Evaluation of Injectable Anesthetics for Major Surgical Procedures
in Guinea Pigs. Contemporary Topics 37 (4): 58.
The article lists several reasons why guinea pigs are considered a
hard species to anesthetize: limited routes for IV administration of drugs,
equipment and resources not readily available, and variable response to
most agents. Because guinea pigs are used fairly frequently in some areas
of research, the authors felt a need to find an effective anesthetic regimen
which could be administered more easily (IP or IM), a regimen which would
abolish specific reflexes known to signify a surgical plane of anesthesia,
and one which would provide sufficient anesthesia/analgesia for major surgical
procedures.
The study compared use of the following anesthetic regimens administered
IM to perform a ovariohystrectomy (OHE): ketamine/xylazine (KX), ketamine/detomidine
(KD), ketamine/medetomidine (KM), telazol/xylazine (TX), telazol/detomidine
(TD)and telazol/medetomidine (TM). Original ketamine doses failed to induce
a surgical plane of anesthesia in the guinea pigs, so dosages were increased
to 60 mg/kg.
Overall, TM proved to be the most reliable regimen. Surgery was successfully
completed in 23 of 29 guinea pigs. In animals where the KD regimen was
used, the anesthetic mixture failed to provide a surgical plane of anesthesia
for the performance of an OHE. As well, detomidine did not provide consistent
and sufficient anesthesia which was determined by variable loss of the
ear pinch response. In those guinea pigs that did ellicit an appropriate
ear pinch response, surgery was still not successfully completed for some
reason or another. A few of the adverse effects seen with the detomidine
groups included: tachypnea, gastric reflux and cyanosis. In general, it
was determined that detomidine is inappropriate for use in the guinea pig.
Questions:
1. What is the reversal agent (alpha-2 adrenergic antagonist) for medetomidine
(alpha-2 agonist) ?
2. Detomidine is responsible for myocardial necrosis in which lab animal
species ?
Answers:
1. Atipamezole hydrochloride (Antisedan). {Marketed with Dormitor in
Compendium alot} (p. 62)
2. Rabbit (p. 61)
Use of Corn-Husk Nesting Material to Reduce Aggression in Caged Mice.
Contemporary Topics 37 (4): 64.
Aggressive behavior in 6-7 weeks old Balb/c mice (8 mice/cage) was
reduced in cages enriched with 300 g of corn-husk nesting material. Mice
were checked for barbering or wounds. On day 4, mice on nesting material
had significantly fewer wounds per mouse than those on standard bedding
alone. The novel enrichment nesting decrease aggressive tendencies while
still providing a complex cage environment.
Questions:
1. Nesting-material enriched cages promote the following behavior(s):
a) tunneling
b) burrowing
c) nesting
d) avoidance
e) all of the above
2. In an enriched environment, How do mice establish stable social
structures?
a) dominance hierarchies
b) territorial aggression
c) social hierarchies
d) none of the above
Answers:
1. E
2. C
Assessment of a Canine Crown Reduction Technique in Nonhuman Primates.
Contemporary Topics 37 (4): 67.
This study evaluated the applicability of a pulpotomy technique used
in human dentistry for canine crown reduction in nonhuman primates (NHP).
They used calcium hydroxide as a pulpal capping agent and amalgram as a
resorative material for disarming these canine teeth. Many techniques have
been described to remove or decrease the sharpness and danger of the NHP
canine teeth. Extraction of the canine tooth is one method, however this
procedure is time consuming and invasive. It can result in maxillo-mandibular
deformities and subsequent complications such as malocclusion and periodontal
diseases. Another method is removal of canine teeth at the level of the
alveolar bone. This procedure does not require restoration because a mucoperiosteal
flap is sutured over the cut surface of the tooth to protect the pulp and
to maintain root vitality. This procedure is time-consuming, invasive,
technically difficult and prone to postoperative complications. Another
method is reduction of the crown of the canine teeth to the level of the
occlusal surface of the premolars and incisors. The crown reduction procedure
requires cutting discs or burrs be used with sufficient cooling; excessive
generation of heat can result in pulp necrosis and subsequent periapical
abscess formation. In this study, histomorphologically. Nonvital teeth
underwent pulpectomy and endontic treatment (root canal procedure) and
a pulpotomy was only performed on the vital pulp. 19 weeks after the procedure,
26 of 27 (96%) teeth on which the modified pulpotomy technique was performed
appeared radiographically normal and had a viable pulp. All 27 teeth had
intact amalgram seals.
