Measurement of femoral and tibial joint reference angles and pelvic limb alignment in cats.

OBJECTIVE: To report pelvic limb joint reference angles, limb alignment, and mechanical axis deviation for the feline pelvic limb. STUDY DESIGN: Cadaveric radiographic anatomic study. ANIMALS: Skeletally mature, mixed breed cats (n = 50). METHODS: Extended pelvic limb radiography was performed and images analyzed to determine femoral anatomic joint reference angles, femoral and tibial mechanical joint reference angles, tibiofemoral angle, metatarsotibial angle, mechanical axis-femur and mechanical axis-metatarsus angles, and mechanical axis deviation of the stifle and tarsus. Mean ± SD and 95% confidence intervals (95% CI) were calculated. RESULTS: Mean ± SD angles and 95% CI were: anatomic lateral proximal femoral (103.9° ± 3.8°; 103.1° - 104.6°), anatomic lateral distal femoral (93.8° ± 2.5°; 93.3° - 94.3°), mechanical lateral proximal femoral (100.5° ± 3.7°; 99.8° - 101.2°), mechanical lateral distal femoral (97.2° ± 2.2°; 96.7° - 97.6°), mechanical medial proximal tibial (88.0° ± 3.2°; 87.3° - 88.6°), mechanical medial distal tibial (107.6° ± 4.8°; 106.6° - 108.5°), mechanical tibiofemoral (7.4° varus ± 2.5°; 6.9° - 7.9°), mechanical metatarsotibial (6.0° valgus ± 3.5°; 5.3° - 6.7°); mechanical axis-femur (3.2° ± 1.4°; 2.9° - 3.5°) and mechanical axis-metatarsus (2.4° ± 2.0°; 1.7° - 2.1°). Mechanical axis deviation of the stifle and of the tarsus were 2.0% ± 0.9% (95% CI: 1.9-2.2) and 0.8% ± 1.0% (95% CI: 0.7-1.0), respectively. CONCLUSIONS: Mean pelvic limb joint reference and limb alignment angles can be used for diagnosing angular limb deformities of the feline pelvic limb and for planning corrective osteotomies in affected cats.

Cortisol and aldosterone response to various doses of cosyntropin in healthy cats.

OBJECTIVE: To determine the lowest dose of cosyntropin on a per body weight basis that would produce maximal cortisol and aldosterone secretion and the ideal timing of blood sample collection after ACTH stimulation in healthy cats. DESIGN: Randomized crossover trial. ANIMALS: 7 adult sexually intact male purpose-bred cats. PROCEDURES: Each cat received saline (0.9% NaCl) solution (control) and 5 doses (125 µg/cat and 10, 5, 2.5, and 1 µg/kg [4.54, 2.27, 1.14, and 0.45 µg/lb]) of cosyntropin IV with a 2-week washout period between treatments. Blood samples were obtained before (baseline) and at 15, 30, 45, 60, 75, and 90 minutes after administration of saline solution or cosyntropin. RESULTS: Serum cortisol and aldosterone concentration increased significantly, compared with baseline values, after administration of all cosyntropin doses. Lower doses of cosyntropin resulted in an adrenocortical response equivalent to the traditional dose of 125 µg/cat. The lowest doses of cosyntropin that stimulated a maximal cortisol and aldosterone response were 5 and 2.5 µg/kg, respectively. Lower doses of cosyntropin resulted in a shorter interval between IV administration of cosyntropin and peak serum cortisol and aldosterone concentrations. CONCLUSIONS AND CLINICAL RELEVANCE: Low-dose ACTH stimulation testing with IV administration of cosyntropin at 5 µg/kg followed by blood sample collection at 60 to 75 minutes resulted in concurrent peak serum cortisol and aldosterone concentrations that were equivalent to those achieved following administration of cosyntropin at 125 µg/cat, the standard dose currently used.

Effects of general anesthesia on plasma colloid oncotic pressure in dogs.

