Measurements of hypoxia ([18F]‐FMISO, [18F]‐EF5) with positron emission tomography (PET) and perfusion using PET ([15O]‐H2O) and power Doppler ultrasonography in feline fibrosarcomas*

The aim of this study was to evaluate if hypoxia in feline fibrosarcomas can be detected. This was done using positron emission tomography (PET), two hypoxia tracers and polarographic pO₂ measurements. Of the seven cats included, five received [¹⁸F]‐fluoromisonidazole and two 2‐(2‐nitro‐1H‐imidazol‐1‐yl)‐N‐(2,2,3,3,3‐pentafluoropropyl) acetamide. Perfusion was evaluated with [¹⁵O]‐H₂O (n = 4) and with contrast‐enhanced power Doppler ultrasonography (n = 5). Hypoxia was detected in three cats. Polarographic pO₂ measurements did not confirm PET results. In the ultrasonographic evaluation, low vascularity and low perfusion were seen with a peripheral vascular pattern and no perfusion in the centre of the tumour. This was in contrast to the [¹⁵O]‐H₂O scans, where central perfusion of the tumour was also found. In conclusion, it appears that hypoxia exists in this tumour type. The presence of tumour necrosis and heterogeneous hypoxia patterns in these tumours may explain the found discrepancies between the applied techniques.     

WHOLE‐BODY BIODISTRIBUTION OF 3′‐DEOXY‐3′‐[18F]FLUOROTHYMIDINE (18FLT) IN HEALTHY ADULT CATS

Positron emission tomography/computed tomography (PET/CT) utilizing 3′‐deoxy‐3′‐[¹⁸F]fluorothymidine (¹⁸FLT), a proliferation tracer, has been found to be a useful tool for characterizing neoplastic diseases and bone marrow function in humans. As PET and PET/CT imaging become increasingly available in veterinary medicine, knowledge of radiopharmaceutical biodistribution in veterinary species is needed for lesion interpretation in the clinical setting. The purpose of this study was to describe the normal biodistribution of ¹⁸FLT in adult domestic cats. Imaging of six healthy young adult castrated male cats was performed using a commercially available PET/CT scanner consisting of a 64‐slice helical CT scanner with an integrated whole‐body, high‐resolution lutetium oxy‐orthosilicate (LSO) PET scanner. Cats were sedated and injected intravenously with 108.60 ± 2.09 (mean ± SD) MBq of ¹⁸FLT (greater than 99% radiochemical purity by high‐performance liquid chromatography). Imaging was performed in sternal recumbency under general anesthesia. Static images utilizing multiple bed positions were acquired 80.83 ± 7.52 (mean ± SD) minutes post‐injection. Regions of interest were manually drawn over major parenchymal organs and selected areas of bone marrow and increased tracer uptake. Standardized uptake values were calculated. Notable areas of uptake included hematopoietic bone marrow, intestinal tract, and the urinary and hepatobiliary systems. No appreciable uptake was observed within brain, lung, myocardium, spleen, or skeletal muscle. Findings from this study can be used as baseline data for future studies of diseases in cats.     

Pilot study utilizing Fluorine‐18 fluorodeoxyglucose‐positron emission tomography/computed tomography for glycolytic phenotyping of canine mast cell tumors

The goal of this prospective pilot study was to use naturally occurring canine mast cell tumors of various grades and stages as a model for attempting to determine how glucose uptake and markers of biologic behavior are correlated. It was hypothesized that enhanced glucose uptake, as measured by 2‐[fluorine‐18]fluoro‐d ‐glucose‐positron emission tomography/computed tomography (F18 FDG PET‐CT), would correlate with histologic grade. Dogs were recruited for this study from a population referred for treatment of cytologically or histologically confirmed mast cell tumors. Patients were staged utilizing standard of care methods (abdominal ultrasound and three view thoracic radiographs), followed by a whole body F18 FDG PET‐CT. Results of the F18 FDG PET‐CT were analyzed for possible metastasis and standard uptake value maximum (SUV_max) of identified lesions. Incisional or excisional biopsies of the accessible mast cell tumors were obtained and histology performed. Results were then analyzed to look for a possible correlation between the grade of mast cell tumors and SUV_max. A total of nine animals were included in the sample. Findings indicated that there was a correlation between grade of mast cell tumors and SUV_max as determined by F18 FDG PET‐CT (p‐value = 0.073, significance ≤ 0.1). Based on the limited power of this study, it is felt that further research to examine the relationship between glucose utilization and biologic aggressiveness in canine mast cell tumors is warranted. This study was unable to show that F18 FDG PET‐CT was a better staging tool than standard of care methods.     

