Anti-inflammatory Drugs in Equine Neonatal Medicine. Part I: Nonsteroidal Anti-inflammatory Drugs

Increased plasma nucleosomes are associated with severe sepsis in foals

Sepsis is a main cause of death in neonatal foals. While the syndrome is not completely understood, sepsis is a dysregulated inflammatory response of the host to infection. It can be difficult to diagnose because of varying and non-specific clinical signs and imperfect diagnostic tests. Increased circulating nucleosome levels have been detected in humans and animals with sepsis, but this has not been documented in foals. Nucleosomes are released extracellularly during neutrophil extracellular trap formation, as well as from damaged and dead cells. We analysed plasma samples from clinically healthy (n = 16), sick non-septic (n = 31) and septic (n = 36) foals using an enzyme-linked immunosorbent assay (ELISA) that targeted nucleosomes. Septic foals with evidence of hypoperfusion and/or organ dysfunction were classified as severe sepsis (n = 24). The main objective was to determine if nucleosome levels were increased in foals with sepsis, particularly those with severe sepsis. Our data identified that nucleosome levels in foals with severe sepsis on the day of study entry were increased significantly compared to all other foals. There was not a significant difference in nucleosome levels between sick non-septic or clinically healthy foals. Foal groups were not age-matched and factors associated with the clinical nature of the study may have affected the results. Further research with larger numbers of foals of similar ages, would be necessary to determine if the analysis of nucleosomes and related biomarkers are helpful adjuncts for the assessment and understanding of equine neonatal sepsis.

Objective assessment of acute pain in foals using a facial expression-based pain scale

BACKGROUND

Pain assessment based on facial expressions has been described in foals.

OBJECTIVES

To extend previous pilot findings of the Equine Utrecht University Scale for Facial Assessment of Pain in Foals (EQUUS-FAP FOAL).

STUDY DESIGN

Prospective blinded case-control study (known groups analysis).

METHODS

Video recordings (30-60 s) of n = 100 foals (38 patients and 62 controls) were collected. Videos were randomised and scored by two observers, blinded for the condition of the animals. Inter- and intra-observer agreement was tested by Intra Class Correlation (ICC) analysis. Differences between patients and controls were tested using Mann-Whitney U test, differences before and after analgesic treatment were tested with Wilcoxon signed rank test. Multilevel binomial logistic regression was performed for statistical weighting of each pain scale item. Receiver operating characteristic (ROC) analysis was performed to determine sensitivity, specificity and cut-off values.

RESULTS

EQUUS-FAP FOAL showed good inter- and intra-observer reliability (ICC coefficient of 0.85 and 0.90 respectively, p < 0.001). Patients had significantly higher pain scores (median score 7, IQR 5.3-7.5) compared with controls (median score 2.5, IQR 1-3, p < 0.001) and the patient pain scores decreased after analgesic treatment (median score 6.5, IQR 5-8 vs. median score 4.5, IQR 3.5-6.5, p < 0.05). Multilevel binomial logistic regression showed the relative importance of the individual scale items. Using the original scale, sensitivity and specificity were 88.2% (95% CI 76%-96%) and 87.9% (81%-98%) respectively, with an area under the ROC curve of 94.9% (92%-98%), based on a cut-off value of ≥4. These values remained similar with the weighted scale based on logistic regression output.

MAIN LIMITATIONS

Videos of included patients were short and acquired by a person in front of the stable.

CONCLUSIONS

The current study shows that EQUUS-FAP FOAL can be effectively used to assess acute pain in young foals.

Pharmacokinetics of single dose administration of three increasing doses of acetaminophen per os in 1-3-month-old foals

BACKGROUND

Acetaminophen is a common analgesic and antipyretic drug used in human medicine and might be an alternative to nonsteroidal anti-inflammatory drugs for treating pain and pyrexia in foals. The pharmacokinetics and safety of differing doses of acetaminophen have not been investigated in foals.

OBJECTIVES

To determine the plasma pharmacokinetics and any changes in haematology and biochemistry profiles following oral administration of single doses of acetaminophen at 10, 20, and 40 mg/kg to foals.

STUDY DESIGN

Randomised cross-over pharmacokinetic study.

METHODS

Six Quarter Horse (two colts and four fillies) foals received 10, 20, and 40 mg/kg acetaminophen orally once. Haematology and biochemistry profiles were performed before and 7 days after each drug administration. Blood samples were collected over 64 h after drug administration and were used to quantify plasma acetaminophen concentrations by liquid chromatography. Pharmacokinetic parameters were determined using compartmental analysis.

