OBJECTIVE To compare morphology of the ciliary cleft (CC) region in dogs after topical administration of latanoprost, pilocarpine, or a combination of latanoprost and pilocarpine.
ANIMALS 6 Beagles.
PROCEDURES A prospective 4-phase crossover study with washout periods was performed. Latanoprost (phase L), pilocarpine (phase P), pilocarpine followed by latanoprost (phase PL), and latanoprost followed by pilocarpine (phase LP) were administered to the right eye. Artificial tears were administered to the left eye (control eye). For each phase, pupil diameter and intraocular pressure (IOP) were measured and ultrasonographic biomicroscopy was performed 2 hours after topical treatment. Angle opening distance (AOD), ciliary cleft width (CCW), ciliary cleft length (CCL), and ciliary cleft area (CCA) were evaluated.
RESULTS All treated eyes had marked miosis without significant differences in pupil diameter among phases. Significant IOP reductions were detected for all phases, except phase P. The AOD and CCA were significantly increased in all phases for treated eyes, compared with results for control eyes. The CCW was significantly increased in phases P, PL, and LP; CCL was significantly increased in phases PL and LP. Comparison of treated eyes among phases revealed that CCW differed significantly between phases L and P and between phases L and PL.
CONCLUSIONS AND CLINICAL RELEVANCE Prostaglandin-mediated and cholinergic-mediated miosis caused variations in CC configurations. When latanoprost and pilocarpine were used in combination, the first drug administered determined the cleft morphology, which was not fully reversed by the second drug. The CC morphology did not fully explain IOP reductions.
Objective—To evaluate the intraoperative and postoperative analgesic effects of intracameral lidocaine hydrochloride injection in dogs undergoing phacoemulsification.
Animals—12 healthy Beagles with healthy eyes.
Procedures—Dogs were randomly assigned to receive 1 of 2 intracameral injections: 2% lidocaine hydrochloride solution (0.3 mL) or an equivalent amount of balanced salt solution (BSS). All dogs were treated with acepromazine (0.05 mg/kg, IV) and cefazolin (30 mg/kg, IV), and tropicamide drops were topically applied to the eyes. Anesthesia was induced with propofol and maintained with isoflurane. The initial end-tidal isoflurane concentration was maintained at 1.2%. Heart rate, respiratory rate, arterial blood pressure, esophageal temperature, inspired and end-tidal isoflurane concentrations, and oxygen saturation were recorded every 5 minutes. The allocated agent was injected intracamerally after aspiration of the same volume of aqueous humor. Ten minutes after injection, phacoemulsification was performed. After surgery began, the isoflurane concentration was adjusted according to heart rate and mean arterial blood pressure. Pain scores were recorded before surgery and at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 6, 8, 16, and 24 hours after extubation.
Results—Isoflurane requirements were significantly higher in the BSS group than in the lidocaine group. Mean ± SD time to administration of supplementary analgesia was significantly shorter in the BSS group (1.4 ± 1.2 hours) than in the lidocaine group (4.9 ± 1.2 hours).
Conclusions and Clinical Relevance—Intracameral lidocaine injection had significant analgesic effects in dogs undergoing cataract surgery. Results of this study suggest the value of intracameral lidocaine injection as an analgesic for intraocular surgery in dogs.
Objective—To evaluate the effects of peribulbar anesthesia (sub-Tenon injection of lidocaine hydrochloride) on akinesia of extraocular muscles, mydriasis, and intraoperative and postoperative analgesia in dogs undergoing phacoemulsification.
Animals—14 Beagles with ophthalmically normal eyes.
Procedures—A blinded randomized controlled trial was performed. Dogs were anesthetized and assigned to 2 treatments: concurrent sub-Tenon injection of 2% lidocaine hydrochloride solution (2 mL) and IV injection of saline (0.9% NaCl) solution (0.02 mL/kg; lidocaine group [n = 7]) or concurrent sub-Tenon injection of saline solution (2 mL) and IV injection of 0.2 mg of atracurium/kg (0.02 mL/kg; control group ). Pupils were dilated by topical application of a combined tropicamide and phenylephrine ophthalmic solution. Ten minutes after the injections, pupil diameter was measured and phacoemulsification was performed. End-tidal isoflurane concentration was used to evaluate intraoperative pain. Subjective pain scores were recorded during the postoperative period.
Results—Akinesia was induced and maintained throughout the surgery in all eyes. Mean ± SD pupil diameter was significantly greater in the lidocaine group (13.7 ± 0.7 mm) than in the control group (12.2 ± 0.8 mm). Isoflurane requirements were significantly lower in the lidocaine group than the control group. However, postoperative pain scores were not significantly different between the groups.
Conclusions and Clinical Relevance—Sub-Tenon injection of lidocaine was an effective method for inducing akinesia of extraocular muscles, mydriasis, and intraoperative analgesia for phacoemulsification in dogs. Therefore, this could be another option for surgical field exposure and pain management during phacoemulsification in dogs.
