Effects of premedication with oral gabapentin on intraocular pressure changes following tracheal intubation in clinically normal dogs.

BACKGROUND: Gabapentin is an antiepileptic drug widely approved as an add-on therapy for epilepsy treatment in human and dogs. There is a clinical impression that gabapentin is a suitable drug which attenuates the IOP elevation associated with tracheal intubation in humans. The present study performed to determine the effects of oral gabapentin on intraocular pressure (IOP) changes following tracheal intubation in dogs. RESULTS: Twenty adult healthy dogs were randomly assigned to treatment (n = 10) and control (n = 10) groups. Dogs in the treatment group received oral gabapentin (50 mg/kg) 2 h before induction of anesthesia and dogs in the control group received oral gelatin capsule placebo at the same time. The dogs were anesthetized with propofol 6 mg/kg, and anesthesia was maintained with a constant infusion of 0.2 mg/kg/min of propofol for 20 min. IOP were measured immediately before induction and then repeated immediately after induction, as well as 5 min, 10 min and 15 min following tracheal intubation in both groups. IOP was significantly higher immediately after induction, and 5 min after tracheal intubation when compared with IOP reading before induction in the control group. There was no statistically significant change in IOPs immediately after induction, and 5 min after tracheal intubation in comparison to the values before induction in the treatment group. CONCLUSIONS: Based on the findings of this study, preanesthetic oral administration of gabapentin significantly prevents an increase in the IOP associated with tracheal intubation in dogs anesthetized with propofol.

Results of the Schirmer tear test performed with open and closed eyes in clinically normal horses.

BACKGROUND: The Schirmer tear test (STT) is widely used in both human and veterinary ophthalmology. Two types of STTs have been developed: STT I and SST II. The STT I measures the basal and reflex tear production and is the most widely used STT. However, several factors influence the STT results such as the person performing the test and the location of the strip placement within the conjunctival sac. The aim of this study was to measure the basal and reflex tear production (STT I) in clinically normal horses with open versus closed eyes. RESULTS: Forty clinically healthy horses without any ocular diseases were included. On day 1, the STT I was first performed on all the horses with the eyes open followed by an STT I with closed eyes performed 30 min later. On day 2, all horses had their eyes closed during the first STT and the eyes open during the second test performed 30 min later. The mean value of the STTs performed on open eye was significantly less than the STT performed on closed eye on both days of examination. CONCLUSION: This study showed a small but statistically significant difference between STT values obtained with open versus closed eyes in clinically normal horses.

Measurement of Tear Production in English Angora and Dutch Rabbits.

The purpose of this study was to establish normal values for tear production tests in different breeds of domestic rabbits. Healthy adult rabbits (n = 60; 120 eyes) of 2 different breeds (English angora and Dutch; n = 15 of each sex and breed) were used in this study. Tear production was measured by using the 1-min Schirmer tear test (STT), phenol red thread test (PRTT), and endodontic absorbent paper point tear test (EAPTT). In addition, horizontal palpebral fissure length was evaluated as a measure of ocular adnexal dimensions. Tear production (mean ± 1 SD) in English angora rabbits was 5.4 ± 1.6 mm/min according to the STT, 25.0 ± 2.7 mm in 15 s for the PRTT, and 18.8 ± 2.1 mm/min by the EAPTT; in Dutch rabbits, these values were 4.6 ± 1.2 mm/min, 23.6 ± 2.3 mm in 15 s, and 16.9 ± 1.7 mm/min, respectively. Only the EAPTT revealed a significant difference in tear production between English Angora and Dutch rabbits. These results provide reference values for tear production in English Angora and Dutch rabbits according to 3 different quantitative tear film assessment methods.

Measurement of tear production using phenol red thread and standardized endodontic absorbent paper points in European pond turtles (Emys orbicularis).

The objective of this study was to determine the aqueous fraction of the tear film using the phenol red thread test (PRTT) and paper point tear test (PPTT) in healthy adult European pond turtles (Emys orbicularis). Twenty-four healthy adult European pond turtles were studied. Measurement of tear secretion was performed using the PRTT and standardized endodontic absorbent PPTT. Horizontal palpebral fissure length (HPFL) was measured using digital calipers and was correlated with the weight of the animal. The mean ± SD PRTT, PPTT, and HPFL values for the left and right eyes were 5.12 ± 1.54 mm/15 sec and 4.62 ± 1.76 mm/15 sec; 4.50 ± 1.25 mm/1 min and 4.20 ± 1.53 mm/1 min; and 8.4 ± 0.6 mm and 8.3 ± 0.6 mm, respectively. No significant differences were detected between right and left eyes of individual turtles or between males and females in all tests. This study represents reference values of tear production in European pond turtles obtained from PRTT and PPTT methods and forms an important baseline study in defining the healthy chelonian ocular surface.

