Cardiovascular Function and Serum Catecholamine Concentrations after Anesthesia and Surgery in the Dog

Peripheral vasoconstriction and plasma catecholamine concentrations were studied in 37 dogs after cervical disc fenestration and salivary gland excision, laparotomy for intestinal anastomoses and cystotomy, or laparotomy for repair of diaphragmatic rupture, gastrotomy, and pyloromyotomy. Meperidine (4.4 mg/kg) was administered before extubation of 12 dogs undergoing laparotomy. Heart rate, respiratory frequency, indirect blood pressure, rectal temperature, toe web temperature, and plasma concentrations of epinephrine and norepinephrine were determined before induction of anesthesia, after intubation, after extubation, at sternal recumbency, and at standing. All dogs were hypothermic during surgery. After surgery, peripheral hypothermia (large rectal-toe web temperature gradients) increased from a mean of 4.6 degrees C after intubation to a mean of 10.4 degrees C when the dogs initially stood. Heart and respiratory rates and blood pressures during recovery were similar to those before anesthesia. Mean plasma catecholamine concentrations were neither significantly higher during recovery than before surgery nor were they increased in any surgical group, including the dogs not treated with meperidine. After anesthesia, 15% of the epinephrine and 12% of the norepinephrine samples were more than two standard deviations above the mean of the preanesthetic concentrations of all dogs. The ratio of all dogs with an epinephrine concentration more than two standard deviations above the mean of baseline epinephrine concentrations was greater at sternal recumbency than before anesthesia and the ratio of dogs with an increased epinephrine concentration at sternal recumbency was greater in the laparotomy dogs (9 of 24) than in the cervical surgery dogs (0 of 12).(ABSTRACT TRUNCATED AT 250 WORDS)     

Controlled Tissue Expansion in the Distal Extremities of Dogs

Controlled tissue expansion using a 100 cc rectangular silicone elastomer expander was performed in the mid-antebrachium and mid-crus of eight adult mixed-breed dogs. Two expander inflation schedules were followed. Group 1 dogs (n = 4) underwent expander inflation using 10 cc sterile saline every other day, and group 2 dogs (n = 4) underwent expander inflation using 15 cc sterile saline every other day until the nominal volume (100 cc) was attained. Significant mean postexpansion increases in skin surface area of 94.1 cm² (35.9%) and 108.9 cm² (37.3%) were measured in the antebrachium and crus, respectively (p < .05). In a second procedure, the expanders were removed and skin flaps were developed from the redundant tissue generated during the expansion process. Single pedicle advancement flaps and transposition flaps were used to cover surgically created defects measuring 5 times 10 cm in the antebrachium and cms. Single pedicle advancement flaps consistently measured 10 × 10 cm and could be advanced to cover defects involving one third of the mid-antebrachial or mid-crural circumference. Transposition flaps were rotated up to 170 and the donor site defects were easily closed under minimal or no tension. Complications included an abscess in one dog and seroma formation in four dogs. Differences in success or complication rates between group 1 dogs and group 2 dogs were not observed; an accelerated inflation schedule using 15 cc sterile saline every other day was recommended.     

Quantitative Ingrowth Analysis of a Porous-coated Acetabular Component in a Canine Model

Histomorphometric analysis of bone ingrowth into a porous-coated acetabular component was evaluated in a canine model. A total of nine prostheses were evaluated, 3 at 6 months, 3 at 12 months, and 3 at 24 months after implantation. All implants were grossly stable at the time of retrieval. The mean percentage of bone ingrowth was 12% at 6 months, 24% at 12 months, and 24% at 24 months. Narrow radiolucent lines noted on microradiographs were more evident at the 6 month time period than at the 12 or 24 month time periods. Bone ingrowth into a porous-coated acetabular component in a weight-bearing model may continue beyond the 6 month time period, and early evaluation of bone ingrowth may underestimate final bone ingrowth.     

