Objective assessment of chronic pain in donkeys using the Donkey Chronic Pain Scale.

OBJECTIVE: To clinically evaluate previously developed pain scales [Donkey Chronic Pain Composite Pain Scale (DCP-CPS), Donkey Chronic Pain Facial Assessment of Pain (DCP-FAP) and combined Donkey Chronic Pain Scale (DCPS)], including behavioural and facial expression-based variables, for the assessment of chronic pain in donkeys. STUDY DESIGN: Prospective, blinded clinical study. ANIMAL: A group of 77 donkeys (34 patients and 43 healthy control animals). METHODS: Animals were assessed by two observers that were blinded to the condition of the animals. RESULTS: Both DCP-CPS and DCP-FAP, and resulting combined DCPS scores, showed good interobserver reliability [intraclass correlation coefficient (ICC) = 0.91, 95% confidence interval (CI) = 0.86-0.95, p < 0.001; ICC = 0.71, CI = 0.50-0.83, p < 0.001 and ICC = 0.84, CI = 0.72-0.91, p < 0.001, respectively]. All scores (DCP-CPS, DCP-FAP and the resulting combined DCPS) were significantly higher for patients than for controls at all time points (p < 0.001 for all three scales). Sensitivity and specificity for identification of pain (cut-off value >3) was 73.0% and 65.1% for DCP-CPS, and 60.9% and 83.3% for DCP-FAP, respectively. For the combined DCPS, sensitivity was 87.0% and specificity 90.9% (cut-off value >6). CONCLUSIONS AND CLINICAL RELEVANCE: Based on behavioural and facial expression-based variables, DCPS proved a promising and reproducible tool to assess different types of chronic pain in donkeys. The combination of behavioural and facial expression-based variables showed the best discriminatory characteristics in the current study. Further studies are needed for refinement of these tools.

Agreement between invasive and oscillometric arterial blood pressure measurement using a high-definition oscillometric device in normotensive New Zealand White rabbits using two different anaesthetic protocols.

OBJECTIVE: To use American College of Veterinary Internal Medicine (ACVIM) criteria to evaluate a high-definition oscillometric (HDO) blood pressure monitoring device versus invasive blood pressure (IBP) measurement in normotensive rabbits anaesthetized with two different anaesthetic protocols. STUDY DESIGN: Prospective experimental study. ANIMALS: A group of 20 healthy adult New Zealand White rabbits weighing 4.36 ± 0.37 kg (mean ± standard deviation). MATERIALS AND METHODS: Rabbits were premedicated with butorphanol 0.5 mg kg-1 and midazolam 0.5 mg kg-1 subcutaneously (SC, group BMA) or ketamine 25 mg kg-1 and medetomidine 0.4 mg kg-1 SC (group KM). Anaesthesia was induced with alfaxalone administered intravenously (group BMA) or isoflurane by face mask (group KM) and maintained with isoflurane in oxygen. IBP was measured from the central auricular artery. The cuff for the HDO monitor was placed distal to the left elbow and distal to the left tarsus. Agreement between invasive and HDO measurements was evaluated using Bland-Altman method. RESULTS: In group KM there was better agreement between the HDO device and IBP when the cuff was placed on the thoracic limb, with 100% and 91% of the readings for mean (MAP) and diastolic arterial pressure (DAP), respectively, within 10 mmHg of the IBP measurements. The agreement, although worse, also met the ACVIM criteria for systolic arterial pressure (SAP; 53% of the readings within 10 mmHg). In group BMA, the device met the criteria with the cuff on the thoracic limb only, and only for MAP and DAP (73% and 75% of the measurements within 10 mmHg of the IBP, respectively) but not for SAP (12%). CONCLUSION AND CLINICAL RELEVANCE: The HDO device met most of the ACVIM criteria for noninvasive blood pressure measurement in anaesthetized rabbits, specifically when the cuff was placed distal to the elbow and the anaesthetic protocol included ketamine and medetomidine.

Effect of different inspired fractions of oxygen on F-shunt and arterial partial pressure of oxygen in isoflurane-anaesthetized and mechanically ventilated Shetland ponies.

