The distribution of calbindinD‐28k and parvalbumin immunoreactive neurons in the somatosensory area of the pigeon pallium

GABAergic interneurons regulate the degree of glutamatergic excitation and output of projection neurons. In this study, we investigated the distribution of calbindinD‐28k (CB) and parvalbumin (PV) in the somatosensory area of the pigeon pallium using immunohistochemical method. Our results show that anatomical structures of the somatosensory area of the pigeon pallium consisted of several subdivisions including the hyperpallium, intercalated hyperpallium, mesopallium, nidopallium and basorostralis. Neuronal density was significantly higher in the intercalated hyperpallium and basorostralis than that in the other subdivisions. The density of the CB immunoreactive neurons was generally similar in all the subdivisions; however, the density of PV immunoreactive neurons was particularly prominent in the basorostralis compared with that in the other subdivisions. In addition, the mean proportion of PV immunoreactive neurons to total neurons was higher than that in the CB immunoreactive neurons in all the subdivisions. In brief, our present study shows that PV immunoreactive neurons in the somatosensory area of the pigeon pallium were significantly abundant compared with CB immunoreactive neurons. This finding needs more studies regarding CB‐ and PV‐related functions in the somatosensory area of the avian pallium.     

Intrinsic innervation of the ileocaecal junction in the horse: Preliminary study

Reason for performing study: In horses, morpho‐functional studies related to the enteric nervous system (ENS) controlling the sphincters are lacking. Objectives: To investigate immunohistochemically the morphology, distribution, density, phenotypes and projections of neurons controlling the ileocaecal junction (ICJ). Methods: Two young horses were anaesthetised and underwent midline laparotomy. The neuronal retrograde fluorescent tracer Fast Blue (FB) was injected into the wall of the ICJ. A post surgical survival time of 30 days was used. Following euthanasia, the ileum and a small portion of caecum were removed. Cryosections were used to investigate the immunoreactivity (IR) of the neurons innervating the ICJ for choline acetyltransferase (ChAT), neuronal nitric oxide synthase (nNOS), substance P (SP), calcitonin gene‐related peptide (CGRP) and neurofilament NF200kDa (NF). Results: Ileal FB‐labelled neurons innervating the ICJ were located in the myenteric plexus (MP) and submucosal plexus (SMP) up to 48 cm and 28 cm, respectively, from the point of the FB injections. Descending MP and SMP neurons were nitrergic (54 ± 11% and 68 ± 4%, respectively), cholinergic (60 ± 19% and 82 ± 11%, respectively), NF‐IR (54 ± 9% and 78 ± 21%, respectively), and SP‐IR (about 20% in both the plexuses). CGRP‐IR was expressed only by SMP descending neurons (45 ± 21%). In both the plexuses descending neurons coexpressing nNOS‐and ChAT‐IR were also observed (25 ± 11% and 61 ± 27%, respectively). Conclusions: The presence of ileal long projecting neurons innervating the ICJ suggests that they are critical for its modulation. Consequently, in bowel diseases in which the resection of the terminal jejunum and proximal ileum are required, it is preferable, whenever possible, to conserve the major portion of the ileum. Potential relevance: The knowledge of the phenotype of ENS neurons of the ileum might be helpful for developing pharmaceutical treatment of the ICJ motility disorders.     

Age-related three-dimensional morphological changes in rat motoneurons innervating diaphragm and longissimus muscles

We investigated age-related morphological changes of rat motoneurons innervating diaphragm muscle (DI-MN) and lumber longissimus muscle (LL-MN) in which quite different activation patterns exist. In young (2-4 months) and old (24-26 months) rats, the motoneurons innervating both muscles were labelled retrogradely by intramuscular injection of cholera toxin B subunit. After a 4-day survival, horizontal slices of the spinal cord were processed with immunohistochemical staining (first antibody to cholera toxin B subunit and second antibody with Cy3) and observed with a confocal microscope. Three-dimensional reconstruction of labelled motoneurons was performed to examine soma and dendrite morphology. As compared to the soma volume in young rats, significantly smaller values were found in old rats in both motoneurons and the degrees of decline were 16.1% in DI-MN and 20.3% in LL-MN. Significant decreases in the thickness of primary dendrites were also found in both motoneurons, and the degrees of decline were 17.5% in DI-MN and 22.3% in LL-MN. Smaller changes were found in DI-MN than in LL-MN, indicating the possibility that increased activation by central drives can attenuate age-related morphological changes of the motor system in the spinal cord.     

