Treatment Protocol of Pyoderma in Dogs

May 28, 2023

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Treatment Protocol of Pyoderma in Dogs

What Is Pyoderma?

Pyoderma is a bacterial skin infection that literally means “pus in the skin”. Bacterial pyoderma in dogs appears as small, raised, red bumps, some with pus in them (or pyogenic), that look a lot like pimples. You may also notice scaly, dry, flakey patches, redness, and inflammation.

Is pyoderma in dogs contagious?

This infection is sometimes compared to impetigo, mainly when referring to puppies. Impetigo is a skin infection common in human children, and the main difference is that impetigo is contagious, while pyoderma is not contagious.

Pyoderma is a bacterial infection that is caused by an overabundance of an ordinary bacterial resident, usually Staphylococcus intermedius, which results in scaled, itchy skin, frequently incorporating pustules and ulcers. It is a relatively common condition in dogs, particularly in warm, moist environments or when the immune system becomes compromised in some way. Antibiotics are usually effective in eliminating this disease, although reoccurrence is common if any or all underlying conditions are not thoroughly addressed.

Pyoderma is a relatively common skin disorder characterized by scaly, itchy skin that frequently develops pustules and ulcers. This uncomfortable disorder is caused by an overabundance of certain varieties of bacteria on the animal’s skin.

Pyoderma, literally meaning “pus in the skin,” often sounds and looks scarier than it is. A relatively common condition in dogs, pyoderma is characterized by skin infection and irritation and can have a huge variety of causes, most of which are suited to different treatments. Knowing what to look out for increases your chances of catching your pup’s case of pyoderma early, leading to better health outcomes and easier treatment.

What Causes Pyoderma?

Pyoderma can have a range of possible causes. :

Allergies
Parasites such as demodex or scabies
Fleas
Bacterial infections
Anatomical issues
Endocrine disorders such as low thyroid levels
Diabetes
Cushing’s disease
Some cancers

The most common of these is bacterial infections in the skin, namely staph. Bacterial pyodermas can be simple, meaning they are triggered by a one-time event like fleas, or complex, meaning it is a recurring issue associated with an underlying disease. Both simple and complex pyodermas can be further categorized into either superficial or deep. Superficial pyoderma, also known as bacterial folliculitis, is a bacterial infection affecting hair follicles and the surface layer of the skin, known as the epidermis. Deep pyoderma, on the other hand, is less common and affects deeper layers of skin.

Certain breeds of dogs, such as pugs or shar-peis, are more prone to skin infection than others, usually due to deep skin folds that breed bacteria in a warm, moist environment. Any skin condition that increases the humidity of the surface of your dog’s skin can increase the chances of developing pyoderma.

Pyoderma can also occur in broken skin, when blood flow to the skin has been impaired, or when a dog has a suppressed immune system due to disease or immunosuppressive medications.

In puppies, pyoderma usually presents in areas with thin hair like the groin and underarms. Skin irritation caused by fleas, ticks, yeast or fungal infections, hormonal imbalances, genetics, and more can all increase the risk of pyoderma for your dog.

Symptoms of Pyoderma in Dogs

Pyoderma is a relatively common disorder in dogs and can occur at any age. Symptoms are similar to many other skin disorders and those most common are:

Blood or pus on skin
Crusting
Foul odor from skin
Hair loss
Itching
Rash
Redness
Scaling
Sensitivity to touch
Swelling
Ulcerated skin
Yellow papules

Types

In many cases, pyoderma occurs as a single incident, but for some dogs, it can become a chronic issue. Certain conditions, such as diseases that compromise the immune system or allergies, may contribute to the pyoderma becoming chronic. Environmental influences, such as a hot, humid climate, may also increase the chances of a case of pyoderma becoming chronic, particularly with dogs that have wrinkles or folds in their skin. Most often pyoderma is superficial, meaning that it only affects the upper layers of the skin, however, it can also attack deeper layers of the skin, making it more challenging to treat. Puppies may also develop temporary cases of pyoderma due to their underdeveloped immune system. Puppy pyoderma, also sometimes referred to as puppy strangles, is generally concentrated in sparsely furred areas, such as the face, groin, belly, or armpits of the animal.

