Utility of antigen testing for the diagnosis of ocular histoplasmosis in four cats: a case series and literature review.

Case series summary This case series describes the clinical utility of antigen testing for the diagnosis of feline ocular histoplasmosis. Four cats with suspected (n = 2) or confirmed (n = 2) ocular histoplasmosis are described: three from Oklahoma and one from California. In one case, serial urine antigen tests, as well as a serum antigen test for Histoplasma capsulatum, were negative; however, light microscopy identified microorganisms consistent with H capsulatum in ocular tissues at necropsy. In a further two cats with recurrent ocular histoplasmosis following long-term systemic antifungal therapy, Histoplasma species urine antigen concentrations were negative, but both cats improved clinically following systemic antifungal therapy and remained in apparent clinical remission after treatment cessation (9-16 months). The final cat displayed profound bilateral endophthalmitis; however, Histoplasma species antigen testing of vitreous humor and subretinal fluid from the left eye was negative. Intralesional organisms were detected on histopathology of both eyes, and H capsulatum was subsequently isolated and sequenced from tissue of one eye. Relevance and novel information These cases highlight the potential difficulty in definitively diagnosing ocular histoplasmosis in cats when conducting antigen testing of serum, urine and even ocular fluids. Although antigen testing has previously proven useful in the diagnosis of disseminated feline histoplasmosis, it may not be adequate in cats with only ocular signs.

Intraocular pressure in free-ranging anuran species in Oklahoma.

Ocular disease appears to be a common issue in anurans. Intraocular pressures were measured for six species of free-ranging anurans in central Oklahoma. No significant differences were identified between left or right eyes. There was a significant negative relationship between the weight of the anuran and intraocular pressure. The intraocular pressure range for the six species was 3-10 mm Hg. Tonometry values in anurans are, to the authors' knowledge, previously unreported and this study provides initial information on intraocular pressure measurement in anurans.

Stability of 1% voriconazole solution in a constant-rate infusion pump for topical ocular delivery to horses.

OBJECTIVE: To establish the effect of storage in a constant-rate infusion (CRI) pump on the sterility and stability of voriconazole 1% solution. PROCEDURE: Nine vials of voriconazole (Vfend(®) I.V.) 1% solution were prepared. Approximately half of each solution was used to prime a commercially available CRI pump with attached subpalpebral lavage system (CRI/SPL unit) with the remaining solution stored in the commercial glass vial. Three CRI/SPL units and their three corresponding vials were stored at one of three temperatures: 23 °C, 33 °C, and 40 °C. The CRI pumps ran for 7 days, and the vials were stored for 30 days. Fungal and aerobic bacterial cultures were performed on the first and last day of the storage period for each vessel. Samples were obtained at regular intervals for determination of voriconazole concentration using high-performance liquid chromatography. RESULTS: No bacterial or fungal contamination was identified in any solution at any time point. All solutions stored in the commercial glass vial remained stable throughout the study period. Multiple CRI/SPL units became blocked with crystallized voriconazole. There was a significant increase in voriconazole concentration after passage through the CRI/SPL units. CONCLUSIONS: Voriconazole 1% solution is not compatible for use in a CRI/SPL unit at temperatures between 23 and 40 °C. Voriconazole 1% solution is stable in the commercial glass vial when stored at controlled temperatures as high as 40 °C for up to 30 days.

Treatment of six cases of equine corneal stromal abscessation with intracorneal injection of 5% voriconazole solution.