OBJECTIVE: To determine the effect of fraction of inspired oxygen (FiO2) on intrapulmonary shunt fraction as measured by F-shunt in ponies during isoflurane anaesthesia. STUDY DESIGN: Prospective, randomized clinical study. ANIMALS: A group of 23 adult Shetland ponies undergoing a total of 32 anaesthetic procedures. METHODS: Ponies were premedicated intravenously (IV) with detomidine (0.01 mg kg-1) and either morphine (0.1 mg kg-1) or butorphanol (0.02 mg kg-1). Anaesthesia was induced with ketamine (2.2 mg kg-1) and midazolam (0.07 mg kg-1) administered IV. Ponies were randomly allocated to maintenance of anaesthesia with isoflurane in oxygen (group TH; FiO2 = 0.95) or a mixture of oxygen and medical air (group TL; FiO2 = 0.65); all ponies were given a constant rate of infusion of detomidine. Animals were mechanically ventilated to maintain PaCO2 between 40 and 50 mmHg. Arterial blood gas analysis was performed every 30 minutes. The F-shunt equation was calculated for each time point T0, T30, T60 and T90. Data were analysed using linear mixed model analysis and presented as mean ± standard deviation (p < 0.05). RESULTS: PaO2 was greater in group TH than in group TL (TH: 406 ± 90, 438 ± 83, 441 ± 69 and 464 ± 53 mmHg versus TL: 202 ± 90, 186 ± 84, 172 ± 85 and 191 ± 98 mmHg at T0, T30, T60 and T90, respectively; p < 0.0001). In TH, F-shunt was < TL. Significant differences were found at T60 (TH: 13.2% ± 4.3 versus TL: 19.4% ± 8.3; p = 0.016) and T90 (TH: 11.7% ± 3.5 versus TL: 18.6% ± 9.5; p = 0.036). CONCLUSIONS AND CLINICAL RELEVANCE: Our findings do not support a beneficial effect of using a reduced FiO2 to improve oxygenation in anaesthetized and mechanically ventilated Shetland ponies.

Clinical effects of two doses of butorphanol with detomidine for intravenous premedication of healthy warmblood horses.

OBJECTIVE: To compare the effects of two different doses of butorphanol combined with detomidine administered intravenously (IV) on quality of sedation, degree of ataxia and anaesthetic induction in horses. STUDY DESIGN: Randomized, blinded, clinical study. ANIMALS: A total of 40 client-owned healthy warmblood horses scheduled for elective surgery under general anaesthesia. METHODS: Horses were randomly allocated to be administered 8 µg kg-1 detomidine IV plus either 20 or 50 µg kg-1 butorphanol IV, with the principal investigator blinded to group allocation. Head height was measured before drug injection and 2 minutes thereafter. Data were compared using unpaired t test. Horses were filmed and scored using Simple Descriptive Scales for sedation (2 and 15 minutes after IV injection), ataxia (at walk, immediately after the 2 minute time point) and quality of swing-door induction following diazepam and ketamine administration. Data are shown as median (and range where appropriate). Scores were compared using chi-square tests (p < 0.05). RESULTS: There were 14 and 17 horses in high-dose (HD) and low-dose (LD) groups respectively. Data from nine horses were excluded. Mean head height reduction did not differ between groups (p = 0.86), nor did sedation scores at 2 minutes (median = 3 in both groups; p = 0.09) or 15 minutes (median = 2 in both groups; p = 0.63). There was no significant difference in the requirement for additional detomidine (p = 0.73) or in induction quality between groups (p = 0.99), but initial ataxia was significantly greater in the HD group 2 (1-3) versus 2.5 (1-3) in the LD group (p = 0.017). CONCLUSIONS AND CLINICAL RELEVANCE: In healthy warmblood horses, simultaneous administration of 50 rather than 20 µg kg-1 butorphanol with 8 µg kg-1 detomidine does not provide greater sedation or affect induction, but it causes more pronounced ataxia shortly after IV injection.

Comparison of different methods to calculate venous admixture in anaesthetized horses.

