A cross‐linked hyaluronan gel accelerates healing of corneal epithelial abrasion and alkali burn injuries in rabbits

Objective To evaluate the efficacy of a chemically modified and cross‐linked derivative of hyaluronan (CMHA‐SX) for treatment of corneal epithelial abrasion and standardized alkali burn injuries. Animals Twelve female New Zealand white rabbits in two groups were used. Procedures Bilateral 6‐mm diameter corneal epithelial abrasions were made in each of six rabbits in one group and 6‐mm standardized alkali burn injuries were made in the second group. A 1% CMHA‐SX formulation was applied topically four times per day in right eye of each rabbit for 1 week, and phosphate buffered saline (PBS) was placed in left (control) eye of each rabbit. The wound size was determined by staining with 1% fluorescein and photographed at the slit lamp with a digital camera at 0, 1, 2, 3 days postoperatively in the first group and 0, 1, 2, 3, 7, 12 days in the second group. Rabbit corneas were collected for histological examination on day 7 in the first group and day 12 in the second group. Results Closure of corneal wound in the abrasion model was complete in the CMHA‐SX treated eye by 48 h. The wound closure rate and thickness of the central corneal epithelium in the CMHA‐SX treated group was greater than in control eyes for both the abrasion and alkali burn injuries. Moreover, the CMHA‐SX treated cornea exhibited better epithelial and stromal organization than the untreated control cornea. Conclusions Chemically modified and cross‐linked derivative of hyaluronan improved corneal wound healing and could be useful for treating noninfectious corneal injuries.     

Basic fibroblast growth factor stimulates epithelial cell growth and epithelial wound healing in canine corneas

Objective  To evaluate the effect of basic fibroblast growth factor (bFGF) on the proliferation of canine corneal epithelial cells and epithelial wound healing.
Animal studied  Canine corneal epithelial cells from the corneas of euthanized dogs and corneal epithelial wounds on one eye from each of 24 dogs.
Procedures  The proliferation of corneal epithelial cells in vitro was measured using the methylthiazolyl-tetrazolium (MTT) assay. A corneal wound on one eye of each dog was made with a corneal trephine (6 mm diameter). Four concentrations of bFGF, 0, 100, 500, and 1000 ng/mL, were applied to the affected eyes of dogs, t.i.d. Fluorescein staining was used to assess closure of the corneal epithelial wound.
Results  The addition of bFGF resulted in a significant increase in epithelial proliferation at 24 h after culture, except 1 ng/mL bFGF. Cells with all bFGF treatments proliferated significantly at 48 and 96 h compared to those in the non-bFGF group. bFGF at a concentration of 10 ng/mL promoted cell proliferation maximally. The wound healing rate in the bFGF-treated groups was greater than that in the control. All corneal wounds in bFGF-treated corneas closed by day 7, whereas two of six corneal wounds in the control showed poor healing. None of the eyes developed corneal clouding or neovascularization during the experiment.
Conclusions  Basic fibroblast growth factor accelerated the proliferation of canine epithelial cells and effectively promoted corneal epithelial wound healing.     

Evaluation of the effects of topical tripeptide-copper complex and zinc oxide on open-wound healing in rabbits

In this study the clinical and histopathological effects of topically applied tripeptide-copper complex (TCC) and zinc oxide on open-wound healing in rabbits was evaluated. Eighteen New Zealand rabbits were divided into three groups: TCC, zinc oxide and no treatment. One full thickness wound was created on each side of the dorsal midline in each rabbit. Wound margins were traced on days 0, 7, 14, and 21 and topical TCC and zinc oxide were applied daily for 21 days to each rabbit in the respective treatment groups. The mean unhealed wound area was significantly smaller in the TCC than in the zinc oxide group on day 7, but it was significantly smaller in the TCC group than in to the control group on days 7, 14 and 21. The mean percentage of wound contraction on day 7 was significantly higher in the TCC than in the zinc oxide group; however, it was significantly higher in the TCC group than in the control group on days 7, 14 and 21. Median time for the coverage of the wound bed with granulation tissue was significantly shorter in the TCC group than in the other groups. Filling of the open wound with granulation tissue to skin level was significantly slower in the control group than in the other two groups. Neutrophil counts decreased regardless of the group in parallel with healing, while neovascularization was best observed in the TCC group. The results suggest that TCC is a better choice in the treatment protocols of open wounds in rabbits than zinc oxide.     

