The effectiveness of the haemodialysate Solcoseryl for second-intention wound healing in horses and ponies

Second-intention healing of limb wounds in horses is often problematic. Solcoseryl is a protein-free, standardized dialysate/ultrafiltrate (HD) derived from calf blood, which has been shown to improve healing in both animals and humans. The efficacy of HD in the healing of deep wounds in horses and ponies was investigated. Deep wounds of 20 by 35 mm were created on both metatarsi (skin, subcutis, periosteum) and on both femoral biceps muscles (skin, subcutis, muscle) of five horses and five ponies. The wounds on one side were treated with HD, four times a week during the period that the wounds were bandaged and once daily thereafter. The wounds on the other side were left untreated. In the first 4 weeks of the healing period HD stimulated healing but inhibited healing thereafter. This pattern was significant for all wound groups (P < 0.001). Because of this change in effect, the overall effect on wound healing over the entire period was not significant (P = 0.77). HD stimulated healing initially by provoking a greater initial inflammatory response, faster contraction and faster formation of granulation tissue. Subsequently, HD inhibited healing because it significantly delayed epithelialization and caused protracted inflammation. The effects of HD were most pronounced in the horses. Because this study distinguished between contraction and epithelialization, it could be shown that HD stimulated contraction but inhibited epithelialization. Therefore, HD is useful in horses for the treatment of deep wounds during the initial phase of healing by second intention, i.e. during the first weeks when wound contraction can be expected. Treatment should be ceased when epithelialization becomes predominant.     

Effects of topical application of taurolidine on second intention healing of experimentally induced wounds in rats

OBJECTIVE: To determine the macroscopic effects of topical application of taurolidine on second intention healing of experimentally induced wounds in rats. ANIMALS: 32 adult Sprague-Dawley female rats. PROCEDURES: In each rat, 2 skin wounds were created in the lumbar area. Groups of 7 rats were assigned to have 1 wound treated topically with hydroxycellulose gel (HDCG), 2% taurolidine in HDCG (T-HDCG), 2% taurolidine-sodium citrate solution, or bacitracin-neomycin-polymyxin B ointment; the other wound was not treated. Four control rats (8 untreated wounds) were used. Wounds were monitored for contraction, epithelialization, and complete healing at 4, 8, and 14 days after wound creation. The number of days to complete healing was also recorded for each wound. RESULTS: Compared with other treatments or untreated wounds, wounds treated with T-HDCG had decreased total healing at day 8 and decreased epithelialization and decreased total healing at day 14. Wounds treated with T-HDCG required approximately 3 days longer to completely heal than all other treated and untreated wounds. Application of bacitracinneomycin-polymyxin B ointment did not enhance wound healing. Mean time to complete healing of untreated wounds in all treatment and control groups was 10.00 to 10.14 days. CONCLUSIONS AND CLINICAL RELEVANCE: In rats, topical application of T-HDCG to wounds had a negative effect on second intention healing by delaying the epithelialization process. In mammals, generally, wounds treated topically with taurolidine may need to be treated and monitored for a longer period than other wounds treated with other common woundhealing compounds or untreated wounds.     

Effects of a proprietary topical medication on wound healing and collagen deposition in horses

Full-thickness skin wounds were created on the dorsum of both metacarpi in 8 horses. Three topical treatment regimens were studied. All wounds were bandaged with a nonadherent dressing, which was held in place with a snug elastic wrap. Group-A wounds were treated with a proprietary topical wound medication that consisted of a spray and an ointment. Group-B wounds were treated with the same regimen, except the putative active ingredients in the ointment were omitted. Group-C wounds were treated with a dry nonadherent bandage only. Wound dressings were changed every day and the limbs were photographed every other day until the wounds were healed. Specimens of normal skin and biopsy specimens of healed wounds were examined histologically and were assayed for hydroxyproline content. Wound healing measurements quantitated for each wound were number of days to healing, maximal wound size attained, day wound contraction commenced, day epithelium first noticed, rate of wound contraction, final wound size, and fraction of the wound that healed by contraction. The cosmetic appearance of the healed wounds was also graded. Significant differences were not noticed in hydroxyproline content, histologic appearance, or any of the wound healing measurements between treatment groups. The cosmetic appearance of healed group-A and -B wounds was significantly better than the appearance of group-C wounds. The topical treatment regimens studied neither enhanced nor inhibited wound healing in this study.     

