Lab Animal

Sudden death in miniature pigs.(WHAT'S YOUR DIAGNOSIS)(Report)

Fluorescent dyes or fluorochromes can be useful tools for analyzing changes in bone morphology. Their presence in bone sections indicates site, time and amount of bone deposition, which cannot be determined using conventional histological techniques (1). Fluorescent dyes were originally used for metal titration because they chelate with metals but are now also used to stain calcified tissues. Yellow tetracyclines, xylenol orange, alizarin red derivatives and green fluorescein derivatives such as calcein can be easily distinguished in bone by the color of their fluorescence. They all share a common iminodiacetic acid group, which chelates with calcium hydroxyapatite, the principal mineral in bone and teeth. Fluorochromes are administered systemically and incorporated into bone during the mineralization phase of ossification. When treated bone is examined under fluorescence microscopy, these fluorochrome dyes exhibit photoluminescence that allows identification of the mineralized tissue. Filter sets for fluorescence microscopy can be chosen for selective excitation of single fluorochromes, or broad band filters may be used for simultaneous visualization of several fluorochromes (1). The administration of several fluorochromes, distinguishable by color, offers distinct advantages over single labels. For example, evaluating the distance between different fluorochromes administered at different times shows both the deposition of bone during a specific time period and the direction of ossification (1).

We used eight 2-year-old female Gottingen miniature pigs (Ellegaard Gottingen Minipigs ApS , Dalmose, Denmark) that weighed on average 45 kg in our study. We created cavities in the premolar and molar regions of the upper and lower jaws that measured 30 mm x 10 mm by surgically removing the teeth in these locations. The pigs were anesthetized during the procedure, and postoperative analgesia consisted of buprenorphine (Temgesic, Essex Pharma, Grunenthal, Germany) administered every 8 h for 3 d and carprofen (Rimadyl, Pfizer GmbH, Karlsruhe, Germany) given once a day for an additional 7 d. In the first four weeks after surgery we also gave the antibiotic enrofloxacin (Baytril-10%, Bayer AG, Leverkusen, Germany) daily to the pigs. After a healing period of 8 weeks, we then added autologous bone collected from the pig's iliac crest or fibula to the cavities.

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To evaluate the dynamics of ossification and bone remodeling, we used polychrome sequential labeling that entailed administering different fluorochromes to the miniature pigs 2, 5 and 8 weeks after adding autologous bone to the jaw defects. …

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