Retrospective assessment of the use of extended-release cabergoline in the management of equine pituitary pars intermedia dysfunction.

Introduction: Dopaminergic agonists are accepted as the most effective treatment for pituitary pars intermedia dysfunction. However, some horses are refractory to daily oral pergolide, the recommended registered treatment. Extended-release cabergoline (ERC) injection may offer an alternative. The objective of this retrospective case series was to describe clinical and endocrinological responses to ERC. Methods: Medical records of horses treated with weekly intramuscular injections of ERC (5 mg/mL, BOVA Aus) at either 0.01 mg/kg (high dose, HD) (n = 10) or 0.005 mg/kg (low dose, LD) (n = 30) were reviewed. Short-term ACTH responses were assessed at 5-8 days using a Wilcoxon signed ranked test. Longer-term ACTH responses (30 to 365 days) were assessed using generalised estimating equations. Results: Five to eight days after the first dose of LDERC, median adrenocorticotropic hormone (ACTH) concentration was lower (p = 0.001), changing from 153 pg/mL (IQR: 78, 331) to 57 pg/mL (IQR: 30, 102). With HDERC, median ACTH concentration was also 153 pg/mL (IQR: 96, 185) before and then 56 pg/mL (IQR: 29, 86) after 5-8 days of treatment (p = 0.047). Over 12 months of treatment, ACTH concentration ranged from 14 to >1,250 pg/mL (median: 51 pg/mL) in horses treated with LDERC and 20 to 472 pg/mL (median: 50 pg/mL) in horses treated with HDERC. Measurements remained above the seasonal reference range in 39.3 and 52.3% of horses treated with LDERC and HDERC, respectively. Clinical improvement was reported by owners in 78.3 and 100% of horses treated with LDERC and HDERC, respectively. Partial, self-limiting inappetence was reported in 30.0% of LDERC and 60% HDERC cases. Seven horses exhibited lethargy (5 LDERC, 2 HDERC). Insulin concentrations measured 30 days post-ERC treatment were no different from baseline. Discussion: Clinical and endocrinological responses were consistent with results of previous reports of oral pergolide treatment. Weekly injection of ERC may be an effective alternative to pergolide; the 0.005 mg/kg dose appeared to be as effective, with less risk of inappetence, than the 0.01 mg/kg dose that has been reported previously.

BEVA primary care clinical guidelines: Equine parasite control.

BACKGROUND: There is a lack of consensus on how best to balance our need to minimise the risk of parasite-associated disease in the individual horse, with the need to limit the use of anthelmintics in the population to preserve their efficacy through delaying further development of resistance. OBJECTIVES: To develop evidence-based guidelines utilising a modified GRADE framework. METHODS: A panel of veterinary scientists with relevant expertise and experience was convened. Relevant research questions were identified and developed with associated search terms being defined. Evidence in the veterinary literature was evaluated using the GRADE evidence-to-decision framework. Literature searches were performed utilising CAB abstracts and PubMed. Where there was insufficient evidence to answer the research question the panel developed practical guidance based on their collective knowledge and experience. RESULTS: Search results are presented, and recommendation or practical guidance were made in response to 37 clinically relevant questions relating to the use of anthelmintics in horses. MAIN LIMITATIONS: There was insufficient evidence to answer many of the questions with any degree of certainty and practical guidance frequently had to be based upon extrapolation of relevant information and the panel members' collective experience and opinions. CONCLUSIONS: Equine parasite control practices and current recommendations have a weak evidence base. These guidelines highlight changes in equine parasite control that should be considered to reduce the threat of parasite-associated disease and delay the development of further anthelmintic resistance.

BEVA primary care clinical guidelines: Diagnosis and management of equine pituitary pars intermedia dysfunction.