Expression analyses of candidate genes related to meat quality traits in squabs from two breeds of meat‐type pigeon

In this study, meat quality traits were compared between squabs from two pigeon breeds: one Chinese indigenous breed, the Shiqi (SQ) meat‐type pigeon, and an imported breed, the white king (WK) meat‐type pigeon. Breed differences were detected in the content of intramuscular fat (IMF) in the breast muscle. SQ squabs had significantly higher IMF content than the WK birds. The shear force value (an objective measure of meat tenderness) of SQ birds was also relatively lower than that of the WK squabs. Further analysis of fatty acids profile revealed that SQ squabs exhibited significant advantage in the synthesis of polyunsaturated fatty acids, while WK squabs were significantly higher in the sum of monounsaturated fatty acids. Breast muscle in the SQ squabs was also significantly higher in the ratio of polyunsaturated fatty acids to saturated fatty acids, as well as the sum of omega 6 fatty acids. Variability of expression levels of functional genes in relation to fat accumulation and meat tenderness was analysed by qRT‐PCR. Gene expression analyses showed that the hepatic expression of LPL (lipoprotein lipase), FABP4 (fatty acid‐binding protein 4), and CAPN2 (calpain‐2) were significantly higher in the SQ squabs. In the breast muscle tissue, the FABP3 (fatty acid‐binding protein 3) and CAPN2mRNA abundance was significantly higher in SQ squabs. Our results suggested that these differentially expressed genes might be candidate genes used in the programmes of targeted selection for squabs with higher IMF content, tender meat, and more favourable fatty acids composition.     

Expression of β2 adrenoceptors within enteric neurons of the horse ileum

The activity of the gastrointestinal tract is regulated through the activation of adrenergic receptors (ARs). Since data concerning the distribution of ARs in the horse intestine is virtually absent, we investigated the distribution of β₂-AR in the horse ileum using double-immunofluorescence. The β₂-AR-immunoreactivity (IR) was observed in most (95%) neurons located in submucosal plexus (SMP) and in few (8%) neurons of the myenteric plexus (MP). Tyrosine hydroxylase (TH)-IR fibers were observed close to neurons expressing β2-AR-IR. Since β₂-AR is virtually expressed in most neurons located in the horse SMP and in a lower percentage of neurons in the MP, it is reasonable to retain that this adrenergic receptor could regulate the activity of both secretomotor neurons and motor neurons innervating muscle layers and blood vessels. The high density of TH-IR fibers near β₂-AR-IR enteric neurons indicates that the excitability of these cells could be directly modulated by the sympathetic system.     

Ultrasonography for the diagnosis of diseases of the tendon and tendon sheath of the biceps brachii muscle