Effects of amnion and live yeast cell derivative on second-intention healing in horses

Equine amnion and live yeast cell derivative were evaluated as a biological dressing and as a topical wound medicament respectively, in the treatment of granulating wounds of the distal portion of the limbs of horses. Wounds measuring 2.5 x 2.5 cm were created on the dorsomedial aspect of the metacarpal and metatarsal region of all 4 limbs of 9 horses. Each wound was assigned randomly to 1 of 3 treatment groups: group C, treated with a nonadherent bandage as a control; group A, treated with amnion beneath a nonadherent bandage; and group L, treated with live yeast cell derivative beneath a nonadherent bandage. Rates of contraction and epithelialization were not significantly different among groups. Percentage of epithelialization for group A was significantly greater throughout the study than for the other groups. Number of days to complete healing was significantly less in group A and significantly greater in group L than in group C. Incidence and severity of exuberant granulation tissue were significantly less in group A than in the other 2 groups. Group L had more frequent and severe cases of exuberant granulation tissue than the other 2 groups.     

Application of Exogenous Esterified Hyaluronan to Equine Distal Limb Wounds

The objective of this study was to evaluate the efficacy of topical application of a hyaluronan (HA) derivative in wound healing with respect to the rate of epithelialization, fibroplasia, angiogenesis and contraction, magnitude of the local inflammatory response, local expression of transforming growth factor-β 1 and 3 (TGF-β 1 and 3), tumor necrosis factor-α (TNF-α), and collagen type III deposition. In six healthy adult horses, six full-thickness skin wounds were created on the dorsal aspect of both metacarpi using a sterile template. Sites were sampled at 0, 1, 2, 5, 14, 21, and 35 days following wounding. Wounds on one limb were dressed with commercially available esterified HA fleece under a nonadherent dressing. The opposite limb was covered with the nonadherent dressing alone (control). Images of the most proximal wounds were used to determine the area of total healing and the relative contributions of epithelialization and contraction to healing. At each sample time, a control and treatment biopsy were taken for histological evaluation and special stains. All samples were evaluated for degree of inflammation, fibroplasia and angiogenesis; in situ hybridization for type III collagen, TGFβ1 and 3, and immunohistochemistry for TNF-α. Mean percentages of total wound healing, epithelialization, and wound contraction were not significantly different between control and treatment groups. In treated horses, initial wound expansion was significantly decreased during the first 2 weeks. Mononuclear cell numbers, counted in the granulation tissue, increased in both control and treated limbs over the entire course of the study. However at day 35 the macrophage numbers counted in the treated horses were significantly increased compared with the control limbs (P < .05). Although not statistically significant, relative staining for type III collagen in the treated wounds was less than that of control wounds. Results of the present study do not support a benefit of an exogenous HA-derivative in the healing of distal limb wounds in horses. The shortcomings of the study design are discussed.     

Evaluation of LHP? (1% hydrogen peroxide) cream versus petrolatum and untreated controls in open wounds in healthy horses: a randomized,blinded control study

Background

Treatment and protection of wounds in horses can be challenging; protecting bandages may be difficult to apply on the proximal extremities and the body. Unprotected wounds carry an increased risk of bacterial contamination and subsequent infection which can lead to delayed wound healing. Topical treatment with antimicrobials is one possibility to prevent bacterial colonization or infection, but the frequent use of antimicrobials ultimately leads to development of bacterial resistance which is an increasing concern in both human and veterinary medicine.

Methods

Standardized wounds were created in 10 Standardbred mares. Three wounds were made in each horse. Two wounds were randomly treated with LHP^® or petrolatum and the third wound served as untreated control. All wounds were assessed daily until complete epithelization. Protocol data were recorded on day 2, 6, 11, 16, 21 and 28. Data included clinical scores for inflammation and healing, photoplanimetry for calculating wound areas and swab cytology to assess bacterial colonization and inflammation. Bacterial cultures were obtained on day 2, 6 and 16.

Results

Mean time to complete healing for LHP^® treated wounds was 32 days (95%CI = 26.9-37.7). Mean time to complete healing for petrolatum and untreated control wounds were 41.6 days (95%CI = 36.2-47.0) and 44.0 days (95%CI = 38.6-49.4) respectively. Wound healing occurred significantly faster in LHP^® wounds compared to both petrolatum (p = 0.0004) and untreated controls (p < 0.0001). There was no significant difference in time for healing between petrolatum and untreated controls. Total scores for bacteria and neutrophils were significantly (p < 0.0001) lower for LHP^® treated wounds compared to petrolatum from day 16 and onwards. Staphylococcus aureus and Streptococcus zooepidemicus were only found in cultures from petrolatum treated wounds and untreated controls.