Determination of reference values for intraocular pressure and Schirmer tear test in clinically normal ostriches (Struthio camelus).

The purpose of this study was to establish normal physiologic reference values for intraocular pressure (IOP) and Schirmer tear test (STT) results in clinically normal ostriches (Struthio camelus). Twenty ostriches of both sexes, 10 juveniles (1.5-2 yr of age) and 10 adults, were included in this study. Complete ophthalmic examination was performed prior to this investigation. STT was performed by inserting a standard sterile STT strip over the ventral lid margin into the ventral conjunctival sac for 60 sec. Following the STT, IOP was measured using applanation tonometry with the Tono-Pen Vet tonometer after topical instillation of one drop of 0.5% proparacaine ophthalmic solution. The mean +/- SD and range of Tono-Pen readings of IOP for all birds was 18.8 +/- 3.5, with a range of 12-24. Mean IOP in juvenile ostriches was 19.7 +/- 3.6. Mean IOP in adult ostriches was 16.9 +/- 2.9. There was no statistically significant difference between young and adult birds (P = 0.07). The mean STT values in the present study were 16.3 +/- 2.5 mm/1 min when measurements from both eyes were averaged. Mean STT in juvenile and adult ostriches was 15.4 +/- 1.8 and 17.2 +/- 2.9 mm/1 min, respectively. There was no statistically significant difference between young and adult birds (P = 0.11). No statistically significant differences between genders were found for any of the results (P > or = 0.41). In conclusion, this study provides normal reference range values for STT and IOP in clinically healthy ostriches.

Results of Schirmer tear test in clinically normal llamas (Lama glama).

PURPOSE: To determine the normal reference range for Schirmer tear test (STT) values in clinically normal llamas (Lama glama) ANIMALS: Nine captive llamas (Lama glama) (seven females and two males) were used in this study. PROCEDURE: Complete ophthalmic examinations were performed without chemical restraint. STT I values were evaluated in both eyes of all llamas using a commercial STT strip of a single lot number (Schirmer-Tränentest(®), Germany). STT II value was also measured in both eyes of seven female llamas. RESULTS: No statistically significant differences among ages or between right and left eyes were found for any of the results. The mean ± SD STT I of 18 eyes of nine llamas was 17.3 ± 1.1 mm/min (Range 15-19 mm/min). The mean ± SD STT II of 14 eyes of seven llamas was 15.4 ± 1.7 mm/min (Range 12.5-17.5 mm/min). A paired samples t-test demonstrated that there was a significant difference between the STT I and II values (P = 0.001). CONCLUSION: This study provides novel data for normal reference ranges of STT I and II values in healthy llamas. Results of this study may assist veterinarians in the diagnosis of ocular surface disease and syndromes affecting the tear film in these species.

Reference values for Schirmer tear tests I and II in clinically normal pigs.

OBJECTIVE: To determine reference values for Schirmer tear tests I and II in clinically normal pigs. ANIMAL STUDIED: Twenty clinically normal Landrace pigs (10 males and females) without ocular abnormalities were used in this study. PROCEDURES: In all pigs, Schirmer tear tests (STT) I and II were performed by using a sterile Schirmer tear test standardized strip (Schirmer-Tränentest(®), Germany) placed in the lower conjunctival fornix for 1 min. RESULTS: For each test (STT I and STT II), no differences were observed between the right and left eyes (P ≥ 0.5). The mean ± SD STT I value was 15.6 ± 3.7 mm/min (range, 10-22 mm/min), while the mean STT II value was 12.4 ± 3.8 mm/minute (range, 5-18 mm/min). The mean STT II value was significantly lower than the STT I level (P < 0.001). Animal gender did not have a significant effect on STT I and II values (P = 0.52). The mean ± SD STT I/II values of 10 juvenile pigs were significantly lower than the mean ± SD STT I/II values of 10 adult pigs (P < 0.001). CONCLUSIONS: This study of 20 Landrace pigs provided valuable information on normal STT I/II in this species. Knowledge of normal STT reference values in pigs enables the clinician to evaluate corneal pathology and diagnose tear deficiency syndromes with greater accuracy.