RESULTS

Median (range) acetaminophen plasma concentrations were 4.4 (1.8-5.1), 6.3 (2.6-12.6), and 14 (7.3-18) μg/ml for the 10, 20, and 40 mg/kg doses, respectively. Median acetaminophen area under the concentration versus time curve (AUC)0-∞ ranged from 25 (11-32), 41 (22-74), and 105 (82-142) h × μg/ml for the 10, 20, and 40 mg/kg doses, respectively. Dose-normalised maximal concentrations and AUC0-∞ values were similar across dose concentrations (p > 0.05). Median terminal half-life for all doses was 2.7-2.8 h. Haematology and biochemistry profiles were normal except for blood urea nitrogen and alkaline phosphatase concentrations.

MAIN LIMITATIONS

Foals were growing throughout the study, starting at 1 month and ending at 3 months. Deposition of drugs changes with age. The sample size was small and only single doses were evaluated. No liver biopsies were performed.

CONCLUSION

Plasma disposition of acetaminophen after a single oral dose of 10, 20, and 40 mg/kg to 1-3-month-old foals varies greatly with the dose. The analgesic and antipyretic effect in foals is unknown.

Analgesia during Parturition in Domestic Animals: Perspectives and Controversies on Its Use

This article analyzes the physiological role of pain during parturition in domestic animals, discusses the controversies surrounding the use of opioids, non-steroidal anti-inflammatory drugs (NSAIDs), and local analgesics as treatments during labor, and presents the advantages and disadvantages for mother and offspring. Labor is a potentially stressful and painful event, due to the contractions that promote expulsion of the fetus. During labor, neurotransmitters such as the prostaglandins contribute to the sensitization of oxytocin receptors in the myometrium and the activation of nociceptive fibers, thus supporting the physiological role of pain. Endogenously, the body secretes opioid peptides that modulate harmful stimuli and, at the same time, can inhibit oxytocin's action in the myometrium. Treating pain during the different stages of parturition is an option that can help prevent such consequences as tachycardia, changes in breathing patterns, and respiratory acidosis, all of which can harm the wellbeing of offspring. However, studies have found that some analgesics can promote myometrial contractility, increase expulsion time, affect fetal circulation, and alter mother-offspring recognition due to hypnotic effects. Other data, however, indicate that reducing the number of uterine contractions with analgesics increases their potency, thus improving maternal performance. Managing pain during labor requires understanding the tocolytic properties of analgesics and their advantages in preventing the consequences of pain.

Parturition in Mammals: Animal Models, Pain and Distress

Parturition is a complex physiological process and involves many hormonal, morphological, physiological, and behavioural changes. Labour is a crucial moment for numerous species and is usually the most painful experience in females. Contrary to the extensive research in humans, there are limited pain studies associated with the birth process in domestic animals. Nonetheless, awareness of parturition has increased among the public, owners, and the scientific community during recent years. Dystocia is a significant factor that increases the level of parturition pain. It is considered less common in polytocous species because newborns' number and small size might lead to the belief that the parturition process is less painful than in monotocous animal species and humans. This review aims to provide elements of the current knowledge about human labour pain (monotocous species), the relevant contribution of the rat model to human labour pain, and the current clinical and experimental knowledge of parturition pain mechanisms in domestic animals that support the fact that domestic polytocous species also experience pain. Moreover, both for women and domestic animal species, parturition's pain represents a potential welfare concern, and information on pain indicators and the appropriate analgesic therapy are discussed.

Enhancing the dissolution of phenylbutazone using Syloid® based mesoporous silicas for oral equine applications

Three mesoporous silica excipients (Syloid® silicas AL-1 FP, XDP 3050 and XDP 3150) were formulated with a model drug known for its poor aqueous solubility, namely phenylbutazone, in an attempt to enhance the extent and rate of drug dissolution. Although other forms of mesoporous silica have been investigated in previous studies, the effect of inclusion with these specific Syloid® silica based excipients and more interestingly, with phenylbutazone, is unknown. This work reports a significant enhancement for both the extent and rate of drug release for all three forms of Syloid® silica at a 1:1 drug:silica ratio over a period of 30 min. An explanation for this increase was determined to be conversion to the amorphous form and an enhanced drug loading ability within the pores. Differences between the release profiles of the three silicas were concluded to be a consequence of the physicochemical differences between the three forms. Overall, this study confirms that Syloid® silica based excipients can be used to enhance dissolution, and potentially therefore bioavailability, for compounds with poor aqueous solubility such as phenylbutazone. In addition, it has been confirmed that drug release can be carefully tailored based on the choice of Syloid® silica and desired release profile.