Catherine A. Loughin

Morphometric features of the craniocervical junction region in dogs with suspected Chiari-like malformation determined by combined use of magnetic resonance imaging and computed tomography

OBJECTIVE To objectively describe morphometric features of the craniocervical junction region of Cavalier King Charles Spaniels (CKCSs) and non-CKCS dogs with suspected Chiari-like malformation (CLM) and identify associations between these features and the presence of other malformations in this region. ANIMALS 216 CKCSs and 58 non-CKCS dogs. PROCEDURES Magnetic resonance and computed tomographic images of the head and craniocervical junction region of patients evaluated because of suspected CLM were assessed for cerebellar compression (CC), ventral spinal cord compression at the C1-C2 articulation (medullary kinking), and dorsal spinal cord compression at the C1-C2 articulation (dorsal compression). A compression index was calculated for each of these 3 locations in each dog. Multiple logistic regression analysis was performed to determine whether breed (CKCS vs non-CKCS) and compression index values were associated with the presence of other craniocervical junction abnormalities. RESULTS All 274 dogs had CC; medullary kinking was identified in 187 (68.2%) and dorsal compression was identified in 104 (38.0%). Atlantooccipital overlapping (AOO) was identified in 76 (27.7%) dogs. Breed of dog (CKCS vs non-CKCS) and value of CC index were the only significant predictors of AOO. The CKCSs had an almost 5-fold decrease in risk of AOO, compared with the non-CKCS dogs, and the risk of AOO nearly doubled for every 10% increase in CC index. CONCLUSIONS AND CLINICAL RELEVANCE The anatomic abnormality responsible for CC was AOO in a substantial percentage of dogs suspected to have CLM. The CC index value may be used to help differentiate subtypes of craniocervical junction abnormalities in dogs.

Diagnostic imaging of the canine stifle: a review.

The stifle joint, a common location for lameness in dogs, is a complex arrangement of osseous, articular, fibrocartilaginous, and ligamentous structures. The small size of its component structures, restricted joint space, and its intricate composition make successful diagnostic imaging a challenge. Different tissue types and their superimposition limit successful diagnostic imaging with a single modality. Most modalities exploit the complexity of tissue types found in the canine stifle joint. Improved understanding of the principles of each imaging modality and the properties of the tissues being examined will enhance successful diagnostic imaging.The stifle joint, a common location for lameness in dogs, is a complex arrangement of osseous, articular, fibrocartilaginous, and ligamentous structures. The small size of its component structures, restricted joint space, and its intricate composition make successful diagnostic imaging a challenge. Different tissue types and their superimposition limit successful diagnostic imaging with a single modality. Most modalities exploit the complexity of tissue types found in the canine stifle joint. Improved understanding of the principles of each imaging modality and the properties of the tissues being examined will enhance successful diagnostic imaging.

Thermal imaging of normal and cranial cruciate ligament-deficient stifles in dogs.

Objective: To investigate the capability of thermography for differentiation between normal stifles and those with cranial cruciate ligament (CCL) rupture in dogs, initially with a full hair coat and 1 hour after clipping the hair coat. Study Design: Prospective study. Animals: Labrador Retrievers (n=6) with normal stifle joints (controls) and adult dogs (n=10) with CCL rupture. Methods: Thermography was performed before, and 60 minutes after, clipping the hair coat from the pelvic limb. Stifle images were classified as normal or abnormal, then subclassified as clipped and unclipped hair coat. CCL deficiency was confirmed at surgery and thermographic images subsequently classified as abnormal before analysis with image processing software. Results: Using image recognition analysis, differentiation between normal and CCL-deficient stifles in both clipped and unclipped dogs was 85% successful on cranial images, medial, caudal, and lateral images were between 75% and 85% successful. Although there were significant increases in skin temperature after clipping in both groups (P<.0002–.0001), there were no significant temperature differences between normal and CCL-deficient stifles when the entire stifle was examined. Conclusion: Thermography was successful in differentiating naturally occurring CCL-deficient stifles in dogs, with a success rate of 75–85%. Clipping is not necessary for successful thermographic evaluation of the canine stifle. Clinical Relevance: Thermography may be a useful imaging modality for diagnosis of CCL deficiency in dogs when CCL rupture is suspected but stifle laxity is not evident.OBJECTIVE To investigate the capability of thermography for differentiation between normal stifles and those with cranial cruciate ligament (CCL) rupture in dogs, initially with a full hair coat and 1 hour after clipping the hair coat. STUDY DESIGN Prospective study. ANIMALS Labrador Retrievers (n=6) with normal stifle joints (controls) and adult dogs (n=10) with CCL rupture. METHODS Thermography was performed before, and 60 minutes after, clipping the hair coat from the pelvic limb. Stifle images were classified as normal or abnormal, then subclassified as clipped and unclipped hair coat. CCL deficiency was confirmed at surgery and thermographic images subsequently classified as abnormal before analysis with image processing software. RESULTS Using image recognition analysis, differentiation between normal and CCL-deficient stifles in both clipped and unclipped dogs was 85% successful on cranial images, medial, caudal, and lateral images were between 75% and 85% successful. Although there were significant increases in skin temperature after clipping in both groups (P<.0002-.0001), there were no significant temperature differences between normal and CCL-deficient stifles when the entire stifle was examined. CONCLUSION Thermography was successful in differentiating naturally occurring CCL-deficient stifles in dogs, with a success rate of 75-85%. Clipping is not necessary for successful thermographic evaluation of the canine stifle. CLINICAL RELEVANCE Thermography may be a useful imaging modality for diagnosis of CCL deficiency in dogs when CCL rupture is suspected but stifle laxity is not evident.