During pulpotomy, the superficial portion of the amputated pulp can
be damaged by various physical forces (heat, pressure, and crushing) and
material (dentinal fragments and other grinding debris), producing fibrin,
hemorrhage, blood clots, thrombosis, and necrosis. Calcium hydroxide was
chosen as a pulpal capping agent because it maintains a viable pulp, stimulates
dentinogenesis, and, therefore, promotes dentinal bridge formation. It
has a high pH (> 12) that is bactericidal and inhibits osteoclastic activities
and subsequent formation of caries. Varnish was used as an intermediary
layer of medicament to seal the exposed pulp and dentinal tubules and to
serve as a barrier between the pulpal capping agent and restorative material,
which was amalgam. Amalgam was chosen to restore the amputated surface
and function of the teeth because it is the most frequently used restorative
material, is easy to use, exhibits minimal expansion and contraction with
temperature changes, improves with time, and is durable. This crown reduction
technique with pulpotomy has many advantages, such as it is faster, less
invasive, results in minimal discomfort, does not require the same degree
of technical expertise necessary to perform a root canal procedure, surgical
extraction, or mucoperiosteal flap surgery, and it promotes the maintenance
of a viable tooth.
Questions:
1. Indicate whether statement is True or False.
a. Extraction of the canine tooth can result in maxillo-mandibular
deformities.
b. Removal of canine teeth at the level of the alveolar bone requires
a pulpotomy procedure before the mucoperiosteal flap is sutured.
c. The crown reduction technique requires a pulpectomy on viable teeth.
d. Calcium hydroxide is used as a pulpal capping agent because it maintains
a viable pulp and stimulates dentinogenesis.
e. Calcium hydroxide is extremely acidic and thus is bactericidal.
f. Some of the advantages to the crown reduction technique are that
it is faster, less invasive, results in minimal discomfort and maintains
a viable tooth.
Answers:
a. T
b. F This procedure does not require restoration because a mucoperiosteal
flap is sutured over the cut surface of the tooth to protect the pulp and
to maintain root vitality.
c. F requires a pulpotomy
d. T
e. F is extremely alkaline
f. T
Rabbit Fur Mite (Listrophorus gibbus) Infestation of New Zealand
White Rabbits. Contemporary Topics 37 (4): 73.
Rare Listrophorus gibbus, rabbit fur mite, infestation was found on
the
underside of the tail by means of tiny dark specks on the pelage of
mostly
older rabbits. Hair samples were plucked and examined by using a light
microscope (40 to 100 X). All form of parasites were seen but eggs.
In adult
mites, four pairs of short legs and a dorsal protuberance of chitin
projecting
over their mouthparts were evident.
Not easily transmissible and without clinical signs, the infestation
was
easily treated with one or two application of a commercially available
carbamate-based acaracide.
Questions:
1- T/F: Rabbit fur mite, Listrophorus gibbus, is rare and easily treatable.
2- Listrophorus gibbus, a fur mite, is easily transmissible to
a) cat and guinea pig
b) rabbit and rat
c) human
d) none of the above
e) all of the above
Answers:
1- True
2- d)
A Mouth Speculum for Orogastric Administration of Compounds to Nonhuman
Primates. Contemporary Topics 37 (4): 76.
Orogastric gavage with use of a mouth speculum for oral administration
of
compound to conscious nonhuman primate is simple to learn and use,
is safe for
the monkeys and handlers, and prevents trauma to the nasal epithelium
of the
monkeys that would be inherent with nasogastric intubation.
Questions:
1- Which method of daily oral administration of test compounds to conscious
nonhuman primate is the least traumatic and most effective for large
quantity?
a) Nasogastric gavage
b) Orogastric gavage with bite bar and large feeding tube
c) via Food
d) none of the above
Answers:
1- b)