Horvath - Dermatology_canine Pyoderma

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INTRODUCTION

Pyoderma and recurrent pyoderma have a high

incidence in small animal practice and can be

frustrating to treat.The treatment protocol should be

formulated specifically for each individual case.

Resolution of secondary pyodermas necessitates

identification of the underlying problems and

successful treatment of the primary condition. Skin

infections can be treated topically, systemically or by

combination of these. This article summarisestreatment strategies for pyoderma with special

emphasis on chronic and recurrent pyodermas.

CLINICAL SIGNS

Dogs with superficial pyoderma may present with a

range of lesions, in any combination.These include

pustules, papules, crusting, epidermal collarettes,

alopecia, scaling, erythema, prur itus and

hyperpigmentation.Which clinical signs are present

in each individual case depends on many factors

including the underlying condition as well as the

stage of infection when the animal is examined.

Certain breeds also tend to produce certain types of

lesions at a higher frequency. Different lesions have

different diagnostic power, e.g. follicular pustules,

although not found commonly, can only be caused

by a small number of diseases with pyoderma being

one of the most common (Ihrke,1987,Mason,1991)

DIAGNOSIS

The diagnosis of canine pyoderma is based on

compatible clinical signs in combination with

cytology consistent with bacterial infection

(pyogranulomatous inflammation with extra- and

intracellular cocci on cytology). With a bit of practice and experience it is easy to perform

cytology in general practice; equipment needed are

slides, a staining system (e.g. Diff Quik or RapiDiff)

and a good microscope.Trial antibacterial therapy is

occasionally useful in the diagnosis of canine

pyoderma. Swabs for bacterial culture and sensitivity

testing are only occasionally used to confirm the

diagnosis and to choose an appropriate antibiotic in

non-responsive cases. For deep pyoderma a skin

biopsy should be taken under sterile conditions and

the specimen transferred to a sterile transport

container containing a moistened gauze swab.Another possibility to prevent surface contamination

is to remove the epidermis prior to taking the biopsy.

TREATMENT

Treatment of canine pyoderma depends on the

extent and depth of the lesions, owner and patient

compliance and the underlying disease. Topical

and/or systemic drugs can be used.

Topical treatment

Topical antibacterial therapy is useful as a sole

therapy or as an adjunct to systemic antibacterials.

Topical medication is available as shampoo, rinse,spray, gel and cream.

Shampoos

Medicated shampoos are commonly used. In

addition to the mechanical action of removing tissue

debris, removing the exudates and reducing the

bacterial population on the skin can aid in the

resolution of bacterial infections of the skin and help

reduce the frequency of relapses in recurrent

pyoderma. In acute cases of superficial and deep

pyoderma shampoos play a supporting role to

achieve faster resolution of clinical signs during

systemic therapy.

Shampoo therapy not only has a cleansing effect,but

also rehydrates the skin and makes the dog feel more

comfortable.Medicated shampoos should be chosen

for each dog and each case individually based on the

coat condition (e.g. dry or oily seborrhoea). In severe

cases it might be necessary to wash the dog every

second day or even daily until remission is achieved.

This can usually be reduced to weekly or fortnightly

as soon as the pyoderma is in remission. Owner

compliance is important as this form of therapy is

very time consuming. It is important to instruct theowner carefully on how to bathe a dog as

shampooing will only be successful if the owner

allows an appropriate contact time followed by

thorough rinsing with warm water to remove

shampoo residues. Many veterinary shampoo

manufacturers produce leaflets that can provide

helpful information for owners. In long haired dogs

it might be useful to clip the dog to ensure good

penetration of the active ingredients to the skin

surface.

Antibacterial shampoos contain ingredients likebenzoyl peroxide, chlorhexidine, ethyl lactate,

povidone-iodine, hexetidine or piroctone olamine.

