EVALUATION OF IMMERSION IN EMULSIFIED ISOFLURANE OR PROPOFOL AS PART OF A TWO-STEP EUTHANASIA PROTOCOL IN MARBLED CRAYFISH (PROCAMBARUS VIRGINALIS).

The marbled crayfish (Procambarus virginalis) is a parthenogenetic invasive species across much of the world, and when found, euthanasia is often recommended to reduce spread to naïve ecosystems. Euthanasia recommendations in crustaceans includes a two-step method: first to produce nonresponsiveness and then to destroy central nervous tissue. Minimal data exist on adequate anesthetic or immobilization methods for crayfish. A population of 90 marbled crayfish was scheduled for euthanasia due to invasive species concerns. The population was divided into six treatment groups to evaluate whether immersion in emulsified isoflurane or propofol solutions could produce nonresponsiveness. Each group was exposed to one of six treatments for 1 h: isoflurane emulsified at 0.1%, 0.5%, 2%, 5%, and 15% or propofol at 10 mg/L and then increased to 100 mg/L. Crayfish from all treatment groups were moved to nonmedicated water after completion of 1 h and observed for an additional 4 h. All crayfish treated with isoflurane showed lack of a righting reflex at 5 min and loss of movement after 30 min. By 240 min (4 h), none of the crayfish from the isoflurane treatment groups regained movement. None of the crayfish in the propofol treatment achieved loss of reflexes or responsiveness, and all remained normal upon return to nonmedicated water. Isoflurane emulsified in water produces nonresponsiveness that is appropriate for the first step of euthanasia, while propofol was insufficient at these treatment doses.

Evaluation of trypsin-like immunoreactivity, pancreatic lipase immunoreactivity, cobalamin, and folate in zoo-housed African painted dogs (Lycaon pictus) at a North American zoological facility.

OBJECTIVE: Assess markers for pancreatic function and gastrointestinal malabsorption in African painted dogs (Lycaon pictus), including canine trypsin-like immunoreactivity (cTLI), canine pancreatic lipase immunoreactivity (cPLI), cobalamin, and folate at one North American facility. ANIMALS: 15 healthy African painted dogs held at one institution were sampled during routine health examinations. METHODS: Blood was collected at routine health examinations, and serum was separated and stored until testing. Serum was analyzed for cTLI, cPLI, cobalamin, and folate. The results were evaluated for correlation to sex, age, and storage time of samples. RESULTS: All individuals had cTLI and folate levels below normal reference ranges for domestic dogs (< 5.0 µg/L and < 7.7 µg/L, respectively). Cobalamin values were within or above reported domestic dog ranges, and cPLI values were within range as well. No analytes were significantly influenced by sex or time in storage, while cTLI was positively correlated with age. CLINICAL RELEVANCE: cTLI and folate did not fall within normal domestic canid reference ranges in this population of healthy African painted dogs. Clinical interpretation of these values based on domestic canid recommendations would indicate clinical disease, which was not apparent in this population. Analytes for pancreatic function and malabsorption or gastrointestinal indicators, including cTLI, cPLI, and folate, in African painted dogs should be interpreted with caution when using domestic dog references ranges.

Role of synaptic inhibition in turtle respiratory rhythm generation.

In vitro brainstem and brainstem-spinal cord preparations were used to determine the role of synaptic inhibition in respiratory rhythm generation in adult turtles. Bath application of bicuculline (a GABA(A) receptor antagonist) to brainstems increased hypoglossal burst frequency and amplitude, with peak discharge shifted towards the burst onset. Strychnine (a glycine receptor antagonist) increased amplitude and frequency, and decreased burst duration, but only at relatively high concentrations (10-100 microM). Rhythmic activity persisted during combined bicuculline and strychnine application (50 microM each) with increased amplitude and frequency, decreased burst duration, and a rapid onset-decrementing burst pattern. The bicuculline-strychnine rhythm frequency decreased during mu-opioid receptor activation or decreased bath P(C)(O(2)). Synaptic inhibition blockade in the brainstem of brainstem-spinal cord preparations increased burst amplitude in spinal expiratory (pectoralis) nerves and nearly abolished spinal inspiratory activity (serratus nerves), suggesting that medullary expiratory motoneurons were mainly active. Under conditions of synaptic inhibition blockade in vitro, the turtle respiratory network was able to produce a rhythm that was sensitive to characteristic respiratory stimuli, perhaps via an expiratory (rather than inspiratory) pacemaker-driven mechanism. Thus, these data indicate that the adult turtle respiratory rhythm generator has the potential to operate in a pacemaker-driven manner.