Limited added value of negative pressure wound therapy compared with calcium alginate dressings for second intention healing in a noncontaminated and contaminated equine distal limb wound model.

BACKGROUND: Distal limb wounds in horses often show aberrant healing due to a slow inflammatory response. In human medicine, negative pressure wound therapy (NPWT) is used for the treatment of chronic wounds with a similar inflammatory response. OBJECTIVES: To compare the effect of NPWT to calcium alginate dressings on the healing of (non) contaminated equine distal limb wounds. STUDY DESIGN: Controlled experiment. METHODS: Circular wounds were created on the left and right dorsomedial metacarpus of 10 horses. In five horses, the wounds were contaminated with Staphylococcus aureus and Pseudomonas aeruginosa. In all horses, one limb was treated with NPWT, the other with calcium alginate dressings. Treatments were applied during nine days for noncontaminated wounds and six days for contaminated wounds. Noninvasive (clinical assessment, bacteriology swabs, thermographic images and wound dimensions) and invasive (biopsies for histology and growth factor analysis) measurements were taken regularly for 71 and 29 days respectively. Effects of selected parameters on continuous dependent variables were analysed using ANOVA, while for discrete dependent variables, logistic regression was applied. RESULTS: In noncontaminated wounds, there was significantly less wound retraction in the early healing stages when treated with NPWT (mean difference [95% CI] = 19.2% [13.3%-25.1%]; P = .005), although wound size was not significantly different between NPWT and control wounds at later healing stages. Noncontaminated control wounds had a significantly higher neutrophil influx (OR [95% CI] = 1.99 [1.49-2.66]; P < .001) and lower macrophage influx (OR [95% CI] = 0.75 [0.60-0.93]; P = .008) compared with NPWT-treated wounds. Bacterial load and the presence of growth factors did not differ between treatments in noncontaminated wounds. In contaminated wounds, no differences between treatments were observed in wound size, histological parameters, bacterial load or growth factor concentration. MAIN LIMITATIONS: Sample size is small. CONCLUSIONS: No long-term advantage was detected with NPWT compared with calcium alginate dressings in noncontaminated or contaminated equine distal limb wounds healing by second intention.

Effects of various wound dressings on microbial growth in perfused equine musculocutaneous flaps.

OBJECTIVE: To compare the effect of multiple wound dressings on microbial growth in a perfused equine wound model. SAMPLE: Abdominal musculocutaneous flaps from 16 equine cadavers. PROCEDURES: 8 full-thickness skin wound covered were created in each flap. Tissues were perfused with saline (0.9% NaCl) solution. Wounds were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa (106 CFUs), incubated, and covered with a dressing containing activated charcoal, boric acid, cadexomer iodine, calcium alginate, manuka honey, nanoparticle silver, or polyhexamethylene biguanide or with a control (nonadherent gauze) dressing. Muscle biopsy specimens were obtained at baseline (immediately prior to dressing application) and 6, 12, 18, and 24 hours later for mean bacterial load (MBL) determination. The MBLs at each subsequent time point were compared with that at baseline within dressing types, and MBLs at each time point were compared among dressing types. RESULTS: MBLs in MRSA-inoculated wounds covered with cadexomer iodine dressings were significantly decreased from baseline at the 6- and 12-hour time points. For P aeruginosa-inoculated wounds, MBLs were significantly increased from baseline in all wounds at various times except for wounds with cadexomer iodine dressings. The MBLs of wounds with cadexomer iodine dressings were lower than all others, although not always significantly different from those for wounds with boric acid, manuka honey, nanoparticle silver, and polyhexamethylene biguanide dressings. CONCLUSIONS AND CLINICAL RELEVANCE: In this nonviable perfused wound model, growth of MRSA and P aeruginosa was most effectively reduced or inhibited by cadexomer iodine dressings. These results and the effect of the dressings on wound healing should be confirmed with in vivo studies.

Evaluation of an osteochondral fragment-groove procedure for induction of metacarpophalangeal joint osteoarthritis in horses.

OBJECTIVE To evaluate lameness and morphological changes associated with an osteochondral fragment-groove procedure as a means of experimental induction of metacarpophalangeal (MCP) joint osteoarthritis within an 11-week period in horses. ANIMALS 6 nonlame adult warmbloods. PROCEDURES The right MCP joint of each horse underwent an osteochondral fragment-groove procedure (day 0). After 1 week of stall rest (ie, starting day 7), each horse was trained daily on a treadmill. Weekly, horses underwent visual and inertial sensor-based assessments of lameness. Both MCP joints were assessed radiographically on days 0 (before surgery), 1, 35, and 77. A synovial fluid sample was collected from the right MCP joint on days 0 (before surgery), 35, 36, 49, 63, and 77 for cytologic and biomarker analyses. On day 77, each horse was euthanized; both MCP joints were evaluated macroscopically and histologically. RESULTS Right forelimb lameness was detected visually and by the inertial sensor system when horses were moving on a straight line after distal forelimb flexion or circling left on days 14 to 77. Compared with presurgical values, synovial fluid interleukin-6, prostaglandin E2, hyaluronic acid, and interleukin-1 receptor antagonist protein concentrations were increased at 2 or 3 time points, whereas tumor necrosis factor-α and interleukin-10 concentrations were decreased at 1 time point. Gross examination of all right MCP joints revealed synovitis and wear lines; synovitis was confirmed histologically. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that a combined osteochondral fragment-groove procedure can be used to induce clinically and grossly observable early MCP joint osteoarthritis during an 11-week period in horses.

