Comparison of the effects of intranasal and intramuscular administrations of zolazepam-tiletamine combination on intraocular pressure in cats

Effects of propofol alone or in combination with ketamine on intraocular pressure in unpremedicated dogs

OBJECTIVE

To determine the effects of propofol (P) alone and in combination with ketamine (KP) at ratios of 1:1, 1:2, and 1:3 on intraocular pressure (IOP) in unpremedicated dogs.

ANIMALS STUDIED

A total of 28 cross-bred healthy dogs.

PROCEDURES

Dogs were randomly assigned to one of four groups (n = 7 per group) to receive intravenous P or KP at 1:1, 1:2, and 1:3 ratios, respectively. The infusion was administered at 0.6 mg/kg/min for 60 min. IOP, cardiorespiratory variables, rectal temperature (RT), and pedal reflex were recorded every 5 min for 60 min, starting from baseline (BL).

RESULTS

There was a statistically significant increase in IOP in all groups: P (p = .011), KP 1:1 (p = .003), KP 1:2 (p = .023), and KP 1:3 (p = .008). The IOP increase was less pronounced in the KP 1:2 group and was only significant (p = .023) at T45 compared with BL. A significant correlation was observed between IOP and SpO2 in P (r = -.215, p = .02), KP 1:2 (r = -.579, p < .01), and KP 1:3 (r = -.402, p < .01) groups. IOP significantly increased due to decreased SpO2 below 86.5% (p < .05).

CONCLUSIONS

Propofol alone and in combination with ketamine may increase preexisting IOP in unpremedicated dogs. SpO2 levels below 86.5% may trigger an increase in IOP. Administering KP in a 1:2 ratio at an infusion rate of 0.6 mg/kg/min does not significantly alter IOP for under 45 min in unpremedicated dogs with sufficient oxygenation.

Effects of intranasal and intramuscular administration of butorphanol and zolazepam-tiletamine combination on intraocular pressure and tear secretion in New Zealand White rabbits

This study aimed to compare the effect of intranasal (IN) and intramuscular (IM) administration of butorphanol and zolazepam-tiletamine (ZT) combination on intraocular pressure (IOP) and tear secretion (TS) in rabbits. Fourteen healthy male New Zealand White rabbits weighing 3.05 ± 0.72 kg, aged between 1 and 2 years old, were included in the study. Animals randomly received 0.5 mg/kg butorphanol and 15 mg/kg ZT combination either with IN or IM administration. IOP and TS were measured at baseline (T0), and followed by 5, 15, 30, 45, and 60 min after drug administration. The sedation variables, the time to onset of sedation, duration of sedation, and sedation scores were also recorded. The route of administration for the butorphanol and ZT combination had no significant effect on the mean IOP (p = .301) and TS (p = .445). Furthermore, there were no significant changes observed in the IOP (p = .472) and TS (p = .348) over time. The time to onset of sedation was earlier in the IN group (4.57 ± 0.79 min) than in the IM group (5.86 ± 0.9 min; p = .0004). The duration of sedation was significantly longer for IM (57.43 ± 3.41 min) compared with IN (45.0 ± 1.91 min; p < .0001). No significant difference in the sedation score was observed between groups at all time points. In conclusion, both IN and IM administration of the butorphanol and ZT combination in rabbits had similar effects on IOP and TS.

Comparison of intraocular pressure in New Zealand White rabbits measured using rebound and applanation tonometers and four different methods of physical restraint

AIMS

To compare intraocular pressure (IOP) measurements obtained in rabbits using rebound (TV) and applanation (TPV) tonometers with four different methods of physical restraint.

METHODS

A total of 20 New Zealand White rabbits (40 eyes) were included in this study. IOP readings were obtained from both eyes using the two different tonometers. The rabbits were placed on a table and restrained by wrapping in a cloth (Method I), by scruffing with rear support (Method II), by wrapping in a cloth and cupped in the hands (Method III), or by a box restrainer (Method IV).

