Pain control in horses: What do we really know?

Currently, approaches to pain control in horses are a mixture of art and science. Recognition of overt pain behaviours, such as rolling, kicking at the abdomen, flank watching, lameness or blepharospasm, may be obvious; subtle signs of pain can include changes in facial expression or head position, location in the stall and response to palpation or human interaction. Nonsteroidal anti‐inflammatory drugs (i.e. phenylbutazone, flunixin meglumine and firocoxib), opioids (i.e. butorphanol, morphine and buprenorphine) and α₂‐adrenergic agonists (i.e. xylazine, detomidine, romifidine and medetomidine) are the most commonly used therapeutic options. Multimodal therapy using constant‐rate infusions of lidocaine, ketamine and/or butorphanol has gained popularity for severe pain in hospitalised cases. Drugs targeting neuropathic pain, such as gabapentin, are increasingly used for conditions such as laminitis. Optimal strategies for management of pain are based upon severity and chronicity, including special considerations for use of intra‐articular or epidural delivery and therapy in foals. Strategies that aim to mitigate adverse effects associated with use of various analgesic agents are briefly discussed.     

Is there a predictable correlation between time of birth, birth and the puerperal period and clinical and hormonal findings in horses?

The investigations were done on 108 mares (78 warm-blooded horses, 25 cold-blooded horses and 5 trotters). To pursue the question in the title, progesterone and estradiol values in jugular vein-blood were examined starting from 30 days before the calculated date of parturition until 30 days after that event. In parallel to that Ca/Mg ratio was measured by means of a semiquantitative test-strip in the milk. Clinical signs of the birth, parturition itself and the post partum period were recorded. In respect to the P4 and E2 values it was that the P4:E2 ratio changed towards parturition in favour to E2 which was interpreted as a sign for the beginning of labour contractions as well as a signal to the ovarian hormonal activity and feed-back regulation. The "predict of the foal-test" by measuring Ca/Mg ratio is helpful only in combination with clinical findings. This test can be used for the decision to induce parturition. Concerning the colour and viscosity of the milk, it was observed to change from grey-aqueous 48 h a.p. through grey-brownish 24 h a.p. to white-yellow and viscous 12 h a.p. The results show that heavy mares more often retain the fetal membranes. They often bear lighter offspring with equally lighter fetal membranes, and the surfaces of the microvilli of the microcotyledonas seem to be smaller. Beside this it is concluded that during pregnancy disturbances in the fetomaternal relations probably exist as a result of a deficiency in placental development that finally results in retention secundinarum.     

Cardiovascular changes in horses with atrial fibrillation and high thyroid hormone concentration: a case–control study

IntroductionHyperthyroidism is a predisposing factor for atrial fibrillation (AF) in humans. The relationship between high thyroid hormone (TH) and AF in horses has not been evaluated.ObjectivesThe aim of this study is to identify whether (1) high TH concentrations were present in horses with AF, (2) other cardiovascular effects were observed in horses with high TH and AF, and (3) TH status affected recurrence rate.AnimalsTwenty-three horses presented with naturally occurring AF.MethodsProspective case–control clinical study. Thyroid hormone concentration was measured in horses presenting with AF. Heart rate, electrocardiogram, blood pressure, and an echocardiogram were recorded as part of their clinical workup. Recurrence rate was determined by owner/veterinarian follow-up.ResultsHigh TH concentration was found in 60% of horses with AF. Horses in the high TH group had a higher heart rate (P=0.001), systolic blood pressure (P=0.019), left ventricular free wall thickness (P=0.026), relative wall thickness (P=0.041) and were more likely to have periods of AF with a rapid ventricular response rate (P=0.022). All horses were successfully converted to normal sinus rhythm. The likelihood of recurrence was not different between groups.ConclusionElevated TH concentration can be found in horses with AF. Other cardiovascular effects of high TH concentrations in other species were also present in horses with AF and elevated TH concentrations. This study recommends measuring TH concentrations in horses presenting for AF with a history of thyroid or iodine supplementation. This study also cautions against TH or iodine supplementation in healthy performance horses.     