OBJECTIVE: To describe a reproducible technique for intrastromal injection in the standing horse for treatment of corneal stromal abscessation. ANIMAL STUDIED: A retrospective clinical study addressing the history, treatment, and outcome of six equids (six eyes) that received intrastromal voriconazole injection. PROCEDURE: Equids having a deep stromal abscess suspected to be of fungal origin were administered intrastromal injection of 5% voriconazole solution under standing sedation in an effort to bring about enhanced resolution of clinical disease. RESULTS: Intracorneal administration of 5% voriconazole solution resulted in resolution of clinical disease, specifically stromal abscessation and secondary uveitis. All animals displayed decreased blepharospasm and no significant complications in the immediate postinjection period. Convalescent periods were subjectively shorter than anticipated with traditional medical therapy. All animals developed mild to moderate stromal fibrosis relative to the initial severity and depth of abscessation. CONCLUSIONS: Intrastromal injection of 5% voriconazole solution may provide a safe and effective treatment option for corneal stromal abscessation in horses. In all reported cases, administration of injection early in the treatment period appeared to contribute to rapid resolution of clinical disease without significant complications. The authors present this technique as an alternative to traditional surgical intervention, being more economical, having shorter treatment duration, and potentially resulting in less scar formation.

Long-term outcome of sudden acquired retinal degeneration syndrome in dogs.

OBJECTIVE: To investigate long-term outcomes and owner-perceived quality of life associated with sudden acquired retinal degeneration syndrome (SARDS) in dogs. DESIGN: Survey study. ANIMALS: 100 dogs with SARDS examined at 5 academic veterinary institutions from 2005 to 2010. PROCEDURES: The diagnosis was based on documented acute vision loss, normal results of ophthalmic examinations, and evaluation of extinguished bright-flash electroretinograms. Primary owners of affected dogs completed a questionnaire addressing outcome measures including vision, systemic signs, and perceived quality of life for their dogs. RESULTS: Age at diagnosis was significantly correlated with positive outcome measures; dogs in which SARDS was diagnosed at a younger age were more likely to have alleged partial vision and higher owner-perceived quality of life. Polyphagia was the only associated systemic sign found to increase in severity over time. Medical treatment was attempted in 22% of dogs; visual improvement was not detected in any. Thirty-seven percent of respondents reported an improved relationship with their dog after diagnosis, and 95% indicated they would discourage euthanasia of dogs with SARDS. CONCLUSIONS AND CLINICAL RELEVANCE: Blindness and concurrent systemic signs associated with SARDS appeared to persist indefinitely, but only polyphagia increased in severity over time. Most owners believed their pets had good quality of life and would discourage euthanasia of dogs with SARDS.

Comparison of the effects of IV administration of meloxicam, carprofen, and flunixin meglumine on prostaglandin E(2) concentration in aqueous humor of dogs with aqueocentesis-induced anterior uveitis.

OBJECTIVE: To compare the effects of meloxicam, carprofen, and flunixin meglumine administered IV on the concentration of prostaglandin E(2) (PGE(2)) in the aqueous humor of dogs with aqueocentesis-induced anterior uveitis. ANIMALS: 15 adult dogs with ophthalmically normal eyes. PROCEDURES: Each dog was assigned to 1 of 4 treatment groups. Treatment groups were saline (0.9% NaCl) solution (1 mL, IV), meloxicam (0.2 mg/kg, IV), carprofen (4.4 mg/kg, IV), and flunixin meglumine (0.5 mg/kg, IV). Each dog was anesthetized, treatment was administered, and aqueocentesis was performed on each eye at 30 and 60 minutes after treatment. Aqueous humor samples were frozen at -80°C until assayed for PGE(2) concentration with an enzyme immunoassay kit. RESULTS: For all 4 treatment groups, PGE(2) concentration was significantly higher in samples obtained 60 minutes after treatment, compared with that in samples obtained 30 minutes after treatment, which indicated aqueocentesis-induced PGE(2) synthesis. For aqueous humor samples obtained 60 minutes after treatment, PGE(2) concentration did not differ significantly among groups treated with saline solution, meloxicam, and carprofen; however, the PGE(2) concentration for the group treated with flunixin meglumine was significantly lower than that for each of the other 3 treatment groups. CONCLUSIONS AND CLINICAL RELEVANCE: Flunixin meglumine was more effective than meloxicam or carprofen for minimizing the PGE(2) concentration in the aqueous humor of dogs with experimentally induced uveitis. Flunixin meglumine may be an appropriate pre-medication for use prior to intraocular surgery in dogs.