Expression of matrix metalloproteinases, type IV collagen, and interleukin-10 in rabbits treated with morphine after lamellar keratectomy

Purpose To study the effects of topical administration of 1% morphine on corneal analgesia in rabbits submitted to lamellar keratectomy and to assess the expression of matrix metalloproteinase‐1, metalloproteinase‐2, metalloproteinase‐9 (MMPs), type IV collagen, and interleukin‐10 (IL‐10) during the treatment. Methods Morphine group (MG) received 50 μL of topical 1% morphine four times daily, while the control group received saline instead. Corneal touch threshold (CTT) and the wound area were assessed until corneal healing. Corneal samples were processed for routine histology, immunohistochemistry, zymography, and ELISA. Results Following keratectomy, CTT increased significantly from 6 to 96 h time points. Mean corneal re‐epithelization rate and scores of leukocyte infiltration did not differ significantly between treatment groups. Immunolabeling pattern for MMP‐1, MMP‐9, and type IV collagen was similar in both treatment groups. In the MG, zymography indicated significantly higher levels of active MMP‐2 on days 6 and 12; and in the latent MMP‐9, on days 3 and 6, and in the active MMP‐9, on day 6. Latent MMP‐2 and MMP‐9, and active MMP‐9 decreased to values close to those of healthy corneas on day 12, but levels of active MMP‐2 remained significantly elevated in the MG. IL‐10 levels measured on days 1–6 were reduced as compared to those of healthy corneal tissue and returned to levels close to those of healthy corneas on day 12. Conclusion Topical morphine promoted corneal analgesia for up to 4 days and did not delay corneal re‐epithelization. The re‐establishment of MMPs and IL‐10 to levels close to baseline values at the end of the study and the expression of type IV collagen in both groups reinforce that, with caution, 1% morphine can be used after lamellar keratectomy in rabbits.     

The effect of low reactive-level laser therapy (LLLT) with helium-neon laser on operative wound healing in a rat model

The effect of low reactive-level laser therapy (LLLT) with a He-Ne laser on operative wound healing was investigated in a rat model. 10-millimeter surgical wounds were created on the backs of Sprague Dawley rats, and animals were assigned to one of eleven groups (n=5). Ten groups received either 8.5 mW or 17.0 mW irradiation of 15 seconds LLLT a day with one of five different irradiation frequencies, i.e. daily (from the 1st to 6th day following surgery), every other day (the 1st, 3rd, and 5th day), on only the 1st day, on only the 3rd day, and on only the 5th day; the 1st day was the day following the surgery. The control group received no irradiation. A skin specimen was harvested from the dorsal thoracic region on the 7th day to measure the rupture strength. The control group had the lowest rupture strength (5.01 N), and the 17.0 mW every other day irradiation group had the highest rupture strength (13.01 N). Statistical differences were demonstrated in the 8.5 mW irradiation setting between the every other day irradiation group and the control group (p<0.05); and in 17.0 mW irradiation setting between the every day irradiation, the every other day, and the 1st day only groups vs. the control group (p<0.01). Histological examination demonstrated that wound healing in the 17.0 mW every other day irradiation group was promoted most significantly such as the prevention of excessive inflammation, increased formation of collagen fibers, and recovery in continuity of tissues. The control group showed poor wound healing and the other experimental groups showed intermediate healing. Thus LLLT with a He-Ne laser was found to promote the healing of operative wounds in the present rat model, in which the most favorable application of LLLT was the 17.0 mW setting of 15 seconds a day with a frequency of every other day.     

Efficacy of florfenicol in the treatment of experimentally induced infectious bovine keratoconjunctivitis.