RESULTS

The mean IOP measurement obtained by TPV was higher than that obtained with the TV for all handling methods. Mean differences (TV-TPV, in mmHg) in IOP were -5.3 (95% Cl = -6.5 to -4.1) for Method 1, -4.7 (95% Cl = -6.2 to -3.29) for Method II, -4.9 (95% Cl = -6.2 to -3.7) for Method III and -7.6 (95% Cl = -9.2 to -5.9) for Method IV. Using the TV tonometer, mean IOP for Method IV was higher than for Method I (mean difference 2.1 (95% Cl = 1.1-3.1)), whereas using the TPV tonometer, mean IOP for Method IV was significantly higher than Method I, II, and III (mean differences: 4.4 (95% Cl = 2.6-5.9), 3.7 (95% Cl = 2-5.3) and 3.8 (95% Cl = 2-5.4), respectively). According to Bland-Altman plots, IOP readings for TPV tended to be higher than those for TV with all handling methods, but with a lack of agreement. The mean difference and 95% limits of agreement for the differences between TV and TPV were -5.4 mmHg (-12.5-1.9 mmHg), -4.7 mmHg (-12.9-3.5 mmHg), -4.9 mmHg (-12-2.2 mmHg), and -7.5 mmHg (-17.4-2.3 mmHg), with Methods I, II, III, and IV, respectively. Comparing TV and TPV, only 7.5%, 12.5%, 27.5%, and 15% of IOP measurements from 20 rabbits were within the range considered clinically acceptable for IOP (± 2 mmHg) for Method I, II, III, and IV, respectively.

CONCLUSION AND CLINICAL RELEVANCE

In conclusion, the physical restraint method should be recorded when IOP is measured in rabbits, and TV and TPV tonometers cannot be used interchangeably (high bias and low proportion of measurements within ± 2 mmHg).

Intraocular pressure and cardiovascular effects of dexmedetomidine premedication and tiletamine-zolazepam for anesthetic induction in dogs

Background and Aim

The effect of anesthetic drugs on intraocular pressure (IOP) is an important concern in ophthalmic surgery. The impact of dexmedetomidine (DEX) combined with tiletamine-zolazepam on IOP is scarcely studied. This study aimed to evaluate IOP and cardiovascular effects in dogs after premedication with 5 μg/kg (DEX5) or 10 μg/kg (DEX10) of intramuscular DEX followed by intravenous tiletamine-zolazepam administration for induction of anesthesia in healthy dogs.

Materials and Methods

Eighteen dogs, American Society of Anesthesiologists I or II, without ocular abnormality were investigated. All dogs were randomly divided into the DEX5 (n = 9) and DEX10 groups (n = 9). The IOP, heart rate (HR), systolic blood pressure (SBP), oxygen saturation, and sedation scale were measured before premedication (baseline), after premedication at 5, 10, 15, and 20 min, after tiletamine-zolazepam administration, after endotracheal intubation, and post-operative.

Results

There were no significant differences between the groups at any time point. The DEX5 and DEX10 groups had significantly decreased HR values at 10 min compared with baseline. The IOP at 20 min was significantly lower compared to the baseline in the DEX10 group. Moreover, the DEX10 group showed increased IOP, HR, SBP, and sedation scale values after induction and intubation compared with 20 min, but these values did not differ significantly from baseline. All parameters of both groups did not change significantly between post-operative and baseline.

Conclusion

Intramuscular DEX (10 μg/kg) is an appropriate premedication in ophthalmic examination or surgical procedures. Moreover, it could be combined with tiletamine-zolazepam for generalized anesthesia in dogs with an ophthalmic problem, as it had no clinically significant effects on IOP or cardiovascular values.

