Treatment of canine pyoderma

Treatment of canine pyoderma
Systemic (antibiotic) and topical therapy can be used in canine pyoderma.
1. 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.
2. 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.
3. 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.

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 Presistant to penicillinases
narrow spectrum/Gram+
synergy with penicillins
and erythromycin
fusidic acid (the only one of this group) :
60 mg/kg div. tid

Sulfonamides-
Diaminopyrimidinesbroad spectrumtrimethoprim-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).
4. 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).