OBJECTIVE: To evaluate efficacy of florfenicol in an induced model of infectious bovine keratoconjunctivitis, using a blinded randomized, controlled trial. ANIMALS: 48 male Holstein calves, 2 to 4 months old. PROCEDURE: Moraxella bovis infection was induced in all calves. When corneal ulcers developed, each calf was assigned randomly to 1 of 3 treatment groups, using a block design determined by corneal ulcer size (day 0). Calves were treated with florfenicol (20 mg/kg of body weight, IM) on days 0 and 2 (IM group; n = 16). Calves of a second group received a single dose of florfenicol (40 mg/kg, SC) on day 0 (SC group; n = 16). The third group of calves was not treated (control group; n = 16). Corneal ulcers were photographed, and each calf was assessed for 30 days after treatment for 10 clinical signs of infection. Corneal ulcer surface areas were measured, and clinical scores were calculated. Ocular secretions for microbiologic culture were obtained weekly from each eye. RESULTS: A Cox regression model indicated that, after adjustment for initial ulcer size, healing rates were 6.2 and 4.8 times greater in calves of the IM and SC groups, respectively, compared with the control group. Clinical scores and surface area measurements for treatment groups were significantly smaller than those for controls during posttreatment weeks 1 through 4. From day 8 through day 29, M bovis was isolated from ocular secretions of 14 of 16 control calves and 1 of 32 treated calves. CONCLUSIONS AND CLINICAL RELEVANCE: Parenterally administered florfenicol reduces corneal ulcer healing time, lessens clinical severity, and reduces the amount of bacterial shedding from calves infected with M bovis.     

Topical application of epidermal growth factor accelerates wound healing by myofibroblast proliferation and collagen synthesis in rat

Recombinant human epidermal growth factor (rhEGF) stimulates the proliferation and migration of epithelial cells in human cell culture systems and animal models of partial-thickness skin wounds. This study investigated the effect of a topical rhEGF ointment on the rate of wound healing and skin re-epithelialization in a rat full thickness wound model, and verified whether or not the rhEGF treatment affected both myofibroblast proliferation and collagen synthesis in the dermis. When rhEGF (10 µg/g ointment) was applied topically twice a day for 14 days, there was significantly enhanced wound closure from the 5th to the 12th day compared with the control (ointment base treatment) group. A histological examination at the postoperative 7th day revealed that the rhEGF treatment increased the number of proliferating nuclear antigen immunoreactive cells in the epidermis layer. In addition, the immunoreactive area of alpha-smooth muscle actin and the expression of prolyl 4-hydroxylase were significantly higher than those of the control group. Overall, a topical treatment of rhEGF ointment promotes wound healing by increasing the rate of epidermal proliferation and accelerating the level of wound contraction related to myofibroblast proliferation and collagen deposition.     

Effect of bovine freeze-dried amniotic membrane (Amnisite-BA™) on uncomplicated canine corneal erosion

Objective   To evaluate the effectiveness of bovine freeze-dried amniotic membrane (FD-AM) (Amnisite-BA™) in the surgical treatment of corneal ulceration in dogs.
Animals studied   Eight normal Shih-tzu dogs.
Procedures   The corneas of 16 eyes were scored with an 8.0-mm trephine under general anesthetic and 100% ethanol was applied to remove a standardized button of corneal epithelium. The eyes were treated as described below and the corneas were evaluated 48 h later. The dogs were divided into four treatment groups: (i) control, (ii) amniotic membrane transplantation (AMT), (iii) nictitating membrane flap and (iv) contact lens. The proportion of the corneal wound that healed was calculated and all eyes were enucleated. Histological sections of cornea were assessed with the proliferating cell nuclear antigen (PCNA) assay.
Results   The proportion of corneas healed in the different treatment groups was (i) 38.02%, (ii) 89.15%, (iii) 52.31%, and (iv) 60.56%. Epithelial healing was significantly increased in the AMT group (ii) ( P  = 0.001) while groups (iii) and (iv) were not significantly different from the control group ( P  = 0.537 and P  = 0.198, respectively). The number of PCNA positive cells was (i) 275.00, (ii) 740.50, (iii) 285.75 and (iv) 420.59, these varying compared with the control group with statistical significance of (ii) P  = 0.002, (iii) P  = 0.999, and (iv) P  = 0.467. The greatest healing rate and epithelial cell proliferation was achieved with AMT compared to the other treatment regimes.
Conclusions  The results of this study show that FD-AM transplantation is an effective treatment for enhancing canine corneal wound healing and suggest that the approach will provide superior results compared to conventional treatments for the condition.     

