalic cats can also develop facial fold intertrigo, it appears to be less common — possibly because they rarely suffer from concurrent ocular problems.
Tail folds
Tail fold intertrigo is recognised in brachycephalic dogs with corkscrew tails, especially the English Bulldog, Boston Terrier and Pug (Paterson, 2017). Strict changes in breed standards introduced by the Kennel Club to eliminate the corkscrew tail conformation has led to a reduction in the number of dogs with this anatomical characteristic. In dogs where this is still seen, the tightly curled tail is closely opposed to the perianal skin, creating a pocket of skin. The skin inside the poorly ventilated crevices created around the tail base, becomes macerated and colonised with bacteria and yeast. The result is a deep cavity containing a malodorous discharge caused by mixed bacterial overgrowth. This causes an intense irritation for the dog and commonly leads to self-inflicted trauma to the site through rubbing. These cases can be challenging to manage and many dogs require surgery to remove the distorted tail bone, which facilitates more effective cleansing of the area (Rubin, 1979; Paterson, 2017).
Body and neck folds
Body and neck fold intertrigo is seen in breeds with excessive skin folds, such as the Shar-Pei, Basset Hound (Figure 2), Bloodhound and many of the Spaniels. In breeds that salivate excessively such as scenthounds or gun dogs, or in breeds that swim such as working dogs like the Newfoundland, wetting of the skin folds leads to maceration of the skin, producing erythema, erosion, swelling and usually yeast over growth (Paterson, 2017).
Body and neck folds can occur as a characteristic anatomical feature of certain breeds but can also be associated with obesity. Brachycephalic dogs with compromised airways and a reduced ability to exercise and hence a propensity to put on weight are, in the author's opinion, overrepresented in this group. Weight loss in such animals can help as part of their therapy to reduce the size of the skin folds (Paterson, 2017).
Lip folds
Lip fold intertrigo is usually recognised in breeds with large lip flaps such as Spaniels (Figure 3) and Saint Bernards (Paterson, 2017). The author has also seen it in smaller breeds such as the Shih Tzu and Miniature Poodle, in whom it has been misdiagnosed as facial pruritus caused by allergy. Owners rarely notice signs of lip fold disease in their pets; the foul smell that accompanies it, often misdiagnosed as halitosis or dental disease, is what brings them to the veterinarian.
Lesions are localised to the skin fold on the lower lip where the upper canine tooth rubs on the skin and may act to trap saliva within the skin fold. The accumulation of saliva and food at this site leads to maceration of the skin and bacterial overgrowth, commonly with Pseudomonas spp. (Paterson, 2017). Typically where infection occurs with Pseudomonas spp. the skin is stained a characteristic green by the pyocyanin pigment produced by the bacteria. In early cases, lesions are pruritic; but as bacteria are elaborated at the site, lesions can quickly become ulcerated and painful. At this stage, cytology is resented by the dog, making assessment of the lesions difficult and topical therapy can become impossible to apply because of the obvious discomfort of the lesions. In cases where lip fold disease is severe and recurrent — especially where dogs will not permit ongoing maintenance therapy — cheiloplasty is necessary to remove the lip folds. This is usually curative (Miller, 2013; Paterson, 2017).
Vulval folds
Vulval fold intertrigo is often associated with conformational problems. For example, a young bitch spayed before her first season with an inverted, immature vulva, and an older whelped bitch with a hyperplastic, flaccid vulva, may both develop intertriginous disease. Urine and vaginal secretions that subsequently accumulate in the deep vulval folds predispose to excoriation and ulceration of the skin. Secondary overgrowth with bacteria is common and, in the author's experience, it is an area that is frequently colonised with Pseudomonas spp. Where there is concurrent urinary tract disease, either in the form of infection or incontinence, bitches may overclean their vulval area, creating or aggravating disease. Therapy of any underlying disease is crucial as part of the management of these dogs, as well as weight loss in obese animals. In severe, recalcitrant disease, surgical vulvoplasty with fixation of the dorsal vulvar commissure to elevate the vulva out of the crevice can be useful and is usually curative (Hammel and Bjorling, 2002).
Overweight bitches, or bitches with heavy mammary tissue during and after suckling puppies, can develop intertrigo of the intramammary folds (Paterson, 2017). While bitches are suckling puppies in a warm whelping pen, friction between skin folds in these poorly ventilated areas, together with trauma to the area from suckling neonates, may create disease. Entire male dogs can develop scrotal fold intertrigo, which presents as erythema and erosion of the skin between the scrotum and the medial aspect of the groin (Paterson, 2017). Malassezia pachydermatis overgrowth is commonly found at this site (Paterson, 2017).
Investigation of intertrigo
Cytology of the affected skin in the intertriginous area is a quick and easy procedure; the following steps (1–6) outline how this can be undertaken by the veterinary nurse during the consultation. In addition, hair plucks and carefully taken skin scrapes may be useful to check for ectoparasites.
Step 1
Typical equipment that is needed includes 4M Scotch® Clear Tape, glass slides and a Romanowsky stain such as Diff-Quik® or Rapi-Diff (Figure 4).