Laparoscopic Cryptorchid Castration in Standing Horses

Objective — This article describes a new technique for laparoscopic cryptorchid castration in standing horses. Study Design — Prospective study. Animals or Sample Population — Eight horses aged 11 months to 3 years and weighing between 300 and 643 kg. Methods — Food was withheld for 24 to 36 hours, and then horses were sedated with detomidine HC1 (0.02 to 0.03 mg/kg) and butorphanol tartrate (0.02 mg/kg). The paralumbar fossa region was desensitized with 2% mepivacaine in an inverted “L” pattern and caudal epidural anesthesia was administered with either xylazine (0.18 mg/kg diluted to 10 to 15 mL with 0.9% sodium chloride) or a combination of 2% mepivacaine and xylazine (0.18 mg/kg). Initial laparoscopic exploration was performed from the left flank; in three horses, right flank laparoscopy was needed to complete the procedure. The spermatic cord was ligated within the abdomen with one or two sutures of 0 polydioxanone suture, and the testis or testes removed through a flank incision. Results — In five horses with no palpably descended testes, standing laparoscopy was the only procedure performed, whereas in two horses, the abdominal testis was removed laparoscopically, and the descended testis was removed under short acting anesthesia. In one horse, with nonpalpable testes, it was determined by laparoscopic observation that the testes were in the inguinal canal, and castration was performed under general anesthesia. No surgical or postoperative complications were noted. The right side of the abdomen, and especially the right vaginal ring, could be easily observed from the left side by passing the laparoscope through a small perforation in the mesocolon of the descending colon or by elevating the descending colon with an instrument or by use of an arm in the rectum. Conclusions — The standing laparoscopic approach combined with or without short-acting anesthesia to remove the descended testis is easily performed. Clinical Relevance — This approach will provide surgeons with another option to castrate cryptorchid stallions.     

REVERSIBLE MAGNETIC RESONANCE IMAGING ABNORMALITIES IN DOGS FOLLOWING SEIZURES

Reversible magnetic resonance (MR) imaging lesions have been described in humans following seizures. This condition has not yet been reported in animals. This paper describes reversible abnormalities identified in 3 dogs using MR imaging that was performed initially within 14 days of the last seizure and follow-up imaging that was performed after 10 to 16 weeks of anticonvulsant therapy. All three dogs had lesions in the piriform/temporal lobes, characterized by varying degrees of hyperintensity on T2-weighted images and hypointensity on T1-weighted images. In one dog, contrast enhancement was evident. On reevaluation, partial resolution occurred in all 3 dogs. In a fourth animal with an olfactory meningioma, similar appearing lesions in the temporal cortex and right and left piriform lobes were identified after seizure activity. A surgical biopsy of the temporal cortex and hippocampus was performed and edema, neovascularization, reactive astrocytosis, and acute neuronal necrosis were evident. These histologic findings are similar to those reported in humans with seizures. Recognizing the potential occurrence of reversible abnormalities in MR images is important in developing a diagnostic and therapeutic plan in canine patients with seizures. Repeat imaging after seizure control may help differentiate between seizure-induced changes and primary multifocal parenchymal abnormalities.     

RADIOGRAPHIC AND COMPUTED TOMOGRAPHIC EVALUATION OF THE CANINE INTERCONDYLAR FOSSA IN NORMAL STIFLES AND AFTER NOTCHPLASTY IN STABLE AND UNSTABLE STIFLES

The role of the intercondylar fossa in cranial cruciate ligament injury has gained notable attention in humans and it's role is now being questioned in animals. Controversy exists regarding the accuracy of radiographs and computed tomography (CT) in evaluating the intercondylar fossa. This study compared radiographic and CT evaluation with gross evaluation of the intercondylar fossa. Six greyhounds were evaluated before notchplasty, immediately after notchplasty and 6 months after notchplasty in stable and unstable stifles. A fossa width index was used for comparison because it negates the effects of patient size and radiographic magnification. The fossa width index is calculated by dividing the width of the intercondylar fossa by the total condylar width.
The fossa width indices of dogs determined from radiographs and CT were not significantly different before notchplasty except for the cranial fossa width indices which were more inconsistent and tended to underestimate the size when compared to gross measurements. At six months, both stable and unstable stifles had refilling of the notchplasty, but the unstable stifles had significantly greater refilling resulting in no significant enlargement in intercondylar fossa size as compared to the prenotchplasty size. Osteophytes that occurred within the intercondylar fossa were less radiopaque and more easily visualized by computed tomography. Computed tomography provided several advantages, including clearer visualization of the intercondylar fossa, avoiding superimposition of the intercondylar fossa by caudal thigh muscles or tuber ischii and the ability to analyze the cranial and caudal components of the intercondylar fossa separately.     