Effects of intramuscular and intranasal administration of midazolam–dexmedetomidine on sedation and some cardiopulmonary variables in New Zealand White rabbits

ObjectiveTo compare the sedative and cardiopulmonary effects of intranasal (IN) and intramuscular (IM) administration of dexmedetomidine and midazolam combination in New Zealand White rabbits.Study designA randomized, crossover experimental study.AnimalsA total of eight healthy New Zealand White rabbits, aged 6–12 months, weighing 3.1 ± 0.3 kg (mean ± standard deviation).MethodsThe animals were randomly assigned to administration of dexmedetomidine (0.1 mg kg^–1) with midazolam (2 mg kg^–1) by either IN or IM route separated by 2 weeks. The electrocardiogram, pulse rate (PR), peripheral haemoglobin oxygen saturation (SpO₂), mean noninvasive arterial pressure (MAP), respiratory frequency (f_R) and rectal temperature were measured before drug administration (baseline), T₀ (onset of sedation) and at 5 minute intervals until recovery. The onset of sedation, duration of sedation and sedation score (SS) were also recorded.ResultsThe PR was significantly lower in treatment IM than in treatment IN over time (p = 0.027). MAP < 60 mmHg developed in two and four rabbits in treatments IN and IM, respectively. SpO₂ progressively decreased over time in both treatments. f_R was lower than baseline at several time points in both treatments. Onset of sedation was shorter in treatment IN (90 ± 21 seconds) than in treatment IM (300 ± 68 seconds) (p = 0.036). Duration of sedation was longer in treatment IM (55.2 ± 8.7 minutes) than in treatment IN (39.6 ± 2.1 minutes) (p = 0.047). No significant difference in SS was observed between treatments (p > 0.05).Conclusions and clinical relevanceCombination of dexmedetomidine (0.1 mg kg^–1) and midazolam (2 mg kg^–1) decreased f_R, PR and SpO₂ regardless of the administration route in New Zealand White rabbits. A more rapid action and shorter duration of sedation were observed after treatment IN than after treatment IM administration.     

Evaluation of LHP? (1% hydrogen peroxide) cream versus petrolatum and untreated controls in open wounds in healthy horses: a randomized,blinded control study

Background

Treatment and protection of wounds in horses can be challenging; protecting bandages may be difficult to apply on the proximal extremities and the body. Unprotected wounds carry an increased risk of bacterial contamination and subsequent infection which can lead to delayed wound healing. Topical treatment with antimicrobials is one possibility to prevent bacterial colonization or infection, but the frequent use of antimicrobials ultimately leads to development of bacterial resistance which is an increasing concern in both human and veterinary medicine.

Methods

Standardized wounds were created in 10 Standardbred mares. Three wounds were made in each horse. Two wounds were randomly treated with LHP^® or petrolatum and the third wound served as untreated control. All wounds were assessed daily until complete epithelization. Protocol data were recorded on day 2, 6, 11, 16, 21 and 28. Data included clinical scores for inflammation and healing, photoplanimetry for calculating wound areas and swab cytology to assess bacterial colonization and inflammation. Bacterial cultures were obtained on day 2, 6 and 16.

Results

Mean time to complete healing for LHP^® treated wounds was 32 days (95%CI = 26.9-37.7). Mean time to complete healing for petrolatum and untreated control wounds were 41.6 days (95%CI = 36.2-47.0) and 44.0 days (95%CI = 38.6-49.4) respectively. Wound healing occurred significantly faster in LHP^® wounds compared to both petrolatum (p = 0.0004) and untreated controls (p < 0.0001). There was no significant difference in time for healing between petrolatum and untreated controls. Total scores for bacteria and neutrophils were significantly (p < 0.0001) lower for LHP^® treated wounds compared to petrolatum from day 16 and onwards. Staphylococcus aureus and Streptococcus zooepidemicus were only found in cultures from petrolatum treated wounds and untreated controls.

Conclusions

Treatment with LHP^® reduced bacterial colonization and was associated with earlier complete wound healing. LHP^® cream appears to be safe and effective for topical wound treatment or wound protection.     

