Objective—To directly assess microcirculatory changes associated with induced hemorrhagic shock by use of sidestream dark field microscopy (SDM) and correlate those values with concurrently measured macrovascular and blood gas variables in healthy anesthetized dogs.
Animals—12 adult dogs.
Procedures—Dogs were anesthetized and splenectomized. Instrumentation and catheterization were performed for determination of macrohemodynamic and blood gas variables. Hemorrhagic shock was induced via controlled hemorrhage to a mean arterial blood pressure (MAP) of 40 mm Hg. Dogs were maintained in the shock state (MAP, 35 to 45 mm Hg) for 60 minutes. An SDM device was used to image microcirculation of buccal mucosa, and vascular analysis software was used to determine microcirculatory variables. These values were compared with other cardiovascular and blood gas variables to determine correlations.
Results—Following hemorrhage, there was a significant decrease in microvascular variables (mean ± SD), including proportion of perfused vessels (82.77 ± 8.32% vs 57.21 ± 28.83%), perfused vessel density (14.86 ± 2.64 mm/m2 vs 6.66 ± 4.75 mm/m2), and microvascular flow index (2.54 ± 0.52 vs 1.59 ± 0.85). Perfused vessel density individually correlated well with macrovascular variables, with heart rate (zero order, partial correlation, and part correlation coefficients = −0.762, −0.884, and −0.793, respectively) and oxygen extraction ratio (−0.734, −0.832, and −0.746, respectively) being the most important predictors.
Conclusions and Clinical Relevance—SDM allowed real-time imaging of the microvasculature and has potential as an effective tool in experimental and clinical applications for monitoring microcirculatory changes associated with hemorrhagic shock and resuscitation in dogs.
Objective—To determine whether increasing the viscosity of a standard hemoglobin-based oxygen-carrying solution (HBOC) would offset its associated vasoconstrictive effects and result in improved microvascular perfusion in healthy splenectomized dogs with experimentally induced hemorrhagic shock.
Animals—12 male American Foxhounds.
Procedures—Each dog underwent anesthesia and splenectomy. Shock was induced by controlled hemorrhage until a mean arterial blood pressure of 40 mm Hg was achieved and maintained for 60 minutes. Dogs were then randomly assigned to receive either a standard or hyperviscous HBOC (6 dogs/group). Sidestream dark-field microscopy was used to assess the effects of shock and HBOC administration on the microcirculation of the buccal mucosa and the jejunal serosa. Video recordings of the microcirculation were collected before shock was induced (baseline) and at intervals up to 180 minutes following HBOC administration. Vascular analysis software was used to compute microcirculatory variables.
Results—Compared with baseline findings, hemorrhagic shock resulted in decreases in all microvascular variables in the buccal mucosa and the jejunal serosa. At all time points following HBOC administration, microvascular variables were similar to initial values and no significant differences between treatment groups were detected. At all time points following HBOC administration, blood and plasma viscosities in dogs treated with the hyperviscous solution were significantly higher than values in dogs receiving the standard solution.
Conclusions and Clinical Relevance—In splenectomized dogs with experimentally induced hemorrhagic shock, administration of a hyperviscous HBOC did not significantly affect microvascular variables, compared with effects of a standard HBOC. Microcirculatory flow returned to baseline values in both treatment groups, suggesting that marked HBOC-associated vasoconstriction did not occur.
To investigate whether decompressive cystocentesis (DC) safely facilitates urethral catheterization (UC) in cats with urethral obstruction (UO).
88 male cats with UO.
Cats were randomly assigned to receive DC prior to UC (ie, DC group cats; n = 44) or UC only (ie, UC group cats; 44). Abdominal effusion was monitored by serial ultrasonographic examination of the urinary bladder before DC and UC or before UC (DC and UC group cats, respectively), immediately after UC, and 4 hours after UC. Total abdominal effusion score at each time point ranged from 0 (no effusion) to 16 (extensive effusion). Ease of UC (score, 0 [easy passage] to 4 [unable to pass]), time to place urinary catheter, and adverse events were recorded.
No significant difference was found in median time to place the urinary catheter in UC group cats (132 seconds), compared with DC group cats (120 seconds). Median score for ease of UC was not significantly different between UC group cats (score, 1; range, 0 to 3) and DC group cats (score, 1; range, 0 to 4). Median change in total abdominal effusion score from before UC and DC to immediately after UC was 0 and nonsignificant in UC group cats (range, −5 to 12) and DC group cats (range, −4 to 8). Median change in effusion score from immediately after UC to 4 hours after UC was not significantly different between UC group cats (score, −1; range, −9 to 5) and DC group cats (score, −1; range, −7 to 5).
CONCLUSIONS AND CLINICAL RELEVANCE
DC did not improve time to place the urinary catheter or ease of UC in cats with UO.
To assess the effect of packed RBC (pRBC) transfusion on thromboelastographic (TEG) tracings in dogs with naturally occurring anemia.
22 clinically anemic dogs that received a pRBC transfusion.