Objective—To evaluate the mydriatic effect of intracameral injection of preservative-free 1% and 2% lidocaine hydrochloride solutions and determine the onset and duration of mydriasis according to the concentration and volume of lidocaine administered in healthy dogs.
Animals—5 healthy adult Beagles weighing 7 to 10 kg, with no apparent ocular disease.
Procedures—A double-blind randomized 9-session crossover trial was designed. Both eyes were assigned to 9 treatments with a minimum 7-day washout period between treatments: 0.1, 0.2, and 0.3 mL of 2% lidocaine solution; 0.1, 0.2, and 0.3 mL of 1% lidocaine solution; and 0.1, 0.2, and 0.3 mL of balanced salt solution. Dogs were anesthetized, and the allocated treatment was injected intracamerally after aspiration of the same volume of aqueous humor from the anterior chamber of each eye. Two perpendicular pupil diameters were measured. Intraocular pressure, heart rate, respiratory rate, ECG readings, and end-tidal partial pressure of CO2 were monitored.
Results—Intracameral injection of 1% or 2% lidocaine solutions in volumes of 0.1 to 0.3 mL induced a significant degree of mydriasis, and the effect was maintained for 74 to 142 minutes. Lidocaine injection had no significant effect on intraocular pressure, heart rate, respiratory rate, ECG readings, or end-tidal partial pressure of CO2.
Conclusions and Clinical Relevance—Intracameral lidocaine injection in healthy dogs induced mydriasis, the timing of which was affected by concentration and volume of lidocaine. This technique could serve as an alternative to topically administered mydriatics for intraocular surgery in dogs.
Objective—To identify a subantimicrobial dose of doxycycline hyclate (SDD) and for the treatment of periodontitis in dogs.
Animals—20 healthy Beagles for measurement of serum doxycycline concentration and 15 Beagles with periodontitis for evaluation of the efficacy of the SDD.
Procedures—5 dogs each received doxycycline hyclate PO at a dose of 1, 2, 3, or 5 mg/kg. Blood samples were collected before and after administration, and serum concentrations of doxycycline were measured via high-performance liquid chromatography. Mean serum doxycycline concentrations were calculated, and SDDs were identified. In a separate trial, the identified SDDs (1 or 2 mg/kg) were administered PO once a day for 1 month to dogs with periodontitis (n = 5/group) and a control group (5) was fed vehicle only during the same period. Degree of gingival attachment and bleeding on probing (present or absent) were recorded. Gingival samples were collected before and after the 1-month period from the same anatomic sites. Degree of matrix metalloproteinase inhibition in gingival samples was determined via gelatin zymography and compared among treatment groups.
Results—Mean serum doxycycline concentrations in healthy dogs that received 1 or 2 mg of doxycycline/kg were consistently significantly lower than the minimal inhibitory doxycycline concentration for treatment of periodontitis throughout the 24-hour posttreatment period. Zymographic intensities were lower in dogs given 1 and 2 mg/kg than in the control dogs, and the degree of gingival attachment and bleeding significantly improved in dogs given 2 mg/kg, compared with in the control dogs and dogs given 1 mg of doxycycline/kg.
Conclusions and Clinical Relevance—A doxycycline dosage of 2 mg/kg daily appeared to be an appropriate subantimicrobial regimen for dogs with periodontitis. Furthermore, this dosage may be suitable for long-term treatment of gelatinolytic inflammatory diseases such as periodontitis in this species.
Objective—To evaluate the use of color Doppler imaging (CDI) for determining the resistive index (RI) of the medial long posterior ciliary artery (mLPCA) in clinically normal conscious dogs.
Animals—18 (10 sexually intact males, 8 sexually intact females) dogs between 1 and 5 years old.
Procedure—Color Doppler ultrasonography was performed on both eyes with dogs in a sitting position. Each eye was imaged from the region dorsal to the zygomatic arch with the transducer positioned in a horizontal plane. The mLPCA was localized, and RI was calculated from velocities obtained for 3 similar Doppler waveforms. To determine the reproducibility of CDI-derived RI, measurements were repeated twice at a 10-day interval.
Results—Mean (± SD) RI of the mLPCA was 0.68 ± 0.07 (95% confidence interval, 0.65 to 0.70; n = 36 eyes). Resistive index did not significantly differ between right and left eyes or male and female dogs. In addition, body weight was not correlated with RI. Repeated measurements of RI did not yield significantly different results (interclass correlation coefficient, 0.8297).
Conclusions and Clinical Relevance—Color Doppler imaging appears to be a valid technique for determination of RI of the mLPCA in conscious dogs. This technique may be useful for investigating the pathophysiologic processes of many ocular and orbital vascular disorders in dogs. (Am J Vet Res 2002;63:211–214)