Causes of Pyoderma in Dogs

Pyoderma is most often caused by the Staphylococcus intermedius bacteria, a common resident on the skin and hair of most dogs, although other bacteria are occasionally to blame. In certain circumstances, these normal bacteria can over colonize on the animal’s skin and cause an infection that leads to itching, skin discoloration, and in some cases, open wounds from scratching. Conditions are most conducive to the formation of this disorder can include:

Allergic reaction
Autoimmune disorder
Immunosuppression
Physical damage to the skin
Warm, moist environments

Pyoderma is usually a secondary infection, which means something else causes the skin to be irritated or broken. Then the bacteria get in the skin, causing pyoderma. Some of the reasons that the skin may be susceptible to an infection include:

Allergic dermatitis
Changes to normal skin bacteria
Cushing’s disease
Excessive moisture
Excessive scratching
Fleas, ticks, or mites
Fungal skin infection
Hypothyroidism
Immune system suppression
Immunosuppressive drugs
Lack of blood flow to the skin
Malnutrition

Diagnosis of Pyoderma in Dogs

Your visit to the veterinarian will most likely start with a full physical examination, with particular attention being paid to the areas that are showing the symptoms, and a thorough history of your canine’s health and a timeline of symptoms can be extremely beneficial to an accurate diagnosis. The symptoms of pyoderma will typically prompt your veterinarian to collect skin samples during the general physical, usually, through a technique know as skin scraping.

These samples are used in a microscopic evaluation of the skin cells, called cutaneous cytology, which is utilized to see infestations and infections that may not be visible to the naked eye. An overabundance of bacteria may be detected microscopically, at which point a culture of the sample will be taken to determine what type of bacteria they are. Routine tests, such as a complete blood count, a biochemistry profile, and a urinalysis, may help to identify any underlying conditions that will need to be addressed before the skin condition can be fully restored.

Superficial pyoderma

Skin fold pyoderma (intertrigo)

These lesions are seen in anatomical defects where there is an important bacterial colonization: lip, facial, vulvar, caudal, obese and mammary folds. The dermatosis is localized with erythema, exudation, suppuration and bad odour.

Impetigo

In juvenile impetigo, subcorneal pustules are present on the ventral side of the body, with crusting. The disease is self-limited. In adult impetigo, large pustules (“bullae”) are seen all over the body. In general, adult impetigo is severe and secondary to an underlying disease (hyperadrenocorticism, glucocorticoid therapy…) or multiple traumas (e.g., during hunting).

Folliculitis

Juvenile folliculitis: numerous follicular pustules are present on the ventral side of the body. The condition often heals at puberty.

Short-haired dog pyoderma: there are generalized follicular pustules, epidermal collarettes and crusts, with a “moth-eaten” hair. Pruritus disappears when the lesion heal.

Secondary folliculitis: this common disease is characterized by follicular pustules, epidermal collarettes and crusts which are often generalized. Pruritus is still present after lesions healing in case of underlying pruritic dermatosis. The disease may also generate pruritus in a usually nonpruritic dermatosis (in such cases pruritus disappears when lesions heal).

“Bacterial hypersensitivity” and/or superficial spreading pyoderma: bacterial hypersensitivity is an uncommon disease based on a clinical triad: erythematous follicular pustules, target lesions/seborrhoeic plaques, haemorrhagic bullae. There is sometimes a severe pruritus. The existence of a real bacterial allergy is presumed and debatable. In superficial spreading pyoderma, nummular areas of alopecia and erythema are centrifugally expanding, with epidermal collarettes and crusts. These lesions are often associated to intact but transient follicular pustules.

Deep folliculitis: it is the so-called acral lick dermatitis, most often a deep follicular bacterial infection with retrograde hidrosadenitis secondary to a psychogenic and/or an allergic cause.

Pyotraumatic folliculitis: some cases of folliculitis (e.g., in Labradors, Retrievers) appear as oozing suppurative plaque with pain. They are surrounded by satellite pustules of folliculitis or even furunculosis, which help to differentiate them from the “classical” pyotraumatic dermatitis.

Deep pyoderma

1 Furunculosis

Acne: papulo-pustules and pustules are seen on the face, particularly the chin, in young dogs.

Secondary furunculosis: localized or generalized pustules are associated or secondary to a folliculitis and the disease is triggered or aggravated by an excessive therapy (e.g., glucocorticosteroids).

Nasal pyoderma: pustules and crusts are present on the bridge of the nose and eyelids. There may be an unpleasant scaring. This true bacterial nasal pyoderma of unknown cause should be differentiated from the sterile eosinophilic furunculosis possibly due to arthropod bites.

Cellulitis
Localized cellulitis

Pressure points pyoderma: there are necrotizing lesions of the elbows, the rump, the stifles, the hocks and the lateral digits. They are due to permanent trauma in heavy dogs.

Various localized cellulites: These are other localized necrotizing lesions (e.g., perianal). Their cause is often unknown; they are sometimes secondary to a furunculosis.