Micro total hip replacement in dogs and cats.

Objective To describe the surgical technique using power-assisted femoral preparation and clinical outcome in 41 dogs and 2 cats surgically treated with the micro total hip prosthesis. Study Design Retrospective case series Animals Dogs (n = 41) and 2 cats Methods Medical records (January 2007–March 2010) of dogs and cats that had MicroTHR were reviewed. Data regarding implant position, cement mantle quality, concurrent surgery, intra- and postoperative complications, operative time, 3-week and 3-month recheck physical examinations, 3-month pelvic radiograph findings, and interval from surgery to any complication were retrieved. Results Six dogs had staged bilateral MicroTHR, 35 dogs and 2 cats had unilateral MicroTHR. Median body weight was 8.2 kg (range, 2.1–14.2 kg) whereas for those that had complications (fracture or luxation) it was 8.6 kg (range, 6.6–14.1 kg). Median operative time was 71 minutes (range, 55–105 minutes). Complications included luxations (5 of 49; 10%) and femoral fracture (1; 2%). Lameness grades assigned at the 3-month recheck examination: 39 (80%) animals were grade 1, 6 (12%) were grade 2, and 4 (8%) were grade 3. Forty-five animals (92%) had good or excellent results. Conclusions MicroTHR is a practical and effective surgery in small breed dogs and cats with coxofemoral disease.OBJECTIVE To describe the surgical technique using power-assisted femoral preparation and clinical outcome in 41 dogs and 2 cats surgically treated with the micro total hip prosthesis. STUDY DESIGN Retrospective case series ANIMALS Dogs (n = 41) and 2 cats METHODS Medical records (January 2007-March 2010) of dogs and cats that had MicroTHR were reviewed. Data regarding implant position, cement mantle quality, concurrent surgery, intra- and postoperative complications, operative time, 3-week and 3-month recheck physical examinations, 3-month pelvic radiograph findings, and interval from surgery to any complication were retrieved. RESULTS Six dogs had staged bilateral MicroTHR, 35 dogs and 2 cats had unilateral MicroTHR. Median body weight was 8.2 kg (range, 2.1-14.2 kg) whereas for those that had complications (fracture or luxation) it was 8.6 kg (range, 6.6-14.1 kg). Median operative time was 71 minutes (range, 55-105 minutes). Complications included luxations (5 of 49; 10%) and femoral fracture (1; 2%). Lameness grades assigned at the 3-month recheck examination: 39 (80%) animals were grade 1, 6 (12%) were grade 2, and 4 (8%) were grade 3. Forty-five animals (92%) had good or excellent results. CONCLUSIONS MicroTHR is a practical and effective surgery in small breed dogs and cats with coxofemoral disease.

Risk Factors and Clinical Relevance of Positive Intraoperative Bacterial Cultures in Dogs with Total Hip Replacement