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.     

Successful treatment of an unusually large corneal epithelial inclusion cyst using equine amniotic membrane in a dog

A 10‐year‐old intact male Yorkshire Terrier was referred for investigation of a large raised and nonpainful corneal lesion oculus dexter. Clinical examination revealed a pale, translucent corneal mass, which occupied half of the corneal surface and measured 11 mm × 11 mm × 13 mm. The mass was removed by superficial keratectomy and equine amniotic membrane (AM) was transplanted into the large corneal defect to cover the wound and provide tectonic support for the remaining cornea. The mass was histologically confirmed as a corneal epithelial inclusion cyst. There was no evidence of recurrence or complication at the surgical site 100 days postoperatively. Corneal epithelial inclusion cysts are uncommon in dogs. Although superficial keratectomy is the recommended treatment for corneal inclusion cyst, the combination of superficial keratectomy and AM transplantation had to be considered as an alternative for repair of large corneal defects. This is the first case report of the combined application of AM and superficial keratectomy to successfully treat a corneal inclusion cyst in a dog.     

Effect of autologous platelet-rich plasma application on cutaneous wound healing in dogs

This study was conducted to identify the effectiveness of platelet-rich plasma (PRP) and efficacy of intralesional injection as a method of application to acute cutaneous wounds in dogs. Healthy adult beagles (n = 3) were used in this study. Autologous PRP was separated from anticoagulant treated whole blood in three dogs. Cutaneous wounds were created and then treated by intralesional injection of PRP in the experimental group, while they were treated with saline in the control group on days 0, 2 and 4. The healing process was evaluated by gross examination throughout the experimental period and histologic examination on day 7, 14 and 21. In PRP treated wounds, the mean diameter was smaller and the wound closure rate was higher than in the control. Histological study revealed that PRP treated wounds showed more granulation formation and angiogenesis on day 7, and faster epithelialization, more granulation formation and collagen deposition were observed on day 14 than in control wounds. On day 21, collagen deposition and epithelialization were enhanced in PRP treated groups. Overall, PRP application showed beneficial effects in wound healing, and intralesional injection was useful for application of PRP and could be a good therapeutic option for wound management in dogs.     

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)     

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.     

Topical treatment of non-healing corneal epithelial ulcers in dogs with aminocaproic acid

The potential efficacy of topical epsilon-aminocaproic acid, an antiplasmin agent, in the treatment of persistent corneal epithelial defects was evaluated in a study of the medical records of 44 dogs, in which 51 eyes had been diagnosed with a corneal epithelial defect lasting more than 10 days, with no apparent underlying cause. At an initial examination all the affected eyes had had non-adherent epithelium removed. Thirty-four of the eyes in 28 dogs examined between January 2000 and March 2003 were also treated by the topical application of a solution of 35.7 mg/ml ophthalmic aminocaproic acid three times a day; the other 17 eyes in 16 dogs treated between October 1997 and March 1999 had received only topical treatment with gentamicin in addition to the debridement. Both groups were assessed clinically at weekly intervals for a maximum of three weeks. The two groups had approximately the same breed distribution, and there were no statistically significant differences between them in terms of their age, sex, affected side or duration of the corneal erosions. After three weeks, 32 of the 34 eyes treated with aminocaproic acid (94.1 per cent) had been cured, compared with seven of the 17 eyes treated with gentamicin (41.2 per cent) (P=0.0001). No adverse drug reactions were reported.     