SMALL ANIMAL G DERMATOLOGY###UK Vet - Vol 12 No 1 January 2007 1

Christa Horvath DrVetMed MRCVS

SCHERING PLOUGH SENIOR CLINICAL SCHOLAR

HOSPITAL FOR SMALL ANIMALS, EASTER BUSH VETERINARY CENTRE, ROSLIN MIDLOTHIAN. EH25 9RG

Ariane Neuber DrVetMed CertVD Dipl ECVD MRCVS

CHILTERN REFERRAL SERVICES, CHALFONT ST GILES, BUCKS. HP8 4AB

GREAT WESTERN REFERRALS, SWINDON, WILTS. SN1 2NR

Management of canine pyoderma



Shampoos licensed for use in dogs in the UK are

listed in Table 1. Benzoyl peroxide, organic iodine

compounds, chlorhexidine and triclosan are able to

kill Staphylococcus intermedius on the skin (Kwochka

and Kowalski, 1991). Each of the active components

listed above has different properties:

G Benzoyl peroxide lowers the pH of the skin and

disrupts the microbial cell membranes. (Burkhart

et al ., 2000).Additionally it is follicular flushing,

keratolytic and strongly degreasing. It is very

useful in deep pyoderma. Benzoyl peroxide is

also drying and bleaching and should therefore

not be used in dry seborrhoea and owners

should be warned about the bleaching effect.

G Chlorhexidine is less irritating than benzoyl

peroxide and is therefore preferable in dogs with

sensitive and dry skin. It is effective against many

Gram positive and Gram negative bacteria with

the exception of some Pseudomonas and Serratia

strains. Chlorhexidine also shows a good residual

antibiotic effect.

G Ethyl lactate is hydrolysed to ethanol and lactic

acid, which lowers the skin pH. Its mode of action is therefore similar to benzoyl peroxide

(de Jaham,2003).

Creams and ointments

The use of various antibiotic creams or ointments is

limited to smaller infected areas. In conditions like

intertrigo, canine acne, callus pyoderma or pedal

folliculitis and furunculosis they can be very helpful.

For larger areas creams cannot be recommended due

to the amount that has to be used. Creams and gels

may contain agents like mupirocin, fucidic acid and

bacitracin, all of which have a narrow antibacterial

spectrum (Table 2).The antibiotic should be able to

permeate superficial skin and not be inactivated by

tissues, fluids or proteins. Clinically, the frequency of

staphylococcal resistance to fucidic acid and

mupirocin is low.Fusidic acid (produced by Fusideum

coccineum) and mupirocin (produced by Pseudomonas

fluorescens) inhibit protein synthesis. Mupirocin has

good activity against Gram-positive cocci, is

bacteriostatic, rather than bactericidal and is not

systemically absorbed. Its penetration is very good,

even in deep pyoderma and therefore it can be used

for interdigital abscesses, chin pyoderma or pressure

point pyoderma. Bacitracin consists of one or more

antimicrobial polypeptides produced by certainstrains of Bacillus licheniformis. It is active against

Gram-positive bacteria and some Gram-negative

cocci. Resistance to bacitracin in staphylococci has

been described (Kruse et al .,1996) and Gram-negative

bacteria are intrinsically resistant to bacitracin,

presumably as a consequence of their outer

membrane permeability barrier. However, acquired

resistance is rare (Werner and Russell, 1999).

Systemic therapy

The vast majority of bacterial skin infections in dogs

are caused by Staphylococcus (S.) intermedius, althoughProteus, Pseudomonas and E. coli can be isolated,

especially from deep infections. For systemic

antibacterial agents prescribe an appropriate

antibiotic (based on sensitivity testing) that

penetrates skin, for an adequate period of time and

avoid concurrent use of corticosteroids.

G For superficial pyoderma prescribe the antibiotic

for a minimum of 21 consecutive days or for

7-14 days after clinical cure.

G Deep pyoderma should be treated for a minimum

of 4 to 6 weeks with treatment continuing for 2

weeks after complete clinical cure.