Step 2
Use 4M Scotch tape and gently press down on the skin in the intertriginous area. Rub the skin with your thumb nail to ensure good tape-to-skin contact. The tape may be pressed onto the skin, repositioned and pressed again on two to three occasions to collect more material (Figure 5).
Step 3
Remove the tape from the skin, curl it back on itself and stick it onto a slide so that the adhesive side is facing upwards (Figure 6).
Step 4
Dip the slide with tape attached into the dark blue stain of a Romanosky stain such as Diff-Quik or Rapi-Diff (Figure 7). Submerge the slide three times, counting slowly to five on each occasion, to ensure adequate emersion (Figure 8).
Step 5
Rinse the tape gently under the tap, with a rinse bottle or submerge in water to remove excess stain (Figure 9a).
Step 6
Remove the tape from the slide, reverse it to stick the adhesive side back onto the slide. Examine under the microscope; scan the slide starting with the lowest objective to gain a general impression before moving onto higher power objectives and oil immersion (Figure 9b).
Cytology findings
In early signs of disease, there may be no colonisation of the skin with organisms. In these cases, cytology may reveal skin squames and very rare bacteria and yeast consistent with normal skin flora.
As the disease becomes more advanced, increased numbers of microorganisms can be identified (bacteria or yeast). The type of organisms that are identified are dependent on both breed and site. The skin of breeds such as the Shar-Pei, Bloodhound and Basset Hound, is commonly colonised with yeast. M. pachydermatis is the most commonly seen yeast, typified by ‘peanut’ or footprint shape on cytology. In brachycephalic breeds, where intertriginous disease affects facial folds, the author's experience is that Staphylococcus spp. is frequently identified on cytology as groups of cocci arranged in pairs, fours or like ‘bunches of grapes’. Areas such as lip folds and vulval folds are commonly colonised by Pseudomonas spp. which appear on cytology as rods. Organism types found on cytology allow appropriate decisions regarding therapy.
Therapy
Where any concurrent disease can be identified and managed, many skin fold problems can be treated by topical therapy (Mueller et al, 2012). However, where severe disease is present or where the dog will not tolerate topical therapy, surgical intervention may be needed.
Medical therapy should be undertaken with topical drugs. As intertrigo represents bacterial or yeast colonisation of the skin rather than true infection, there can be no real place for systemic therapy with antibiotics or antimycotics (Miller et al, 2013). Topical therapy should also be selected on the basis of cytology. To facilitate penetration of topical medication, the area should be gently clipped to remove any soiled hair. Formulations of topical antiseptics which may be used to great effect include wipes, sprays, mousses and shampoos. Active components of topical formulations include acetic acid, benzoyl peroxide, chlorhexidine, chloroxylenol and ethyl lactate (Mueller et al, 2012). The author favours chlorhexidine as a useful antibacterial and antimycotic agent. It should be used at high concentrations of 2–4%. Acetic acid has excellent activity against Pseudomonas spp. and is useful where clinical signs, cytology and culture are suggestive of this bacteria (Mueller et al, 2012). This should be used at a concentration of 2–2.5%. Acetic acid is available in proprietary veterinary products but normal domestic vinegar can be diluted 50:50 with warm water and applied to lesions to produce similar antibacterial effects. Acetic acid should be used with care on delicate skin around mucus membranes, especially where ulceration is present. Antimycotic agents include boric acid, chlorhexidine, clotrimazole, enilconazole and miconazole. After assessment of an area with cytology, and once topical antibacterial or antimycotic therapy have been used to remove surface overgrowth, it is important to prevent recurrence of the disease. Maintenance therapy can be undertaken using an antiseptic cleanser on the site daily, reducing to twice weekly where appropriate, followed by a protective, emollient ointment such as petroleum jelly to reduce skin-to-skin abrasions. Occlusive ointments should not be used unless the area has been cleansed first.
Prevention
Once intertrigo develops, the skin becomes erythematous, swollen and ulcerated. At this stage the condition is painful and dogs will resent therapy, especially in sensitive areas such as the lip and vulva folds. The author would suggest that as part of a general health check, skin folds should be assessed; the veterinary nurse is ideally placed to do this. When a nurse consultation is with a new puppy owner, it is important — especially if it is their first dog, and particularly if it is a brachycephalic breed — that they are guided through the technique to clean skin fold areas. The younger the puppy when the cleaning regimen is introduced, the more readily the dog will accept it. However, it is possible to train older dogs to accept regular cleansing of skin folds, providing they are introduced to it slowly and never forcibly restrained to facilitate cleansing. When training puppies, it is imperative they are only gently restrained and that positive rewards, usually in the form of high-value treats, are used prior to the commencement of cleaning. Product selection is also important and the author would favour a gentle antiseptic cleaner in the form of a wipe so that the dog is not frightened by getting fluid into their mouth or eyes. If the puppy starts to manifest signs of apprehension or fear, cleaning should be stopped immediately, and positive rewards should be reintroduced to relax the puppy and create a positive emotional state, before recommencing. The aims of cleaning, whether for a puppy or mature dog, are to create a positive experience so they readily accept it.
Intertrigo is common in primary care. Early owner education should form an essential part of routine nurse pet health checks, especially in puppies. Prophylactic use of topical therapy of skin folds can prevent development of intertrigo, which can be more challenging to manage once it becomes painful and the pet resents therapy.