OBJECTIVE: The aim of this study was to compare different methods to determine venous admixture (Q˙s/Q˙t) in anaesthetized horses. The first objective was to estimate Q˙s/Q˙t using jugular venous blood oxygen content (Q˙s/Q˙tjugular), and a fixed value for the oxygen extraction (F-shunt). The second objective was to assess the influence of blood pressure and positioning on oxygen extraction. The third objective was to perform regression analysis between jugular and mixed venous blood oxygen tensions. STUDY DESIGN: Prospective, experimental trial. ANIMALS: The study was performed with seven warmblood horses that were anaesthetized with detomidine, butorphanol, ketamine, diazepam and isoflurane in oxygen. METHODS: Multiple simultaneous arterial, jugular venous and pulmonary arterial blood samples were taken under normotensive and hypotensive conditions in lateral and dorsal recumbency. Arterial, mixed venous, and end-capillary oxygen content were calculated. RESULTS: A significant correlation between Q˙s/Q˙t and Q˙s/Q˙tjugular was found [intraclass correlation coefficient (ICC) = 0.68, p < 0.001], and Bland-Altman analysis showed a bias of -11.5% and wide limits of agreement (-27.7% to 4.6%). F-shunt significantly correlated with Q˙s/Q˙t (ICC = 0.88, p < 0.001), and Bland-Altman analysis showed a lower bias (-1.97) and narrower limits of agreement (-13.8% to 9.9%). Positioning and blood pressure significantly influenced oxygen extraction. The regression formula was Y = 0.80X + 2.61 (where Y is the calculated mixed venous oxygen tension and X is the jugular venous oxygen tension) when outliers were excluded (ICC=0.82, p < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE: This study shows that F-shunt provides reasonable estimates of Q˙s/Q˙t but can possibly be improved by using simple algorithms without the need for pulmonary arterial catheterization. These algorithms use blood pressure- and positioning-dependent oxygen extraction and regression analysis between jugular venous and pulmonary arterial oxygen tension. Although promising, the validity of these algorithms needs to be determined in future studies.

Development and Preliminary Validation of an Equine Brief Pain Inventory for Owner Assessment of Chronic Pain Due to Osteoarthritis in Horses.

An owner-completed questionnaire was designed to monitor the level of chronic pain and impact on quality of life in horses with osteoarthritis (OA). A standardized approach to develop and validate subjective-state scales for clinical use was followed. Scale items were generated through literature review, focus group meetings, and expert panel evaluation. The draft tool was tested for reading level and language ambiguity and piloted in 25 owners/caregivers of horses with osteoarthritis, with factor analysis performed on responses. The resulting revised questionnaire is currently undergoing validation in a larger sample population of 60 OA and 20 sound control horses. In the pilot group, 21 people (84%) found the questionnaire easy to complete and 22 people (88%) found it useful. It could be completed within 5 min by all participants. Readability scores (Flesch Reading Ease Score, Flesch-Kincaid grade level, SMOG index) indicated an English language reading level comparable to that of 6th to 7th grade in the U.S. system (age 11-12 years). Cronbach's alpha of all items in the tool was 0.957, indicating excellent inter-item correlation. Interim analysis for 23 OA horses from the sample population showed good test-retest reliability and higher scores compared to 5 control horses. Full validation must be completed for the instrument to be used in clinical practice.

A systematic review of the prevalence of post-operative complications after general anaesthesia in adult horses (2000-2023).

BACKGROUND: Equine post-operative morbidity represents a significant concern for both veterinary surgeons and horse owners. OBJECTIVES: To estimate the prevalence of post-operative complications in horses after elective/non-abdominal surgery or colic surgery. STUDY DESIGN: Systematic review. METHODS: A database search identified eligible studies which reported the prevalence of equine post-operative complications published as a full paper in English in a peer-reviewed journal between 2000 and 2023. Studies were evaluated using the JBI Critical Appraisal Checklist for Prevalence Studies and GRADE (Grading of Recommendations, Assessment, Development and Evaluations) framework. Data for the most commonly reported complications were analysed using Chi-squared analysis of weighted means to answer 13 PICO (Population, Intervention, Comparator and Outcomes) questions. RESULTS: Sixty-seven studies met inclusion criteria. Data for eight post-operative morbidities (colic, surgical site complications, myopathy/neuropathy, laminitis, diarrhoea/colitis, fever/pyrexia, jugular thrombophlebitis/thrombosis, respiratory complications) were sufficient to allow statistical analyses. The weighted mean of the overall proportion of post-operative complications after elective/non-abdominal surgery is 17.48% (95% confidence interval [95% CI]: 13.20-22.92), significantly increasing to 55.62% (95% CI: 45.79-65.03) after colic surgery (odds ratio [OR] 6.63; 95% CI: 5.83-7.56; p < 0.001). The most commonly reported morbidity was post-operative colic, with a weighted mean prevalence of 7.45% (95% CI: 4.83-11.76) after elective/non-abdominal surgery, significantly rising to 26.46% (95% CI: 19.11-35.97) after colic surgery (OR 4.11; 95% CI: 3.60-4.71; p < 0.001). The weighted mean prevalence of surgical site complications, laminitis, diarrhoea/colitis, fever/pyrexia, jugular thrombophlebitis/thrombosis and respiratory complications were significantly higher after colic surgery compared with elective/non-abdominal surgery. Myopathy/neuropathy was the only morbidity where prevalence was not different between groups (OR 1.86; 95% CI: 0.86-4.16; p = 0.16). MAIN LIMITATIONS: The majority of studies were retrospective. Morbidity definitions, data collection periods, follow-up time and methods varied between studies. CONCLUSIONS: Based on current evidence, the prevalence of post-operative colic, surgical site complications, laminitis, diarrhoea/colitis, fever/pyrexia, jugular thrombophlebitis/thrombosis and respiratory complications is significantly higher after colic surgery compared with elective/non-abdominal surgery under general anaesthesia.