BACKGROUND: Pituitary pars intermedia dysfunction (PPID) is a prevalent, age-related chronic disorder in equids. Diagnosis of PPID can be challenging because of its broad spectrum of clinical presentations and disparate published diagnostic criteria, and there are limited available treatment options. OBJECTIVES: To develop evidence-based primary care guidelines for the diagnosis and treatment of equine PPID based on the available literature. STUDY DESIGN: Evidence-based clinical guideline using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework. METHODS: Research questions were proposed by a panel of veterinarians and developed into PICO or another structured format. VetSRev and Veterinary Evidence were searched for evidence summaries, and systematic searches of the NCBI PubMed and CAB Direct databases were conducted using keyword searches in July 2022 and updated in January 2023. The evidence was evaluated using the GRADE framework. RESULTS AND RECOMMENDATIONS: The research questions were categorised into four areas: (A) Case selection for diagnostic testing, pre-test probability and diagnostic test accuracy, (B) interpretation of test results, (C) pharmacological treatments and other treatment/management options and (D) monitoring treated cases. Relevant veterinary publications were identified and assessed using the GRADE criteria. The results were developed into recommendations: (A) Case selection for diagnostic testing and diagnostic test accuracy: (i) The prevalence of PPID in equids aged ≥15 years is between 21% and 27%; (ii) hypertrichosis or delayed/incomplete hair coat shedding provides a high index of clinical suspicion for PPID; (iii) the combination of clinical signs and age informs the index of clinical suspicion prior to diagnostic testing; (iv) estimated pre-test probability of PPID should be considered in interpretation of diagnostic test results; (v) pre-test probability of PPID is low in equids aged <10 years; (vi) both pre-test probability of disease and season of testing have strong influence on the ability to diagnose PPID using basal adrenocorticotropic hormone (ACTH) or ACTH after thyrotropin-releasing hormone (TRH) stimulation. The overall diagnostic accuracy of basal ACTH concentrations for diagnosing PPID ranged between 88% and 92% in the autumn and 70% and 86% in the non-autumn, depending on the pre-test probability. Based on a single study, the overall diagnostic accuracy of ACTH concentrations in response to TRH after 30 minutes for diagnosing PPID ranged between 92% and 98% in the autumn and 90% and 94% in the non-autumn, depending on the pre-test probability. Thus, it should be remembered that the risk of a false positive result increases in situations where there is a low pre-test probability, which could mean that treatment is initiated for PPID without checking for a more likely alternative diagnosis. This could compromise horse welfare due to the commencement of lifelong therapy and/or failing to identify and treat an alternative potentially life-threatening condition. (B) Interpretation of diagnostic tests: (i) There is a significant effect of breed on plasma ACTH concentration, particularly in the autumn with markedly higher ACTH concentrations in some but not all 'thrifty' breeds; (ii) basal and/or post-TRH ACTH concentrations may also be affected by latitude/location, diet/feeding, coat colour, critical illness and trailer transport; (iii) mild pain is unlikely to have a large effect on basal ACTH, but caution may be required for more severe pain; (iv) determining diagnostic thresholds that allow for all possible contributory factors is not practical; therefore, the use of equivocal ranges is supported; (v) dynamic insulin testing and TRH stimulation testing may be combined, but TRH stimulation testing should not immediately follow an oral sugar test; (vi) equids with PPID and hyperinsulinaemia appear to be at higher risk of laminitis, but ACTH is not an independent predictor of laminitis risk. (C) Pharmacologic treatments and other treatment/management options: (i) Pergolide improves most clinical signs associated with PPID in the majority of affected animals; (ii) Pergolide treatment lowers basal ACTH concentrations and improves the ACTH response to TRH in many animals, but measures of insulin dysregulation (ID) are not altered in most cases; (iii) chasteberry has no effect on ACTH concentrations and there is no benefit to adding chasteberry to pergolide therapy; (iv) combination of cyproheptadine with pergolide is not superior to pergolide alone; (v) there is no evidence that pergolide has adverse cardiac effects in horses; (vi) Pergolide does not affect insulin sensitivity. (D) Monitoring pergolide-treated cases: (i) Hormone assays provide a crude indication of pituitary control in response to pergolide therapy, however it is unknown whether monitoring of ACTH concentrations and titrating of pergolide doses accordingly is associated with improved endocrinological or clinical outcome; (ii) it is unknown whether monitoring the ACTH response to TRH or clinical signs is associated with an improved outcome; (iii) there is very weak evidence to suggest that increasing pergolide dose in autumn months may be beneficial; (iv) there is little advantage in waiting for more than a month to perform follow-up endocrine testing following initiation of pergolide therapy; there may be merit in performing repeat tests sooner; (v) timing of sampling in relation to pergolide dosing does not confound measurement of ACTH concentration; (vi) there is no evidence that making changes after interpretation of ACTH concentrations measured at certain times of the year is associated with improved outcomes; (vii) evidence is very limited, however, compliance with PPID treatment appears to be poor and it is unclear whether this influences clinical outcome; (viii) evidence is very limited, but horses with clinical signs of PPID are likely to shed more nematode eggs than horses without clinical signs of PPID; it is unclear whether this results in an increased risk of parasitic disease or whether there is a need for more frequent assessment of faecal worm egg counts. MAIN LIMITATIONS: Limited relevant publications in the veterinary scientific literature. CONCLUSIONS: These findings should be used to inform decision-making in equine primary care practice.