SMALL ANIMAL G DERMATOLOGY### UK Vet - Vol 12 No 1 January 20072

Brand name Agent

Coatex, VetPlus Chloroxylenol

Salicylic acid

Sodium thiosulfate

Etiderm, Virbac Ethyl lactate

Benzalkonium chloride

MalAcetic, DermaPet Acetic acid

Boric acid

Malaseb, VetXX Chlorhexidine

Miconazole

Paxcutol, Virbac Benzoyl peroxide

Sebomild P, Virbac Ammonium lactate

Piroctone olamine

Essential fatty acids

Chitosanide

TABLE 1: Antibacterial shampoos

Brand name Ingredient Licensed in UK for Manufacturer

use in dogs

Fuciderm Sodium fusidate Yes VetXX

Fucidin Sodium fusidate No VetXX

Flamazine cream Silver sulphadiazine No Smith & Nephew

Betadine Povidone-iodine No Seton Healthcare Group

Bactroban Mupirocin 2% No Polyfarma Ltd, Smith Klein Beacham

Surolan Miconazol, polymyxin Yes Janssen Animal HealthB, prednisolone

TABLE 2: Antibacterial ointments



If treatment is stopped just as the lesions clear, there

is usually relapse. It is important to explain this to the

owner from the beginning of the treatment and

stress the importance of keeping appointments for

checks.All cases should be re-evaluated within three

weeks and again before discontinuation of antibiotics

by a vet.Sometimes it is necessary to clip parts of the

hair coat to better visualize the skin for lesions.

Some antibiotics (penicillin,amoxicillin, streptomycin,

and ampicillin) are unsuitable for treating pyoderma

because they do not achieve therapeutic

concentrations in the skin. Ideally, the antibacterial

should have a narrow spectrum. In most cases it ischosen empirically after inflammatory cells and

cocci have been demonstrated on skin cytology.The

choice can be made on the basis of culture and

sensitivity testing, but this is only strictly necessary in

cases that appear resistant to therapy or when rodshaped bacteria are found on cytology. Drugs

commonly used include narrow spectrum agents

(e.g. clindamycin and lincomycin) and broad

spectrum agents such as cephalosporins (first

generation), (Frank and Kunkle, 1993) potentiated

sulphonamides and clavulanic acid-potentiated

amoxicillin (Table 3). Most veterinary dermatologists

reserve fluoroquinolones for use after culture and

sensitivity testing or for staphylococci which prove

resistant to the drugs above (Ihrke, 1987, Paradis et

al ., 1990, Paradis et al ., 2001,Ganiere et al ., 2004).

Failure to respond

If there is no response to treatment, the chosen

SMALL ANIMAL G DERMATOLOGY###UK Vet - Vol 12 No 1 January 2007 3

Fig. 1b: Alopecia, hyperpigmentation, scaling and erythema,

closer view.

Fig. 1a: Superficial spreading pyoderma.

Fig. 1c: The same dog after treatment with cephalexin;

the underlying cause was atopic dermatitis.

Fig. 2b: Superficial pyoderma beneath the axillae.

Fig. 2a: Superficial pyoderma on the ventral abdomen.

Fig. 2c: The same dog after treatment with cephalexin;

the underlying cause was food hypersensitivity.



SMALL ANIMAL G DERMATOLOGY### UK Vet - Vol 12 No 1 January 20074

Drug Product Manufacturer Drug class Licensed in Recommended

Spectrum UK for dogs dose/kg for

pyoderma

Erythromycin Erythromycin Abbot macrolide no 15 mg q 8h

tablets Laboratories Ltd antibiotic; gram

Sovereign positive and

gram negative

Lincomycin Lincocin tablets Pfizer Animal lincosamide yes 20-30 mg q 12h

Health antibiotic; gram

positive and many

anaerobes

Cephalexin Ceporex Schering-Plough 1st generation yes 20-30 mg q 8-12h

Animal Health cephalosporin;