Characteristics of 18F-FDG and 18F-FDOPA PET in an 8-year-old neutered male Yorkshire Terrier dog with glioma: long-term chemotherapy using hydroxyurea plus imatinib with prednisolone and immunoreactivity for PDGFR-β and LAT1

An 8-year-old neutered male Yorkshire Terrier dog presented with head pressing, vestibular ataxia, neck tenderness, and no oculocephalic reflex. A demarcated lesion in the pons was identified on MRI. The patient was tentatively diagnosed with a glioma and was treated with hydroxyurea plus imatinib and prednisolone. After 30 days of therapeutic treatment, the patient showed a clear improvement in neurological signs, which lasted for 1117 days. On day 569 after the initiation of treatment, ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) was performed with no significant findings on visual analysis. The average and maximal standardized uptake values (SUVs) were 1.92 and 2.29, respectively. The tumor-to-normal-tissue (T/N) ratio was 0.97. The first evidence of clinical deterioration was noticed on day 1147. On day 1155, 3,4-dihydroxy-6-[¹⁸F]-fluoro-l-phenylalanine (¹⁸F-FDOPA)-PET was performed. High uptake of ¹⁸F-FDOPA was observed in the intracranial lesion. The mean and maximal SUVs of the tumor were 1.59 and 2.29, respectively. The T/N ratio was 2.22. The patient was euthanized on day 1155 and histopathologic evaluations confirmed glioma (astrocytoma). This case shows that chemotherapy with hydroxyurea plus imatinib may be considered in the treatment of canine glioma. Furthermore, this is the first case describing the application of ¹⁸F-FDG and ¹⁸F-FDOPA in a dog with glioma.     

Intra‐ and interobserver agreement in the interpretation of navicular bones on radiographs and computed tomography scans

Reasons for performing study: Criteria for the radiographic evaluation of navicular bones in horses have been published to standardise classification of radiographic signs. However, intra‐ and interobserver agreement have not been established. Objective: To determine intra‐ and interobserver agreement in the evaluation of radiographic and computed tomographic (CT) navicular changes. It was hypothesised that: 1) intraobserver agreement would be better than interobserver agreement; 2) agreement would be better for CT than for radiography; and 3) pathological changes would be recognised with greater certainty with CT. Methods: Radiographs and CT scans of 60 cadaver navicular bones were evaluated by 3 observers using published criteria. A subset of 30 studies was evaluated twice by one observer. Agreement was tested using the kappa statistic. Certainty about pathological changes was evaluated by giving the observers the option to choose ‘not sure’. Results: Agreement varied from poor to almost perfect for radiographic evaluation and from poor to substantial for CT evaluation. For radiographic evaluation mean interobserver agreement was fair, as it was for CT evaluation. For radiographic evaluation mean intraobserver agreement was moderate as it was for CT evaluation. Pathological changes were evaluated with greater certainty on CT scans compared to radiographs; however, this was not associated with improved agreement. Conclusions: Variations in classification of navicular lesions in radiographic and CT studies were considerable between and within observers and challenge the use of such studies for diagnostic and prognostic purposes. Potential relevance: The results of this study allowed the identification of evaluation criteria with sufficient precision to be useful for navicular bone evaluation.     