Topical use of 5% acyclovir cream for the treatment of occult and verrucous equine sarcoids: a double-blinded placebo-controlled study.

BACKGROUND: Previous studies mention the use of topical acyclovir for the treatment of equine sarcoids. Success rates vary and since the bovine papillomavirus (BPV) lacks the presence of a kinase necessary to activate acyclovir, there is no proof of its activity against equine sarcoids. RESULTS: Twenty-four equine sarcoids were topically treated with acyclovir cream and 25 with a placebo. Both creams were applied twice daily during 6 months. Before the start of the treatment and further on a monthly basis, photographs and swabs were obtained. On the photographs, sarcoid diameter and surface area were measured and verrucosity of the tumours was quantified using a visual analog scale (VAS). The swabs were analysed by PCR for the presence of BPV DNA and positivity rates were calculated as the number of positive swabs divided by the total number of swabs for each treatment group at each time point. Success rates were not significantly different between both treatment groups. There was also no significant effect of treatment on sarcoid diameter, surface area or VAS score. For the swabs, a significantly higher BPV positivity rate was found for acyclovir treated tumours compared to placebo treated sarcoids only after 1 month of treatment and not at other time points. CONCLUSIONS: None of the results indicate that treatment with acyclovir yields any better results compared to placebo treatment.

Comparison of antibacterial effects among three foams used with negative pressure wound therapy in an ex vivo equine perfused wound model.

OBJECTIVE To compare antibacterial effects among 3 types of foam used with negative-pressure wound therapy (NPWT) in an ex vivo equine perfused wound model. SAMPLES Abdominal musculocutaneous flaps from 6 equine cadavers. PROCEDURES Each musculocutaneous flap was continuously perfused with saline (0.9% NaCl) solution. Four 5-cm circular wounds were created in each flap and contaminated with 106 CFUs of both Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA). After a 1-hour incubation period, 1 of 4 treatments (NPWT with silver-impregnated polyurethane foam [NPWT-AgPU], polyurethane foam [NPWT-PU], or polyvinyl alcohol foam [NPWT-PVA] or a nonadherent dressing containing polyhexamethylene biguanide without NPWT [control]) was randomly applied to each wound. An 8-mm punch biopsy specimen was obtained from each wound immediately before and at 6, 12, 18, and 24 hours after treatment application to determine the bacterial load for both P aeruginosa and MRSA. RESULTS The bacterial load of P aeruginosa for the NPWT-PVA treatment was significantly lower than that for the other 3 treatments at each sampling time after application, whereas the bacterial load for the NPWT-AgPU treatment was significantly lower than that for the NPWT-PU and control treatments at 12 hours after application. The bacterial load of MRSA for the NPWT-PVA treatment was significantly lower than that for the other 3 treatments at each sampling time after application. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that wounds treated with NPWT-PVA had the greatest decrease in bacterial load; however, the effect of that treatment on wound healing needs to be assessed in vivo.

Treatment of sarcoids in equids: 230 cases (2008-2013).

OBJECTIVE To evaluate outcomes following treatment of sarcoids in equids and to identify risk factors for treatment failure in these patients. DESIGN Retrospective case series. ANIMALS 230 equids with 614 sarcoids. PROCEDURES Records were searched to identify equids treated for ≥ 1 sarcoid between 2008 and 2013. A standardized protocol was used to determine treatment choice (electrosurgery, electrosurgery with intralesional placement of cisplatin-containing beads, topical administration of imiquimod or acyclovir, cryosurgery, bacillus Calmette-Guerin vaccine injection, or intralesional injection of platinum-containing drugs). Data regarding animal, tumor, treatment, and outcome variables were collected. Complete tumor regression without recurrence for ≥ 6 months was considered a successful outcome. Success rates were calculated; binary logistic regression analysis was used to identify risk factors for treatment failure and to compare effects of the 2 topical treatments. A χ(2) test was used to compare effects of the number of Bacillus Calmette-Guerin vaccine or cisplatin-containing drug injections on outcome. RESULTS The overall success rate was 460 of 614 (74.9%). Electrosurgical excision resulted in the highest treatment success rate (277/319 [86.8%]); odds of treatment failure were significantly greater for intralesional injection of platinum-containing drugs, cryosurgery, and topical acyclovir treatment. Odds of treatment failure were also significantly greater for sarcoids on equids with multiple tumors than for solitary lesions, and significantly lower for sarcoids on equids that received concurrent immunostimulating treatment for another sarcoid than for those on patients that did not receive such treatment. CONCLUSIONS AND CLINICAL RELEVANCE Selection bias for treatments was inherent to the study design; however, results may assist clinicians in selecting treatments and in determining prognosis for equids with sarcoids treated according to the described methods.