Pharmacokinetic study of rhizoma Curcumae oil and rhizoma Curcumae oil-β-cyclodextrin inclusion complex in pigs after oral administration

Pharmacokinetics of rhizoma Curcumae oil-pure drug (RCO-PD) and its β-cyclodextrin inclusion complex (RCO-βCD) were studied in a randomized two-way crossover design following a single oral administration of the two formulations. Germacrone concentrations in plasma were determined by high-performance liquid chromatography with UV detector. The concentrations vs. time data were analyzed by a noncompartmental pharmacokinetic method. The result showed that germacrone in both groups was rapidly absorbed followed by a slow elimination. The main parameters in RCO-PD group were as follows: t(1/2λz) 6.63±1.08 h, C(max) 2.50±0.34 μg/mL, MRT 7.19±0.93 h, and AUC(0-∞) 13.92±2.75 mg/L·h, while in RCO-βCD group, t(1/2λz) 6.77 ± 0.67 h, C(max) 2.98±0.24 μg/mL, MRT 8.87±0.76 h, and AUC(0-∞) 21.60 ± 1.95 mg/L·h, respectively. The above results indicated that C(max), T(max), AUC(0-t), AUC(0-∞), and MRT in RCO-βCD group were significantly different from RCO-PD group, and the relative bioavailability of RCO-βCD group is significantly higher while compared to RCO-PD group (F=156%, with its 90% confidence interval of 145-169%).     

Is there a relationship between clinical presentation,diagnostic and radiographic findings and outcome in horses with osteoarthritis of the small tarsal joints?

Reasons for performing study: Despite the possibility that sound horses may have radiographic signs consistent with osteoarthritis of the small tarsal joints (OA‐STJ), a diagnosis of ‘bone spavin’ as a cause of lameness is often made based only on radiographic examination. Objectives: To determine whether severity of radiographic change and response to treatment are correlated with the duration and degree of lameness and the response to intra‐articular anaesthesia in horses with OA‐STJ. Methods: A retrospective study of all horses that showed a positive response to intra‐articular anaesthesia of the STJ was performed. Details of history, clinical presentation and diagnostic findings were recorded. Radiographs of affected tarsi were evaluated and scored independently by 2 observers. Follow‐up was via a telephone questionnaire with the owner. Statistical analysis was used to assess the association between the duration and degree of lameness, the response to intra‐articular anaesthesia and radiographic findings. Response to treatment was compared with the findings from the diagnostic work‐up. Results: Ninety‐one horses were included (61 unilateral and 30 bilateral lameness). Fifty‐nine percent of horses had been lame for over 2 months. There was no association between the duration and degree of lameness, or between duration or degree of lameness, intra‐articular anaesthesia and radiographic findings. Response to treatment showed a significant positive association with less severe radiographic changes within the tarsometatarsal (TMT) joint. Follow‐up was available for 48% of cases, with 52% horses returning to the same level of exercise. Conclusions: There is no association between the duration and degree of lameness, the response to intra‐articular anaesthesia and radiographic findings in horses with OA‐STJ. However, horses that improved following treatment tended to have less marked TMT joint pathology. Potential relevance: Response to intra‐articular anaesthesia should remain the gold standard for diagnosis of OA‐STJ. Predicting which cases are likely to improve following treatment remains difficult.     

Sialolithiasis in horses: A retrospective study of 25 cases (2002–2013)

This study evaluated outcomes of surgical treatment of equine sialolithiasis, highlighting cases involving the proximal parotid salivary duct. Sialoliths in the proximal parotid duct were difficult to identify radiographically and more frequently associated with draining tracts and sialadenitis compared with sialoliths in the distal parotid duct. Ultrasonography confirmed the diagnosis of sialolithiasis in all cases in which there was no radiographic evidence of a sialolith. All cases of proximal parotid duct sialolithiasis required transcutaneous removal. A longer duration of illness was observed in cases of proximal parotid duct sialolithiasis compared with cases involving the distal parotid duct, and in cases requiring transcutaneous removal compared with cases requiring transoral removal. Recurrence of sialolithiasis was documented in 24% of cases, all of which were located in the distal parotid duct. The average time to recurrence was 2.8 years.     

