Biomechanics of landing in injured and uninjured chickens and the role of meloxicam

Birds use their legs and wings when transitioning from aerial to ground locomotion during landing. To improve our understanding of the effects of footpad dermatitis (FPD) and keel bone fracture (KBF) upon landing biomechanics in laying hens, we measured ground-reaction forces generated by hens (n = 37) as they landed on force plates (Bertec Corporation, Columbus, OH) from a 30 cm drop or 170 cm jump in a single-blinded placebo-controlled trial using a cross-over design where birds received an anti-inflammatory (meloxicam, 5 mg/kg body mass) or placebo treatment beforehand. We used generalized linear mixed models to test for effects of health status, treatment and their interaction on landing velocity (m/s), maximum resultant force (N), and impulse (force integrated with respect to time [N s]). Birds with FPD and KBF tended to show divergent alterations to their landing biomechanics when landing from a 30 cm drop, with a higher landing velocity and maximum force in KBF compared to FPD birds, potentially indicative of efforts to either reduce the use of their wings or impacts on inflamed footpads. In contrast, at 170 cm jumps fewer differences between birds of different health statuses were observed likely due to laying hens being poor flyers already at their maximum power output. Our results indicate that orthopedic injuries, apart from being welfare issues on their own, may have subtle influences on bird mobility through altered landing biomechanics that should be considered.

Effects on hematology and blood biochemistry profile of intramuscular meloxicam injection in Brahminy kite and Barn owl

BACKGROUND

Meloxicam is used widely for exotic animal analgesia, but its toxicity in common raptor species in Thailand is unclear.

OBJECTIVES

This study evaluated the single-dose effect of intramuscular meloxicam in common raptor species in Thailand for short-term and long-term periods.

METHODS

Twenty-two raptors were administered a single 1 mg/kg dose of meloxicam individually via intramuscular injection. The following were evaluated: clinical appearance, body weight, body condition score, body temperature, fecal appearance, complete blood cell count, and biochemistry panel before (day 0) and after the injection (1, 7, and 30 days). The collected samples were categorized into three groups: Brahminy kite (Haliastur indus) (n = 10), adult Barn owl (Tyto javanica) (n = 4), and juvenile Barn owl (n = 8).

RESULTS

None of the raptors in the study groups showed any abnormalities. The hematological profiles were significantly different in the short-term period (day 1 and day 7). The creatinine, aspartate aminotransferase, and creatinine kinase increased in several groups. On the other hand, the packed cell volume decreased in the Brahminy kite and juvenile Barn owl groups. According to the findings, an intramuscular injection of 1 mg/kg meloxicam affected the blood biochemistry panel of the muscle, but the affected raptors recovered within one week.

CONCLUSIONS

An intramuscular injection of meloxicam at a single 1 mg/kg dose in Brahminy kites and Barn owls was not associated with the morbidity, hepatotoxicity, gastrointestinal toxicity, and nephrotoxicity in the short- and long-term periods.

Pharmacokinetics, Milk Residues, and Toxicological Evaluation of a Single High Dose of Meloxicam Administered at 30 mg/kg per os to Lactating Dairy Cattle

Adverse effects associated with overdose of NSAIDs are rarely reported in cattle, and the risk level is unknown. If high doses of NSAIDs can be safely administered to cattle, this may provide a longer duration of analgesia than using current doses where repeated administration is not practical. Meloxicam was administered to 5 mid-lactation Holstein dairy cows orally at 30 mg/kg, which is 30 times higher than the recommended 1 mg/kg oral dose. Plasma and milk meloxicam concentrations were determined using high-pressure liquid chromatography with mass spectroscopy (HPLC-MS). Pharmacokinetic analysis was performed by using noncompartmental analysis. The geometric mean maximum plasma concentration (C_max) was 91.06 µg/mL at 19.71 h (T_max), and the terminal elimination half-life (T_1/2) was 13.79 h. The geometric mean maximum milk concentration was 33.43 µg/mL at 23.74 h, with a terminal elimination half-life of 12.23 h. A thorough investigation into the potential adverse effects of a meloxicam overdose was performed, with no significant abnormalities reported. The cows were humanely euthanized at 10 d after the treatment, and no gross or histologic lesions were identified. As expected, significantly higher plasma and milk concentrations were attained after the administration of 30 mg/kg meloxicam with similar half-lives to previously published reports. However, no identifiable adverse effects were observed with a drug dose 30 times greater than the industry uses within 10 days of treatment. More research is needed to determine the tissue withdrawal period, safety, and efficacy of meloxicam after a dose of this magnitude in dairy cattle.