Comparison of tepoxalin, carprofen, and meloxicam for reducing intraocular inflammation in dogs.

OBJECTIVE: To compare effects of orally administered tepoxalin, carprofen, and meloxicam for controlling aqueocentesis-induced anterior uveitis in dogs, as determined by measurement of aqueous prostaglandin E(2) (PGE(2)) concentrations. ANIMALS: 38 mixed-breed dogs. PROCEDURES: Dogs were allotted to a control group and 3 treatment groups. Dogs in the control group received no medication. Dogs in each of the treatment groups received an NSAID (tepoxalin, 10 mg/kg, PO, q 24 h; carprofen, 2.2 mg/kg, PO, q 12 h; or meloxicam, 0.2 mg/kg, PO, q 24 h) on days 0 and 1. On day 1, dogs were anesthetized and an initial aqueocentesis was performed on both eyes; 1 hour later, a second aqueocentesis was performed. Aqueous samples were frozen at -80 degrees C until assayed for PGE(2) concentrations via an enzyme immunoassay kit. RESULTS: Significant differences between aqueous PGE(2) concentrations in the first and second samples from the control group indicated that aqueocentesis induced uveitis. Median change in PGE(2) concentrations for the tepoxalin group (10 dogs [16 eyes]) was significantly lower than the median change for the control group (8 dogs [16 eyes]), carprofen group (9 dogs [16 eyes]), or meloxicam group (9 dogs [16 eyes]). Median changes in PGE(2) concentrations for dogs treated with meloxicam or carprofen were lower but not significantly different from changes for control dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Tepoxalin was more effective than carprofen or meloxicam for controlling the production of PGE(2) in dogs with experimentally induced uveitis. Tepoxalin may be an appropriate choice when treating dogs with anterior uveitis.

Use of grid keratotomy for the treatment of indolent corneal ulcer in a llama.

A case of indolent corneal ulcer in a llama (Llama glama) is described. Diagnostic testing included a complete ophthalmic examination with corneal cytologic and histopathologic examination. Successful management involved grid keratotomy and topical application of neomycin-polymixin-bacitracin and atropine 1% ointments. Weekly follow-up examinations are described until healing was considered complete.

Evaluation of a comparative pathogenesis between cancer-associated retinopathy in humans and sudden acquired retinal degeneration syndrome in dogs via diagnostic imaging and western blot analysis.

OBJECTIVE: To evaluate dogs with sudden acquired retinal degeneration syndrome (SARDS) for evidence of pituitary gland, adrenal gland, and pulmonary neoplasia and antiretinal antibodies and to evaluate dogs with neoplasia for antiretinal antibodies. ANIMALS: 57 clinically normal dogs, 17 with SARDS, and 53 with neoplasia. PROCEDURE: Thoracic radiography, ultrasonography of adrenal glands, and contrast-enhanced computed tomography of pituitary glands were performed in 15 dogs with SARDS. Western blot analysis was performed on sera of all dogs; recoverin (23 kd) and arrestin (48 kd) retinal antibodies were used as positive controls. RESULTS: Neoplasia was not detected via diagnostic imaging in dogs with SARDS. Western blot analysis revealed bands in all dogs ranging from > 48 to < 23 kd. Prominent bands with equivalent or greater density than 1 or both positive controls at the 1:1,000 dilution, and present at the 1:3,000 dilution, were detected in 28% of clinically normal dogs, 40% of dogs with neoplasia, and 41% of dogs with SARDS. No bands in dogs with SARDS had a consistent location of immune activity, and none were detected at the 23-kd site. The area around the 48-kd site had increased immune activity in all 3 groups. CONCLUSIONS AND CLINICAL RELEVANCE: The etiology of SARDS in dogs does not appear to be similar to cancer-associated retinopathy in humans on the basis of absence of differential antibody activity against retinal proteins. Although dogs with SARDS often have clinical signs compatible with hyperadrenocorticism, neoplasia of the adrenal glands, pituitary gland, or lungs was not detected.