Histologic evaluation of the immediate effects of diamond burr debridement in experimental superficial corneal wounds in dogs

Purpose To evaluate the corneal changes immediately after diamond burr debridement of superficial corneal wounds in dogs. Spontaneous chronic corneal epithelial defects (SCCEDs) are the most common form of canine recurrent corneal ulcers. The diamond burr has been used in the management of corneal lesions in humans since 1983. Recently, it has been successfully used in the treatment of SCCEDs in dogs; however, little has been documented as to its mechanism of action. Methods Five adult female research dogs euthanized for reasons unrelated to the study were included, providing 10 normal eyes. An excimer laser spatula was used for epithelial removal after delineation with an 8 mm punch biopsy trephine. Diamond burr debridement was performed for 30 and 45 s in five eyes each (groups 1 and 2 respectively). The procedure was performed on the ventral half of the experimental defect as well as ventral normal cornea, immediately after euthanasia, and prior to enucleation. Samples were processed routinely for histologic evaluation and stained with periodic acid–Schiff. Results No stromal defects could be identified under light microscopy. In experimental corneal wounds, multi‐focal areas remained covered by the epithelial basement membrane (BM) after diamond burr treatment in both groups (group 1 = 48%±16SD, group 2 = 26%±12SD). Removal of BM on group 2 was significantly higher than group 1 (P < 0.05). Conclusions The diamond burr allows a safe method of debridement and does not create defects beyond the epithelial BM in corneal wounds in normal dogs. Evaluation of the diamond burr debridement in cases of SCCEDs is warranted.     

Pathologic, hematologic, and serologic changes in rabbits given T-2 mycotoxin orally and exposed to aerosols of Aspergillus fumigatus conidia

The influence of immunosuppression by T-2 mycotoxin on the fungal disease aspergillosis was investigated in rabbits. Four groups of rabbits (groups 1A, 1B, 3A, and 3B) were given 0.5 mg of T-2 toxin/kg of body weight/day, PO; in addition, rabbits of groups 3A and 3B were exposed to aerosols of Aspergillus fumigatus conidia from days 7 through 16. Rabbits of groups 2A and 2B were exposed to A fumigatus aerosols, but were not given T-2 toxin, and rabbits of group 0 served as controls. Two rabbits of group 1A, 1 rabbit of group 1B, and 1 rabbit of group 3A died before scheduled necropsy. Rabbits of groups 1A, 2A, and 3A were killed and necropsied on day 17, and the remaining rabbits (groups 0, 1B, 2B, and 3B) were killed and necropsied on day 28. Changes caused by T-2 toxin included leukopenia, marginal anemia, and increased number of and morphologic changes in nucleated erythrocytes by day 21, followed by a regenerative hematologic response. Serum alkaline phosphatase and sorbitol dehydrogenase activities and antibody response to A fumigatus (as measured by an indirect hemagglutination test) were decreased by T-2 toxin ingestion. Rabbits with aspergillosis had leukocytosis, increased PCV, and increased antibody response to A fumigatus. Histologic lesions consisting of centrilobular hepatocellular swelling, portal and periportal fibrosis, and lymphocyte necrosis and/or depletion within secondary lymphoid tissue were observed in most rabbits treated with T-2 toxin. Normal defense mechanisms against A fumigatus infection were compromised by T-2 treatment, as evidenced by the severity and extent of lung lesions, greater number of hyphal elements observed, and greater number of colonies of A fumigatus isolated from rabbits of groups 3A and 3B. There were no significant changes in group-0 rabbits.     

Tolerance of the rabbit cornea to an n-butyl-ester cyanoacrylate adhesive (Vetbond)

Objective An n‐butyl‐ester cyanoacrylate adhesive available for veterinary surgery (Vetbond^®, 3M) was tested in rabbits for corneal irritation. Procedures Two experimental procedures were used on 24 rabbits: injection of the adhesive into an intralamellar corneal pocket (n = 10) and application of the glue to a mid‐stromal corneal defect (n = 14). In both experiments the eyes were examined for 20 days for evidence of corneal irritation and tolerance. At the end of each experiment, histopathologic studies were performed on all corneas. Results The corneal reaction to the intrastromally injected cyanoacrylate was characterized clinically by slight edema and vascularization localized to the vicinity of the adhesive. A moderate foreign body‐type reaction was found histologically. Following application of the adhesive to a central stromal defect, the treated corneas remained totally clear and histopathologic examination showed that the healing process was not altered compared to the controls. The mean retention time of the glue patch was 14 days. Conclusions Intrastromal injection and surface application to a corneal defect of n‐butyl‐ester cyanoacrylate to a corneal defect induced only a mild inflammatory response and did not interfere with the reparative process. These findings suggest that this surgical adhesive would be acceptable for treating corneal ulcerations in animals.     