Comparison of intratesticular and intramuscular administration of zolazepam-tiletamine combination on sedation, induction, and recovery qualities and vital variables in cats undergoing castration: a prospective, randomized, clinical study

This study was aimed to compare the effects of intratesticular (IT) and intramuscular (IM) administration of the zolazepam-tiletamine (ZT) combination on sedation, induction, and recovery qualities and vital variables in cats undergoing castration. Fourteen clinically client-owned healthy cats were randomly assigned to receive 10 mg/kg ZT by either IT or IM routes. Temperament score, injection reaction score, induction time, intubation time, surgical length, anesthesia time, recovery time, and full recovery time were evaluated. Sedation score, heart rate (HR), respiratory frequency (f_R), peripheral hemoglobin oxygen saturation (SpO₂), mean arterial pressure (MAP), and rectal temperature (RT) variables were assessed at baseline (T0), T5, T10, T15, and T30. Median temperament score and injection reaction score were not different between groups. Induction time was significantly (p = 0.0244) shorter for the IT group (142.6 ± 29.9) than IM (290 ± 48.7 seconds). Length of anesthesia was longer in the IM group (median 290; ranged 120-540 minutes) than the IT group (median 140; ranged 98-180 minutes) (p = 0.0279). Time to standing and time to full recovery were significantly shorter in IT than IM. A recovery quality score did not significantly differ between groups (p = 0.2268). No statistically significant differences were detected between IT and IM administration regarding sedation score, HR, SpO₂, MAP, and RT. The IT administration of 10 mg/kg ZT induces shorter onset of sedation and recovery time than IM administration, thereby it can be suggested for cats undergoing castration. Both administration routes produce effective sedation with limited physiological changes in anesthesia variables.

Sedative and physiologic effects of tiletamine-zolazepam following buccal administration in cats

OBJECTIVES

The aim of this study was to describe the sedative and some physiological effects of tiletamine-zolazepam following buccal administration (BA) in cats.

METHODS

Seven healthy spayed European shorthair cats (three males, four females) were studied twice in this randomized, blinded, crossover study. Each cat received two doses of tiletamine-zolazepam by BA: the low-dose (LD) group consisted of 5 mg/kg of each drug, and the high-dose (HD) group consisted of 7.5 mg/kg of each. Baseline systolic blood pressure (SAP), heart rate (HR), respiratory rate (RR) and a sedation score were recorded prior to administration of each treatment. The same variables plus the percentage of hemoglobin saturated with oxygen as measured by pulse oximetry (SpO2) were recorded at predefined intervals for the next 2 h.

RESULTS

All cats completed the study. No retching or vomiting were observed. Hypersalivation was observed in 0/7 and 3/7 for LD and HD groups, respectively (P = 0.2). There were significant changes in scores over time for posture, response to clippers and response to manual restraint for both groups, without differences between groups. RR, HR and SAP changed significantly over time. SAP and RR were significantly lower for the HD than for the LD group. No values for hemoglobin saturation <95% were observed.

CONCLUSIONS AND RELEVANCE

BA of tiletamine-zolazepam at the doses studied here is a simple and effective method for chemical restraint in cats, where the LD group had a lower impact on SAP and RR than the HD group.

Effects of aqueous suppressants and prostaglandin analogues on early wound healing after glaucoma implant surgery

A hypertensive phase frequently develops in the early postoperative period after glaucoma shunt operations. Anti-glaucoma eye drop use is essential when postoperative intraocular pressure (IOP) is not controlled. We investigated whether the use of early topical anti-glaucoma medication affects wound healing following glaucoma tube surgery. Eyes were randomly assigned to receive topical aqueous suppressant (timolol-dorzolamide fixed combination), prostaglandin (PG) analogue (travoprost), or normal saline (control group). First, we observed the effects of topical eye drops on Tenon’s tissue in non-operated eyes in rabbits. Second, we examined the effects of these eye drops on rabbit eyes that underwent Ahmed glaucoma drainage device implantation, including the effects on the histopathological appearance of their blebs. Interleukin-2 in the Tenon’s tissue was elevated in the PG group when compared to the control and aqueous suppressant groups (P = 0.006). In non-operated eyes, IOP was similar among the groups (P = 0.545). After glaucoma implant surgery, the average height of the inner collagenous layer and the average height of the α-SMA-positive blebs were the least in the aqueous suppressant group (P = 0.013, P = 0.001, respectively) at 4 weeks postoperatively. IOP was lower in the aqueous suppressant group than that in the control and PG groups (P = 0.001) following tube surgery. After Ahmed tube surgery, early treatment with aqueous suppressant decreased fibrosis in the bleb, but early treatment with the PG analogues did not.