OBJECTIVE: To describe the ultrasonographic appearance of the normal and diseased biceps brachii tendon and its tendon sheath in dogs. STUDY DESIGN: A prospective clinical study. ANIMALS: One hundred twenty client-owned dogs. METHODS: In the first part of the study, the ultrasonographic appearance of the normal biceps brachii muscle and the surrounding soft tissue was determined in 27 healthy dogs. Standard views were described and established. In the second part, 120 dogs with suspected pathology of the biceps brachii muscle were examined ultrasonographically. Fifty-five of these dogs had no sonographic changes, and 65 dogs had sonographically detectable pathologic changes of the tendon or the tendon sheath or both. The mean age of the affected dogs was 3.7 years. The ratio of males to females was 1.95:1. Sedation or anesthesia of the dogs was required because of the extreme movements of the leg necessary for the examination. To achieve a perpendicular view of the tendon and the tendon sheath, the area of the shoulder joint was rotated outward and abducted as far as possible. Examination of the muscle-tendon apparatus of the biceps brachii muscle was divided into 4 main sections. RESULTS: Linear transducers (7.5-10 MHz) allowed the soft tissue structures to be easily visualized with ultrasonography. Pathologic changes of the tendon and tendon sheath were visualized sonographically by using high-frequency linear probes. Partial or complete tendon rupture, medial luxation of the tendon, corpora libera in the tendon sheath, and tenosynovitis were clearly shown. CONCLUSIONS: High-frequency ultrasonography using linear transducers allows the examiner to accurately define the pathologic changes in the region of the biceps brachii tendon in dogs. CLINICAL RELEVANCE: The use of sonography for diagnosis of disease processes of the tendon and tendon sheath of the biceps brachii muscle complements clinical and radiographic examination findings.     

Epidemiology of Chlamydia psittaci Infection in Racing Pigeons and Pigeon Fanciers in Beijing,China

Over 3 million racing pigeons (Columba livia) are registered in Beijing City Center for gambling purposes. During 2008–2010, we evaluated the occurrence and prevalence of Chlamydia psittaci in racing pigeons as well as the possible zoonotic transmission to pigeon fanciers in six districts of Beijing where pigeon races are particularly popular. C. psittaci‐specific serum antibody titres were obtained from 370 pigeons and 79 fanciers using enzyme‐linked immunosorbent assay. In addition, 206 and 67 throat swabs were, respectively, collected from pigeons and fanciers and tested for the presence of chlamydial antigen using immunofluorescence. C. psittaci‐specific serum antibody was detected in 37 of 370 pigeons and 19 of 79 fanciers. Of 206 pigeon clinical specimens, 55 were positive for C. psittaci antigen, while 16 of 67 swabs from the pigeon fanciers were positive. Based on ompA sequence analysis, the genotype of several avian and human isolates was genotype B. Thus, both high‐titre C. psittaci‐specific antibody and C. psittaci‐specific antigen were found with relatively high frequency in the pigeon flocks as well as in the pigeon fanciers. Our study suggests that C. psittaci infection is prevalent among the racing pigeon population in Beijing. Moreover, detection of serum antibodies and antigen in pigeon fanciers suggests that exposure and possible zoonotic transmission of C. psittaci from racing pigeons to humans does occur. In view of the life‐threatening respiratory illness C. psittaci may cause in humans, regulatory public health measures, to prevent further spread of the pathogen in avian populations and possible transmission to exposed humans, are urgently needed.     

Computed tomographic morphometry of the biceps brachii muscle tendon of dogs affected by the medial coronoid disease

The objective of this study was to measure the biceps brachii muscle (BBM) attachment to the medial coronoid process (MCP) using computed tomography images and to compare these data between clinically healthy and dogs affected by medial coronoid disease (MCD). Computed tomography was performed in MCD-affected and healthy dogs. Multiplanar reconstruction views were obtained to measure distance (cm) of the BBM attachment point to the MCP. Results showed that the mean BBM attachment point-to-MCP was 1.42 ± 0.23 cm in MCD-affected and 1.27 ± 0.20 cm in healthy dogs, respectively. In dogs with MCD, the BBM attachment point-to-MCP was significantly more abaxial than in clinically healthy dogs (p < .001). The results of this study support the hypothesis that the BBM attachment site is more abaxial to the MCP and therefore may contribute to supraphysiological overload leading to MCD. Albeit more research is necessary, this study proves a relationship between the BBM attachment point and the development of MCD.     