Comparison of ultrasonography versus radiography for the diagnosis of dorsal fragmentation of the metacarpophalangeal or metatarsophalangeal joint in horses.

OBJECTIVE: To compare clinical usefulness of ultrasonography versus radiography for detection of fragmentation of the dorsal aspect of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in horses. DESIGN: Cross-sectional study. ANIMALS: 36 horses with fragmentation of the MCP (n = 19) and MTP (29) joints. PROCEDURES: In all joints, radiography (4 standard projections) and ultrasonography were performed prior to arthroscopic examination and fragment removal. Number and location of fragments identified radiographically and ultrasonographically were compared with arthroscopic findings. RESULTS: Radiographic and arthroscopic findings were in agreement with respect to both number and location of fragments in 21 of the 48 (44%) joints. Ultrasonographic and arthroscopic findings were in agreement with respect to number and location of fragments for 46 of the 48 (96%) joints. In the remaining 2 joints, arthroscopy revealed additional fragments that were not identified ultrasonographically. When ultrasonographic findings were compared with radiographic findings, more fragments were seen ultrasonographically in 3 joints and fewer fragments were seen ultrasonographically in 1 joint. Ultrasonographic findings also confirmed the absence (4 joints) or presence (3 joints) of fragmentation at the dorsoproximal aspect of the joint that had been suspected on the basis of radiographic findings. Ultrasonography was also able to determine the location of the fragments in the joints where this was not possible radiographically. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the present study suggested that ultrasonography was a useful method for determining the number and location of fragments in horses with dorsal fragmentation of the MCP or MTP joint.

Laparoscopic ovariectomy in mares using a polyamide tie-rap.

OBJECTIVE: To describe use of a polyamide tie-rap to ligate the mesovarium during standing laparoscopic ovariectomy in mares. STUDY DESIGN: Prospective study. ANIMALS: Ten mares. METHODS: Bilateral ovariectomy was performed in 10 mares. Standing laparoscopic ovariectomy was performed using 3 portals in the paralumbar fossa. A commercial polyamide tie-rap was prepared as a loop and marked with 4 colored lines close to the buckle, to enable us to check whether the loop was tightened securely. The ovary was grasped with forceps and after the mesovarium was minimally transected cranially and caudally, the loop of the tie-rap was inserted in the abdomen and placed around the mesovarium. It was firmly tightened, until at least 3 of the 4 marks were visible, then the end of the tie-rap was cut. The ovary was transected and removed through an enlarged 3rd portal. The contralateral ovary was removed similarly through the opposite paralumbar fossa. Repeat laparoscopy was performed in 8 mares, 2, 3, 4, and 12 weeks later. RESULTS: None of the mares had postoperative discomfort. On repeat laparoscopy, there was complete encapsulation of the stump and tie-rap after 3-4 weeks. In 2 mares, an adhesion between the left stump and the mesentery of the descending colon was observed. CONCLUSION: Ligation of the mesovarium can be easily and safely performed using a polyamide tie-rap during standing laparoscopic ovariectomy in mares. CLINICAL RELEVANCE: Standing laparoscopic ovariectomy using a polyamide tie-rap is a safe, technically easy and reliable surgical procedure in the mare.

Surgical correction of ear curling caused by scar tissue formation in a horse.

An 18-month-old Belgian Warmblood mare was evaluated because it had injured the outer convex aspect of the left auricle. Second intention healing of the wound area caused tissue contracture, which resulted in the tip of the ear curling backward. By use of a technique involving undermining of the skin and a flap of granulation tissue on the medial aspect of the wound area and multiple incisions of the auricular cartilage, the curling was relieved and the ear regained a more normal shape. A skin graft was applied to cover the existing wound defect in an attempt to accelerate wound healing; thermoplastic material was contoured to fit the inner concave surface of the ear for immobilization and fixation of the ear in its final shape after surgery. Thirty days after surgery, the graft had healed completely and the ear had a normal conformation. The successful outcome of this treatment suggests that correction of an ear deformity secondary to scar tissue formation by use of an adapted surgical technique and appropriate materials can be achieved with good cosmetic results in horses.