Rilexin Virbac Animal gram positive and

Health UK gram negative

Cefadroxil Cefa-Tabs Fort Dodge 1st generation yes 10-22 mg q 12h

Animal Health cephalosporin;

gram positive and

gram negative

Ciprofloxacin Ciproxin tablets Bayer Animal fluoroquinolone; no 5-15 mg q 12hHealth gram positive and

gram negative,

Mycoplasma

Enrofloxacin Baytril Bayer Animal fluoroquinolone; yes 5-10 mg q 24h

Health gram positive and

gram negative,

Mycoplasma

Marbofloxacin Marbocyl Vetoquinol UK fluoroquinolone;

Ltd gram positive and yes 2-5 mg q 24h

gram negative,

Mycoplasma

Clavulanic acid- Synulox Pfizer Animal gram positive and yes 12-25 mg q 8-12hpotentiated Health gram negative

amoxicillin

Trimethoprim- Norodine Norbrook gram positive and yes 15-30 mg q 12h

sulphonamide Laboratories gram negative

Tribrissen Schering-Plough

Animal Health

Clindamycin Antirobe Pfizer Animal lincosamide yes 5-10 mg q 12h

Health antibiotic; gram

positive and many

anaerobes

Doxycycline Ronaxan Merial tetracycline yes 2.5-5 mg q 24h

TABLE 3: Systemic antibiotics



UK Vet - Vol 11 No 1 January 2006 5

antibiotic may have been inappropriate for the

suspected infection. At this point culture and

sensitivity testing should be performed.

Relapse

In cases that respond to antibiotics but relapse within

a week after treatment has been discontinued,

consider prescribing a longer course of treatment.

Potential underlying causes should be investigated e.g.

with uncontrolled atopic dermatitis regular relapses

of the secondary pyoderma is to be expected.

Immunomodulatory therapy

Immunomodulation has been attempted with

various agents, including levamisole and cimetidine

(an H2 histamine receptor blocker) but specific

SMALL ANIMAL G DERMATOLOGY###

Fig. 3a: Collie with severe FAD.

Fig. 3b: Chronic superficial pyoderma with alopecia,

erythema, hyperpigmentation and crusts.

Fig. 3c: Skin lesion in remission after a course of

cephalexin and flea treatment, nice hair regrowth.

Fig. 4b: Multiple draining tract, closer view.

Fig. 4a: Generalised deep pyoderma in a 1-year-old

Mastino Neapolitano with generalised demodicosis.

Fig. 4c: The same dog three months after treatment with

clavulanic acid potentiated amoxicillin and ivermectin.



UK Vet - Vol 12 No 1 January 20076

details on efficacy have not been published.The use

of these drugs is reported but the author has no

experience with the dose rates. (Scott et al . 2001).

Levamisol restores normal numbers of lymphocytes

(T cells) thus leading to normal function of these

cells. Cimetidine may act by reversing T-suppressor-

mediated immune suppression (Kwochka, 1993).

However proof of immuno-incompetence in

veterinary medicine is not routinely available which

implies that the use of levamisol for this purpose is

anecdotal.

Various bacterins (autogenous vaccines e.g. produced

by the Royal Veterinary College), S. aureus phage

lysate (Staphage Lysate, SPL, Delmont Laboratories,

Swarthmore, US.) and Propionibacterium acnes

(Immunoregulin, Immunovet) have been used, with

the autogenous preparation being the only product

available for use in the UK.The mechanism of action

is unknown but they are hypothesised to improve

cell-mediated immunity, impacting on non-specific

and humoral immunity (Nesbitt and Schmitz, 1977,

DeBoer,1990,Scott et al . 2001).Protocols for the useof bacterins vary from 0.5 ml subcutaneously twice

a week to 1-2 ml weekly, duration of treatment

should be at least 10 weeks with success rates ranging

from 30-70% (DeBoer, 1990, Kwochka, 1993).

DeBoer reported a long-term success rate of 50%

with Staphage Lysate over a period of 22 months

(DeBoer et al ., 1990).