Comparative Evaluation of Two Surgical Scrub Preparations in Cattle

One hundred seventeen cattle that had undergone surgery were assigned randomly to two preoperative skin preparation protocols. Group 1 (60 animals) skin preparation was with povidone-iodine soap and isopropyl alcohol, whereas group 2 (57 animals) had skin preparation with chlorhexidine gluconate and isopropyl alcohol. Quantitative microbial culture plates were used to estimate the number of colony forming units (CFUs) before skin preparation (prescrub), after skin preparation (postscrub), after surgery (postoperative), and in room air (environment). A significant decrease in CFU occurred postscrub for both skin preparations ( P <.05). Chlorhexidine and alcohol preparation resulted in significantly fewer CFUs (LSMean ± SE = 2.79 CFU ± 1.74) and a greater percentage reduction in CFUs (98.64%± 2.01) postscrub than povidone and alcohol (LSMean ± SE = 10.27 CFUs ± 1.51, 93.29%± 1.85); ( P <.005). Group 2 had a significantly higher frequency of negative cultures postscrub (49.1%) compared with group 1 (18.3%) ( P <.001). The number of postoperative CFUs were not significantly different between the two treatment groups. Wound infection frequency for clean surgical procedures was not significantly different between the two skin preparation protocols (group 1 = 9.8%, group 2 = 10.7%), however, infection frequency was significantly higher for surgical procedures with a ventral abdominal approach (5 of 14, 35.7%), compared with a flank approach (1 of 41, 2.4%) or other approaches (orthopedic procedures) (1 of 16, 6.3%) ( P <.05). Both skin preparation protocols were effective and safe in decreasing the skin microflora population of cattle before surgery and although preparation with chlorhexidine gluconate and alcohol resulted in less CFUs immediafly postscrub, the frequency of surgical wound infection was similar for both protocols.     

Holding Power of Different Pin Designs and Pin Insertion Methods in Avian Cortical Bone

Objective —To measure pullout strength of four pin types in avian humeri and tibiotarsi bones and to compare slow-speed power and hand insertion methods.
Study Design —Axial pin extraction was measured in vitro in avian bones.
Animal Population —Four cadaver red-tailed hawks and 12 live red-tailed hawks.
Methods —The pullout strength of four fixator pin designs was measured: smooth, negative profile threaded pins engaging one or two cortices and positive profile threaded pins. Part 1: Pins were placed in humeri and tibiotarsi after soft tissue removal. Part 2: Pins were placed in tibiotarsi in anesthetized hawks using slow-speed power or hand insertion.
Results —All threaded pins, regardless of pin design, had greater pullout strength than smooth pins in all parts of the study ( P < .0001). The cortices of tibiotarsi were thicker than the cortices of humeri ( P < .0001). There were few differences in pin pullout strengths between threaded pin types within or between bone groups. There were no differences between the pullout strength of pins placed by slow-speed power or by hand.
Conclusions —There is little advantage of one threaded pin type over another in avian humeri and tibiotarsi using currently available pin designs. There were few differences in pin pullout strengths between humeri and tibiotarsi bones. It is possible that the ease of hand insertion in thin cortices minimizes the potential for wobbling and therefore minimizes the difference between slow-speed drill and hand insertion methods.
Clinical Relevance —Threaded pins have superior bone holding strength in avian cortices and may be beneficial for use with external fixation devices in birds.     

A Comparison of Indirect Blood Pressure Monitoring Techniques in the Anesthetized Cat

Objective —To determine the accuracy of three indirect blood pressure monitoring techniques (oscillometric technique [OS], Doppler [DOP], and optical plethysmography [OP] [blood pressure determined with a pulse oximeter waveform]) when compared with direct arterial pressure measurement in cats. Study Design —Prospective study. Animal Population —Eight healthy (five female, three male), domestic short-hair cats, weighing 3.5 ± 0.8 kg Methods —Cats were anesthetized with isoflurane. The inspired concentration of isoflurane was adjusted to produce mild hypotension (80 to 100 mm Hg direct systolic), moderate hypotension (60 to 80 mm Hg direct systolic), and severe hypotension (<60 mm Hg direct systolic). Indirect pressure measurements were obtained from the thoracic limb and compared with concurrent direct measurement using regression analysis and a modification of Bland and Altman's technique. Results —All three techniques underestimated systolic pressure. OS produced the best prediction of systolic pressure with a bias ± precision of -15.9 ± 8.1 mm Hg. DOP and OP were relatively inaccurate with a bias ± precision of -25 ± 7.4 mm Hg and -25 ± 7.5 mm Hg. All three techniques correlated well with direct pressure with r values of 0.81, 0.88, and 0.88 for OS, DOP, and OP. DOP and OP provided an accurate prediction of direct mean arterial pressure with a bias ± precision of -0.8 ± 6 mm Hg and 0.6 ± 5.5 mm Hg. Correlation was good between DOP and mean arterial pressure with r = 0.89. Correlation was also good between OP and mean arterial pressure with r = 0.90. Conclusions —OS provided the most accurate prediction of direct systolic pressure. DOP and OP provided a good prediction of mean arterial pressure in the cat. Clinical Relevance —All three of these techniques are useful for detecting trends. Direct monitoring of blood pressure should be considered if accurate blood pressure measurement is required.