OBJECTIVE: To determine the magnitude of the change in colloid oncotic pressure (COP) associated with general anesthesia in dogs undergoing a variety of elective procedures. DESIGN: Cohort study. ANIMALS: 50 client-owned dogs. PROCEDURES: For each dog, preanesthetic and postanesthetic PCV, plasma total solids (TS) concentration, and COP were determined. The procedures requiring anesthesia, volume of crystalloid fluids administered IV, duration of anesthesia, age, weight, and sex were recorded. RESULTS: Postanesthetic PCV (mean +/- SD, 41.8 +/- 5.4%), TS concentration (6.3 +/- 0.8 g/dL), and COP (19.4 +/- 3.6 mm Hg) were significantly decreased, compared with preanesthetic values (48.8 +/- 5.9%, 7.2 +/- 0.7 g/dL, and 24.4 +/- 4.2 mm Hg, respectively). None of the variables tested could be used to reliably predict changes in COP. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that COP in healthy dogs may decrease by 5 mm Hg on average after general anesthesia and that this decrease may not be reliably predicted by the volume of fluids administered IV during anesthesia or by the concurrent measured decrease in TS concentration.

Situs inversus totalis in a dog with a chronic diaphragmatic hernia.

Situs inversus totalis is a rare, congenital condition that is characterized by the development of the thoracic and abdominal viscera in a mirror image to their normal orientation. This case report describes the condition in a 4-year-old, spayed female Doberman pinscher that was evaluated for dyspnea following sedation. Radiography confirmed a diaphragmatic hernia. Situs inversus was discovered during surgical correction. The diaphragmatic rent was repaired, and the dog was clinically normal at recheck 13 months after surgery.

Use of radiographic measures and three-dimensional computed tomographic imaging in surgical correction of an antebrachial deformity in a dog.

CASE DESCRIPTION: A 1-year-old 7.4-kg (16.3-lb) castrated male mixed-breed dog was evaluated because of intermittent lameness and an antebrachial angular limb deformity. CLINICAL FINDINGS: The left forelimb had gross antebrachial external rotation (approx 90 degrees ) and marked procurvatum. Radiography revealed a severe partially compensated biapical antebrachial angular limb deformity. Measurements of medial proximal radial angle (MPRA) and lateral distal radial angle (LDRA) were obtained from orthogonal radiographs of the proximal and distal segments of the radius, respectively. Elbow joint-to-carpus translation was quantified. Deformities were localized and quantified by the center of rotation of angulation (CORA) method. Computed tomographic 3-dimensional image reconstructions of the antebrachium and carpus were completed to create 3 life-size stereolithographic models. TREATMENT AND OUTCOME: 2 closing wedge radial osteotomies were performed at the level of the CORAs and stabilized with bone plates and screws. RESULTS: Frontal and sagittal plane alignments were corrected to 8 degrees and 15 degrees , respectively (reference limits, 0 degrees to 8 degrees and 8 degrees to 35 degrees , respectively). The MPRA was corrected from 55 degrees to 68 degrees , and LDRA was corrected from 32 degrees to 76 degrees (values considered normal are approx 85 degrees and 87 degrees , respectively). Elbow joint-to-carpus translation was improved by 42.5%. After 8 weeks, radiography revealed bone union. Owners considered the outcome acceptable, on the basis of limb appearance and lack of lameness at 1 year after surgery. CONCLUSIONS AND CLINICAL RELEVANCE: A segmental radiographic planning technique combined with the CORA method, computed tomography, and stereolithography may be useful in the characterization of and planning corrective surgery for forelimb deformities in dogs.

Determination of pelvic limb alignment in the large-breed dog: a cadaveric radiographic study in the frontal plane.

OBJECTIVES: To report a method for radiographic determination of the mechanical axis of the canine pelvic limb and its relationship to the joints and bone axes. To report reference ranges for the relationships between the axes of the pelvic limb and for joint position relative to the pelvic limb axis. STUDY DESIGN: Cadaveric radiographic anatomic study. ANIMALS: Pelvic limbs (n=101) from normal midsized to large breed dogs; tibiae (n=105) from dogs with cranial cruciate ligament disease (previous study). METHODS: Extended full-limb radiography was performed and images analyzed to determine: mechanical joint reference angles (femur, tibia), pelvic limb axis, tibiofemoral and metatarsotibial angle, mechanical axis-femur/metatarsus angle, and mechanical axis deviation (MAD) of the stifle/tarsus. RESULTS: Mean mechanical angles were: lateral proximal femoral (103.7 degrees +/-5.4 degrees ), lateral distal femoral (98.6 degrees +/-2.5 degrees ), medial proximal tibial (92.2 degrees +/-1.8 degrees ), medial distal tibial (95.9 degrees +/-2.2 degrees ), tibiofemoral (9.1 degrees varus +/-2.8 degrees ), metatarsotibial (0.6 degrees valgus +/-2.1 degrees ). Mean mechanical axis-femur and-metatarsus angles were 5.6 degrees (+/-1.7 degrees ) and 2.9 degrees (+/-1.5 degrees ), respectively. Mean MAD of the stifle and tarsus were 3.6% (+/-1.1%) and 1.2% (+/-0.6%), respectively. Tibial angles were not different between dogs with and without cranial cruciate ligament disease. CONCLUSIONS: Mechanical axes of the canine pelvic limb and their relationship to the joints can be determined by full-limb radiography. CLINICAL RELEVANCE: Techniques and reference ranges may be useful for diagnosis, surgical planning, and postoperative assessment of pelvic limb deformities.