Effects of maternal treatment with β‐hydroxy‐β‐metylbutyrate and 2‐oxoglutaric acid on femur development in offspring of minks of the standard dark brown type

The aim of the study was to evaluate the effect of the diet, mother type and sex of the offspring on the mechanical and geometric parameters of long bones as well as bone tissue density in minks. Primiparous and multiparous dams were supplemented with β‐hydroxy β‐methylbutyrate (a metabolite of leucine, at the daily dosage of 0.02 g/kg of body weight) and/or 2‐oxoglutaric acid (a precursor of glutamine, at the daily dosage of 0.4 g/kg of body weight) during gestation. The diet did not influence bone tissue density and the length of the humerus. An increase in the length of the femur was noted in male offspring delivered by multiparous dams. The diet resulted in an increase in the weight of the humerus in males from multiparous dams and a decrease in offspring from primiparous dams. Heavier femora were noted in male offspring delivered by both types of dams. The maximum elastic strength of the humerus was higher in the offspring delivered by multiparous than primiparous dams, irrespective of the offspring sex. The diet resulted in reduction in the ultimate strength of the femur in the male offspring delivered by primiparous dams. Only females born by multiparous dams, irrespective of the diet, showed a significant increase in the cross‐sectional area of the humerus, while a significant decline was noted in males delivered by multiparous dams and in all the offspring delivered by primiparous dams. An increase in the cross‐sectional area of the femur was noted in the offspring delivered by multiparous dams, while reduction was observed in the offspring delivered by primiparous dams. These results have shown for the first time that the presence of β‐hydroxy‐β‐methylbutyrate or 2‐oxoglutaric acid in the diet of pregnant primiparous or multiparous dams unambiguously affects the geometry and mechanical properties of offspring's long bones.     

Resection of the incisive bone and rostral maxillae for removal of an ossifying fibroma in an 18‐year‐old Warmblood gelding

A 510 kg, 18‐year‐old Warmblood gelding used for high level dressage was presented with a 6 week history of a growing mass at the rostral aspect of the incisive bone. Radiographic examination of the maxillae showed an osteolytic lesion between the left maxillary central and intermediate teeth spreading caudally into the hard palate. Biopsy of the mass was consistent with an aggressive oral fibrosarcoma. Diagnostic work‐up ruled out metastatic lesions. An amputation of the incisive bone and part of the rostral maxillae was performed with the intent of removing the mass in healthy margins. However, the neoplastic tissue extended to the rostral aspect of the ventral nasal conchae and a resection in healthy margins was not performed to avoid surgical complications due to communication with the nasal conchae. After surgery, the horse's appetite and food uptake were not impaired and cosmetic appearance was excellent. Active drains were used in order to prevent any submucosal collection of fluids. Histopathological examination of the surgical margins of the removed maxillae confirmed the presence of tumoural tissue. Even though excision of the tumour was not complete, no macroscopic local recurrence was reported post operatively at 36 months' follow‐up. Based on histological re‐evaluation of the removed tissue and the absence of recurrence a definitive diagnosis of ossifying fibroma was made.     

The long‐term effect of α‐ketoglutarate,given early in postnatal life,on both growth and various bone parameters in pigs

The long‐term effect of α‐ketoglutarate (AKG) given for 21–24 days post‐partum, on the skeleton of commercial pigs, was investigated. In experiment A, 12 pigs were given AKG [0.1 g/kg of body weight (b.w.) per day per os], while 12 controls were administered vehicle. At day 169, the left and right femur, humerus and sixth ribs were analysed for mechanical and geometrical properties and quantitative computed tomography. In experiment B, 32 piglets were divided equally into an AKG group (0.3 g/kg of b.w. per day) or a control group. Blood, taken at days 24 and 53 was analysed for plasma 17 β‐oestradiol. The main bone effect of AKG was to increase bone length in the sixth rib (7.3%, p < 0.01), ultimate strength (23%, p < 0.05), Young´s modulus (52%, p < 0.001) and maximum elastic strength (31%, p = 0.056) compared with controls. In both experiments, AKG preferentially increased the growth of female piglets, whilst for male piglets AKG had the opposite effect. In addition, AKG elevated plasma 17 β‐oestradiol levels compared to those of controls at the end of the period of treatment (20%, p = 0.002). It is concluded that AKG has long‐term effects on rib properties when given early in postnatal life whilst it elevates plasma 17 β‐oestradiol levels only so long as it is being administered.     