Effects induced by exercise on lymphocyte β-adrenergic receptors and plasma catecholamine levels in performance horses

The effect of dynamic exercise on complete blood cell count, lymphocyte β-adrenergic receptor and plasma catecholamine (adrenaline and noradrenaline) levels in horses performing different disciplines were investigated during rest and after exercise. Blood samples were collected from jumping horses (n=6), Arabian Endurance horses (n=6) and Standardbred trotters (n=6) before and immediately after competition. Dynamic exercise caused a significant increase in red blood cell count (Standardbred trotters: P=0.0012), haemoglobin concentration (jumping horses: P=0.001; Standardbred trotters: P=0.01), haematocrit percentage (Standardbred trotters: P=0.005), neutrophil percentage (jumping horses: P=0.0003), lymphocyte percentage (jumping horses: P=0.0003), monocyte percentage (Standardbred trotters: P=0.0008), lymphocyte β-AR numbers (jumping horses: P=0.01; Arabian Endurance horses: P=0.016; Standardbred trotters: P=0.05), plasma adrenaline concentration (Standardbred trotters: P=0.0001) and plasma noradrenaline levels (Standardbred trotters: P=0.003). It is concluded that acute increases in plasma catecholamine concentrations depended on the exercise performed and may induce up-regulation of β-AR in equine lymphocytes. However, the exact mechanism of β-AR up-regulation still remains unclear.     

Safety evaluation of combination vinblastine and toceranib phosphate (Palladia®) in dogs: a phase I dose-finding study

Combining drugs with known single-agent activity that lack overlapping dose-limiting toxicities (DLT) and exert antitumour activity through different mechanisms could improve clinical outcome. As toceranib and vinblastine meet these requisites, a phase I trial was performed in combination in dogs with mast cell tumours. The DLT for the simultaneous combination was neutropenia and the maximally tolerated dose was vinblastine (1.6 mg m(-2) every other week) concurrent with toceranib (3.25 mg kg(-1) PO, every other day). This represents greater than a 50% reduction in dose intensity for vinblastine (compared with single-agent use) and as such does not support this combination based on current drug combination paradigms. Although a strict adherence to dose paradigms speaks against the combination, evidence of significant activity (71% objective response) and enhanced myelosuppression suggest additive or synergistic activity. A prospective randomized evaluation comparing this combination with standard single-agent treatments would seem prudent to interrogate this potential.     

Some Pharmacokinetic Parameters of R-(–)- and S-(+)-Ketoprofen: The Influence of Age and Differing Physiological Status in Dairy Cattle

The pharmacokinetic parameters of ketoprofen have previously been studied in cattle, but no studies have been performed on differing ages and metabolic situations in these animals. The aim of this work was to study the possible modifictions of the pharmacokinetics of ketoprofen enantiomers that may result from age, lactation or gestation in dairy cattle. Three groups of Holando Argentino cattle contained, respectively, 8 cows in early lactation, 8 pregnant cows and 8 newborn calves. Four animals from each group received the enantiomer R-(-)-ketoprofen, the other four animals received the S-(+) enantiomer, all by intravenous injection at a dose of 0.5 mg/kg. Significant differences between the three categories of animals were obtained in elimination half-life (t1/2) (1.52, 0.87 and 0.31 and 1.71, 0.69 and 0.26 in newborn calves, cows in early lactation and cows in gestation, respectively), mean residence time (MRT) (0.45, 1.25, 2.20 and 0.38, 0.99, 2.47 h, in cows in gestation, cows in early lactation and newborn calves, respectively) and area under the plasma concentration-time curve (AUC) (0.87, 2.93, 3.24, and 0.67, 2.78, 5.13 (microg/h)/ml in cows in gestation, cows in early lactation and newborn calves, respectively, for the R-(-) and S-(+) enantiomer, respectively. In calves, there was a significant difference in AUC (3.24 vs 5.13 (microg/h)/ml between R-(-)- and S-(+)-ketoprofen. In view of the differences between calves and adult cattle in the pharmacokinetic results for ketoprofen, the effects of age and physiological status (lactation, gestation) should be taken into account for therapeutic regimens.     

