Chemical restraint and analgesia in the horse

Clinical and Antinociceptive Effects of Distal Inferior Alveolar Nerve Block in Ponies With Tramadol 5% or Lidocaine 2

This study aimed to compare the antinociceptive effects of tramadol 5% and lidocaine 2% on mental nerve block in horses of the Brazilian Pony breed. Eight adult non-pregnant mares were used in this study. The ponies were tranquilized with acepromazine (5 µg kg^-1, IV), and the infiltration of the mental foramen was performed in Treatment 1- tramadol 5% (T, 150 mg) or Treatment 2- lidocaine 2% (L, 60 mg), both at a total dose of 3 ml in each foramen. Heart rate (HR), respiratory rate (RR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), rectal temperature (RT), and formation of skin lesions (SL) were evaluated. Evaluation of nociception of the outer lip (OL), inner lip (IL), and gingiva (GG) were performed using an electronic von Frey device with the evaluation of the ponies' reactions to each stimulus. From these reactions, we determined latency time (LT) and duration of antinociception (DAN). Analysis of variance with 16 observations was performed for HR, RR, SAP, DAP, MAP, LT and DAN. Data were expressed as mean ± standard deviation and the means were compared by the SNK and Student's t-test (P< 0.05). Changes in HR, RR, SAP, DAP, and MAP between evaluation times were associated with the effects of acepromazine (P>0.05). No formation of skin lesions was observed. Latency time did not differ between treatments (P>0.05). Both lidocaine 2% and tramadol 5% produced an antinociceptive effect. We conclude that the duration of the antinociceptive effect of tramadol 5% is longer than that of lidocaine 2%.

A Retrospective Study of Cryptorchidectomy in Horses: Diagnosis, Treatment, Outcome and Complications in 70 Cases

Simple Summary

Cryptorchidism is the failure of one or both testes to descend into the scrotum and is considered to be one of the most common developmental disorders in horses. The aim of the study was to review medical records of horses referred for uni- or bilateral cryptorchidism. It was observed that the Western Riding horse breeds were the most affected, and that left abdominal and right inguinal retentions were the most frequent. Transabdominal ultrasound was the most reliable diagnostic tool to localize the retained testis. Standing laparoscopic and open inguinal cryptorchidectomy were elected as the surgical treatment of choice, in case of abdominal retention and inguinal retention respectively. For incomplete abdominal retention, laparoscopy was the preferred treatment, even though an open inguinal approach was a viable option for the concurrent removal of the descended testis.

Abstract

The aim of the study was to investigate the breed predisposition and the diagnostic and surgical management of horses referred for cryptorchidism. The breed, localization of retained testis, diagnosis, type of surgical treatment and complications were analyzed. Seventy horses were included in the study; the Western Riding horse breeds were the most affected (Quarter Horse 34/70, 48.5%; Appaloosa 9/70, 12.8%). In unilateral cryptorchids (65/70, 92.8%) the most common location for a retained testis was the left abdomen (28/65, 43%), while in bilateral cryptorchids (5/70, 7.1%), bilateral abdominal retention was the most frequent (3/5, 6%). Information about testis localization was achieved through transabdominal ultrasound (30/49 cases, 61.2%), through per rectum palpation (21/49 cases, 42.9%) and through inguinal palpation (14/49 cases, 28.9%). Cryptorchidectomy was achieved with standing laparoscopy (44/70 cases, 62.8%), or with open inguinal orchiectomy in general anesthesia (26/70 cases, 37.2%). Complications during laparoscopy were spleen puncture (1/44, 2.2%), a self-limiting bleeding from the spermatic cord (10/44 cases, 22.7%), hyperthermia (3/44 cases, 6.8%), and emphysema (15/44, 34%). During inguinal open cryptorchidectomy difficulties with identifying the inguinal testis during surgery (8/26 cases, 30.8%) and a moderate and self-limiting swelling of the inguinal region after surgery (17/26, 65.4%) were observed. For orchiectomy, a standing laparoscopy was confirmed as the preferred procedure for an abdominally retained testis with almost no complications.

Histologic effects of MicroPulse™ transscleral cyclophotocoagulation in normal equine eyes

OBJECTIVE

Determine the immediate post-operative effects of MicroPulse^™ transscleral cyclophotocoagulation (MP-TSCPC) in healthy equine eyes.