Comparison of oral esomeprazole and oral omeprazole in the treatment of equine squamous gastric disease.

BACKGROUND: Oral omeprazole is the accepted treatment for equine squamous gastric disease (ESGD); however, it is not universally effective. Esomeprazole results in more consistent and pronounced acid suppression in men and is more effective than omeprazole in the treatment of oesophageal and gastric disease. Pharmacodynamic and pilot clinical studies have indicated esomeprazole might also be more effective than omeprazole in horses. OBJECTIVES: To compare the efficacy and safety of oral esomeprazole and omeprazole pastes in the treatment of ESGD and, where present, concurrent equine glandular gastric disease (EGGD). STUDY DESIGN: Randomised, single-blinded controlled trial. METHODS: Horses presenting with grade ≥2 ESGD lesions were randomly allocated to receive 4 mg/kg of either a buffered esomeprazole or omeprazole paste orally once daily for 28 days before gastroscopy being repeated within a further 3 days. Videos and images were anonymised and subsequently graded blind by one researcher. The severity of ESGD (and EGGD) lesions before and after treatment, and thereby treatment responses, were compared using univariable logistic regression. RESULTS: A higher proportion of horses had ESGD healing in response to esomeprazole treatment (63/74, 85%) than with omeprazole treatment (43/73, 59%) (odds ratio [OR]: 4.00, 95% confidence interval [CI]: 1.81, 8.82, p = 0.001). In a subset of horses that had concurrent EGGD, a greater proportion of the horses treated with esomeprazole had lesions ≤grade 1 (esomeprazole 28/51, 55%; omeprazole 6/24, 25%; OR: 3.65, 95% CI: 1.25, 10.71, p = 0.02) Using grade 0 as the benchmark for EGGD healing, the difference remained significant (OR: 4.44, 95% CI: 1.33, 14.85, p = 0.02). MAIN LIMITATIONS: It may not be possible to extrapolate these results to other populations with different signalment or management. CONCLUSIONS: Oral-buffered esomeprazole was a more effective treatment for ESGD (and concurrent EGGD) than oral-buffered omeprazole.

Evaluation of the treatment of equine glandular gastric disease with either long-acting-injectable or oral omeprazole.