Effect of Lavage Solution Type on Bronchoalveolar Lavage Fluid Cytology in Clinically Healthy Horses.

Equine bronchoalveolar lavage (BAL) is usually performed with 250-500 mL of isotonic saline at pH 5.5. The acidic pH of saline may cause an increase in airway neutrophil count 48 h after BAL. Other isotonic solutions such as Ringer's solution, phosphate-buffered saline (PBS) or Plasma-Lyte 148® have a neutral pH of 7.4 and might be a better choice for BAL by not provoking inflammation and the influx of neutrophils into airways. BAL was performed in four healthy horses in four different lung lobes using four different solutions in a randomized crossover design. In each lobe, BAL was performed twice with a 48 h interval using 250 mL of solution. Automated total nucleated cell counts (TNCs) were recorded, and differential cell counts in lavage fluid were determined by two investigators blinded to treatments. The mean volume of BAL fluid retrieved was 51 ± 14%. The mean neutrophil percentage (%N) increased from 1.5 ± 0.9% to 14.7 ± 9.6% at 48 h (p < 0.001) but was not significantly affected by the solution used or the lung lobe sampled. In conclusion, in this study, the influx of neutrophils into airways after BAL was independent of the type of isotonic solution used and the lung lobe sampled. Saline remains an appropriate solution for BAL in horses.

Laparoscopic vs. open adrenalectomy: perioperative data and survival analysis in 70 dogs with an adrenal tumor.

Adrenalectomy is the treatment of choice in case of functional adrenal tumors and malignant adrenal incidentalomas. Laparoscopic adrenalectomy (LA) in dogs has gained popularity in recent years, however, clinical studies on large patient populations are scarce. This retrospective study describes perioperative and recurrence data, survival, and prognostic factors in 70 dogs that underwent LA or open adrenalectomy (OA) in our hospital between 2008 and 2022. Diagnosis was based on history, clinical signs, endocrine function tests and advanced diagnostic imaging. Laparoscopic adrenalectomy was performed in 42 dogs (n = 27 naturally occurring hypercortisolism, n = 4 pheochromocytoma, n = 1 pheochromocytoma with concurrent hypercortisolism, n = 10 incidentaloma) and OA in 28 dogs (n = 22 hypercortisolism, n = 3 pheochromocytoma, n = 3 incidentaloma). Bilateral adrenalectomy was performed in 8/70 dogs. Surgical duration of LA and OA did not differ significantly in unilateral and bilateral procedures (P = 0.108 and P = 0.101, respectively). Systemic hypertension occurred in 7/41 and 1/28 dogs during LA and OA, respectively (P = 0.130). Hypotension occurred in 2/41 and 4/28 dogs during LA and OA, respectively (P = 0.214). A total of 40/42 dogs in the LA group and 27/28 in the OA group survived to discharge (P = 0.810). Mean hospital stay was significantly shorter (P = 0.006) after LA (1.5 days, range 1-3) than after OA (2.2 days, range 1-4). No significant differences were demonstrated between LA and OA groups in recurrence of adrenal-dependent endocrine disease (P = 0.332), disease-free period (P = 0.733) and survival time (P = 0.353). The disease-specific 1-, 2- and 3-year survival rates were 95, 89, and 89% after LA and 92, 88, and 81% after OA. Tumor size was significantly associated with the occurrence of a recurrence. In addition, tumor size had a negative effect on the disease-free period and survival time. This study shows a favorable outcome of both LA and OA in dogs. Based on low perioperative complication rate, short hospitalization time and long-term outcomes comparable to OA in selected cases, the less invasive laparoscopic approach is considered the preferred technique.