Treatment of Pain in Birds

This article provides an overview of the current understanding of evidence-based clinical analgesic use in birds. The field of avian analgesia has dramatically expanded during the last 20 years, affording more options for alleviating both acute and chronic pain. These options include opioids, nonsteroidal anti-inflammatory drugs, local anesthetics, and/or other drugs like gabapentin, amantadine, and cannabinoids, acting at different points in the nociceptive system thereby helping to provide greater pain relief while reducing the risk of adverse effects when combined.

PHARMACOKINETICS OF MELOXICAM AFTER A SINGLE 1.5 MG/KG INTRAMUSCULAR ADMINISTRATION TO NURSEHOUND SHARKS (SCYLIORHINUS STELLARIS) AND ITS EFFECTS ON HEMATOLOGY AND PLASMA BIOCHEMISTRY

A single-dose meloxicam pharmacokinetic (PK) study was performed with eight clinically healthy nursehound sharks (Scyliorhinus stellaris) maintained under human care. Meloxicam was administered IM at a dosage of 1.5 mg/kg to six animals; two animals were administered elasmobranch physiological saline solution (EPSS) IM as a negative control group. Blood samples were obtained prior to and at 12 predetermined times during the first 36 h after administration. Effects on hematology and plasma biochemistry were compared prior to and 24 h after administration. No animal died or showed clinical signs during the study. A significant increase in creatinine kinase and aspartate aminotransferase was found in both EPSS and meloxicam groups and could be considered a direct consequence of sampling and handling required for the PK study. Observed mean time to maximum plasma concentration ± SEM was 2.58 ± 0.47 h and observed mean maximum plasma concentration ± SEM was 806 ± 66 ng/ml; mean terminal half-life ± SEM was 15.97 ± 1.20 h; mean residency time ± SEM was 23.40 ± 2.25 h. Area under the plasma concentration-versus-time curve extrapolated to infinity ± SEM was 15.52 ± 1.70 h·µg/ml. This study suggests that meloxicam 1.5 mg/kg IM in nursehound sharks is likely to result in clinically relevant plasma levels for periods of 24 h without producing significant alterations in blood analytics, although further PK studies with meloxicam IV in sharks are needed. Future PK and pharmacodynamic studies with different drugs and doses are needed in elasmobranchs to establish safe and effective treatment protocols.

Pharmacokinetics of grapiprant administered to red-tailed hawks (Buteo jamaicensis) after food was withheld for 24 hours

OBJECTIVE

To identify an oral dose of grapiprant for red-tailed hawks (RTHAs; Buteo jamaicensis) that would achieve a plasma concentration > 164 ng/mL, which is considered therapeutic for dogs with osteoarthritis.

ANIMALS

6 healthy adult RTHAs.

PROCEDURES

A preliminary study, in which grapiprant (4 mg/kg [n = 2], 11 mg/kg [2], or 45 mg/kg [2]) was delivered into the crop of RTHAs from which food had been withheld for 24 hours, was performed to obtained pharmacokinetic data for use with modeling software to simulate results for grapiprant doses of 20, 25, 30, 35, and 40 mg/kg. Simulation results directed our selection of the grapiprant dose administered to the RTHAs in a single-dose study. Plasma grapiprant concentration, body weight, and gastrointestinal signs of RTHAs were monitored.

RESULTS

On the basis of results from the preliminary study and simulations, a grapiprant dose of 30 mg/kg was used in the single-dose study. The geometric mean maximum observed plasma concentration of grapiprant was 3,184 ng/mL, time to maximum plasma grapiprant concentration was 2.0 hours, and the harmonic mean terminal half-life was 17.1 hours. No substantial adverse effects were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Although the single dose of grapiprant (30 mg/kg) delivered into the crop achieved plasma concentrations > 164 ng/mL in the RTHAs, it was unknown whether this concentration would be therapeutic for birds. Further research that incorporates multidose assessments, safety monitoring, and pharmacodynamic data collection is warranted on the use of grapiprant in RTHAs from which food was withheld versus not withheld.