Relationships among muscle fiber type composition,fiber diameter and MRF gene expression in different skeletal muscles of naturally grazing Wuzhumuqin sheep during postnatal development

The aim of this study was to determine the relationships among muscle fiber‐type composition, fiber diameter, and myogenic regulatory factor (MRF) gene expression in different skeletal muscles during development in naturally grazing Wuzhumuqin sheep. Three major muscles (i.e. the Longissimus dorsi (LD), Biceps femoris (BF) and Triceps brachii (TB)) were obtained from 20 Wuzhumuqin sheep and 20 castrated rams at each of the following ages: 1, 3, 6, 9, 12 and 18 months. Muscle fiber‐type composition and fiber diameter were measured using histochemistry and morphological analysis, and MRF gene expression levels were determined using real‐time PCR. In the LD muscle, changes in the proportion of each of different types of fiber (I, IIA and IIB) were relatively small. In the BF muscle, a higher proportion of type I and a 6.19‐fold lower proportion of type IIA fibers were observed (P < 0.05). In addition, the compositions of type I and IIA fibers continuously changed in the TB muscle (P < 0.05). Moreover, muscle diameter gradually increased throughout development (P < 0.05). Almost no significant difference was found in MRF gene expression patterns, which appeared to be relatively stable. These results suggest that changes in fiber‐type composition and increases in fiber size may be mutually interacting processes during muscle development.     

Reduced dietary protein level influences the free amino acid and gene expression profiles of selected amino acid transceptors in skeletal muscle of growing pigs

This study was conducted to evaluate the effect of reduced dietary protein level on growth performance, muscle mass weight, free amino acids (FAA) and gene expression profile of selected amino acid transceptors in different fibre type of skeletal muscle tissues (longissimus dorsi, psoas major, biceps femoris) of growing pigs. A total of 18 cross‐bred growing pigs (Large White × Landrace × Duroc) with initial body weight (9.57 ± 0.67 kg) were assigned into three dietary treatments: 20% crude protein (CP) diet (normal recommended, NP), 17% CP diet (low protein, LP) and 14% CP diet (very low protein, VLP). The results indicated improved feed‐to‐gain ratio was obtained for pigs fed LP and NP diets (p < 0.01), while the pigs fed VLP diet showed the worst growth performance (p < 0.01). There was no significant difference in the weights of longissimus dorsi and psoas major muscle between LP and NP groups (p > 0.05). Majority of the determined FAA concentration of LP group were greater than or equal to those of NP group in both longissimus dorsi and psoas major muscle (p < 0.01). Further, the mRNA expression levels of sodium‐coupled neutral amino acid transceptor 2, L‐type amino acid transceptor 1 and proton‐assisted amino acid transceptors 2 were higher in skeletal muscle tissue in LP group compared to those of the pigs fed NP or VLP diet. These results suggested that reduced dietary protein level (3 points of percentage less than recommended level) would upregulate the mRNA expression of amino acid transceptors to enhance the absorption of FAA in skeletal muscle of growing pigs. There seems to be a relationship between response of AA transceptors to the dietary protein level in skeletal muscle tissue of different fibre type. To illustrate the underlying mechanisms will be beneficial to animal nutrition.     

Pharmacokinetics of oral transmucosal and intramuscular dexmedetomidine combined with buprenorphine in cats

Plasma concentrations and pharmacokinetics of dexmedetomidine and buprenorphine after oral transmucosal (OTM) and intramuscular (i.m.) administration of their combination in healthy adult cats were compared. According to a crossover protocol (1‐month washout), a combination of dexmedetomidine (40 μg/kg) and buprenorphine (20 μg/kg) was given OTM (buccal cavity) or i.m. (quadriceps muscle) in six female neutered cats. Plasma samples were collected through a jugular catheter during a 24‐h period. Plasma dexmedetomidine and buprenorphine concentrations were determined by liquid chromatography–tandem mass spectrometry. Plasma concentration–time data were fitted to compartmental models. For dexmedetomidine and buprenorphine, the area under the plasma concentration–time curve (AUC) and the maximum plasma concentrations (C_max) were significantly lower following OTM than following i.m. administration. For buprenorphine, time to reach C_max was also significantly longer after OTM administration than after i.m. injection. Data suggested that dexmedetomidine (40 μg/kg) combined with buprenorphine (20 μg/kg) is not as well absorbed from the buccal mucosa site as from the intramuscular injection site.     