A Translational Model for Repeated Episodes of Joint Inflammation: Welfare, Clinical and Synovial Fluid Biomarker Assessment.

This study investigates repeated low-dose lipopolysaccharide (LPS) injections in equine joints as a model for recurrent joint inflammation and its impact on animal welfare. Joint inflammation was induced in eight horses by injecting 0.25 ng of LPS three times at two-week intervals. Welfare scores and clinical parameters were recorded at baseline and over 168 h post-injection. Serial synoviocentesis was performed for the analysis of a panel of synovial fluid biomarkers of inflammation and cartilage turnover. Clinical parameters and a final synoviocentesis were also performed eight weeks after the last sampling point to assess the recovery of normal joint homeostasis. Statistical methods were used to compare the magnitude of response to each of the 3 LPS inductions and to compare the baseline and final measurements. Each LPS injection produced consistent clinical and biomarker responses, with minimal changes in welfare scores. General matrix metalloproteinase (MMP) activity and joint circumference showed greater response to the second LPS induction, but response to the third was comparable to the first. Gylcosaminoglycans (GAG) levels showed a significantly decreased response with each induction, while collagen-cleavage neoepitope of type II collagen (C2C) and carboxypropetide of type II collagen epitope (CPII) showed quicker responses to the second and third inductions. All parameters were comparable to baseline values at the final timepoint. In conclusion, a consistent, reliable intra-articular inflammatory response can be achieved with repeated injections of 0.25 ng LPS, with minimal impact on animal welfare, suggesting potential as a refined translational model of recurrent joint inflammation.

Methods Used for Endotracheal Tube Cuff Inflation and Pressure Verification in Veterinary Medicine: A Questionnaire on Current Practice.

Endotracheal intubation is a routine procedure in veterinary anaesthesia, yet no consensus guidelines exist for endotracheal tube (ETT) cuff inflation and pressure measurement. The aim of this study was to assess current practice of ETT cuff inflation and seal verification in veterinary medicine. An online questionnaire was distributed among veterinary professionals who administer anaesthesia, comprising six demographic and twelve ETT cuff-related questions per species. N = 348 questionnaires were completed. Cuff pressure was measured by 30% of respondents in cats, 32% in dogs and 9% in both farm animals and horses. Anaesthesia diplomates were not more likely to measure cuff pressure than others, except in cats (OR: 1.8; 95% CI: 1.1−2.9). The most frequently selected recommended range of cuff pressure was 20−30 cm H2O, regardless of species, although >30 cm H2O was selected significantly more often in horses compared to dogs, cats and farm animals. The preferred technique to verify cuff seal was minimal occlusive volume in dogs, cats and farm animals, whereas in horses, the preferred method was verification of normal capnogram waveform. ETT cuff pressure measurement remains uncommon in veterinary anaesthesia. The development of consensus recommendations for cuff inflation, including evidence-based target cuff pressure ranges for various species and different ETT models or materials, can help to improve practice.

Reporting of anaesthesia and pain management in preclinical large animal models of articular cartilage repair - A long way to go.

Animal models continue to be used to investigate cartilage repair strategies. Adequate anaesthesia and pain management are essential in order to guarantee acceptable animal welfare as well as reproducible experimental results. This systematic review evaluates reporting of anaesthesia and pain management in surgical large animal models (horse, pig, dog, goat and sheep) of (osteo)chondral repair. Manuscripts published between 2015 and 2020 were included after a comprehensive search strategy. Data were evaluated using descriptive statistics and qualitative review. Out of 223 eligible studies, 220 studies contained incomplete information on anaesthetic and pain management. Pre-, intra- and post-operative analgesia were not mentioned in 68%, 94%, and 64% of manuscripts respectively. A total of 176 studies reported that animals underwent general anaesthesia during surgery. Surprisingly, 30% of these articles did not provide any detail on anaesthetic management, while 37% reported using inhalant, hypnotic or sedative drugs only, without mention of analgesics. Pain monitoring was not reported in 87% of manuscripts. The vast majority of preclinical large animal studies on cartilage repair did not meet veterinary clinical standards for anaesthesia and analgesia, and failed to report according to the ARRIVE international guidelines. In light of serious welfare, ethical and translational validity concerns, improvement is urgently needed.