Intraocular pressure and Schirmer tear test results in clinically normal Long-Eared Hedgehogs (Hemiechinus auritus): reference values.

OBJECTIVE: The present study was undertaken to establish reference values for Schirmer tear test (STT) and intraocular pressure (IOP) in the long-eared hedgehog (Hemiechinus auritus). ANIMALS: Fourteen healthy long-eared hedgehogs (H. auritus) of either sex were studied. PROCEDURES: The hedgehogs were individually immobilized with an intramuscular injection of combined Ketamine (20 mg/kg) and Diazepam (0.5 mg/kg), and each animal underwent ophthalmic examinations including: STT, tonometry, biomicroscopy, and indirect ophthalmoscopy. RESULTS: No significant effects of animal gender, weight, side (right vs. left eye) were found in this study. Mean (SD) STT values for all eyes (n = 28) were 1.7 ± 1.2 mm/1 min with a range of 0-4 mm/1 min. Mean STT in male animals was 2.2 ± 1.2. Mean STT in female Hedgehogs was 1.3 ± 1.1. Mean (SD) IOP values by applanation tonometry were 20.1 ± 4.0 mmHg (range 11.5-26.5 mmHg). Mean (SD) IOP values by applanation tonometry were 18.2 ± 4.0 and 22.0 ± 3.2 mmHg for males and females, respectively. CONCLUSIONS: This study reports STT and IOP findings in long-eared hedgehogs (H. auritus).

Effects of short-term oral administration of propranolol on tear secretion in clinically normal dogs.

This study evaluated the effects of short-term oral administration of propranolol on tear secretion in 15 clinically normal crossbreed dogs. The treatment group (n = 8) received propranolol (2 mg/kg q8h) orally for 7 days. The control group (n = 7) received placebo during the study. Schirmer I tear tests were performed on both eyes 1 d prior to drug administration (T(0)), at 1 (T(1)), 3 (T(3)), and 7 (T(7)) days of treatment. Tear production in dogs, measured by STT, was not significantly reduced in both groups.

The effects of ketamine-midazolam anesthesia on intraocular pressure in clinically normal dogs.

OBJECTIVE: To determine the effects of intravenous ketamine-midazolam anesthesia on intraocular pressure (IOP) in ocular normotensive dogs. ANIMALS: Thirteen adult mixed-breed dogs. PROCEDURES: Dogs were randomly assigned to treatment (n = 7) and control (n = 6) groups. Dogs in the treatment group received intravenous ketamine 15 mg/kg and midazolam 0.2 mg/kg and dogs in the control group received intravenous saline. The time of intravenous drug injection was recorded (T(0)). Measurements of IOP were then repeated 5 min (T(5)) and 20 min (T(20)) following the intravenous administration of ketamine-midazolam combination and saline in both groups. RESULTS: Measurements showed normal IOP values in both groups. The mean + or - SD baseline IOP values for treatment and control groups were 13.00 + or - 1.47 and 10.33 + or - 2.20, respectively. For baseline IOP values, there was no significant difference between treatment and control groups (P = 0.162). In the treatment group, the subsequent post-treatment mean + or - SD values were 15.64 + or - 2.17 (5 min), and 14.92 + or - 1.98 (20 min). There was no evidence of statistical difference between baseline values and post-treatment values after treatment with ketamine-midazolam (P(5) = 0.139; P(20) = 0.442). In control eyes, the mean + or - SD values at 5 and 20 min were 10.41 + or - 2.01 and 10.16 + or - 1.69, respectively. There was no significant difference between baseline values and post-treatment values in control group (P(5) = 1.000; P(20) = 1.000). CONCLUSION: Ketamine-midazolam combination has no clinically significant effect on IOP in the dog.

Effects of ketamine-diazepam and ketamine-acepromazine combinations on intraocular pressure in rabbits.