Conclusions

Treatment with LHP^® reduced bacterial colonization and was associated with earlier complete wound healing. LHP^® cream appears to be safe and effective for topical wound treatment or wound protection.     

Second-intention repair in the horse and pony and management of exuberant granulation tissue.

Second-intention repair is faster in ponies than in horses and faster in body wounds than in limb wounds. To a large extent, the differences between horses and ponies can be explained by differences in the local inflammatory response, which are a result of the functional capacity of leukocytes. In ponies, leukocytes produce more inflammatory mediators,resulting in better local defense, faster cellular debridement, and a faster transition to the repair phases, with more wound contraction. In horses,leukocytes produce fewer mediators, initiating a weak inflammatory response, which becomes chronic. This inhibits wound contraction and gives rise to the formation of exuberant granulation tissue. The anatomic environment that influences the inflammatory response and wound contraction most probably determines the differences between body and limb wounds. In body wounds, better perfusion results in faster initiation of the inflammatory phase. The weaker local resistance results in a greater degree of contraction. In limb wounds, particularly of horses, the initial inflammatory response is weak and wound contraction is restricted. Both factors give rise to chronic inflammation, which further inhibits wound contraction and promotes exuberant granulation tissue. The high incidence of exuberant granulation tissue in limb wounds of horses can thus be explained by the chronicity of the inflammatory response as well as by the common use of bandages during treatment. Chronic inflammation is often not recognized as a cause of exuberant granulation tissue. It must be prevented and treated to promote the healing process. Bandages and casts stimulate the formation of exuberant granulation tissue; however, they are advantageous in many respects and play an important role in support of the overall healing process.     

Factors regulating collagen synthesis and degradation during second-intention healing of wounds in the thoracic region and the distal aspect of the forelimb of horses

OBJECTIVE: To determine significant molecular and cellular factors responsible for differences in second-intention healing in thoracic and metacarpal wounds of horses. ANIMALS: 6 adult mixed-breed horses. PROCEDURE: A full-thickness skin wound on the metacarpus and another such wound on the pectoral region were created, photographed, and measured, and tissue was harvested from these sites weekly for 4 weeks. Gene expression of type-I collagen, transforming growth factor (TGF)-beta1, matrix metalloproteinase (MMP)-1, and tissue inhibitor of metalloproteinase (TIMP)-1 were determined by quantitative in situ hybridization. Myofibroblasts were detected by immunohistochemical labeling with alpha-smooth muscle actin (alpha-SMA). Collagen accumulation was detected by use of picrosirius red staining. Tissue morphology was examined by use of H&E staining. RESULTS: Unlike thoracic wounds, forelimb wounds enlarged during the first 2 weeks. Myofibroblasts, detected by week 1, remained abundant with superior organization in thoracic wounds. Type-I collagen mRNA accumulated progressively in both wounds. More type-I collagen and TGF-beta1 mRNA were seen in forelimb wounds. Volume of MMP-1 mRNA decreased from day 0 in both wounds. By week 3, TIMP-1 mRNA concentration was greater in thoracic wounds. CONCLUSIONS AND CLINICAL RELEVANCE: Greater collagen synthesis in metacarpal than thoracic wounds was documented by increased concentrations of myofibroblasts, type-I collagen mRNA,TGF-beta1 mRNA, and decreased collagen degradation (ie, MMP-1). Imbalanced collagen synthesis and degradation likely correlate with development of exuberant granulation tissue, delaying healing in wounds of the distal portions of the limbs. Factors that inhibit collagen synthesis or stimulate collagenase may provide treatment options for horses with exuberant granulation tissue.     

Effect of topical administration of epidermal growth factor on healing of corneal epithelial defects in horses

OBJECTIVE-To characterize healing of corneal epithelial defects in horses and to evaluate the ability of epidermal growth factor (EGF) to modulate rate of corneal epithelial healing in horses. SAMPLE POPULATION: 20 eyes in 12 adult horses. PROCEDURE: Corneal epithelial wounds were created by mechanically debriding the limbus. Corneal healing was recorded for 3 treatment groups: 50 microg of EGF/ml (n = 5 eyes), 5 microg of EGF/ml (7), and PBS solution (8). Corneal healing was recorded once daily after instillation of fluorescein stain by use of photography and calculating the area of the wound, using imaging software. RESULTS: After corneal debridement, re-epithelialization was rapid and progressed in a linear fashion for the first 5 to 7 days after surgery in all groups. After that period, rates of healing decreased. A profound increase in the degree of inflammation, neovascularization, melanosis, and scarring was observed in eyes treated with the high dose of EGF (50 microg/ml), but there was not a statistical difference in mean healing time or in mean decrease in radius during the linear phase between the control and either EGF treatment groups. However, for all 8 horses in which both eyes were debrided, the first eye healed significantly faster than the second eye, regardless of treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Beneficial effects of topical administration of a high dose of EGF for acceleration of healing of corneal defects in eyes of horses are outweighed by the intensity of the associated inflammatory response.     