Objective assessment of chronic pain in donkeys using the donkey chronic pain scale (DCPS): A scale-construction study.

Assessment of chronic pain is very important for monitoring and improving welfare and quality of life in donkeys. Freedom from disease and pain is one of the 'five freedoms' underlying animal welfare. The aim of the current study was to develop a pain scale for assessment of chronic pain in donkeys (Donkey Chronic Pain Scale; DCPS), including behavioural and facial expression-related parameters. The scale was applied to 77 donkeys (38 donkeys diagnosed with chronic health problems by means of clinical examination and additional diagnostic procedures and 39 healthy control animals). Animals were assessed twice daily for three consecutive days by two observers that were not masked to the condition of the animals but were unaware of the analgesic treatment regimens. Both composite, facial expression-based and combined DCPS pain scales showed excellent inter-observer reliability (Cronbach's alpha = 0.98, 0.96 and 0.98 respectively; P < 0.001). Individual composite and facial expression-based pain scores and the resulting combined DCPS showed significant differences between donkeys with chronic conditions and control donkeys at all time points (P < 0.001). A DCPS cut-off of 6 showed good sensitivity and specificity (92% and 82.5% respectively) for presence of a chronic painful condition. Facial expression-related parameters separately showed low sensitivity. In conclusion, it is possible to use a composite pain scale for assessment of chronic pain in donkeys, based on behavioural and facial expression-based parameters. Further studies are needed to validate this pain scale before it can be used in veterinary practice.

Treatment effects of intra-articular triamcinolone acetonide in an equine model of recurrent joint inflammation.

BACKGROUND: Intra-articular triamcinolone acetonide is a widely used treatment for joint inflammation despite limited scientific evidence of its efficacy. OBJECTIVES: To investigate if intra-articular triamcinolone acetonide has sustained anti-inflammatory effects using an equine model of repeated joint inflammation. STUDY DESIGN: Randomised controlled experimental study. METHOD: For three consecutive cycles 2 weeks apart, inflammation was induced in both middle carpal joints of eight horses by injecting 0.25 ng lipopolysaccharide (LPS). After the first LPS injection only, treatment with 12 mg triamcinolone acetonide (TA) followed in one randomly assigned joint, while the contralateral joint was treated with sterile saline (control). Clinical parameters (composite welfare scores, joint effusion, joint circumference) were recorded and synovial fluid samples were analysed for various biomarkers (total protein, WBCC; PGE2 ; CCL2; TNFα; MMP; GAGs; C2C; CPII) at fixed timepoints (post injection hours 0, 8, 24, 72 and 168). The effects of time and treatment on clinical and synovial fluid parameters and the presence of time-treatment interactions were tested using a linear mixed model for repeated measures with horse as a random effect, and time and treatment as fixed effects. RESULTS: The TA treated joints showed significantly higher peak synovial GAG concentrations (Difference in means 283.1875 µg/mL, 95% CI 179.8, 386.6, P < 0.000), and PGE2 levels (Difference in means 77.8025 pg/mL, 95% CI 21.2, 134.4, P < 0.007) after the first inflammation induction. Significantly lower TP levels were seen with TA treatment after the second induction (Difference in means -7.5 g/L, 95% CI -14.8, -0.20, P < 0.04) . Significantly lower WBCC levels were noted with TA treatment after the first (Difference in means -23.7125 × 109  cells/L, 95% CI -46.7, -0.7, P < 0.04) and second (Difference in means -35.95 × 109  cells/L, 95% CI -59.0, -12.9, P < 0.002) inflammation inductions. Significantly lower general MMP activity was also seen with TA treatment after the second inflammation inductions (Difference in means -51.65 RFU/s, 95% CI -92.4, -10.9, P < 0.01). MAIN LIMITATIONS: This experimental study cannot fully reflect natural joint disease. CONCLUSIONS: In this model, intra-articular TA seems to have some anti-inflammatory activity (demonstrated by reductions in TP, WBCC and general MMP activity) up to 2 weeks post treatment but not at 4 weeks. This anti-inflammatory effect appeared to outlast a shorter-lived, potentially detrimental effect illustrated by increased synovial GAG and PGE2 levels after the first induction.