OBJECTIVE To report incidence and relevance of positive intraoperative total hip replacement (THR) bacterial cultures taken at the time of surgical closure in dogs having unilateral THR. STUDY DESIGN Retrospective case series. ANIMALS Dogs (n = 100) with cemented (CFX), cementless (BFX), or hybrid THR. METHODS Medical records (January 2007-March 2010) of dogs that had THR were reviewed. Signalment, type and side of THR, concurrent surgery, operative and anesthetic times, intraoperative coxofemoral closing (CC) bacterial culture results, organism cultured, duration of postoperative antibiotic administration, physical examination findings at 3 weeks, 3 months, and at 6 months to 1 year after surgery, radiographic findings at 3 months and between 6 months and 1 year after surgery, and incidence of complications were retrieved. RESULTS There was a significant difference in duration of surgery between CC culture negative and CC culture positive groups (103.27 minutes versus 122.50 minutes, respectively, P < .038) and in total anesthetic time between CC culture negative and culture positive groups (165.20 minutes versus 189.50 minutes, respectively, P < .038). There was no significant difference between CC culture negative and culture positive groups for median age (30 months versus 39 months, respectively, P < .75), median weight (36.91 kg versus 35.68 kg, respectively, P < .61), median clinical signs (4 months versus 3.5 months, respectively, P < .65), sex (males 44.32% versus females 25.00%, respectively, P < .20), laterality (left 55.68% versus right 50.00%, respectively, P < .71), concurrent surgery (extracapsular lateral imbrication/medial patella luxation/lateral patella luxation [ECLI/MPL/LPL] 22.73% versus none 25.00%, respectively, P < 1.00), and THR type (hybrid 17.05% versus 25.00% respectively; CFX 60.23% versus 75.0%; BFX 22.73% versus 0.0%; Fishers exact test P < .17). CONCLUSIONS Surgical and anesthetic duration were significantly associated with positive CC culture results. Positive CC culture results were not associated with adverse results at 3 months and at 6-month to 1-year follow-up evaluation.

Medical Infrared Imaging (Thermography) of Type I Thoracolumbar Disk Disease in Chondrodystrophic Dogs

OBJECTIVE To: (1) determine the success of medical infrared imaging (MII) in identifying dogs with TLIVDD, (2) compare MII localization with magnetic resonance imaging (MRI) results and surgical findings, and (3) determine if the MII pattern returns to that of normal dogs 10 weeks after decompression surgery. STUDY DESIGN Prospective case series. ANIMALS Chondrodystrophic dogs (n = 58) with Type I TLIVDD and 14 chondrodystrophic dogs with no evidence of TLIVDD. METHODS Complete neurologic examination, MII, and MRI studies were performed on all dogs. Dogs with type I TLIVDD had decompressive surgery and follow-up MII was performed at 10 weeks. Pattern analysis software was used to differentiate between clinical and control dogs, and statistical analysis using anatomic regions of interest on the dorsal views were used to determine lesion location. Recheck MII results were compared with control and pre-surgical images. RESULTS Computer recognition pattern analysis was 90% successful in differentiating normal dogs from dogs affected by TLIVDD and 97% successful in identifying the abnormal intervertebral disc space in dogs with TLIVDD. Statistical comparisons of the ROI mean temperature were unable to determine the location of the disc herniation. Recheck MII patterns did not normalize and more closely resembled the clinical group. CONCLUSIONS MII was 90% successful differentiating between normal dogs and 97% successful in identifying the abnormal intervertebral disc space in dogs with TLIVDD. Abnormal intervertebral disc space localization using ROI mean temperature analysis was not successful. MII patterns 10 weeks after surgery do not normalize.

Delayed primary surgical treatment in a dog with a persistent right aortic arch.

A 5-year-old, 1.36-kg, neutered male Yorkshire terrier was referred for evaluation of a persistent right aortic arch with concurrent megaesophagus. The dog was 3 months old when clinical signs were first noted, 2 years of age when diagnosed with megaesophagus, and 4 years of age when diagnosed with vascular ring anomaly (VRA). Surgical correction of the VRA was performed when the dog was 5 years of age, after gastrostomy tube feeding for 1 year to maintain nutritional requirements and mitigate the degree and duration of the esophageal distention. Thirteen months after surgery, the dog was eating soft dog food with no vomiting or regurgitation.