Influence of wound shape on wound contraction in horses.

Three sets of paired circular and square full-thickness skin wounds were made on the dorsum of the metacarpus (n = 48) of 8 horses. Each wound was 6.25 cm2 in area. The wounds were treated topically with an ointment, nonadherent dressing, and bandaged with a snug elastic wrap. Wounds were photographed every other day until healing was complete. Wound areas were measured and exponential and linear wound healing models were applied to the wound healing data generated. Wound healing variables measured for each wound were: number of days to healing, maximal size attained, rate of wound contraction (calculated by use of first-order and linear models), final wound size, and percentage of wound that healed by contraction. The exponential model fit the data significantly better than the linear model. The maximal size attained by circular wounds was significantly smaller than the maximal size attained by square wounds. Wound shape did not influence the rate of wound healing. On the basis of our findings, conversion of circular defects to square defects would not speed wound healing.     

Effect of wound location and the use of topical collagen gel on exuberant granulation tissue formation and wound healing in the horse and pony

Preformed collagen gel was topically applied to cutaneous wounds of the equine dorsal fetlock (thoracic limb) and metatarsal regions to evaluate the effect on exuberant granulation tissue production and wound healing. In 6 horses and 3 ponies (less than 140 cm high at the withers and less than 365 kg), 36 standardized cutaneous limb wounds were surgically induced (4 wounds/animal); 18 wounds were treated topically with collagen gel, and 18 wounds were not treated (controls). Collagen gel was initially applied to the wound at 0, 2, or 7 days after wound formation (groups 1, 2, and 3, respectively). Four measurements were regularly made: amount of wound contraction and the size of the granulation bed, epithelial covering, and total wound. Sequential skin and wound biopsies were evaluated histologically to assess wound healing. Using a computer, data were analyzed for differences in the 4 measurements between treated and control wounds, between fetlock wounds and metatarsal wounds, and among groups 1, 2, and 3. Analyses were performed on days 15 and 45 of wound healing and on the final day of healing. A significant difference (P greater than 0.05) in the production of exuberant granulation tissue, rate of epithelialization, or degree of wound contraction was not detected between the collagen-treated and control wounds. Total healing time and final scar size were similar. Wound healing patterns were significantly different (P less than 0.05) in the fetlock wounds and metatarsal wounds. All wounds enlarged up to day 15 with fetlock wounds enlarging significantly more than did the metatarsal wounds.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of bandaging on second intention healing of wounds of the distal limb in horses

Objective   To evaluate the effect of a non-occlusive dressing incorporated in a 3-layer bandage on second intention healing of wounds of the distal portion of the limb.
Study Design   Untreated wounds in 33 adult horses used in four studies using the same wound-healing model conducted over 5 years.
Methods   Standardised, full-thickness wounds were made in the skin overlying the dorsomedial aspect of the mid-metacarpus; 17 horses were bandaged with a non-occlusive dressing covered by gauze-coated cotton wool that was compressed with adhesive tape; 16 horses were left unbandaged. Wounds were photographed weekly for 9 weeks and the images were analysed electronically.
Results   There were significant effects associated with bandage (P < 0.0001), week (P < 0.001), and bandage by week interaction (P < 0.0001). There was no difference in wound area at the first time-point after wound creation (P = 0.38). After week 1, there was a difference between bandaged and unbandaged wounds in wound area at each measurement until the end of the study. Bandaged wounds showed greater and more prolonged retraction. Unbandaged wounds retracted for 2 weeks before beginning to contract, whereas bandaged wounds continued to retract for 3 weeks. In bandaged wounds excess granulation tissue required regular trimming, but not in unbandaged wounds. There was no difference between groups in the total days to healing or the overall rate of healing.
Conclusions   These results should be treated with caution until validated with contemporaneous, controlled studies. Covering a wound with a non-occlusive dressing in a 3-layer bandage led to greater wound retraction, modulated the rate of wound contraction and promoted excessive granulation tissue. If excessive granulation tissue is excised regularly, bandaging has no effect on total time to healing.     