Generalized cellulitis

Pyodemodicosis: There is an extensive necrotizing skin disease, which is secondary to a generalized demodicosis (an immunodeficiency status).

Various generalized cellulites: necrotizing lesions are extensive and often secondary to other immunodeficiencies.

The interdigital pyoderma complex

There are very numerous causes of non infectious pododermatitis with erythema, oedema, oozing and alopecia. The same lesions are present in interdigital pyoderma along with furunculosis, ulcerations, fistulae and necrosis (cellulitis). Interdigital pyoderma is often secondary.

Pseudo-pyoderma

Pyotraumatic dermatitis

The typical lesions have an acute onset and are characterized by alopecia, erythema, oozing, suppuration, pruritus and/or pain. These lesions are common, and most often associated to pruritic skin disease. They are poorly understood (sometimes due to vasculitis?). There is a spontaneous healing in a few days, but a short treatment is useful.

Juvenile pyodermas

Juvenile pyoderma of new-born puppies: crusty lesions are present on the face, thorax and dorso-lumbar area. They might be due to trauma. No treatment is required since there is a spontaneous healing.

Juvenile cellulitis: The aetiology of this disease is unknown. The typical clinical aspect is a facial oedema and furunculosis, with fistulae, crusting and a suppurative otitis externa. Adenopathy and sterile abscesses (cellulitis) are present. The onset of this uncommon disease occurs before 4 months of age in one or several puppies of a litter. There is a spontaneous healing in a few weeks with scaring but treatment is required.

Diagnosis of canine pyoderma

Diagnosis of canine pyoderma is based on history, physical examination and complementary examinations: cytology, histopathology and bacteriology.

Cytology

In intertrigo (skin fold pyoderma), images of “bacterial colonization” are observed, i.e., healthy neutrophils, Cocci and Bacilli in an extracellular position and degenerated neutrophils in a state of phagocytosis. In impetigo and folliculitis, impaired (degenerated) neutrophils are only found. The pictures of Cocci phagocytosis are not particularly numerous. This is an image of “bacterial invasion”, i.e., the penetration of pathogenic germs into the skin. The significance of the pictures of phagocytosis differs considerably depending on whether they are observed on the surface or in a cutaneous lesion. In effect, when they are observed inside the skin (epidermis, hair follicles, dermis) one might consider that the phagocytosed germs are pathogenic and that there is a real bacterial pustulosis. In contrast, phagocytosis observed on the surface indicates multiplication of germs which are not necessarily and probably rarely pathogenic. In deep pyoderma cytology is less likely to reveal the germs and pictures of phagocytosis, although they must be looked for. Frequently there are a granulomatous reaction, eosinophils and red blood cells. Bacterial colonization is observed in pyotraumatic dermatitis as in intertrigo but it is not significant and treatment with antibiotic does not result in remission. In juvenile cellulitis, the degenerated neutrophils are very numerous, with a granulomatous reaction. No germs are seen.

Histopathology

This will show typical lesions, but is relatively rarely performed for the diagnosis of canine pyoderma, except in case of difficult differential diagnosis.

Bacteriology

This can confirm the bacterial infection and allows sensitivity testing.

Treatment of canine pyoderma

Systemic (antibiotic) and topical therapy can be used in canine pyoderma.

Selection of antibiotics

The criteria for the choice of an antibiotic are as follows: appropriate kinetics and good cutaneous penetration, activity against Staphylococci, activity in pus and reactive tissues, bactericidal activity rather than bacteriostatic activity particularly in severe cases, easy administration (oral, q12h or q24h), absence of secondary effects, reasonable cost. The choice can be empirical, particularly in superficial pyoderma, after cytological examination of pus from an intact pustule which shows bacterial invasion. Bacteriology and sensitivity testing must be used in case of deep pyoderma, recurrent pyoderma, when cytology shows a complex flora with rods, and in case of empirical antibiotic therapy failure. They can be repeated during therapy.

Dosage and duration of treatment

Ideal doses must be used and duration of treatment must be long enough (a few weeks to several months depending of extension and depth of lesions, and always beyond clinical cure). Maintenance pulse treatment (e.g., 2 to 3 days a week) can be used in chronically relapsing pyoderma but it could theoretically select resistant strains as well as the use of subminimal doses. They are both used for economical reasons but the former is preferable.

Antibiotics useable in canine pyoderma

Antibiotics useful in canine pyoderma are included in the following table. They all have a good cutaneous diffusion (because of their liposolubility) and can be given orally, which is useful because of long therapeutic courses (ease of administration). They are all bactericidal except macrolides which are bacteriostatic.