Pharmacokinetic profile of Ceftiofur Hydrochloride Injection in lactating Holstein dairy cows

Ceftiofur (CEF), a broad‐spectrum third‐generation cephalosporin, exhibits a good activity against a broad range of gram‐negative and gram‐positive bacteria, including many that produce β‐lactamase. To design a rational dosage regimen for the drug in lactating Holstein dairy cows, the pharmacokinetic properties of ceftiofur hydrochloride injection were investigated in six cows after intravenous, intramuscular, and subcutaneous administration of single dose of 2.2 mg/kg BW (body weight). Plasma concentration–time curves and relevant parameters were best described by noncompartmental analysis through WinNonlin 6.3 software. After subcutaneous administration, the absolute bioavailability was 61.12% and the T_1/2λz (elimination half‐life) was 8.67 ± 0.72 hr. The C_max (maximum plasma concentration) was 0.88 ± 0.21 μg/ml and T_max (the time after initial injection to when C_max occurs) was 1.50 ± 0.55 hr. The MRT (mean residence time) was 11.00 ± 0.30 hr. Following intramuscular administration, the C_max (1.09 ± 0.21 μg/ml) was achieved at T_max (1.20 ± 0.26 hr) with an absolute availability of 70.52%. In this study, the detailed pharmacokinetic profiles of free and total CEF showed that this drug is widely distributed and rapidly eliminated and may contribute to a better understanding of the usage of ceftiofur hydrochloride injection in Holstein dairy cows.     

Identification of polymorphisms and association analysis with meat quality traits in the porcine KIAA1717 and HUMMLC2B genes

Skeletal muscle genes are potential candidates for production and meat quality. Screening a subtracted cDNA library constructed with mRNA obtained from longissimus dorsi muscles of F1 hybrids Landrace × Yorkshire and their female parents Yorkshire, we isolated two partial sequences coding for the H3-K4-specific methyltransferase (KIAA1717) and skeletal muscle myosin regulatory light chain (HUMMLC2B) genes. Database search revealed KIAA1717 and HUMMLC2B encoded proteins with SET domain and EF-hand calcium binding motif, respectively. In the present work we identified their partial polymorphisms and two SNPs, one (C1354T) at the 3′ untranslated region (UTR) of KIAA1717 and one (A345G) at the SINE (PRE-1) element of HUMMLC2B, both created/disrupted a restriction site for endonuclease Msp I. The selected pigs were genotyped at the KIAA1717 C1354T and HUMMLC2B A345G sites by means of a PCR-RFLP protocol. Significant associations were observed for the KIAA1717 C1354T polymorphic site with meat marbling (longissimus doris (p < 0.05), biceps femoris (p < 0.01)) and intramuscular fat (p < 0.01). HUMMLC2B A345G were significantly associated with meat pH (longissimus doris (p < 0.05), biceps femoris (p < 0.01)), drip loss (p < 0.01), water holding capacity (p < 0.01) and meat color value (longissimus doris (p < 0.01), biceps femoris (p < 0.05)). Further studies are needed to confirm these preliminary results.     

Motor Neuron Organization and Corticospinal Fibers in the Cervical Intumescence of the Raccoon (Procyon lotor) Spinal Cord

Experiments were performed on 19 raccoons to determine the organization of the spinal alpha motoneurons innervating the muscles of the thoracic limb. Chromatolysis of motoneurons was provoked by resecting major nerves or removing individual muscles or muscle groups. Proximal intrinsic limb muscle motoneurons were located cranially in the cervical spinal intumescence and distal muscle motoneurons more caudally. Flexor motoneurons were generally dorsal and more laterally located within the lateral motoneuronal cell group than were the cell bodies innervating their extensor antagonists. The distribution of motor cortex projections to motoneurons was studied in five raccoons by selective silver impregnation of degenerating fibers after unilateral motor cortex ablation. Degenerating cortical projections within the motoneuronal cell group (Rexed's lamina IX) were seen only in the more dorsal and the lateral portions in the seventh and eighth cervical and the first thoracic spinal cord segments. Motor cortex preterminal and terminal fibers were in close apposition to the proximal dendrites and the somata of alpha motoneurons innervating primarily the more distal limb musculature and particularly the intrinsic muscles of the manus.     

