Geology topics

R. S. Larsen

Publications and source records attributed to R. S. Larsen.

3 recordsLinked to original sources

USGS2003

Differential mortality of male spectacled eiders ( Somateria fischeri ) and king eiders ( Somateria spectabilis ) subsequent to anesthesia with propofol, bupivacaine, and ketoprofen

Twenty free-ranging spectacled eiders ( Somateria fischeri ; 10 male, 10 female), 11 free-ranging king eiders ( Somateria spectabilis ; 6 male, 5 female), and 20 female common eiders ( Somateria mollissima ) were anesthetized with propofol, bupivacaine, and ketoprofen for the surgical implantation of satellite transmitters. Propofol was given to induce and maintain anesthesia (mean total dose, 26.2-45.6 mg/kg IV), bupivacaine (2-10 mg/kg SC) was infused into the incision site for local analgesia, and ketoprofen (2-5 mg/kg IM) was given at the time of surgery for postoperative analgesia. Four of 10 male spectacled eiders and 5 of 6 male king eiders died within 1-4 days after surgery. None of the female spectacled or common eiders and only 1 of the 5 female king eiders died during the same postoperative period. Histopathologic findings in 2 dead male king eiders were severe renal tubular necrosis, acute rhabdomyolysis, and mild visceral gout. Necropsy findings in 3 other dead male king eiders were consistent with visceral gout. We suspect that the perioperative use of ketoprofen caused lethal renal damage in the male eiders. Male eiders may be more susceptible to renal damage than females because of behavioral differences during their short stay on land in mating season. The combination of propofol, bupivacaine, and ketoprofen should not be used to anesthetize free-ranging male eiders, and nonsteroidal anti-inflammatory drugs should not be used perioperatively in any bird that may be predisposed to renal insufficiency.

Journal of Avian Medicine and Surgery↗

USGS2003

Failure to transmit avian vacuolar myelinopathy to mallard ducks

Avian vacuolar myelinopathy (AVM) is a neurologic disease that has been diagnosed in free-ranging birds in the southeastern United States. Bald eagles ( Haliaeetus leuocephalus ), American coots ( Fulica americana ), and mallards ( Anas platyrhynchos ) have been affected. Previous investigations have not determined the etiology of this disease. In November and December 2002, we attempted to induce AVM in game-farmed mallards through four, 7-day exposure trials. Mallards were housed in six groups of eight, with two of these groups serving as controls. One group was housed with AVM-affected coots; one group was tube fed daily with water from the lake where affected coots were captured; one group was tube fed daily with aquatic vegetation ( Hydrilla verticillata ) from the same lake; and another group was tube fed daily with sediment from the lake. No ducks exhibited clinical neurologic abnormalities consistent with AVM and no evidence of AVM was present at histopathologic examination of brain tissue. Although limitations in sample size, quantity of individual doses, frequency of dose administration, duration of exposure, and timing of these trials restrict the interpretation of the findings, AVM was not readily transmitted by direct contact, water, hydrilla, or sediment in this investigation.

Manitoba, Wisconsin↗

USGS2002

Clinical features of avian vacuolar myelinopathy in American coots

Objective —To characterize clinical features of avian vacuolar myelinopathy (AVM) in American coots. Design —Case-control study. Animals —26 AVM-affected American coots and 12 unaffected coots. Procedures —Complete physical, neurologic, hematologic, and plasma biochemical evaluations were performed. Affected coots received supportive care. All coots died or were euthanatized, and AVM status was confirmed via histopathologic findings. Results —3 severely affected coots were euthanatized immediately after examination. Seventeen affected coots were found dead within 7 days of admission, but 5 affected coots survived > 21 days and had signs of clinical recovery. Abnormal physical examination findings appeared to be related to general debilitation. Ataxia (88%), decreased withdrawal reflexes (88%), proprioceptive deficits (81%), decreased vent responses (69%), beak or tongue weakness (42%), and head tremors (31%), as well as absent pupillary light responses (46%), anisocoria (15%), apparent blindness (4%), nystagmus (4%), and strabismus (4%) were detected. Few gross abnormalities were detected at necropsy, but histologically, all AVM-affected coots had severe vacuolation of white matter of the brain. None of the control coots had vacuolation. Conclusions and Clinical Relevance —Although there was considerable variability in form and severity of clinical neurologic abnormalities, clinical signs common in AVM-affected birds were identified. Clinical recovery of some AVM-affected coots can occur when supportive care is administered. Until the etiology is identified, caution should be exercised when rehabilitating and releasing coots thought to be affected by AVM.

Journal of the American Veterinary Medical Associa↗