Key Points

• A study was conducted to determine the sedation protocols and re-sedation (i.e., inadequate primary sedation) rates reported by 10 equine veterinarians in the performance of 363 power-floating procedures.
• The study revealed that the power dentistry test procedure was most profitable when re-sedation did not occur, and that inadequate primary sedation was the key factor contributing to incidence of re-sedation.
• Lack of a standard of care for the equine dentistry procedure resulted in widely varying re-sedation rates ranging from 2.5% to 73.5%, with an overall rate of 27.8%.
• DORMOSEDAN® (detomidine hydrochloride) was used as an alpha-2 agonist sedative in 92.1% of the cases, but usually in combination protocols and, in 67% of the cases, at suboptimal (less than the lowest approved) dose.
• The study revealed five consequences of re-sedation compared to cases where re- sedation was not required: longer procedure time, lower quality of sedation, higher sedation fees to the client, higher sedation costs to the veterinarian, and a decreased effective hourly billing rate (EHBR) for nonsedation charges.
• The three veterinarians with the lowest re-sedation rates (representing 96 cases) had a superior quality-of-sedation score (4.22 vs. 3.15 on a five-point scale from lowest to highest) and a $40.24 better EHBR ($330.32 vs. $290.08) for nonsedation charges when compared with the three veterinarians with highest re-sedation rates (representing 113 cases).
• The two most common causes of re-sedation were a sub-optimal initial sedative dose and failure to allow adequate time (at least 5 minutes) to elapse between administration of the sedative and initiation of the power floating procedure.
• Results indicate that a re-sedation rate of ≤ 10% is an achievable goal and associated with superior case outcomes in terms of quality, time, and compensation.
• Practitioners can establish an effective sedation protocol by using an equine-approved sedative such as DORMOSEDAN at an appropriate primary dose that provides an adequate response, tracking the resedation rate, and adjusting the protocol accordingly.
• An effective sedation protocol may be applied not only to power floating but to any repetitive procedure (eg, diagnostic procedures, examinations, wound treatment) in equine practice.

As practiced today, equine sedation for standing procedures typically involves administering a combination of any of several sedatives, tranquilizers, or opioid analgesics.

Alpha-2 agonists are widely used in these combination protocols because they provide rapid andreversible, dose-dependent sedation, are nonnarcotic (nonscheduled), and produce clinically significant analgesia as well asprofound sedation.

Although Zoetis does not endorse extra-label use of products, the practice of multidrug sedation remains the norm in equine medicine. This is partly due to the limitations of xylazine, the original veterinary alpha-2 agonist.

Xylazine is short acting, delivers comparatively poor analgesia, and has a lower alpha-2 receptor specificity and potency compared to detomidine hydrochloride (DORMOSEDAN, Zoetis),1-4 a more potent and selective alpha-2 agonist developed after the introduction of xylazine.

This has given rise to the use of various off-label drug combinations for equine sedation, an approach intended to provide a synergistic or supplementary effect to compensate for the limitations of xylazine.

Examples include use of DORMOSEDAN and xylazine (two alpha-2 agonists) and DORMOSEDAN or xylazine and butorphanol (an alpha-2 agonist and opioid). When combination protocols are used, each drug is usually given at lower than recommended dosages, often for purposes of reducing drug costs.

An important disadvantage of this deliberate underdosing is suboptimal depth and duration of sedation. When that occurs, the horse resumes vigilance, lifts its head, moves about, and needs to be re-sedated or “topped up.” This interrupts and prolongs the procedure and adds to drug costs.

The study described in this report evaluated the frequency of re-sedation reported by 10 equine veterinarians and the effect of re-sedation on procedure duration, quality of sedation, and economic return to the veterinarian. Power floating using a motorized grinding tool was used as the test procedure in all cases.

This provided a relatively uniform procedure, billable on a cost-plus-fee basis, with minimal variation in time and technique for evaluating outcomes. A large number of cases (n = 363) gave statistical validity to the study.

Study Design

Ten equine practitioners were selected for the study. All 10 participants used DORMOSEDAN as a component of their sedation protocol,either as monotherapy at relatively high doses or combined with other agents at lower than approved doses. Veterinarians administered DORMOSEDAN by the approved intramuscular (IM) or intravenous (IV) routes according to individual preference.

A diary study format was used whereby participants provided on-site data in response to a standard set of questions for each case. Each veterinarian documented up to 40 power dentistry cases requiring standing sedation. For each equine patient, the veterinarian recorded the sedation protocol used, whether re-sedation was required, overall duration of the procedure, and quality of sedation achieved as scored on a 1 to 5 scale from lowest to highest quality.

If multidrug protocols were used, each drug was identified and the dosage volume and time of administration were indicated.

Participating veterinarians also noted the fee charged for each case, itemized by sedation and nonsedation charges. An average effective hourly rate (EHBR) was calculated for nonsedation fees, the component of the total fee not affected by additional drug costs that can be passed on to the client.

The EHBR was prorated by the average time to completion of the procedure, using the following formula: where EHBR is in dollars, Fp is the fee for the procedure, and Tp is the time for completion of the procedure.

Average EHBRs were calculated for cases requiring re-sedation and those requiring primary sedation only. EHBR = Fp ÷ (Tp mins ÷ 60 mins),

Results Sedation Regimens

Four different protocols were used for primary sedation and seven different protocols for re-sedation, usually involving multidrug combinations given at partial dosages of the individual agents used. Five of the 10 veterinarians used DORMOSEDAN in combination with other sedative or analgesic agents as a primary sedation regimen, while four veterinarians used DORMOSEDAN as primary monotherapy. One veterinarian used xylazine and butorphanol as primary cotherapy.

For re-sedation, five veterinarians used regimens that differed from their primary regimen. The remaining five veterinarians used their primary regimens for re-sedation. Two veterinarians used DORMOSEDAN exclusively for primary sedation and re-sedation. DORMOSEDAN was used in 92.1% of the cases in the study, either for primary or secondary sedation or both.

Sedation Dosing Patterns

The two most common reasons for needing to re-sedate an animal is:

1. Inadequate level of primary sedation. (too small of a starting dose for that particular animal)
2. Inadequate wait time after giving the sedation before starting the procedure.

All 10 participating veterinarians used DORMOSEDAN in either their primary or secondary protocols. Figure 1 (on page 4) shows the distribution of DORMOSEDAN dosage sizes for 363 cases. In a total of 243 cases (66.9%), the attending veterinarian used DORMOSEDAN at a dosage less than the lowest approved dose of 0.009 mg/lb (20 μg/kg). The highest DORMOSEDAN dose given to any individual horse was 0.016 mg/lb, slightly less than the maximum approved dose of 0.018 mg/lb (40 μg/kg). There were no adverse drug-associated safety events in any horse treated with DORMOSEDAN.

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Press release by ZOETIS