Nano Total Hip Replacement in 12 Dogs

Objective To determine the short-term clinical outcome of nano total hip replacement (NanoTHR) in dogs. Study Design Retrospective case series. Animals Dogs (n = 12). Methods Medical records (2009–2011) of dogs that had nano-THR were reviewed for signalment, weight, clinical signs, side, age, prosthesis sizes, concurrent surgeries performed, complications, operative time, 3-month postoperative pelvic radiograph results, and lameness scores. Results Breeds were Yorkshire Terriers (n = 6), Toy Poodles (2), with 1 each of Maltese, Pomeranian, Cavalier King Charles Spaniel, and Shih-Tzu. Median body was 4.87 kg (range, 2.5–5.90 kg) and median age, 35.75 months (range, 12–144 months). Radiographs were taken in 4 dogs at 12 days (n = 2), 14 days (1), and 30 days (1) after surgery because of presentation for an acute grade 5 lameness. Three dogs had femoral fractures distal to the femoral implant tip and 1 dog displaced the acetabular implant medially. After revision surgery, all femoral fractures were assessed as healed with intact plate fixation. The dog with the medially displaced acetabular component responded to conservative management including strict confinement and analgesic administration. Eight dogs (58%) were assigned a grade 1 lameness and 4 dogs were grade 2 (33%) at 12-week examination. The 3 dogs with grade 5 lameness scores found to have femoral fractures within 1 month after surgery, subsequently improved to grade 1 (n = 1) and 2 (2) 12 weeks after revision surgery. The dog with medial acetabular displacement improved to a grade 2 lameness 12 weeks after conservative management. Conclusions Although all 12 dogs had good-to-excellent outcomes, 33% experienced significant complications associated with the technique. As improvements in instrumentation and refinements in the technique are developed, NanoTHR can be considered an alternative to the femoral head and neck ostectomy (FHO) or medical management of coxofemoral disease for toy breed dogs. Further studies with a larger number of dogs and longer follow-up times are required.OBJECTIVE To determine the short-term clinical outcome of nano total hip replacement (NanoTHR) in dogs. STUDY DESIGN Retrospective case series. ANIMALS Dogs (n = 12). METHODS Medical records (2009-2011) of dogs that had nano-THR were reviewed for signalment, weight, clinical signs, side, age, prosthesis sizes, concurrent surgeries performed, complications, operative time, 3-month postoperative pelvic radiograph results, and lameness scores. RESULTS Breeds were Yorkshire Terriers (n = 6), Toy Poodles (2), with 1 each of Maltese, Pomeranian, Cavalier King Charles Spaniel, and Shih-Tzu. Median body was 4.87 kg (range, 2.5-5.90 kg) and median age, 35.75 months (range, 12-144 months). Radiographs were taken in 4 dogs at 12 days (n = 2), 14 days (1), and 30 days (1) after surgery because of presentation for an acute grade 5 lameness. Three dogs had femoral fractures distal to the femoral implant tip and 1 dog displaced the acetabular implant medially. After revision surgery, all femoral fractures were assessed as healed with intact plate fixation. The dog with the medially displaced acetabular component responded to conservative management including strict confinement and analgesic administration. Eight dogs (58%) were assigned a grade 1 lameness and 4 dogs were grade 2 (33%) at 12-week examination. The 3 dogs with grade 5 lameness scores found to have femoral fractures within 1 month after surgery, subsequently improved to grade 1 (n = 1) and 2 (2) 12 weeks after revision surgery. The dog with medial acetabular displacement improved to a grade 2 lameness 12 weeks after conservative management. CONCLUSIONS Although all 12 dogs had good-to-excellent outcomes, 33% experienced significant complications associated with the technique. As improvements in instrumentation and refinements in the technique are developed, NanoTHR can be considered an alternative to the femoral head and neck ostectomy (FHO) or medical management of coxofemoral disease for toy breed dogs. Further studies with a larger number of dogs and longer follow-up times are required.

Atlantooccipital Overlap and Other Craniocervical Junction Abnormalities in Dogs

The term craniocervical junction abnormality (CJA) is an umbrella term for a variety of malformations that occur in the craniocervical region. These abnormalities include Chiari-like malformation, atlantooccipital overlapping, atlantoaxial instability, occipitoatlantoaxial malformations, atlantoaxial dural bands, and dens abnormalities. Syringomyelia can occur secondary to any of these malformations or a combination. Clinical signs in dogs with a CJA typically include neck pain and varying signs associated with a cervical myelopathy. MRI of CJAs with computed tomography imaging is necessary for a full evaluation. Some dogs with CJAs respond to medical management, but for most surgery is the treatment of choice.

Medical infrared thermal imaging of cats with hyperthyroidism

OBJECTIVE To determine the usefulness of medical infrared thermal imaging (MITI) as a screening tool for hyperthyroidism in cats, evaluate the need for hair clipping over the ventral aspect of the neck to achieve optimal images, and determine whether there is a change in thermal patterns at 1 and 3 months after radioactive sodium iodide I 131 treatment. ANIMALS 17 cats with and 12 control cats without hyperthyroidism. PROCEDURES All cats underwent MITI first with the hair present and then after the hair was clipped. Each cat with hyperthyroidism was subsequently appropriately treated SC with radioiodide; reevaluations, including MITI before and after hair clipping and measurement of serum thyroxine concentration, were performed 1 and 3 months after treatment. RESULTS The MITI had 80.5% and 87.5% accuracy in differentiating hyperthyroid cats from clinically normal cats before and after the hair over the ventral aspect of the neck was clipped. Among cats with an initial serum thyroxine concentration > 4.0 μg/dL, the success rate for MITI-detected response to radioiodide treatment at the 1-month reevaluation was 92.86% in unshaved cats and 85.71% in shaved cats. The success rate for MITI-detected response to radioiodide treatment at the 3-month reevaluation was 100% in unshaved and shaved cats. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that MITI was successful in differentiating between hyperthyroid cats and clinically normal cats and identifying patients with thyroxine concentration within reference interval after radioactive sodium iodide I 131 treatment.