Pharmacokinetics of a Single Dose of Oral Meloxicam in Rehabilitated Wild Brown Pelicans (Pelecanus occidentalis)

Because of concerns regarding potential adverse effects of meloxicam in pelicans reported by several zoos and wildlife rehabilitation facilities, this study was undertaken to determine the pharmacokinetics of a single oral dose of meloxicam in brown pelicans (Pelecanus occidentalis). A pilot study was performed with 6 apparently healthy wild adult brown pelicans of unknown sex during rehabilitation, administered a single oral dose of meloxicam at 0.2 mg/kg. Plasma drug concentrations were monitored for 24 hours but failed to capture the elimination phase of the drug. Consequently, a principal study monitored plasma concentrations for 120 hours. Six additional adult wild brown pelicans, 3 males and 3 females, approaching releasable condition in rehabilitation were split into 3 groups and each orally administered 0.2 mg/kg meloxicam. Blood samples were collected at baseline and at 4 additional time points that differed between groups. Plasma concentrations were measured with liquid chromatography-mass spectrometry. The mean maximum plasma concentration was 1.22 µg/mL and was achieved at 24 hours after drug administration. The elimination half-life was 36.3 hours, the longest reported to date for any avian species. Further studies are needed to determine the pharmacokinetics of multiple doses of meloxicam and other routes of administration, as well as the pharmacodynamics and safety profile of meloxicam in brown pelicans. On the basis of the results of these investigations, caution is advised when dosing brown pelicans with meloxicam until more studies are completed. By extrapolation, close taxonomic relatives in the order Pelecaniformes may also warrant additional studies.

Gerontology of Psittacines

With recent improvements in the husbandry, nutrition, and veterinary care of captive psittacines, the avian clinician must be familiar with common medical condition seen in geriatric parrots. A review of the theory of evolution and avian senescence is provided. Five clinically relevant medical conditions are described: organ failure, atherosclerosis, neoplasia, cataracts, and osteoarthritis.

Development of an in Vivo Lipopolysaccharide Inflammation Model to Study the Pharmacodynamics of COX-2 Inhibitors Celecoxib, Mavacoxib, and Meloxicam in Cockatiels (Nymphicus hollandicus)

Nonsteroidal anti-inflammatory drugs (NSAIDs) are used frequently in avian medicine for their antipyretic, analgesic, and anti-inflammatory properties during surgery and for diseases that cause tissue damage and inflammation. NSAIDs inhibit cyclooxygenase (COX) enzymes, which are responsible for the induction of pyresis, pain, and inflammation. In our study, a lipopolysaccharide-induced (LPS) pyresis model was optimized using cockatiels (Nymphicus hollandicus) as subject birds (four males/three females) and validated in two females and one male, characterized by an intravenous bolus injection of LPS (7.5 mg/kg) administered at T₀ and T₂₄ (24 hours following the first LPS injection). To demonstrate the feasibility of the model to assess pharmacodynamic (PD) parameters of different NSAIDs, mavacoxib 4 mg/kg (four males/four females), celecoxib 10 mg/kg (four males/four females) and meloxicam 1 mg/kg (four males/four females) were evaluated in the model at dosages used frequently in practice. The PD parameters (body temperature, mentation, posture, preference of location in the cage, and prostaglandin E₂ [PGE₂] plasma concentrations) were determined for 10 hours following the second LPS injection. At the doses evaluated, mavacoxib and celecoxib significantly reduced LPS-induced hypothermia, but had no clear effects on other clinical signs of illness. In contrast, no effect on hypothermia or clinical appearance was observed in the LPS-challenged cockatiels treated with meloxicam. All three NSAIDs were able to inhibit the increase in LPS-induced PGE2 plasma concentrations, yet the effect was most pronounced in the birds treated with meloxicam. Consequently, the presented model opens perspectives for future dose-effect PD studies to optimize analgesic protocols in cockatiels.

Pharmacokinetic profiles of meloxicam after single IV and PO administration in Bilgorajska geese

The purpose of this study was two-fold: I) to determine the pharmacokinetic profile of meloxicam (MLX) in geese after intravenous (IV) and oral (PO) administration and II) to assess tissue residues in muscle, heart, liver, lung, and kidney. Ten clinically normal female Bilgorajska geese were divided into two groups (treated, n = 8; control, n = 2). Group 1 underwent a 3-phase parallel study with a 1-week washout period. In phase I, animals received MLX (0.5 mg/kg) by IV administration; the blood was collected up to 48 hr. In phases II and III geese were treated orally at the same dosage for the collection of blood and tissue samples, respectively. Group 2 served as control. After the extraction procedure, a validated HPLC method with UV detection was used for plasma and organ analysis. The plasma concentrations were quantifiable up to 24 hr after both the administrations. The elimination phase of MLX from plasma was similar in both the administration groups. The clearance was slow (0.00975 L/hr*Kg), the volume of distribution small (0.0487 L/kg), and the IV half-life was 5.06 ± 2.32 hr. The average absolute PO bioavailability was 64.2 ± 24.0%. Residues of MLX were lower than the LOQ (0.1 µg/kg) in any tested tissue and at any collection time. The dosage used in this study achieved the plasma concentration, which provides analgesia in Hispaniolan Amazon parrots for 5 out of 24 hr after PO administration. MLX tissue concentrations were below the LOD of the assay in tissue (0.03 µg/ml). A more sensitive technique might be necessary to determine likely residue concentrations in tissue.