Control of cryptosporidiosis in neonatal goat kids: efficacy of a product containing activated charcoal and wood vinegar liquid (Obionekk®) in field conditions

Many compounds have been screened for their potential anti-cryptosporidial activity in ruminants but none of them has been totally efficient in controlling the disease. A product containing activated charcoal and wood vinegar liquid demonstrated a good efficacy in controlling clinical signs and oocyst excretion in calves experimentally infected. This product (Obionekk(?), Obione, Charentay, France) was given to goat kids in field conditions. The product was administered in a preventive way at the dose rate of 3.75 g/day/kid of Obionekk(?) from the age of 3 days to the age of 17 days in suspension in milk replacer twice or three times a day. A significant reduction of oocyst excretion was observed when the product was given 3 times a day when compared to control group. The clinical signs (diarrhoea) were significantly reduced whatever the rhythm of distribution when compared to control group. These results demonstrated the efficacy of Obionekk(?) in preventing cryptosporidiosis in goat kids in field conditions.     

Effects of Shading and Regaining Natural Light Treatment on Leaf Color and Physiological Changes of Pennisetum setaceum 'Rubrum'北大核心CSCD

To explore the effect of light on the leaf color and physiological changes of Pennisetum setaceum 'Rubrum', the natural light was used as a control, and the shading net with 10% transniittance was used to shading the new leaves until the new leaves fully devloped. Then, remove sun-shade net and using natural light for re-lighting treatmetn. And then the dynamic changes of leaf color parameters and related physiological indexes at different development stages were measured. The results showed that the new leaves of Pennisetum setaceum ' R u b r u m ' were green after shading, and the leaf color parameters L and b values were increased significantly, and the value of a decreased significantly. The contents of chlorophyll a and chlorophyll b were increased significantly, while anthocyanin, flavonoid, soluble sugar content and phenylalnine ammonialyase, chalcone isomerase activities were significantly decreased. The polyphenol oxidase and peroxidase activities were not changed significantly. After the re-lighting treatment, the leaf color gradually turned purple, and the leaf color parameter changed opposite to shading treatmetn. The change of physiological indexes was opposite to the decrease or increase after shading. The PPO and POD activities were not significantly changed, either. © 2019 China Agricultural University. All rights reserved.     

Effects of oral supplementation with β-carotene on concentrations of β-carotene, vitamin A and α-tocopherol in plasma, colostrum and milk of mares and plasma of their foals and on fertility in mares

In this study, effects of oral β-carotene supplementation to mares (β-carotene group: 1000 mg/day, n = 15; control group: n = 15) from 2 weeks before foaling until 6 weeks thereafter on concentrations of β-carotene, vitamin A and α-tocopherol in plasma, colostrum and milk and plasma of their foals were determined. In addition, effects on fertility were studied. Beta-carotene concentrations increased in plasma and colostrum of β-carotene-supplemented mares compared to control mares (p < 0.05). In mares of both groups, β-carotene concentrations were higher in colostrum than in milk (p < 0.05). In foals, β-carotene concentrations increased with colostrum uptake and were higher in foals born to supplemented mares (p < 0.05; control group: 0.0003 ± 0.0002 μg/ml on day 0, 0.008 ± 0.0023 μg/ml on day 1; β-carotene group: 0.0005 ± 0.0003 μg/ml on day 0, 0.048 ± 0.018 μg/ml on day 1). Concentrations of vitamin A and α-tocopherol were higher in colostrum than in milk (p < 0.05) but did not differ between groups. Concentration of α-tocopherol in plasma of mares decreased over time and in foals, increased markedly within 4 days after birth. All but one mare (control group) showed oestrus within 2 weeks post-partum. Occurrence of oestrus did not differ between groups. More mares of the control group (7/7 vs. 5/12 in the β-carotene group) became pregnant after being bred in first post-partum oestrus (p < 0.05). In conclusion, β-carotene supplementation to mares increased β-carotene concentrations in plasma, colostrum and milk of mares and plasma of their foals but had no positive effects on fertility.