The repair of segmental bone defects with porous bioglass: an experimental study in goat

This study was exclusively conducted to evaluate healing of surgically created defects on the radius of adult Black Bengal goat after implantation of porous bioglass blocks and compare the process kinetics with normal healing. Twelve Black Bengal goats were divided randomly into two groups: control and experimental group implanted with bioglass blocks. Unicortical bone defects in radius were generated in all animals under aseptic condition. Local inflammatory reaction and healing of wound, radiological investigations, histological studies, oxytetracycline leveling and angiographic studies were performed up to 90th day post-operatively and compared with normal healing. It has been found that extensive new bone formation originating from host bone towards the implant whereas in control, the process was active from both the ends; the defect site appeared as homogenous nonfluorescent area. Thus, porous bioglass promoted bone formation over the entire extension of the defect independent of size of block in comparison to control group.     

Efficacy and safety of topical administration of selamectin for treatment of ear mite infestation in rabbits

OBJECTIVE: To evaluate the efficacy and safety of topical administration of selamectin in rabbits naturally infested with Psoroptes cuniculi. DESIGN: Randomized controlled trial. ANIMALS: 48 mixed-breed domestic rabbits with active P. cuniculi mite populations and clinical ear lesions. PROCEDURES: Rabbits were randomly allocated to 1 of 6 treatment groups. On day 0, rabbits in groups 1 and 2 were given vehicle, rabbits in groups 3 and 4 were given selamectin at a dose of 6 mg/kg (2.7 mg/lb), and rabbits in groups 5 and 6 were given selamectin at a dose of 18 mg/kg (8.2 mg/lb). On day 28, rabbits in groups 2, 4, and 6 were given a second dose of vehicle or selamectin. Otoscopic examinations were performed and ear lesion size was measured weekly for 8 weeks. Quantitative viable mite counts were performed on day 56. RESULTS: On days 7 through 56, lesion sizes for all selamectin-treated groups were significantly lower than sizes for control groups; there were no significant differences in lesion sizes among selamectin-treated groups. All rabbits in the 2 control groups had viable adult P. cuniculi mites for the duration of the study, as determined by otoscopic examination, whereas all rabbits in the 4 selamectin-treated groups were free from P. cuniculi mites on days 7 through 56. No adverse reactions associated with selamectin treatment were observed. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that topical application of selamectin at a dose of 6 or 18 mg/kg can completely eliminate mites from rabbits naturally infested with P. cuniculi.     

Reconstruction of corneal epithelium with cryopreserved corneal limbal stem cells in a rabbit model

The integrity and transparency of the cornea plays a key role in preserving vision. This paper reports a procedure to create an artificial sheet of corneal epithelium from cryopreserved limbal stem cells (LSCs) and to use this for corneal transplantation. Corneal LSCs were isolated from biopsy specimens of rabbit limbal lamellar and cryopreserved in liquid nitrogen at 2–4 passages. The cells were grown in culture medium for 12–14 days on top of a cell-free human amniotic membrane framed on a nitrocellulose sheet. The corneal epithelium generated was transplanted into the right eyes of 14 LSC deficient (LSCD) rabbits (seven experimental animals, seven controls) with corneal damage. The seven LSCD rabbits in the experimental group were transplanted with a corneal epithelial sheet generated from the cryopreserved corneal LSCs. Four LSCD rabbits were used as the vehicle control and were transplanted with a cell-free amniotic membrane, and the remaining three LSCD rabbits were negative controls without transplantation. Over a 2-month recovery period, 2/7 animals in the experimental group recovered completely, four recovered partially and one did not respond. In the control groups, three negative controls and three vehicle controls lost their vision completely, and one of the vehicle controls partially recovered transparency of the cornea Following treatment, corneal transparency of the experimental rabbits was significantly improved compared to controls (P < 0.05). The results indicated that cryopreserved corneal LSCs can repair damaged rabbit cornea, suggesting a possible new clinical approach to reconstruction of corneal epithelium.