Laser flaremetric evaluation of experimentally induced blood-aqueous barrier disruption in cats

Effect of oral administration of robenacoxib on inhibition of paracentesis-induced blood-aqueous barrier breakdown in healthy cats

OBJECTIVE To determine the effect of oral administration of robenacoxib on inhibition of anterior chamber paracentesis (ACP)-induced breakdown of the blood-aqueous barrier (BAB) and assess whether robenacoxib can cross an intact BAB in healthy cats. ANIMALS 12 healthy adult domestic shorthair cats. PROCEDURES Cats received robenacoxib (6-mg tablet in a treat, PO; n = 6) or a control treatment (treat without any drug, PO; 6) once daily for 3 days, beginning 1 day before ACP. One eye of each cat served as an untreated control, whereas the other underwent ACP, during which a 30-gauge needle was used to aspirate 100 μL of aqueous humor for determination of robenacoxib concentration. Both eyes of each cat underwent anterior chamber fluorophotometry at 0 (immediately before), 6, 24, and 48 hours after ACP. Fluorescein concentration and percentage fluorescein increase were used to assess extent of ACP-induced BAB breakdown and compared between cats that did and did not receive robenacoxib. RESULTS Extent of BAB breakdown induced by ACP did not differ significantly between cats that did and did not receive robenacoxib. Low concentrations of robenacoxib were detected in the aqueous humor (mean, 5.32 ng/mL; range, 0.9 to 16 ng/mL) for 5 of the 6 cats that received the drug. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that oral administration of robenacoxib did not significantly decrease extent of BAB breakdown in healthy cats. Detection of low robenacoxib concentrations in the aqueous humor for most treated cats indicated that the drug can cross an intact BAB.

Development of septic polysynovitis and uveitis in foals experimentally infected with Rhodococcus equi

Rhodococcus equi is one of the most important causes of disease in foals. Infection is typically characterized by pyogranulomatous pneumonia although extrapulmonary infections occur occasionally. Uveitis and polysynovitis have been reported in foals naturally infected with R. equi and are thought to be the result of an immune-mediated process. However, the pathogenesis of these conditions is poorly understood. The objectives of this study were to document the occurrence of uveitis and polysynovitis after experimental infection with R. equi and to determine if these disorders are the direct result of infection at these sites. Foals between 3 and 4 weeks of age were infected intratracheally with virulent R. equi using inocula of 1×10⁸ CFU (high inoculum; n = 16) or 1×10⁷ CFU (low inoculum; n = 12). Foals were monitored twice daily and necropsy was performed 14 days post-infection. Aqueous humor and synovial fluid were collected aseptically and the percentage of affected lung was calculated. The mean (± SD) percentage of affected lung was significantly higher with the high inoculum (31.8 ± 14.6%) than with the low inoculum (14.4 ± 11.4%). Fourteen of 25 foals developed uveitis and 20 of 28 foals developed polysynovitis. R. equi was cultured from the aqueous humor of 11 foals and from the synovial fluid of 14 foals. The risk of development of polysynovitis and protein concentration in the aqueous humor were significantly higher in foals that received the high inoculum. These results indicate that polysynovitis and uveitis are septic complications associated with the severity of lung disease.

Effects of oral administration of anti-inflammatory medications on inhibition of paracentesis-induced blood-aqueous barrier breakdown in clinically normal cats

OBJECTIVE

To assess inhibitory effects of orally administered anti-inflammatory medications on paracentesis-induced intraocular inflammation in clinically normal cats.

ANIMALS

30 clinically normal domestic shorthair cats.

PROCEDURES

Cats were randomly assigned to a control group and 4 treatment groups. Cats in the treatment groups received an anti-inflammatory medication orally once daily at 7 AM (acetylsalicylic acid [40.5 mg/cat], meloxicam [0.1 mg/kg], prednisone [5 mg/cat], or prednisolone [5 mg/cat]) for 5 days beginning 2 days before paracentesis-induced breakdown of the blood-aqueous barrier (BAB) and continuing until 2 days after paracentesis. Paracentesis of the anterior chamber was performed in 1 randomly selected eye of each cat. Fluorophotometry was performed in both eyes of each cat immediately before (time 0) and 6, 24, and 48 hours after paracentesis.

RESULTS

At 24 and 48 hours after paracentesis, fluorescein concentration in the eye subjected to paracentesis in the cats receiving prednisolone was decreased, compared with that in the control cats. At 48 hours, a decrease in the fluorescein concentration was also apparent in the eye subjected to paracentesis in the cats receiving meloxicam, compared with that in the control cats. There was no evidence of treatment effects for acetylsalicylic acid or prednisone. There was no evidence of treatment effects in eyes not subjected to paracentesis.

CONCLUSIONS AND CLINICAL RELEVANCE

Orally administered prednisolone and meloxicam significantly decreased intraocular inflammation in clinically normal cats with paracentesis-induced BAB breakdown. Oral administration of prednisolone or meloxicam may be an effective treatment for cats with uveitis.

Feline glaucoma--a comprehensive review

Cats with glaucoma typically present late in the course of disease. It is likely that glaucoma in cats is under-diagnosed due to its insidious onset and gradual progression, as well as limitations of some commonly used tonometers in this species. Treatment of glaucoma in feline patients presents a clinical challenge, particularly as glaucoma is often secondary to other disease processes in cats. In this review, we consider the clinical features, pathophysiology, and classification of the feline glaucomas and provide current evidence to direct selection of appropriate treatment strategies for feline glaucoma patients.

Fluorophotometric and tonometric evaluation of ocular effects following aqueocentesis performed with needles of various sizes in dogs

OBJECTIVE

To measure ocular effects (blood-aqueous barrier breakdown and intraocular pressure [IOP]) following aqueocentesis performed with needles of various sizes in dogs.

ANIMALS

28 healthy adult dogs.

PROCEDURES

24 dogs underwent unilateral aqueocentesis (24 treated eyes and 24 contra-lateral untreated eyes); 25-, 27-, or 30-gauge needles were used in 3 treatment groups (n = 8/group). Four dogs were untreated controls. Aqueocentesis was performed during sedation and topical anesthesia. Anterior chamber fluorophotometry was performed before and after aqueocentesis on day 1. On days 2 through 5, sedation and fluorophotometry were repeated. Intraocular pressure was measured with a rebound tonometer at multiple time points.

RESULTS

Aqueocentesis resulted in blood-aqueous barrier breakdown detected via fluorophotometry in all treated eyes, with barrier reestablishment by day 5. On day 2, the contralateral untreated eyes of all 3 groups also had significantly increased fluorescence. Use of a 25-gauge needle resulted in a significant increase in treated eyes' anterior chamber fluorescence on days 3 and 5 as well as a significant increase in IOP 20 minutes following aqueocentesis, compared with the other treatment groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Aqueocentesis performed with a 25-gauge needle resulted in the greatest degree of blood-aqueous barrier breakdown and a brief state of intraocular hypertension. Use of a 27- or 30-gauge needle is recommended for aqueous paracentesis. A consensual ocular reaction appeared to occur in dogs following unilateral traumatic blood-aqueous barrier breakdown and may be of clinical importance.

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.

Canine and feline uveitis

The clinical signs of uveitis occur as a result of inflammation within the vascular coat of the eye, which causes breakdown of the blood-aqueous barrier and blood-retinal barrier. Many infectious and noninfectious causes can incite episodes of uveitis. Although a complete diagnostic evaluation is highly recommended to identify any underlying etiologic agent, many cases remain idiopathic in nature. The goals of therapy are preserving vision, minimizing pain, and halting inflammation.