BACKGROUND: Equine glandular gastric disease (EGGD) is common in domesticated horses and can be challenging to treat. Oral omeprazole (ORLO) is used widely but the clinical response is frequently poor. OBJECTIVES: To compare rates of EGGD healing and improvement between ORLO and a long-acting injectable omeprazole preparation (LAIO). STUDY DESIGN: Retrospective clinical study. METHODS: The case records and gastroscopy images of horses presenting to masked for peer review over a 12-month period were reviewed, with images blindly assessed by one of the authors. Treatment responses to 4 mg/kg LAIO administered every 7 days for 2 and 4 weeks were compared with ORLO 4 mg/kg PO q24hrs for 4 weeks. Data were compared using a Mann-Whitney U test with post-hoc Dunn's test, Chi-squared test and a Fisher's exact test. RESULTS: Thirty-three horses that received LAIO and 12 that received ORLO were identified. Nine horses in the LAIO had received other treatments previously. The groups were comparable in signalment and EGGD lesion severity. Long-acting injectable omeprazole was found to be non-inferior to ORLO. LAIO was associated with better healing rates than ORLO at 4 weeks (LAIO-80%; ORLO-42%; p = 0.02), and reduction in lesion severity at 2 and 4 weeks in the LAIO group but not in the ORLO group at 4 weeks. Eighteen percent of horses in the LAIO group and 50% in the ORLO group did not heal at 4 weeks. There was no association between rate of healing or improvement and resolution or improvement of clinical signs. Six localised and self-limiting injection site reactions were identified in 4 horses treated with LAIO (6.7%). MAIN LIMITATIONS: Retrospective design, small numbers and the use of other treatments prior to use of LAIO. CONCLUSIONS: LAIO was found to be non-inferior to oral omeprazole for EGGD. Larger blinded randomised clinical trials are justified.

A study investigating the treatment of equine squamous gastric disease with long-acting injectable or oral omeprazole.

BACKGROUND: Equine squamous gastric disease (ESGD) is a highly prevalent disease in horses, particularly in elite athletes. Some horses respond slowly, or fail to respond, to the licensed treatment, oral omeprazole (ORLO). OBJECTIVES: To compare rates of ESGD healing and improvement between ORLO and a long-acting injectable omeprazole preparation (LAIO). STUDY DESIGN: Retrospective clinical study. METHODS: The case records and gastroscopy images of horses presenting to Rainbow Equine Hospital over a 12-month period were reviewed, with images being reviewed blind by one of the authors (David Rendle). Treatment responses were compared between horses that received 2 or 4 injections of 4 mg/kg LAIO at weekly intervals, and horses that received ORLO at 4 mg/kg PO SID for 4 weeks. Data were compared using a Mann-Whitney test with post hoc Dunn's test, chi-squared test or Fisher's exact test. RESULTS: Fifty-six horses met the inclusion criteria: 29 received LAIO and 27 received ORLO. Treatment groups were comparable in terms of signalment and ESGD lesions. There was a difference in rate of healing when LAIO and ORLO treatment groups were compared at 28 days (LAIO-97%; ORLO-67%; p = .005; OR = 14(1.8-158)), but no difference between LAIO at 14 days and ORLO at 28 days (LAIO-86%; ORLO-67%; p = .12; OR = 3.1 (0.9-10)). Five localised and self-limiting injection site reactions were identified in 3 horses out of 98 injections (5.1%). MAIN LIMITATIONS: The study was limited by its retrospective nature, absence of randomisation and limited numbers. CONCLUSIONS: Four weeks of treatment with LAIO resulted in better rates of ESGD healing than 4 weeks of ORLO. Larger more robust studies of LAIO are warranted.

Pharmacokinetics of pergolide after intravenous administration to horses.