PHARMACOKINETICS OF A SUSTAINED-RELEASE FORMULATION OF MELOXICAM AFTER SUBCUTANEOUS ADMINISTRATION TO AMERICAN FLAMINGOS ( PHOENICOPTERUS RUBER)

Meloxicam is commonly used in avian medicine to relieve pain and inflammation, but the recommended dosing frequency can be multiple times per day, which can contribute to stress during convalescence. In this study, the pharmacokinetics of a sustained-release formulation of meloxicam were determined after subcutaneous administration of a single 3-mg/kg dose to eight healthy adult American flamingos ( Phoenicopterus ruber). Blood samples were collected before (time 0) and at 0.5, 1, 4, 8, 12, 24, 48, 96, and 120 hr after drug administration. Analysis of meloxicam in plasma samples was conducted with the use of reversed-phase high-performance liquid chromatography, and pharmacokinetic parameters were calculated by noncompartmental analysis. Plasma concentrations reached a mean maximum (±standard deviation) of 7.65 (±2.39) μg/ml at 0.56 (±0.18) hr with a terminal half-life of 1.76 (±1.41) hr. Based on these findings, this sustained-release formulation of meloxicam does not extend the interval between treatments as compared to the regular formulation, so it is not recommended in American flamingos at this time.

ABSENCE OF ACUTE TOXICITY OF A SINGLE INTRAMUSCULAR INJECTION OF MELOXICAM IN GOLDFISH ( CARASSIUS AURATUS AURATUS): A RANDOMIZED CONTROLLED TRIAL

Meloxicam is a nonsteroidal anti-inflammatory drug with preferential cyclooxygenase-2 inhibitory activity. It is frequently used in veterinary medicine, including in fish species. The efficacy and safety of meloxicam, however, has not yet been reported in adult fish. The purpose of this study was to evaluate the acute toxicity of a single intramuscular injection of meloxicam in goldfish ( Carassius auratus auratus). Following 3 wk of acclimation, 32 goldfish were randomly assigned to two groups of 16 individuals. Fish from the treatment group received a single intramuscular injection of 5 mg/kg meloxicam, while the fish from the control group received a single intramuscular injection of a 0.9% sodium chloride solution using a similar volume (1 ml/kg). No external lesions, mortality, or modifications in behavior or position in the water column were noted during the following 72 hr. Three days after the initial injection, all fish were euthanized by immersion in a solution of tricaine methanesulfonate. Complete postmortem and histologic evaluations were performed for each fish. Hemorrhage and muscular necrosis were observed at the site of injection in fish from both groups. Multiple granulomas of undetermined etiology were detected in numerous organs from fish of both groups. No statistically significant differences were detected in regard to the lesions observed in these two groups. This study demonstrates that a single intramuscular injection of meloxicam at a dosage of 5 mg/kg does not cause acute toxicity in goldfish.

Intertarsal Joint Stabilization in a Bateleur Eagle (Terathopius ecaudatus) Using a Novel Application of a Braided Suture and Titanium Button System

A 32-year-old adult captive male bateleur eagle (Terathopius ecaudatus) with a history of laxity, degenerative joint disease, and varus deviation of the distal left hindlimb for several years was presented for evaluation of left hindlimb lameness and was diagnosed with chronic subluxation of the left intertarsal joint. After failing to improve with conservative management and pain medication, surgical stabilization of the joint was performed using a novel application of a braided suture and titanium button system. Unsatisfactory clinical improvement and postsurgical reevaluation indicated that the initial surgical stabilization was unsuccessful. The surgery was repeated, and the animal showed postsurgical improvement in intertarsal joint stability, weight-bearing, and lameness for a period of several years with use and adjustment of chronic pain medications. The novel surgical technique described in this case report represents an additional treatment option for management of avian intertarsal joint subluxations. Presurgical planning should consider the unique anatomic features and variability of the avian tarsometatarsus to avoid surgical complications.

Evidence-Based Advances in Avian Medicine

This article presents relevant advances in avian medicine and surgery over the past 5 years. New information has been published to improve clinical diagnosis in avian diseases. This article also describes new pharmacokinetic studies. Advances in the understanding and treatment of common avian disorders are presented in this article, as well. Although important progress has been made over the past years, there is still much research that needs to be done regarding the etiology, pathophysiology, diagnosis, and treatment of avian diseases and evidence-based information is still sparse in the literature.