An investigation of phagocytosis and intracellular killing of Staphylococcus intermedius by canine neutrophils in vitro

The Effectiveness of Fluorescent Light Energy as Adjunct Therapy in Canine Deep Pyoderma: A Randomized Clinical Trial

A single centre, single-blinded, prospective, randomized, controlled clinical study was conducted to evaluate the effectiveness of twice weekly fluorescent light energy therapy (Phovia™) as adjunct to systemic antibiotics in the management of deep pyoderma in dogs. Dogs with clinical lesions consistent with deep pyoderma, positive bacterial culture, and showing neutrophil engulfing bacteria at cytology were included in the study. Assessments were undertaken weekly for 8 weeks and every 2 weeks thereafter until 12 weeks after enrolment. At each visit, lesions were scored and cytology was conducted to determine a neutrophil engulfing bacteria score. All dogs (Groups A and B) were treated with systemic antibiotic twice daily, and Group B received additionally Phovia twice weekly. Median treatment duration was 11.7 weeks for Group A and 5.7 weeks for Group B. After 8 weeks of treatment, the percentage of dogs that achieved clinical resolution was 35.0% and 88.0% for Groups A and B, respectively. Lesion scores showed highly statistically significant difference in favour of Group B from week 3 to 8, and neutrophil engulfing bacteria scores showed statistical difference from week 2 onwards in favour of Group B. These results indicate that Phovia, when used as an adjunct to systemic antibiotics, can accelerate time to clinical resolution in cases of canine deep pyoderma.

Fluorescence biomodulation in the management of canine interdigital pyoderma cases: a prospective, single-blinded, randomized and controlled clinical study

BACKGROUND

Interdigital pyoderma is a common multifactorial, inflammatory disease of the canine interdigital skin. Lesions commonly become infected secondarily. In addition to management of the underlying cause, management of the chronic inflammatory changes in the interdigital skin created by secondary infection and by the release of keratin into deep tissues is required. Fluorescence biomodulation appears to modulate the inflammatory process in dermatological disorders and has shown promise in preliminary studies evaluating its use in superficial and deep pyoderma in dogs.

HYPOTHESIS/OBJECTIVES

To evaluate the effect of a fluorescence biomodulation (FB) system used in conjunction with systemic antibiotic on clinical manifestations of canine interdigital pyoderma (CIP), compared to dogs treated with antibiotic alone.

ANIMALS

Thirty-six dogs diagnosed with CIP.

METHODS AND MATERIALS

Dogs were randomly allocated to treatment groups of either antibiotic alone (Group A) or antibiotic plus twice-weekly FB application (Group B). Dogs were scored over a 12 week period on the basis of two measured parameters: a global lesion score composed of four different lesions types and neutrophil engulfing bacterial scores.

RESULTS

A statistically significant decrease was seen by Week 3 in both measured parameters for Group B compared to Group A. The mean time-to-resolution of lesions was 4.3 weeks in Group B and 10.4 weeks in Group A.

CONCLUSION AND CLINICAL IMPORTANCE

The FB system shows promise as an adjunct therapy to systemic antibiotic use in the management of CIP.

Restoring catalase activity in Staphylococcus aureus subsp. anaerobius leads to loss of pathogenicity for lambs

Staphylococcus aureus subsp. anaerobius, a microaerophilic and catalase-negative bacterium, is the etiological agent of abscess disease, a specific chronic condition of sheep and goats, which is characterized by formation of necrotic lesions that are located typically in superficial lymph nodes. We constructed an isogenic mutant of S. aureus subsp. anaerobius (RDKA84) that carried a repaired and functional catalase gene from S. aureus ATCC 12600, to investigate whether the lack of catalase in S. aureus subsp. anaerobius plays a role in its physiological and pathogenic characteristics. The catalase activity had no apparent influence on the in vitro growth characteristics of RDKA84, which, like the wild-type, did not grow on aerobically incubated agar plates. Restoration of catalase activity in RDKA84 substantially increased resistance to H₂O₂ when analyzed in a death assay. The intracellular survival rates of the catalase-positive mutant RDKA84 in polymorphonuclear neutrophils (PMN) isolated from adult sheep were significantly higher than those of the wild-type, while no differences were found with PMN isolated from lambs. RDKA84 showed significantly lower survival rates in murine macrophages (J774A.1 cells) than the wild-type strains did, whereas, in bovine mammary epithelial cells (MAC-T), no differences in intracellular survival were observed. Interestingly, the virulence for lambs, the natural host for abscess disease, of the catalase-positive mutant RDKA84 was reduced dramatically in comparison with wild-type S. aureus subsp. anaerobius in two experimental models of infection.

Immunomodulation and immunodeficiency

This article briefly reviews the concepts of immunodeficiency and immunomodulation as they relate to selected skin diseases in the dog and cat. Immunodeficiency states are uncommon and may be associated with a subnormal or down-regulated immune system, including humoral deficiencies, such as IgA, and abnormal lymphocyte or neutrophil function. Establishing a causal relationship between a skin disease and presumed immunodeficient state has been difficult due to the rarity of such conditions, and the limited nature of the techniques used to characterise the immune system response. Severe combined immunodeficiency in dogs is a well characterised primary immunodeficiency state involving lymphocytes; retrovirus infection in cats may lead to an acquired immunodeficient state with some association with certain dermatological conditions although it remains unclear that infection is causally linked with disease. Immunomodulation usually implies stimulating the immune system along a beneficial pathway. Such a therapeutic approach may involve a wide variety of agents, for example intravenous immunoglobulin. There are few randomised controlled trials with veterinary patients that unequivocally demonstrate beneficial responses to immunomodulatory agents. Interferons are cytokines of major interest in human and veterinary medicine for their antiviral, anti-tumour and immunomodulatory effects. The advent of veterinary-licensed products containing recombinant interferon may enable demonstration of the efficacy of interferons for conditions such as canine papillomatosis and feline eosinophilic granuloma complex. Canine pyoderma has been treated with a number of presumed immunomodulatory agents with limited success. With more detailed knowledge of the pathogenesis of pyoderma it may be possible to develop efficacious immunomodulators.