OBJECTIVE: To determine the pharmacokinetics of pergolide after IV administration to horses. ANIMALS: 8 healthy adult horses. PROCEDURES: Pergolide mesylate was administered IV at a dose of 20 µg/kg (equivalent to 15.2 µg of pergolide/kg) to each horse, and blood samples were collected over 48 hours. Pergolide concentrations in plasma were determined by means of high-performance liquid chromatography-tandem mass spectrometry, and pharmacokinetic parameters were determined on the basis of noncompartmental methods. RESULTS: After IV administration of pergolide, mean ± SD clearance, elimination half-life, and initial volume of distribution were 959 ± 492 mL/h/kg, 5.64 ± 2.36 hours, and 0.79 ± 0.32 L/kg, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: With an elimination half-life of approximately 6 hours, twice-daily dosing may be more appropriate than once-daily dosing to reduce peak-trough fluctuation in pergolide concentrations. Further pharmacodynamic and pharmacokinetic studies of pergolide and its metabolites will be necessary to determine plasma concentrations that correlate with clinical effectiveness to determine the therapeutic range for the treatment of pituitary pars intermedia dysfunction.

Determination of pergolide in horse plasma by UPLC-MS/MS for pharmacokinetic applications.

Pergolide, an ergot-derived dopamine D2 receptor agonist, is used extensively as an orally administered treatment for pituitary pars intermedia dysfunction (PPID) in horses. One of the barriers associated with pergolide determinations in plasma for pharmacokinetic applications has been the technically demanding requirement for sensitivity. The objective of our work was to develop a simple assay for the determination of pergolide in plasma and demonstrate its potential application in the study of pergolide pharmacokinetics (PK) in horses. A UPLC-MS/MS assay was developed with a simple sample preparation involving methanol protein precipitation and injection of supernatant. The assay was applied to samples from a horse dosed with 10mg pergolide (as the mesylate salt) by nasogastric intubation. Plasma samples were collected over a 48h period. The assay demonstrated performance sufficient to enable application to low level PK studies. Within-batch precision and accuracy were within acceptance criteria; precision was less than 10% RSD (n=5) and accuracy was -7.3% at 0.014ng/mL, the lower limit of quantification was 0.006ng/mL and the method detection limit was 0.002ng/mL. In the treated horse, Cmax was 0.40ng/mL and the assay easily allowed determination of plasma levels in the elimination phase to 48h. In conclusion, this assay using UPLC-MS/MS and methanol protein precipitation easily meets the challenging demands of pergolide analyses in plasma.

The analysis of pergolide residues in horse plasma by LC with fluorescence detection.

Pergolide is used to treat pituitary pars intermedia dysfunction (equine Cushing's Disease), a neurodegenerative condition associated with loss of dopaminergic inhibition of the pituitary in horses. After oral administration, only low concentrations of the drug are achieved in plasma, making drug detection and quantification difficult. While direct analysis of plasma using sensitive MS/MS techniques is possible, dirty plasma samples and mobile phase buffers can cause instrumentation to become rapidly incapacitated. A method using LC with fluorescence detection was developed for pergolide analysis. LOQ for the instrumentation was 2 ng/mL when using direct injection of horse plasma samples, while interferences from the matrix were nominal. The use of SPE provided cleaner extracts and increased the LOQ in plasma samples to 0.15 ng/mL. The LC method developed allowed high sample throughput before pre-columns required replacement, which was extended when SPE cleanup was used. The effectiveness of SPE for the cleanup and preconcentration of plasma samples containing pergolide was demonstrated with spiked and naturally incurred samples; LC-MS/MS was used to validate the SPE method against direct injection samples.

Advances in chemistry applied to forensic science.

Acts of terrorism, an increase in the use of firearms, drug abuse, the use of so-called date-rape drugs, and driving whilst under the influence of drugs, are just some of the subjects frequently in the news. In the absence of fingermarks and of material leading to the recovery of DNA, the forensic scientist has to rely upon chemical analysis of trace amounts of materials including explosives, drugs, toxicological specimens, firearms discharge residues, fibres, glass, paint, soil etc., in order to establish or eliminate links between suspect and victim and/or scene. This tutorial review describes analytical problems facing the forensic chemist, and the current methods and techniques employed to tackle them.