Modulation of proteolytic activity associated with persistent corneal ulcers in dogs

Canines affected with corneal lesions demonstrate increased proteolytic activity at the affected site. Canines that develop persistent corneal ulcers and maintain elevated levels of proteolytic activity respond to protease inhibitor therapy with polysulpated glycosaminoglycan, PSGAG. In this study, the proteolytic activity expressed in lacrimal fluid of canines was evaluated as normal (1.15 U mL⁻¹) or healed (1.19 U mL⁻¹). Six of the 26 dogs affected with persistent corneal ulcers, however, had a protease level consistent with the unaffected control animals. These dogs did not appear to respond to PSGAG therapy. Two pathophysiologies for persistent corneal ulcers are indicated. Identifying which mode is active could help determine the therapeutic treatment needed.     

The treatment of corneal ulcers

The anatomy of the cornea and the method of assessing corneal damage are described. The many causes of ulcerative keratitis are stated. The general principles of treatment are set down. Particular treatments are then described according to the causative agent and to the type of ulcer. In a paper of this length it will not be possible to consider the specific treatment of each and every type of corneal ulceration that occurs in the dog. The causes of ulcerative keratitis are many and this paper will consider the general principles involved and, in particular, some of the more common varieties of corneal ulcer. Résumé. On a décrit l'anantomie de la cornée et la méthode pour évaluer le dommage cornéen. Les nombreuses causes de la kératite à hypopyon sont réglées. Les principes généraux du traitement sont posés. Puis les traitements particuliers sont décrits selon l'agent pathogène et le type de l'ulcère. Zusammenfassung . Die Anatomie von der Hornhaut und die Methode, die kornealen Schäden zu abzuschätzen, werden beschrieben. Viele Ursachen von Hypopyonkeratitis werden angegeben. Die allgemeinen Grundsätze der Behandlung werden aufgeschoben. Dann werden besondere Behandlungen nach dem verursachenden Mittel und nach dem Typ vom Geschwür beschrieben.     

Antibiotic susceptibility of bacterial isolates from corneal ulcers of dogs in Taiwan

OBJECTIVES: To analyse antibiotic susceptibility of bacteria associated with ulcerative keratitis in dogs. METHODS: Bacteria isolated from 190 eyes with ulcerative keratitis were identified, and the antibiotic susceptibility of isolates was studied. RESULTS: In total, 258 species of bacteria were isolated from the 190 eyes. Of the isolates, 78 per cent were Gram-positive and 28 per cent were Gram-negative bacteria. The most commonly isolated Gram-positive bacteria in dogs were Staphylococcus spp (49 per cent), Streptococcus spp (7 per cent) and Corynebacterium spp (7 per cent); while Pseudomonas aeruginosa (7.6 per cent) and Escherichia coli (5.8 per cent) were the commonest Gram-negative pathogens. Resistance to commonly used ophthalmic antibiotics was seen in Staphylococcus, Streptococcus, Corynebacterium, Pseudomonas and Escherichia species isolates. CLINICAL SIGNIFICANCE: Isolates from dogs with corneal ulcers in Taiwan may be resistant to several commonly used ophthalmic preparations. Ciprofloxacin showed good action against most isolates, with the notable exception of Streptococcus species. Chloramphenicol or cephalothin had the best in vitro action against the Streptococcus species isolates.     

Spontaneous chronic corneal epithelial defects in dogs: a review

Spontaneous chronic corneal epithelial defects (SCCEDs) in dogs are typically found in middle-aged dogs of all breeds. These epithelial defects may be present for weeks to months, particularly if left untreated or if treated inappropriately. Typical histopathological findings include loss of the corneal epithelial basement membrane and formation of a superficial, acellular, hyalinized zone in the stroma. Together, these histological abnormalities lead to delayed wound healing and poor epithelial adhesion. Epithelial debridement, anterior stromal puncture, grid keratotomy, and superficial keratectomy are the most common treatment options applied to the defects. Procedures that address the stromal changes present generally have a higher success rate than epithelial debridement alone.     