Radiographic measurement of canine tibial angles in the sagittal plane.

OBJECTIVE: To describe a method for radiographic measurement of the mechanical joint angles of the tibia in the sagittal plane and report reference ranges for a population of dogs with cranial cruciate ligament disease, and specifically for Labrador Retrievers. STUDY DESIGN: Retrospective evaluation of radiographs. ANIMALS: Canine tibia (n=150) of dogs evaluated for cranial cruciate ligament disease; 104 tibiae were from Labrador Retrievers, 46 tibiae were from other medium- to large-breed dogs. METHODS: Medial-lateral radiographs were used to establish anatomic landmarks and measure the mechanical cranial distal tibial angle (mCrDTA) and mechanical caudal proximal tibial angle (mCaPTA). RESULTS: For all tibiae mean mCrDTA was 81.6 degrees and mCaPTA, 63.6 degrees . For Labrador Retriever tibiae mean mCrDTA was 81.7 degrees and mCaPTA, 63.8 degrees . For non-Labradors, means mCrDTA was 81.5 degrees and mCaPTA, 63 degrees . Labrador Retrievers were significantly younger than non-Labradors in our study population. No significant differences were noted between Labrador Retrievers and non-Labradors for mCrDTA or mCaPTA and correlations between mCrDTA and mCaPTA were neither strong nor significant. CONCLUSION: A method was established for radiographic measurement of mechanical joint angles of the canine tibia in the sagittal plane. Reference ranges are reported for a population of Labrador Retrievers and a population of non-Labradors with cranial cruciate ligament disease. CLINICAL RELEVANCE: Measurement method and reference ranges provided for mechanical tibial angles may be used to aid in diagnosis, surgical planning, and postoperative critique for hindlimb angular deformities.

Radiographic measurement of the proximal and distal mechanical joint angles in the canine tibia.

OBJECTIVE: To describe a method for radiographic measurement of proximal and distal mechanical joint angles of the canine tibia. Normal ranges were established for a population of dogs, and specifically, Labrador retrievers, with cranial cruciate ligament rupture. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Tibiae (n=105) of dogs evaluated for cranial cruciate ligament rupture; 70 tibiae were from Labrador retrievers, 35 tibiae were from other breeds. METHODS: Anatomic landmarks were established and craniocaudal radiographs were used to measure the mechanical medial proximal (mMPTA) and distal (mMDTA) tibial angles in the frontal plane. RESULTS: Means (+/-SD) for all tibiae were mMPTA, 93.30+/-1.78 degrees, and mMDTA, 95.99+/-2.70 degrees. For Labrador retrievers, means were mMPTA, 93.38+/-1.81 degrees, and mMDTA 96.34+/-2.51 degrees. No significant differences were detected between Labrador Retrievers and non-Labrador retrievers with respect to mMPTA (power=0.5) or mMDTA (power=0.342). Labrador Retrievers were significantly younger than non-Labradors (P=.003). CONCLUSION: A method for measurement of the mechanical joint angles of the canine tibia in the frontal plane was established and reference ranges for a population of dogs and Labrador Retrievers with cranial cruciate ligament rupture are reported. CLINICAL RELEVANCE: The established method of measurement and references ranges can be used to aid in diagnosis, determining indications, and surgical planning for angular limb deformities of the tibia, especially when affected bilaterally. The methodology and reference values may also be used for postoperative critique.