*Class*	*Characteristics*	*Examples*
Macrolides	narrow spectrum/Gram+	erythromycin : 30 to 50 mg/kg div. bid or tid lincomycin : 40 to 50 mg/kg div. bid or tid clindamycin : 5,5 to 11 mg/kg sid or div. Bid tylosin : 40 mg/kg div. bid
Penicillins M	resistant to penicillinases narrow spectrum/Gram+	oxacillin : 30 to 50 mg/kg div. bid
Penicillins A potentiated by clavulanic acid	resistant to penicillinases larger spectrum	amoxicillin-clavulanic acid : 25 mg/kg/div. bid
Cephalosporins	resistant to penicillinases broad spectrum	cephalexin : 30 to 60 mg/kg div. Bid cefadroxil : 44 to 70 mg/kg div. bid
Cephalosporin P	resistant to penicillinases narrow spectrum/Gram+ synergy with penicillins and erythromycin	fusidic acid (the only one of this group) : 60 mg/kg div. tid
Sulfonamides- Diaminopyrimidines	broad spectrum	trimethoprim-sulfa : 30 mg (i.e., 5 mg trimethoprim)/kg sid or div. Bid baquiloprim-sulfadimethoxine : 30 mg (i.e., 5mg baquiloprim)/kg q.48h ormetoprim-sulfadimethoxine : 30 mg (i.e., 5mg ormetoprim)/kg sid after a single double dose the first day
Fluoroquinolones	broad spectrum excellent tissue penetration (not to be used in puppies of giant breeds)	enrofloxacin : 5mg/kg sid of div. Bid marbofloxacin : 2 mg/kg sid difloxacin : 5 mg/kg sid orbifloxacin : 2.5 mg/kg sid

Penicillin G (which is injectable) and A are sensitive to penicillinases. Aminoglycosides have a low cutaneous diffusion (they are hydrosoluble), are injectable and toxic. Chloramphenicol has a bad reputation in humans and the cat (haematologic toxicity). Tetracyclines have a very low activity against Staphylococci. These antibiotics are never or rarely used in canine pyoderma. Rifampicin is effective against Staphylococci but, as it is still used to treat human tuberculosis, it should be used when there is no other possibility (5 to 10 mg/kg SID). In addition, it should be then associated to a betalactamine to prevent the selection of resistant strains of Staphylococci. Mupirocine, a topically active bactericidal antibiotic, in a polyethylene glycol base is effective against Gram+ Cocci, is not systematically absorbed and is not chemically related to other antibiotics. It can be used in localized pyodermas (acne, pressure point pyoderma, interdigital pyoderma).

Associated treatments

Topical therapy is always beneficial in canine pyoderma, particularly in superficial staphylococcal disease. Clipping can be useful and is necessary in deep pyoderma such as cellulitis. The main useful topical products are chlorhexidine (lotion and/or shampoo), povidone-iodine (lotion and/or shampoo), benzoyl-peroxide (shampoo and eventually gel), ethyl-lactate (shampoo). They should be used frequently, e.g., once a day, at the beginning of therapy. Later, frequency of application may decrease. Each shampoo should be followed by the application of an appropriate humectant. Topical or systemic glucocorticoids should never be used in true canine pyoderma, even in case of pruritus, because they cause severe relapses (“rebound effect”). In contrast they can be used and are effective in pseudo-pyoderma (e.g., oral prednisolone: 1 mg/kg/day for pyotraumatic dermatitis and 2 mg/kg/day for juvenile cellulitis).

2 Types Of Pyoderma

There are two types of pyoderma in dogs:

Superficial Pyoderma: When the infection gets into the first epidermal layer of the skin, just below the surface and the hair follicles, it’s superficial. This type is the most common form of pyoderma.
Deep Pyoderma: Deep pyoderma in dogs is an infection that gets into the root of the hair follicle.When this occurs, it can be harder to treat.

Where Does Pyoderma Appear?

A dog can have pyoderma anywhere on his body. However, here are some places where a deep infection is more likely to occur:

Chin
Elbow
Hocks
Knees
Lip fold
Skin folds
Muzzle
Spaces between the toes
Vulvar folds

Pyoderma In Puppies

Puppies have extra sensitive skin that’s more susceptible to skin infections, which is why puppy pyoderma can occur. The main difference with puppy pyoderma is the underlying cause of it is just being a puppy.

Puppy pyoderma is most common in areas where the skin doesn’t have hair to protect it, especially their super cute, soft belly. This form of pyoderma looks similar to adult pyoderma but usually requires less intervention to treat. If your vet decides medication is necessary, they may only recommend a topical spray or ointment as needed.