Sustained Intra-Articular Release and Biocompatibility of Tacrolimus (FK506) Loaded Monospheres Composed of [PDLA-PEG1000]-b-[PLLA] Multi-Block Copolymers in Healthy Horse Joints.

There is an increasing interest in controlled release systems for local therapy in the treatment of human and equine joint diseases, aiming for optimal intra-articular concentrations with no systemic side effects. In this study, the intra-articular tolerability and suitability for local and sustained release of tacrolimus (FK506) from monospheres composed of [PDLA-PEG1000]-b-PLLA multiblock copolymers were investigated. Unloaded and tacrolimus-loaded (18.4 mg tacrolimus/joint) monospheres were injected into the joints of six healthy horses, with saline and hyaluronic acid (HA) in the contralateral joints as controls. Blood and synovial fluid were analysed for the tacrolimus concentration and biomarkers for inflammation and cartilage metabolism. After an initial burst release, sustained intra-articular tacrolimus concentrations (>20 ng/mL) were observed during the 42 days follow-up. Whole-blood tacrolimus levels were below the detectable level (<0.5 ng/mL). A transient inflammatory reaction was observed for all substances, evidenced by increases of the synovial fluid white blood cell count and total protein. Prostaglandin and glycosaminoglycan release were increased in joints injected with unloaded monospheres, which was mitigated by tacrolimus. Both tacrolimus-loaded monospheres and HA transiently increased the concentration of collagen II cleavage products (C2C). A histologic evaluation of the joints at the endpoint showed no pathological changes in any of the conditions. Together, these results indicate the good biocompatibility of intra-articular applied tacrolimus-loaded monospheres combined with prolonged local drug release while minimising the risk of systemic side effects. Further evaluation in a clinical setting is needed to determine if tacrolimus-loaded monospheres can be beneficial in the treatment of inflammatory joint diseases in humans and animals.

Pain in osteoarthritis.

This article focuses on pain associated with osteoarthritis (OA). It first describes the basic biology of articular cartilage and other joint structures and the defining features of the osteoarthritic disease process. Subsequently, the possible origins of pain in OA are discussed before embarking on how to manage this clinical entity. The emphasis is on the pharmacologic management of joint pain, and attention is paid to systemic therapeutic strategies as well as to local (intra-articular) treatment modalities. Nonmedical ways of modulating joint pain are briefly mentioned, but not extensively discussed, as these are outside the scope of this article.

Objective Assessment of Acute Pain in Foals Using a Facial Expression-Based Pain Scale.

Pain assessment is very important for monitoring welfare and quality of life in horses. To date, no studies have described pain scales for objective assessment of pain in foals. Studies in other species have shown that facial expression can be used in neonatal animals for objective assessment of acute pain. The aim of the current study was to adapt a facial expression-based pain scale for assessment of acute pain in mature horses for valid pain assessment in foals. The scale was applied to fifty-nine foals (20 patients and 39 healthy controls); animals were assessed from video recordings (30-60 s) by 3 observers, who were blinded for the condition of the animals. Patients were diagnosed with acute health problems by means of clinical examination and additional diagnostic procedures. EQUUS-FAP FOAL (Equine Utrecht University Scale for Facial Assessment of Pain in Foals) showed good inter- and intra-observer reliability (Cronbach's alpha = 0.95 and 0.98, p < 0.001). Patients had significantly higher pain scores compared to controls (p < 0.001) and the pain scores decreased after treatment with NSAIDs (meloxicam or flunixin meglumine IV) (p < 0.05). Our results indicate that a facial expression-based pain scale could be useful for the assessment of acute pain in foals. Further studies are needed to validate this pain scale.

Long-Term in Vivo Performance of Low-Temperature 3D-Printed Bioceramics in an Equine Model.