Thermal cautery of the cornea for treatment of spontaneous chronic corneal epithelial defects in dogs and horses

A thermal cautery technique was used to treat spontaneous chronic corneal epithelial defects (SCCEDs) in 9 eyes of 8 dogs and 2 eyes of 2 horses. Animals were sedated, and a topical anesthetic was applied. A handheld thermal cautery unit was then used to make multiple, small (< or = 1 mm in diameter), superficial burns throughout the affected area. The cautery unit was applied just until the slightest degree of contraction of the collagen fibrils was observed. After the stromal bed of the defect was treated, a rim of epithelium that extended approximately 1 mm around the denuded stroma was also subjected to thermal cautery. Following surgery, a contact lens was placed in dogs but not in horses, and the eye was treated with broad-spectrum antimicrobial ophthalmic solutions. Defects in all 11 eyes healed with minimal scarring; mean time to healing in dogs was 2.1 weeks (range, 2 to 3 weeks). The defect healed in 1 week in 1 horse and in 2 weeks in the other. Many therapeutic options are available for the treatment of SCCEDs. Procedures such as epithelial debridement and anterior stromal puncture have been shown to have a high rate of success. In cases for which these less invasive procedures fail, our results suggest that thermal cautery may be a reasonable alternative to previously described treatments for SCCEDs in dogs and horses prior to more invasive procedures such as superficial keratectomy.     

Topical administration of cyclosporine for treatment of keratoconjunctivitis sicca in dogs.

Sixty dogs with chronic keratoconjunctivitis sicca were treated by topical administration of 2% cyclosporine twice daily. Causes and duration of keratoconjunctivitis varied. Tear production improved in 75 of 100 eyes, and corneal pigmentation decreased in 45 of 67 eyes. Six factors were evaluated to determine their influence on treatment outcome. The only significant variable was the initial Schirmer tear test value. Side effects were few. Evidence of burning in response to application of cyclosporine resolved with change in the formulation of the topical solution.     

Indolent-like corneal ulcers in 3 horses

Three horses were admitted with indolent-like corneal ulcers. All horses were treated topically with antibiotics. Two horses had ulcers with redundant epithelial borders, which were debrided with cotton-tipped applicators after topical anesthesia was induced. One ulcer healed after 2 debridements. Of 2 horses treated surgically, one had complications.     

Grid keratotomy as a treatment for superficial nonhealing corneal ulcers in 10 horses

OBJECTIVE: To describe the clinical symptoms of 10 cases of superficial nonhealing corneal ulcers in horses and to evaluate the results of grid keratotomy in these patients. DESIGN: Retrospective study. ANIMALS: Ten horses with superficial nonhealing corneal ulceration in one eye. PROCEDURE: The signalment, history and clinical symptoms are reported of 10 patients with superficial nonhealing corneal ulcers during the period from August 2003 to February 2005. Grid keratotomy was performed in all cases. In addition, the surgical procedure of grid keratotomy and response to therapy are described. RESULTS: Horses generally responded well to grid keratotomy (eight cases healed after one grid keratotomy and one horse healed after a second grid keratotomy; one case was not available for follow-up). Only 2/10 had discomfort after treatment and only 2/9 had some degree of scarring after treatment. The healing time, which was known in seven cases, averaged 8.4 days (+/- SD 4). CONCLUSIONS AND CLINICAL RELEVANCE: Grid keratotomy is an appropriate option for treatment of superficial nonhealing corneal ulcers in horses. The procedure is simple to perform. It generally induces a rapid and uncomplicated healing of the cornea. Only in a limited number of cases does a small amount of scarring occur.     

Topical (pour-on) ivermectin in the treatment of chronic generalized demodicosis in dogs

Twelve privately owned dogs with chronic generalized demodicosis were treated topically along the dorsal midline with 1.5 mg kg⁻¹ of 0.5% pour-on ivermectin for cattle three times per week for 3–6 months. All 12 dogs had a substantial reduction in clinical signs and in the number of Demodex canis mites found on skin scrapings. Only two dogs, however, became skin-scrapings negative after 3 and 5 months of treatment, respectively. In these two dogs treatment was prolonged for an additional 4 weeks past the negative scrapings. One dog relapsed 2 months after cessation of therapy; the other is still free of symptoms 1.5 years later. The cure rate, based on the lack of recurrence of clinical signs for 12 months after discontinuation of ivermectin administration, was 1 of 12 dogs (8%). Adverse reactions were not seen.     

Healing of experimentally induced corneal ulcers in horses

Corneal ulcers to the depth of the anterior third of the stroma were created surgically in both eyes of 10 ponies. One eye in each pony was treated topically with chloramphenicol and 1% atropine ophthalmic ointments 3 times per day; the contralateral eye was not treated topically. All ponies were given phenylbutazone orally for relief of ocular pain. Fluorescein-stained ulcers were measured once a day. The median healing time of the treated eyes (11 days) and the median healing time of the nontreated eyes (13.5 days) were found not to be significantly different. Clinically, however, more severe complications arose in the nontreated eyes.