OBJECTIVE: To determine the effects of ketamine-diazepam and ketamine-acepromazine combinations on intraocular pressure (IOP) in rabbits. STUDY DESIGN: Randomized clinical trial. ANIMALS: Sixteen adult New Zealand white rabbits approximately one year old, weighing 2.3 +/- 0.2 kg were used in this study. METHODS: The animals were randomly divided into two groups of eight each (KA and KD). The pre-treatment IOPs were recorded in both groups (T0). All rabbits in group KA received intramuscular ketamine-acepromazine (ketamine 30 mg kg(-1) + acepromazine 0.5 mg kg(-1)). Ketamine-diazepam (ketamine 30 mg kg(-1) + diazepam 1 mg kg(-1)) was administered intramuscularly in members of group KD. The IOP values were measured at 5 (T(5)), 15 (T(15)), and 20 (T(20)) minutes after drug administration in both treatment groups. RESULTS: Significant increases in IOP values were observed in both treatment groups at T(5,) T(15), and T(20) in comparison to the baseline values. In group KA the mean +/- SD IOP at T(5,) T(15), and T(20) were 37 +/- 13 (p < 0.001), 35 +/- 4 (p < 0.001) and 34 +/- 4 mmHg (p < 0.001). The post-treatment mean +/- sd values in group KD were 23 +/- 8 (p = 0.002), 23 +/- 5 (p < 0.001) and 23 +/- 6 mmHg (p = 0.001) at 5, 15, and 20 minutes respectively. CONCLUSION AND CLINICAL RELEVANCE: Both ketamine-diazepam and ketamine-acepromazine combinations increased IOP after intramuscular administration in rabbits.

Effect of acepromazine or xylazine on tear production as measured by Schirmer tear test in normal cats.

OBJECTIVE: To evaluate the effect of acepromazine or xylazine on Schirmer tear test 1 results in clinically normal cats. ANIMALS: Sixteen healthy cross-breed cats. PROCEDURE: The animals were randomly divided into two groups of eight cats each. The first group was sedated with acepromazine alone (0.2 mg/kg) and the second group received only xylazine (2 mg/kg). All cats had Schirmer tear test (STT) readings taken prior to sedation and at 15 and 25 min postsedation. RESULTS: Sedation with acepromazine or xylazine in cats with normal pre-sedation STT 1 values caused a statistically significant decrease in mean values of tear production in both groups. In acepromazine group the mean +/- SEM STT at T(15) and T(25) were 4.31 +/- 0.98 (P < 0.001) and 5.18 +/- 1.07 (P = 0.002). The post-treatment mean +/- SEM values in xylazine group were 2.18 +/- 0.97 (P < 0.001) and 2.62 +/- 1.17 (P = 0.001) at 15 and 25 min respectively. Comparison between T(15) and T(25) in acepromazine group (P = 0.49) and xylazine group (P = 0.56) revealed no significant differences. CONCLUSION: These observations indicate that both acepromazine or xylazine significantly reduced tear production in clinically normal cats. In cats, clinicians should measure STT values prior to utilizing acepromazine or xylazine as sedatives in order to accurately assess the results. Moreover, sterile ocular lubricant or tear replacement should be used as a corneal protectant during sedation with these drugs.

The effects of intravenous ciprofloxacin on the electrocardiogram of healthy dogs.

The purpose of this study was to evaluate the electrocardiographic effects of single intravenous dose of ciprofloxacin in dogs. Ten adult cross-breed dogs of both sexes were selected as the sample population. Baseline electrocardiographic values were recorded just before drug administration. Then the dogs received intravenous infusion of ciprofloxacin (10 mg/kg) over the fifteen minutes. The ECGs recorded at 15, 30, 60 and 120 minutes after ciprofloxacin administration. The ECG measurements of heart rate, PR interval, QRS interval, ST segment, T-wave amplitude and QT interval were taken from lead II. There was a small but significant increase in the longest QT intervals over baseline at T60 (P = 0.041). The mean PR intervals, QTc intervals, JT intervals, ST segment, T-wave amplitude did not differ significantly before and after ciprofloxacin except for JT intervals at T60 (P = 0.041). At this measurement point, there was an increased QT interval value of 0.02 second or 9.51% in comparison to the baseline. In Conclusions, Only minor QT intervals changes were observed after ciprofloxacin injection. Despite the occurrence of ECG changes following intravenous ciprofloxacin administration neither dangerous rhythm disturbances nor serious ECG changes were seen in this study.