Detection of the EGFP sequence in breast muscle of 3‐year‐old chicken after transfection using sonoporation

In our continuing effort to generate transgenic chickens, sonoporation was chosen to insert an exogenous gene into the chicken genome. An EGFP expression vector (pCAG‐EGFPac) and microbubbles were injected into the central disc of stage‐X blastoderm or the germinal crescent of stage‐4 embryos, followed by ultrasonic vibration. Nineteen chicks out of 108 treated embryos hatched, six females and six males out of these 19 chicks grew to sexual maturity and two females and three males lived for 3 years. Genomic DNA from 17 out of 35 gonads from embryos and chicks that died before sexual maturity was EGFP‐positive by PCR. No EGFP sequence was detected in the genomic DNA of 322 embryos from six sexually mature females and the semen from four sexually mature males by PCR. When genomic DNA was obtained from various tissues of five 3‐year‐old chickens, the EGFP sequence was amplified from the genomic DNA of the breast muscle of a female (No. 85). The above sequence was subjected to DNA sequencing and verified to be the EGFP sequence. These results showed that sonoporation is an effective tool for the transduction of exogenous genes into chicken embryos for the generation of transgenic chickens.     

Effect of increased feeding of dietary α‐linolenic acid by grazing on formation of the cis9,trans11–18:2 isoform of conjugated linoleic acid in bovine milk

Feeding systems such as grazing affect the fatty acid profile of bovine milk fat. In addition, milk fat is formed as the product of fatty acid metabolism in cow bodies before being secreted into milk. However, how grazing influences milk fatty acid profile through the metabolism has not been completely characterized. When fatty acid concentrations in Holstein milk were compared between grazing and non‐grazing periods, α‐linolenic acid was significantly higher in the grazing period than in the non‐grazing period. This could be explained with an increase in α‐linolenic acid feeding with grazing. α‐linolenic acid had a linear positive correlation with conjugated linoleic acid (9c,11t‐18:2) (CLA) and vaccenic acid (VA) during the grazing period, whereas CLA had higher correlation with linoleic acid rather than with α‐linolenic acid during the non‐grazing period. These data indicate that the high content of dietary α‐linolenic acid affects CLA and VA formation in milk of grazing periods via α‐linolenic acid metabolism into VA.     

Different prostaglandin F2α secretion in response to oxytocin injection between pregnant and non‐pregnant cows: effect of the day of oxytocin challenge test for determining the difference

The present study was conducted to determine the difference in plasma prostaglandin F₂α metabolite concentrations following oxytocin (OT) challenge between pregnant and non‐pregnant cows. Experiment 1: cows were subjected to the OT challenge test on days 12, 14 or 16 (day of estrus = day 0) with or without prior insemination and plasma 13,14‐dihydro‐15‐keto prostaglandin F₂α (PGFM) concentrations were measured from ?30 to 180 min after OT injection. On day 16, the increment of plasma PGFM concentrations in response to OT injection was significantly smaller in pregnant than that in cyclic cows. On days 12 and 14, there was little OT‐induced PGFM secretion and no difference in PGFM increase between the pregnant and cyclic cows. Experiment 2: cows were inseminated on day 0 and subjected to the OT challenge test on day 16. Cows were classified into non‐pregnant/early embryonic death (NP/EED), late embryonic death (LED) and pregnant (PREG) groups. The increment of PGFM concentrations in response to OT injection was less in both PREG and LED groups than that in the NP/EED group. In conclusion, plasma PGFM secretion induced by OT is suggested as the base of pregnancy diagnosis prior to returning estrus in cows.