The effects of topical oxygen therapy on equine distal limb dermal wound healing

Topical oxygen therapy (TOT) has been used in human medicine to promote healing in chronic wounds. To test the efficacy and safety of TOT in horses, an experimental wound model was created by making 1 standardized dermal wound on each limb of 4 healthy horses (n = 16). Each wound was fitted with an oxygen delivery cannula and covered with a bandage. One limb of each front and hind pair was randomly assigned to the treatment group (fitted with an oxygen concentrator device), with the contralateral limb assigned to the control group (no device). Wound area, epithelial area, and contraction were measured every 3 to 4 d. Biopsy samples and culture swabs were taken on days 16 and 32 to evaluate angiogenesis, fibroplasia, epithelial hyperplasia, inflammation and bacterial growth. Mean healing time in treated wounds (45 d, range: 38 to 52 d) was not significantly different from that in the paired control wounds (50 d, range: 38 to 62 d). Topical oxygen therapy had little effect on dermal wound healing in this experimental wound model in healthy horses.     

The modified Meek technique as a novel method for skin grafting in horses: evaluation of acceptance, wound contraction and closure in chronic wounds

REASONS FOR PERFORMING STUDY: The acceptance of skin grafts in horses is unpredictable and the final cosmetic result can be disappointing. Besides movement and infection, graft failure is often caused by chronic inflammation, inherently present during second intention healing of limb wounds in horses. In human burns affected by infection and inflammation, the acceptance of the island skin grafts of the modified Meek technique appeared to be better than meshed sheet skin grafts. HYPOTHESIS: The percentage take of Meek micrografts is higher than of other techniques; and rates of both wound contraction and epithelialisation are increased. METHODS: Large traumatic limb wounds of 13 horses healing by second intention were grafted using the modified Meek technique. Photographs of the wounds were taken at set intervals. Wound areas, and areas of acceptance and rejection were determined using a digital image post processor (Scion Image). The percentages of take, wound contraction and epithelialisation were calculated. RESULTS: The initial mean wound area was 7500 mm2. Graft acceptance was mean +/- s.d. 93.7 +/- 5.9%. Wound closure was due to contraction (55.2 +/- 11.1%) and epithelialisation (44.8 +/- 11.1%) and resulted in a 96.7 +/- 3.6% reduction of the initial wound area 29.1 +/- 6 days after grafting. All wounds showed functional and cosmetic healing. CONCLUSIONS: The method for skin grafting in horses achieved higher percentages of take than reported previously and consistent cosmetic and functional results. The grafts increased not only the rate of epithelialisation but also had a strong positive effect on wound contraction, resulting in rapid closure and smaller scars. POTENTIAL RELEVANCE: The modified Meek technique proved to be a novel technique for skin grafting equine wounds in clinical practice, which can be performed easily. The molecular background of the increase of wound contraction by the grafts may provide a clue in the search for medicinal stimulation of wound contraction during second intention healing.     

Effects of 25% propylene glycol hydrogel (Solugel) on second intention wound healing in horses

OBJECTIVE: To evaluate the effect of a commercially available 25% propylene glycol hydrogel preparation (Solugel; Johnson and Johnson Medical, North Ryde, Australia) on healing of full-thickness skin wounds on the distal aspect of the limb in horses. STUDY DESIGN: Experimental. ANIMALS: Eight Standardbred horses. METHODS: Standardized (2.5 x 2.5 cm) full-thickness skin wounds were created over the mid-dorsomedial aspect of both metacarpi in 8 horses. One wound in each horse was dressed with saline solution (0.9% NaCl) soaked gauze, and one was treated with Solugel under dry regular gauze; wounds were then bandaged with gauze-coated cotton wool and elastic adhesive bandages. Wounds were videorecorded and rebandaged twice weekly until healed. Wound healing variables were measured from the videorecordings using a computer software package and analyzed as a randomized complete block design with repeated measures. Where necessary variables were made positive for analysis; significance was set at P <.05. RESULTS: The area of the wound at the first bandage change did not vary between treated and untreated wounds. Treatment had no effect on the total rate of healing, rate of healing during the retraction phase of healing, rate of healing after the retraction phase was complete, or the amount the wounds retracted. CONCLUSIONS: Using this model of wound healing, Solugel had no effect on second intention healing of distal limb wounds in horses. CLINICAL RELEVANCE: Solugel does not appear to have any beneficial effect on healing of small full-thickness skin wounds to the distal limb of horses.     