More than meets the eye: subretinal aspirate from an acutely blind dog.

A 14-year-old, spayed female Cocker Spaniel was presented to the Boren Veterinary Medical Teaching Hospital at Oklahoma State University with acute loss of vision in the right eye and a history of intermittent bloody diarrhea of unknown duration. Small, white, plaque-like lesions in the retina and subretina were visualized by direct ophthalmic examination, and aspirated with ultrasound-guidance. A direct smear of the subretinal fluid was highly cellular and contained large numbers of pleomorphic organisms consistent with Prototheca sp. The structures were round, oval, or elongated, 4-6 microm width and 8-16 microm in length and surrounded by a thin, clear cell wall. Small, central, pink to purple nuclei were observed in some organisms, but in most, the nuclei were obscured by a deeply basophilic, granular cytoplasm. Some organisms contained endospores. Negatively-stained structures of similar size and shape were considered to be empty casings (theca) of ruptured sporulating and nonsporulating forms of the organism. Protothecosis usually is a disseminated, fatal disease in dogs. The Prototheca organisms observed in this case showed characteristic morphology, illustrating the ability to diagnose protothecosis in cytologic samples.

Ocular penetration of oral doxycycline in the horse.

OBJECTIVE: To investigate intraocular penetration of orally administered doxycycline in the normal equine eye and to compare intraocular and serum doxycycline concentrations. Procedures Six mares were administered doxycycline at 10 mg/kg every 12 h by nasogastric tube for 5 days. Blood, aqueous, and vitreous samples were collected on days 1 and 5. All samples were assayed for doxycycline concentrations. Aqueous and vitreous samples were also assayed for protein quantitation. RESULTS: Doxycycline was rapidly absorbed after the first dose (T(max) value of 1.42 +/- 1.28 h); and elimination of doxycycline occurred slowly (median t(1/2) = 10.88 h). Doxycycline could not be detected in the aqueous on days 1 and 5, nor could it be detected in the vitreous on day 1. On day 5, the mean vitreous doxycycline concentration was 0.17 +/- 0.04 microg/mL at 2 h after drug administration. CONCLUSIONS: Repeated oral administration of doxycycline in the horse resulted in steady state serum concentrations of < 1 microg/mL; however, it did not result in appreciable concentrations of drug in the aqueous and vitreous in normal eyes.

Laser applications for corneal disease.

The clinical use of the carbon dioxide (CO2) laser and diode laser is increasing in veterinary medicine. New applications for their use are being explored, including ophthalmic applications. The use of lasers for small-animal corneal disease is fairly limited due to several factors. The ideal laser for corneal use is the excimer laser due to its extremely precise photoablative capability. However, the excimer laser is unlikely ever to become practical for veterinary use. The frequency of corneal disease in small animals in which tissue ablation is indicated is relatively low. And for most of these diseases, routine surgical techniques work as well or better than laser ablation. The CO2 laser can be used on corneal tissue, but must be used very cautiously so as not to ablate too deeply, creating serious scarring or perforation. There are also concerns regarding its effect on corneal nerves, stromal collagen, and corneal endothelium. The CO2 laser can be very effective in ablating limbal tumors with corneal extension. The use of the laser is less invasive, technically less difficult, and faster because of excellent hemostasis. The diode laser, due to its high melanin absorption, can be used effectively to ablate epibulbar melanomas with corneal stromal invasion.

Lasers in ophthalmology.

Laser technology continues to progress with the addition of new lasers, new delivery systems, and new applications. The introduction of lasers to veterinary ophthalmology has radically changed the level of care that we can provide to our patients. The development of the diode laser has particularly had an impact on veterinary ophthalmology. The diode's affordability, portability, and broad applications for veterinary patients have allowed laser surgery to become a routine part of veterinary ophthalmology practice. Educating the public and veterinary community in available laser techniques will generate improved ophthalmic care and provide more data on which to build future applications.