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نوع المنشور

ورقة مؤتمر

المؤلفون

Objectives: Claw lesions leading to lameness are frequent health disorders in dairy cows and require commonly surgical

correction for treatment. As part of a pain management protocol, local anesthesia is necessary for such surgical

interventions. Although, intravenous regional (IVRA) and nerve block anesthesia (NBA) are described in textbooks the

efficacy and onset of these two techniques are not yet evaluated in dairy cows. Therefore, efficacy and onset of

anesthesia in the distal hind limb after IVRA and NBA were tested by means of pain stimulation techniques.

Materials and Methods: Six healthy, non-lactating, non-pregnant German HF cows were used in a cross- over design

study. In all cows IVRA and NBA were tested in lateral recumbency on a surgical tipping table. For IVRA, 20 ml procaine

(Procasel 2%, WDT, Germany) were injected into the V. digitalis dorsalis communis III after application of an esmarch

bandage in the metatarsal region. NBA was performed at four sites using about 15 ml procaine at each site (A: superficial

and B: deep branches of the fibular nerve distally of the tarsal joint; C: lateral and D: medial branches of the tibial nerve

proximally of the due claws). Anesthesia was tested by assessment of thresholds of I: Electrical stimulation (Grass S48

Square Pulse Stimulator) at the dorso-lateral coronary band as well as soft skin of heel, and II) mechanical pressure

stimulation at the lateral and medial sites of the bulb of heel, flexor tendon and fetlock joint. Stimulation was performed

before (control) and 5, 7.5, 10, 12.5, 15 and 20 min after anesthesia. Reaching of the threshold level was assumed when

first, slight responses on stimulation such as claw movements were recognized. One cow was excluded from statistical

evaluation, because 20 min after anesthesia electrical stimulation revealed no complete onset of anesthesia. Results

were statistically evaluated by ANOVA for repeated measurements (SAS package Vers. 9.3).

Results: Before anesthesia reaction thresholds for electrical stimulation were in average 37 V (+/- 9, range 25 – 60) and

for pressure stimulation 17 N (+/- 4, range 9 – 20). Twenty min after anesthesia in statistically evaluated cows, tested

thresholds reached the preset maximum level of 150 V and 20 N for electrical and pressure stimulation, respectively.

However, the excluded cow showed after IVRA no reactions on pressure stimulation at 20N but reacted on electrical

stimulation at 120 V. After NBA all evaluated cows reached the maximum preset levels of electrical pain stimulation after

12,5 min at the heel and after 10 min at the coronary band. Maximum stimulation levels were reached not before 15 min

after IVRA which was significantly delayed compared to NBA cows (group and group * time interaction effects p < 0.05).

Conclusions: IVRA and NBA lead generally to anesthesia in the distal hind limb of dairy cows. Because in one cow IVRA

failed to induce full anesthesia, efficacy of both techniques need to be tested in a larger number of cows. Onset of

anesthesia in the distal hind limb of cows is significantly delayed after IVRA compared to NBA. Surgical treatments of

claw lesions in the field are commonly performed under time constraints. Therefore, the delay in the onset of anesthesia

after IVRA may have practical relevance in the view of animal welfare, when surgical interventions are executed before

full onset of anesthesia is achieved

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