Location of sympathetic postganglionic and sensory neurons innervating the testis in the male chicken

Sympathetic postganglionic and sensory neurons were labelled by injections of horseradish peroxidase into the testis of the male chicken. The total number of labelled neurons in the paravertebral, prevertebral, dorsal root and nodose ganglia was 943 on average for five chickens. Sympathetic postganglionic neurons were located in the paravertebral ganglia T3-LS3 (10% of the total number of labelled neurons), especially in T6 and T7, and in the prevertebral ganglia adjacent to the adrenal glands and aorta (19%). They were found almost ipsilaterally. No labelled neurons were observed in the dorsal motor nucleus of the vagus. Sensory neurons were found bilaterally in the dorsal root ganglia T2-LS3 (71%), especially in T5 to T7. Over a quarter of labelled sensory neurons were located in the contralateral dorsal root ganglia. In the nodose ganglia, only a few labelled sensory neurons were observed (much less than 1%). These results indicate that, unlike the ovary, the testis of the chicken tends to be innervated by ipsilaterally located sympathetic postganglionic and sensory neurons, with the sensory neurons being more numerous than the sympathetic postganglionic neurons.     

Leucine alone or in combination with glutamic acid,but not with arginine,increases biceps femoris muscle and alters muscle AA transport and concentrations in fattening pigs

Forty‐eight Duroc × Large White × Landrace pigs with an average initial body weight of 77.09 ± 1.37 kg were used to investigate the effects of combination of leucine (Leu) with arginine (Arg) or glutamic acid (Glu) on muscle growth, free amino acid profiles, expression levels of amino acid transporters and growth‐related genes in skeletal muscle. The animals were randomly assigned to one of the four treatment groups (12 pigs/group, castrated male:female = 1:1). The pigs in the control group were fed a basal diet (13% Crude Protein), and those in the experimental groups were fed the basal diet supplemented with 1.00% Leu (L group), 1.00% Leu + 1.00% Arg (LA group) or 1.00% Leu + 1.00% Glu (LG group). The experiment lasted for 60 days. Results showed an increase (p < 0.05) in biceps femoris (BF) muscle weight in the L group and LG group relative to the basal diet group. In longissimus dorsi (LD) muscle, Lys, taurine and total essential amino acid concentration increased in the LG group relative to the basal diet group (p < 0.05). In LG group, Glu and carnosine concentrations increased (p < 0.05) in the BF muscle, when compared to the basal diet group. The Leu and Lys concentrations of BF muscle were lower in the LA group than that in the L group (p < 0.05). A positive association was found between BF muscle weight and Leu concentration (p < 0.05). The LG group presented higher (p < 0.05) mRNA levels of ASCT2, LAT1, PAT2, SANT2 and TAT1 in LD muscle than those in the basal diet group. The mRNA levels of PAT2 and MyoD in BF muscle were upregulated (p < 0.05) in the LG group, compared with those in the basal diet group. In conclusion, Leu alone or in combination with Glu is benefit for biceps femoris muscle growth in fattening pig.     

Genotype and dietary lysine deficiency affect carcass and muscle amino acid composition of pigs growing from 10 to 25 kg body weight