In a recently published study the clinical efficacy of

staphylococcal autogenous bacterin was evaluated in

dogs with idiopathic recurrent pyoderma. In all dogs

S. intermedius was cultured. Both groups received a4-week course of antibiotics. One group received

additional injections of the bacterin, the other

received no additional treatment. Comparison of

lesion scores of the control group and treated group

showed significantly higher scores in the control

group compared to the group receiving bacterin.No

adverse reactions to bacterin therapy were noticed

(Curtis et al ., 2006).The dogs in this study were still

treated at the end of a 9-18 month follow-up period.

These results are quite promising, but further studies

should be performed with large numbers of dogs

and a long follow-up period. Currently there are no

other licensed products available in the UK.

RECURRENT PYODERMA

Long term management of recurrent superficial or

deep pyoderma relies on various factors including

the identification of underlying causes and owner

compliance. Recurrent pyoderma is commonly a

lifelong disease and therefore regular re-examination

and detailed discussion with the owner about the

underlying disease and the forms of therapy that are

available are very useful. If owner compliance and

patient temperament allow lifelong shampoo

therapy, this can be a very effective form of therapywith very low occurrence of side effects and less

worries about the potential to induce antibacterial

resistance.The frequency of washes has to be assessed

in each case individually by the owner and the

veterinary surgeon. Localised lesions can be treated

with antibacterial creams. Immunomodulatory

therapy can be added as mentioned above. If an

underlying cause can be identified and successfully

treated, the pyoderma might resolve, otherwise

extended antibiotic regimes can be used. Recurrent

pyoderma can be a difficult disease to manage.

Success is closely linked to owner compliance.

Owners must be willing to invest a lot of time and

money in the management of their pet.

For long term management various treatment

protocols are suggested. After clinical remission on

full dose antibacterial therapy consider:

1. Maintenance antibiotic therapy using suboptimal

doses to maintain remission. The chosen drug

should have minimal side effects and little

potential to develop resistances. For example, if

the dog requires 500 mg of cephalexin twice a

day, this dose should slowly be tapered to 250 mg

once a day or every other day.2. Pulse therapy at full dose on some days, with

drug-free days in between has been used

(Kwochka, 1993).The number of days on and off

medication varies from patient to patient and

must be individually assessed.

For pulse therapy the full therapeutic dose should be

given. For example a dog is prescribed 500 mg

cephalexin q 12h in Week 1, in Week 2 the dog

receives no antibiotics, in Week 3 cephalexin is given

as for Week 1 (one week on, one week off). If this

regime works, the time off periods can be extendedgradually (DeBoer, 1990).

CONCLUSION

Single episodes of pyoderma should be treated as

necessary with topical and/or systemic antibacterial

treatment at the right dose and for an adequate

period of time. Recurrent cases of pyoderma require

a more extensive work-up with identification of the

underlying condition, and if possible, correction

thereof.An individual management programme that

might change over time depending on the

requirements of the individual patient, should be

formulated.This might include the use of shampoos,immunmodulatory treatment and/or pulse therapy

with antibiotics. In all cases efforts should be made

to identify an underlying cause.

REFERENCE

BURKHART, C. N., SPECHT, K. and NECKERS, D. 2000 Synergistic

activity of benzoyl peroxide and erythromycin. Skin Pharmacol Appl Skin

Physiol 13 292-6.

CURTIS, C. F., LAMPORT, A. I. and LLOYD, D. H. 2006 Masked,

controlled study to investigate the efficacy of a Staphylococcus

intermedius autogenous bacterin for the control of canine idiopathic

recurrent superficial pyoderma. Vet Dermatol 17 163-8.DE JAHAM, C. 2003 Effects of an ethyl lactate shampoo in conjunction

with a systemic antibiotic in the treatment of canine superficial bacterial

SMALL ANIMAL G DERMATOLOGY###



Horvath - Dermatology_canine Pyoderma

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