Bone has great self-healing capacity, but above a certain critical size, bone defects will not heal spontaneously, requiring intervention to achieve full healing. Among the synthetic calcium phosphate (CaP) bone replacement materials, brushite (CaHPO4·2H2O)-based materials are of particular interest because of their degree of solubility and the related high potential to promote bone regeneration after dissolution. They can be produced tailor-made using modern three-dimensional (3D) printing technology. Although this type of implant has been widely tested in vitro, there are only limited in vivo data and less so in a relevant large animal model. In this study, material properties of a 3D-printed brushite-based scaffold are characterized, after which the material is tested by in vivo orthotopic implantation in the equine tuber coxae for 6 months. The implantation procedure was easy to perform and was well tolerated by the animals, which showed no detectable signs of discomfort. In vitro tests showed that compressive strength along the vertical axis of densely printed material was around 13 MPa, which was reduced to approximately 8 MPa in the cylindrical porous implant. In vivo, approximately 40% of the visible volume of the implants was degraded after 6 months and replaced by bone, showing the capacity to stimulate new bone formation. Histologically, ample bone ingrowth was observed. In contrast, empty defects were filled with fibrous tissue only, confirming the material's osteoconductive capacity. It is concluded that this study provides proof that the 3D-printed brushite implants were able to promote new bone growth after 6 months' implantation in a large animal model and that the new equine tuber coxae bone model that was used is a promising tool for bone regeneration studies.

Orthotopic Bone Regeneration within 3D Printed Bioceramic Scaffolds with Region-Dependent Porosity Gradients in an Equine Model.

The clinical translation of three-dimensionally printed bioceramic scaffolds with tailored architectures holds great promise toward the regeneration of bone to heal critical-size defects. Herein, the long-term in vivo performance of printed hydrogel-ceramic composites made of methacrylated-oligocaprolactone-poloxamer and low-temperature self-setting calcium-phosphates is assessed in a large animal model. Scaffolds printed with different internal architectures, displaying either a designed porosity gradient or a constant pore distribution, are implanted in equine tuber coxae critical size defects. Bone ingrowth is challenged and facilitated only from one direction via encasing the bioceramic in a polycaprolactone shell. After 7 months, total new bone volume and scaffold degradation are significantly greater in structures with constant porosity. Interestingly, gradient scaffolds show lower extent of remodeling and regeneration even in areas having the same porosity as the constant scaffolds. Low regeneration in distal regions from the interface with native bone impairs ossification in proximal regions of the construct, suggesting that anisotropic architectures modulate the cross-talk between distant cells within critical-size defects. The study provides key information on how engineered architectural patterns impact osteoregeneration in vivo, and also indicates the equine tuber coxae as promising orthotopic model for studying materials stimulating bone formation.

Cartilage-derived biomarkers and lipid mediators of inflammation in horses with osteochondritis dissecans of the distal intermediate ridge of the tibia.

OBJECTIVE: To assess whether reported alterations in metabolism of cartilage matrix in young (0 to 24 months old) horses with osteochondritis dissecans (OCD) may also be found in older (24 to 48 months old) horses with clinical signs of OCD and to investigate the role of eicosanoids in initiating these clinical signs. SAMPLE POPULATION: Synovial fluid was collected from 38 tarsocrural joints of 24 warmblood horses with (22 joints of 16 horses) or without (16 joints of 8 horses) clinical signs and a radiographic diagnosis of OCD of the distal intermediate ridge of the tibia. PROCEDURES: Turnover of type II collagen was investigated by use of specific immunoassays for synthesis (carboxypropeptide of type II collagen [CPII]) and degradation (collagenase-cleaved fragments of type II collagen [C2C]) products. Furthermore, glycosaminoglycan (GAG), leukotriene (LT) B(4), cysteinyl LTs, and prostaglandin (PG) E(2) concentrations were determined, and concentrations in joints with OCD were compared with those in joints without OCD. RESULTS: Concentrations of CPII, C2C, and GAG did not differ significantly between affected and nonaffected joints. Fluid from joints with OCD had significantly higher LTB(4) and PGE(2) concentrations than did fluids from nonaffected joints. CONCLUSIONS AND CLINICAL RELEVANCE: Altered collagen or proteoglycan turnover was not detected in 24- to 48-month-old horses at the time they developed clinical signs of OCD of the distal intermediate ridge of the tibia. However, increased concentrations of LTB(4) and PGE(2) in fluid of joints with OCD implicate these mediators in the initiation of clinical signs of OCD.