Procedures—After induction of anesthesia with isoflurane, each snake was instrumented with an arterial catheter connected to a pressure transducer and oscilloscope to obtain invasive measurements of systolic (SAP), diastolic (DAP), and mean (MAP) arterial blood pressure as well as a pressure waveform. A cuff connected to an oscillometric device was placed on the tail immediately distal to the vent for noninvasive measurements. Heart rate, respiratory rate, and invasive and noninvasive measurements of SAP, DAP, and MAP were obtained every 5 minutes for 45 minutes. Delivered isoflurane concentration was increased in 15-minute increments to induce hypotension. Repeatability of each device and fixed and proportional biases between devices were calculated.
Results—Throughout most of the measured ranges of blood pressures, the oscillometric unit overestimated the SAP and underestimated the DAP and MAP, compared with respective direct measurements. When the invasively determined SAP was > 100 mm Hg, the oscillometric unit underestimated all 3 variables. Fixed bias was significant for SAP and DAP, and proportional bias was significant for SAP and MAP.
Conclusions and Clinical Relevance—When using an oscillometric blood pressure monitor on anesthetized boid snakes, veterinarians can potentially monitor changes in blood pressure, although the displayed readings may underestimate DAP and MAP and overestimate SAP. Indirect measurements of blood pressure made with the oscillometric device cannot substitute for direct measurements.
4 wild adult rat snakes (Pantherophis alleghaniensis) were evaluated after ingesting spherical or ovoid foreign bodies.
Physical examination revealed a large, firm mass at the level of the stomach in each snake. Radiographic findings were consistent with ingestion of a golf ball (3 snakes) or an artificial egg (1 snake). Signs consistent with prolonged impaction included scale loss, dermal abrasions, and apparent loss of body condition in one snake and regional skin ulceration, dehydration, and generalized muscle atrophy in another.
TREATMENT AND OUTCOME
Nonsurgical removal of the foreign body was attempted in anesthetized or heavily sedated snakes by external manipulation in the orad direction. A golf ball was removed through the oral cavity without complications in 1 snake. In the other 3 snakes, tension caused by the advancing foreign body resulted in full-thickness skin rupture in the cervical region. The procedure was completed with the use of a balloon catheter to aid foreign body advancement for 1 of the 3 snakes, and the skin defect was closed. The procedure was converted to esophagotomy for the other 2 snakes. Three snakes recovered and were released; 1 died of complications from prolonged impaction and esophageal perforation.
The described nonsurgical techniques for removal of ingested round or ovoid foreign bodies were associated with substantial complications in 3 of 4 treated rat snakes. Although a nonsurgical method for removal of ingested objects such as golf balls could benefit snakes, the methods used for these patients did not appear to be more beneficial than traditional gastrotomy.