Amino acid (AA) composition of body protein is considered constant although there are evidences that AA pattern in pigs may be altered by different factors. Pigs with different body composition and protein deposition rates—like fatty and lean pigs—may differ in AA composition, with possible consequences on their AA requirements. This work investigates effects of genotype and dietary lysine deficiency on AA composition of carcass and muscles of Iberian and Landrace × Large White pigs. Twenty‐eight barrows (10 kg body weight [BW]), 14 from each breed, were used. They were randomly assigned to two experimental diets according to a factorial arrangement (two breeds × two diets). Diets were isonitrogenous and isoenergetic (200 ± 1 g CP/kg dry matter (DM); 14.7 ± 0.1 MJ ME/kg DM) and with identical chemical composition except for lysine concentration (10.9 and 5.20 g lysine/kg DM, for lysine‐adequate (AL) diet and lysine‐deficient (DL) diet respectively). Pigs were individually housed, and daily feed allowance was adjusted on a weekly basis according to BW. Pigs were slaughtered at 25 kg BW. Isoleucine, valine and phenylalanine concentration were higher in carcass protein of Iberian pigs (p < .01). In longissimus muscle, higher concentration of arginine, isoleucine, phenylalanine, lysine and valine (p < .001–p < .05), and lower of methionine (p < .001) were detected in Iberian pigs, whereas phenylalanine, leucine, lysine, threonine and methionine concentration decreased and arginine increased (p < .001–p < .05) when pigs were fed DL diet. Genotype and lysine deficiency effects were moderate in the AA composition of protein of biceps femoris muscle. The results show that AA proportions in protein of carcass and longissimus muscle can be influenced by pig genotype and conditions of lysine shortage. The biceps femoris muscle, with different functional and metabolic properties, shows more constant AA composition than longissimus, which seem to prevail independent from genotype or nutritional challenges.     

A physiologically based pharmacokinetics model for florfenicol in crucian carp and oral‐to‐intramuscular extrapolation

Yang, F., Sun, N., Sun, Y. X., Shan, Q., Zhao, H. Y., Zeng, D. P., Zeng, Z. L. A physiologically based pharmacokinetics model for florfenicol in crucian carp and oral‐to‐intramuscular extrapolation. J. vet. Pharmacol. Therap.  36 , 192–200. In this study, an oral physiologically based pharmacokinetics (PBPK) model was developed for florfenicol in crucian carp (Carassius auratus). Subsequently, oral‐to‐intramuscular extrapolation was performed and the two models were used to predict florfenicol concentrations in the edible tissues of crucian carp. The oral model gave good predictions in most tissues, except for kidney and liver in which the florfenicol concentrations were underestimated at the later time points. In contrast, using the intramuscular model, the concentrations in the kidney were overestimated at the later time points. Both models had the best predictive ability in the main edible tissue, the muscle. The oral model also accurately predicted the florfenicol concentrations in the muscle after multiple doses. The present study demonstrated the feasibility of predicting florfenicol concentrations in the edible tissues of crucian carp using a route‐to‐route extrapolation method.     

Pharmacokinetics of marbofloxacin in pigs after intravenous and intramuscular administration of a single dose of 8 mg/kg: dose proportionality,influence of the age of the animals and urinary elimination

The pharmacokinetics of marbofloxacin in pigs were evaluated as a function of dose and animal age following intravenous and intramuscular administration of a 16% solution (Forcyl^®). The absolute bioavailability of marbofloxacin as well as the dose proportionality was evaluated in 27‐week‐old fattening pigs. Blood PK and urinary excretion of marbofloxacin were evaluated after a single intramuscular dose of 8 mg/kg in 16‐week‐old male pigs. An additional group of 12‐week‐old weaned piglets was used for the evaluation of age‐related kinetics. The plasma and urine concentration of marbofloxacin was determined using a HPLC method. Pharmacokinetic parameters were calculated using noncompartmental methods. After intravenous administration in 27‐week‐old fattening pigs, the total body clearance was 0.065 L/h·kg. After intramuscular administration to the same animals, the mean observed C_max was 6.30 μg/mL, and the AUC_INF was 115 μg·h/mL. The absolute bioavailability was 91.5%, and dose proportionality was shown within the dose range of 4–16 mg/kg. The renal clearance was about half of the value of the total clearance. The total systemic clearance values significantly decreased as a function of age, being 0.092 L/h·kg and 0.079 L/h·kg in pigs aged 12 and 16 weeks, respectively.