ANIMALS STUDIED

Ten adult horses.

METHODS

MP-TSCPC was performed on sedated horses in 12 eyes (4 groups) using the following parameters (power, duration, duty cycle): (1) 2000 mW, 180 seconds, 31.3%; (2) 3000 mW, 180 seconds, 31.3%; (3) 3000 mW, 270 seconds, 31.3%; and (4) 3000 mW, 270 seconds, 50%. Three additional eyes were left untreated (control). Eyes were monitored clinically until euthanasia (mean = 3 hours post-procedure). Histologic sections were assessed with light microscopy and transmission electron microscopy (TEM).

RESULTS

MP-TSCPC was well tolerated by sedated horses. Adverse effects were only noted in Group 4: ocular hypertension (n = 3/3), conjunctival burns (3/3), aqueous flare (2/3), and a corneal erosion (1/3). Histologic scoring of Group 4 was statistically greater than other treated groups (1-3) and control eyes (P ≤ .021). TEM showed subtle changes to the mitochondria and plasma membrane infoldings of the basilar surface of the nonpigmented epithelium in all treated eyes.

CONCLUSIONS

MP-TSCPC does not cause immediate post-procedure adverse clinical effects or pronounced morphological changes to the ciliary body, except with the highest laser settings evaluated (power 3000 mW, duration 270 seconds, duty cycle 50%).

Evaluation of cranial tibial and extensor carpi radialis reflexes before and after anesthetic block in cats

Objectives This study aimed to test the extensor carpi radialis and cranial tibial reflexes in cats before and after anesthetic block of the brachial and lumbosacral plexus, respectively, to determine whether they depend on a myotatic reflex arc. Methods Fifty-five cats with a normal neurologic examination that were referred for elective gonadectomy were divided into group 1 (29 cats) for testing the extensor carpi radialis reflex, and group 2 (26 cats) for testing the cranial tibial reflex. In group 1, the extensor carpi radialis reflex was tested after anesthetic induction and 15 mins after brachial plexus block with lidocaine. In group 2, the cranial tibial, withdrawal and patellar reflexes were elicited in 52 hindlimbs and retested 15 mins after epidural anesthesia. Results In group 1, before the anesthetic block, 55.17% of the cats had a decreased and 44.83% had a normal extensor carpi radialis reflex. After the block, 68.96% showed a decreased and 27.59% a normal reflex. No cat had an increased or absent reflex before anesthetic block. In group 2, prior to the anesthetic block, 15.38% of the cats had a decreased cranial tibial reflex and 84.62% had a normal response, whereas after the block it was decreased in 26.92% and normal in 73.08% of the cats. None of the cats had an increased or absent reflex. Regarding the presence of both reflexes before and after anesthetic block, there was no significant difference at 1% ( P = 0.013). Conclusions and relevance The extensor carpi radialis and cranial tibial reflexes in cats are not strictly myotatic reflexes, as they are independent of the reflex arc, and may be idiomuscular responses. Therefore, they are not reliable for neurologic examination in this species.

Tranquilização de asininos com acepromazina associada ou não ao diazepam

Avaliaram-se os efeitos da acepromazina isolada ou associada ao diazepam em asininos. Cinco asininos foram submetidos a dois protocolos anestésicos: os do grupo acepromazina (AC) receberam acepromazina, 0,1mg/kg/IV, e os do grupo acepromazina-diazepam (ACD), acepromazina na mesma dose e via do AC, associada ao diazepam, 0,1mg/kg/IV. Foram mensuradas as frequências cardíaca (FC) e respiratória (FR) e a temperatura retal (TR) e analisadas variáveis eletrocardiográficas, tranquilização, período de latência, início do prolapso peniano e grau de ataxia. A tranquilização iniciou-se aos 10,4±0,9 minutos nos asininos do AC e aos 4,8±1,1 nos do ACD. Ocorreu prolapso peniano aos 4,2±1,3min no AC e aos 2,7±0,4 no ACD. A FC elevou-se aos 15 e 30min no AC. Não ocorreu variação significativa nas variáveis eletrocardiográficas e na temperatura retal. A FR diminuiu no AC a partir de 60min e no ACD a partir de 30min. A distância focinho-solo reduziu-se significativamente em ambos os grupos e nos momentos a partir de 15min. Concluiu-se que a acepromazina promove tranquilização discreta, e a adição do diazepam potencializa a tranquilização, diminui o período de latência e aumenta a ataxia.