For each dog, a blood sample was collected before and within 3 hours after completion of the pRBC transfusion for a CBC, nonactivated TEG analysis, and measurement of blood viscosity. Wilcoxon signed rank tests were used to compare CBC, viscosity, and TEG variables between pretransfusion and posttransfusion blood samples. Multivariable linear regression was used to assess the effects of pretransfusion-posttransfusion changes in Hct, WBC count, and platelet count on changes in TEG variables.
Median posttransfusion Hct (21%; range, 13% to 34%) was significantly greater than the median pretransfusion Hct (12.5%; range, 7% to 29%). Packed RBC transfusion was associated with a median increase in Hct of 6.2% (range, 1.2% to 13%). Maximum amplitude significantly decreased from 74.9 to 73.8 mm and clot strength significantly decreased from 14,906 to 14,119 dynes/s after pRBC transfusion. Blood viscosity significantly increased, whereas platelet and WBC counts significantly decreased after transfusion. Multivariable linear regression revealed that pretransfusion-posttransfusion changes in Hct, WBC count, and platelet count were not associated with changes in TEG variables.
CONCLUSIONS AND CLINICAL RELEVANCE
Results indicated that pRBC transfusion had only small effects on the TEG tracings of hemodynamically stable dogs. Therefore, large changes in TEG tracings following pRBC transfusion are unlikely to be the result of the transfusion and should be investigated further.
Case Description—A 2.96-kg (6.5-lb) 9-month-old spayed female domestic longhair cat was admitted for removal of a tracheal foreign body.
Clinical Findings—The cat had moderate respiratory distress but otherwise appeared to be healthy. Thoracic radiography revealed a foreign body in the trachea.
Treatment and Outcome—The cat was anesthetized and endoscopy of the trachea was performed in an attempt to retrieve the foreign body. Endoscopic removal was unsuccessful because of the shape and smooth texture of the foreign body. Surgical removal of the foreign body was not considered ideal because of its location and the risks associated with tracheotomy. Fluoroscopic-guided placement of an over-the-wire balloon catheter caudal to the foreign body was followed by inflation of the balloon and gradual traction in an orad direction, which resulted in successful removal of the foreign body (identified as a piece of landscaping gravel). The cat required supplemental oxygen and supportive care following removal of the foreign body.
Clinical Relevance—A fluoroscopic technique was used as a minimally invasive alternative to endoscopy or open-chest surgery for removal of a foreign body from the trachea of a cat. Use of this technique allowed uninterrupted ventilation of the cat throughout the procedure. (J Am Vet Med Assoc 2010;237:689-694)
Objective—To determine whether dogs with head trauma have a greater incidence of seizures than the general canine patient population.
Design—Retrospective case series.
Animals—259 client-owned dogs.
Procedures—Medical records of dogs evaluated for head trauma at The Ohio State University Veterinary Medical Center from 1999 to 2009 were reviewed. Data were collected regarding the cause of the head trauma, physical examination and neurologic examination findings, comorbidities, and the development of seizures during hospitalization. A telephone survey was conducted to question owners regarding the development of seizures after discharge. Relationships between the nature of the head trauma and the development of seizures were then examined.
Results—3.5% of dogs with head trauma developed in-hospital seizures, and 6.8% of dogs with head trauma for which follow-up information was available developed seizures after hospital discharge, compared with an epilepsy rate of 1.4% in our hospital. Dogs that developed in-hospital seizures were significantly more likely to have been hit by a car or experienced acceleration-deceleration injury. Additionally, 10% of dogs with traumatic brain injury had in-hospital seizures. No visit or patient characteristics were significantly associated with the development of out-of-hospital seizures.
Conclusions and Clinical Relevance—Dogs with head trauma may develop seizures at a greater rate than dogs in the general canine patient population. Particularly in the immediate to early posttraumatic period, clinicians should remain vigilant for the development of posttraumatic seizures and treat patients accordingly.
Objective—To determine efficacy of a protocol for managing urethral obstruction (UO) in male cats without urethral catheterization.
Animals—15 male cats with UO in which conventional treatment had been declined.
Procedures—Laboratory testing and abdominal radiography were performed, and cats with severe metabolic derangements or urinary calculi were excluded. Treatment included administration of acepromazine (0.25 mg, IM, or 2.5 mg, PO, q 8 h), buprenorphine (0.075 mg, PO, q 8 h), and medetomidine (0.1 mg, IM, q 24 h) and decompressive cystocentesis and SC administration of fluids as needed. Cats were placed in a quiet, dark environment to minimize stress. Treatment success was defined as spontaneous urination within 72 hours and subsequent discharge from the hospital.
Results—Treatment was successful in 11 of the 15 cats. In the remaining 4 cats, treatment was considered to have failed because of development of uroabdomen (n = 3) or hemoabdomen (1). Cats in which treatment failed had significantly higher serum creatinine concentrations than did cats in which treatment was successful. Necropsy was performed on 3 cats in which treatment had failed. All 3 had severe inflammatory disease of the urinary bladder, but none had evidence of bladder rupture.
Conclusions and Clinical Relevance—Results suggested that in male cats, a combination of pharmacological treatment, decompressive cystocentesis, and a low-stress environment may allow for resolution of UO without the need for urethral catheterization. This low-cost protocol could serve as an alternative to euthanasia when financial constraints prevent more extensive treatment.