Management of traumatic fistulous withers and wounds of the lumbar dorsal spinous processes of horses and donkeys used for pack animals

Over a three year period, eighty-nine (89) traumatically induced wounds on the withers and lumbar area of donkeys and horses were treated by the ambulatory clinic at Universidad Nacional Autónoma de México. The wounds generally resulted from poorly fitting pack equipment. Treatment regimens were divided into two categories: 1) conservative topical therapy plus padding or 2) surgical debridement and primary wound closure. Conservative therapy with topical medications and padding was successful in many cases in spite of the fact that the animals generally continued working. However, recurrence of lesions following conservative therapy was common. Surgical treatment was used primarily in cases refractory to conservative therapy. As a result of surgical intervention, clients tended to comply with recommendations to stop working the animal. The convalescent time was shorter, and the recurrence rate was lower following surgery than for conservative therapy.     

Wounds of the pastern and foot region managed with phalangeal casts: 50 cases in 49 horses (1995–2006)

Objective   Describe the use of a phalangeal cast as treatment for wounds in the pastern and foot region of horses. Secondly, to evaluate the healing and soundness of horses treated with phalangeal casts.
Design   Retrospective study of 49 horses.
Procedures   Medical records of 49 horses that were treated with a phalangeal cast for 50 cases of wounds in the pastern and foot region at equine referral hospitals from 1995 to 2006 were reviewed and follow-up information was obtained.
Results   Treatment consisted of wound debridement, lavage, wound closure (28 wounds), cast application and antibiotics (84%). At follow-up, the majority of horses were sound (42 of 47 wounds, 89.4%), three horses were still lame and one horse was euthanased because of persistent lameness. Three horses were lost to follow-up. There was no statistical difference between the outcomes of horses treated acutely (<24 h) or after a 24-h delay. Similarly, the involvement of synovial structures in the wound did not significantly influence outcome.
Conclusions   In this study, wounds involving the pastern and foot that were treated with a phalangeal cast carried a good prognosis for soundness (89.4%) and cosmetic healing (89.5%). The phalangeal casts were well-tolerated and effective.     

The effect of low level laser therapy (LLLT) on wound healing in horses.

Laser therapy is used in many countries, including South Africa, for the treatment of skin wounds. Low level galium aluminium arsenide (GaAlAs) laser was administered to full thickness skin wounds (3 x 3 cm) induced surgically on the dorsal aspect of the metacarpophalangeal joints of 6 crossbred horses in a randomised, blind, controlled study. Treated wounds that received a daily laser dosage of 2 J/cm2 were compared with nontreated control wounds on the opposite leg. There were no wound complications. Both groups of wounds were cleaned daily using tap water. Wound contraction and epithelialisation were evaluated using photoplanimetry. There were no significant differences in wound contraction or epithelialisation between the laser treated and the control wounds. It was therefore concluded that laser therapy had no clinically significant effect on second intention wound healing in this study.     

Effect of topical rh-TGF-beta 1 on second intention wound healing in horses

OBJECTIVE: To investigate the effects on wound healing of transforming growth factor-beta 1 as a topical treatment to full-thickness, excisional wounds of the distal limb of horses. DESIGN: A randomised block study using four horses, each with wounds assigned to four treatment groups. ANIMALS: Four adult Standardbred geldings. PROCEDURE: Four, 4 cm2, full-thickness wounds were created on the dorsomedial and dorsolateral aspect of the metacarpus or metatarsus of each limb of four horses, giving a total of 64 wounds. For each limb, wounds were randomly assigned to four treatment groups: no treatment (control), carrier (Methyl Cellulose gel), 50 ng/wound rhTGF-beta 1 in carrier, and 500 ng/wound rhTGF-beta 1 in carrier. Wounds were treated on day 0 and day 8. Effects of treatment were evaluated on the basis of the presence of exuberant granulation tissue requiring excision, number of times excision was required, total wound area, area of epithelialisation, area of granulation, and histological evaluation of biopsy samples of wounds on day 8 and excised wounds on day 21. RESULTS: Topical application of TGF-beta 1 at the two concentrations studied had no significant effect on the total area of wounds (P = 0.7), the area of granulation tissue (P = 0.78), the area of epithelialisation (P = 0.92), histological assessment or subjective clinical assessment of wounds. CONCLUSION: TGF-beta 1 had no beneficial effects on wound healing. Additional trials are needed to test if it has value for wound treatment in horses.