Comparison of morphine and butorphanol as pre-anaesthetic agents in combination with romifidine for field castration in ponies

OBJECTIVE

The aim of this study was to compare two different alpha2 agonist-opioid combinations in ponies undergoing field castration.

STUDY DESIGN

Prospective double-blind randomized clinical trial.

ANIMAL POPULATION

Fifty-four ponies undergoing field castration.

MATERIALS AND METHODS

The ponies were randomly allocated to receive one of three different pre-anaesthetic medications [intravenous (IV) romifidine 100 microg kg(-1) and butorphanol 50 micro kg(-1); romifidine 100 microg kg(-1) and morphine 0.1 mg kg(-1) IV, or romifidine 100 microg kg(-1) and saline IV] before induction of anaesthesia with ketamine 2.2 mg kg(-1) IV. Further doses of romifidine (25 microg kg(-1)) and ketamine (0.5 mg kg(-1)) were given when required to maintain anaesthesia. Quality of sedation, induction of anaesthesia, maintenance of anaesthesia, recovery, and surgical condition were assessed using a visual analogue scale scoring system and compared. The effects of the different drug combinations on heart and respiratory rate were evaluated and the recovery time was recorded.

RESULTS

Anaesthesia was considered adequate for surgery in all ponies. No anaesthetic complications were observed. Quality of sedation was significantly better in the butorphanol group compared with the control group (p = 0.0428). Overall quality of anaesthesia was better in the butorphanol group compared with morphine (p = 0.0157) and control (p < 0.05) groups. Quality of induction of anaesthesia and recovery were not significantly different between groups, nor were the surgical conditions, recovery time and the number of repeated anaesthetic doses required during the procedure. Muscle twitches were observed in both the control and morphine groups. Maintenance of anaesthesia was judged to be smoother in the butorphanol group compared with the morphine and control groups (p = 0.006). Heart rate decreased significantly (p < 0.01) in all groups after administration of sedatives but did not differ significantly between groups at any time point.

CONCLUSION

The combination of butorphanol and romifidine was found to provide better sedation compared with the other drug combinations.

CLINICAL RELEVANCE

The combination of butorphanol and romifidine provided better sedation, but morphine was found to be a suitable alternative to butorphanol. Use of morphine and butorphanol in combination with alpha2 agonists should be further investigated to assess their analgesic effects.

Management of gastrointestinal pain

Choice of an analgesic for gastrointestinal pain requires consideration of the cause of the pain, desired duration of pain relief, need for sedation, and potential side effects and toxicity, particularly in light of other drugs being used and effects on the gastrointestinal tract. It is imperative that close monitoring be continued to ensure that surgical lesions or worsening conditions are detected. Recent research in the field may lead to new drugs, drug combinations, and avenues of treatment that minimize the side effects of these drugs while maximizing their efficacy.

Management of equine orthopedic pain

Pain management is an extremely vital part of equine orthopedic surgery. Providing optimum analgesia for the patient will decrease recovery time, decrease physiologic stress on the animal, and provide maximum comfort during the post-operative period. The major analgesic drug categories and routes covered are nonsteroidal anti-inflammatory drugs, local anesthetics, intra-articular drugs, and epidurals.

Traditional and non-traditional uses of anesthetic drugs--an update

Many new or modified injectable anesthetic techniques are available for use in horses. This increased availability allows the clinician to select the technique most appropriate for the patient and clinical circumstance. The use of sedative and anesthetic drugs in managing a variety of anesthesia-related and unrelated aspects of patient care is also increasing. As we begin to use these techniques in the clinical management of our patients, it is important to remember that, while there are more options, no single anesthetic agent or combination of agents is devoid of undesirable effects. Knowledge of the pertinent advantages and disadvantages of the drugs when used individually and in combination and appropriate patient monitoring are essential to ensure a positive outcome.

Sedatives, tranquilizers, and stimulants

Drugs of relevance to equine practice that modify the central nervous system (CNS) can be broadly classified as depressants or stimulants. The pharmacologic mechanisms of action, uses, and side effects of selected CNS depressant and stimulant drugs in horses are reviewed. Knowledge of the way these CNS-modifying drugs may affect performance is limited.