Risk factors for recurrence of clinical signs associated with thoracolumbar intervertebral disk herniation in dogs: 229 cases (1994-2000)

OBJECTIVE: To assess risk factors for recurrence of clinical signs associated with thoracolumbar intervertebral disk disease (IVDD) in dogs that had decompressive laminectomy without attempted prophylactic treatment of other disk spaces. DESIGN: Retrospective study. ANIMALS: 229 dogs. PROCEDURE: Medical records of dogs that had decompressive laminectomy without prophylactic fenestration for a first episode of IVDD and were available for follow-up were reviewed. Information on 7 clinical and 8 radiographic potential risk factors were recorded. RESULTS: Clinical signs associated with recurrence of IVDD developed in 44 (19.2%) dogs. Ninety-six percent of recurrences developed within 3 years after surgery. Recurrence developed in 25% of Dachshunds and 15% of dogs of other breeds combined. Number of opacified disks was a significant risk factor for recurrence. Risk increased with number of opacified disks in an almost linear manner; each opacified disk increased risk by 1.4 times. Dogs with 5 or 6 opacified disks at the time of first surgery had a recurrence rate of 50%. CONCLUSIONS AND CLINICAL RELEVANCE: When all likely episodes of recurrence are considered and a long follow-up period is achieved, true rate of recurrence of IVDD appears to be higher than in many previous reports. Dogs with multiple opacified disks at the time of first surgery should be considered a high-risk subpopulation.     

Magnetic resonance imaging findings in dogs with thoracolumbar intervertebral disk disease: 69 cases (1997-2005)

OBJECTIVE: To determine magnetic resonance imaging (MRI) abnormalities in dogs with intervertebral disk disease (IVDD) and develop a classification scheme for IVDD in dogs based on MRI findings. DESIGN: Retrospective case series. ANIMALS: 69 dogs. PROCEDURE: Medical records of dogs admitted because of thoracolumbar IVDD in which MRI of T9 through L7 had been performed were reviewed. RESULTS: A total of 759 intervertebral disk spaces were examined. Of these, 342 (45.1%) were classified as having a normal MRI appearance; the remaining 417 (54.9%) had various types of IVDD. Disk degeneration was identified in 276 disk spaces in 56 dogs, bulging of the intervertebral disk was identified in 37 disk spaces in 24 dogs, disk protrusion was identified in 54 disk spaces in 32 dogs, and disk extrusion was identified in 50 disk spaces in 48 dogs. Cartilage endplate changes were identified in 35 vertebrae in 17 dogs, and increased signal intensity of the spinal cord was identified in 21 dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Four types of IVDD (disk degeneration, bulging of the intervertebral disk, disk protrusion, and disk extrusion) were identified on the basis of MRI findings in dogs with thoracolumbar IVDD. We recommend that a standardized nomenclature be adopted for the various types of thoracolumbar IVDD in dogs.     

Canine intervertebral disk disease: a retrospective study of clinical outcome in 238 dogs (2003-2004)

The aim of the study was the assessment of the prognosis of intervertebral disk diseases on the basis of a large case load with the help of currently available therapy modalities. Medical records of 238 dogs presented within 2 years (2003-2004) with neurological deficits resulting from intervertebral disk disease and surgical treatment at the Department of Small Animal Medicine and Surgery of the University of Veterinary Medicine Hannover were reviewed. 85% of the patients showed a good and 15% a poor long-term functional outcome. Both the presence of deep pain sensation and the weight of the dog were the only variables detected as having a significant impact on prognosis. The time needed to motor function improve depended on the degree of neurological deficits before surgery, and patients with a cervical lesion had a more rapid recovery than patients with a thoracolumbal disease. All other variables, including age, previous signs of intervertebral disk disease, preoperative steroid medication, a lower motor neuron involvement and durotomy did not significantly influence the outcome. Radiographic changes of the vertebral column such as spondylosis, spondylarthrosis, a narrowed disk space up to a fusion of the vertebral bodies mostly were found at the site of a removed intervertebral disk. In dogs with intervertebral disk disease evaluated in the current study a good result could be obtained after surgical decompression.     

Adverse effects and outcome associated with dexamethasone administration in dogs with acute thoracolumbar intervertebral disk herniation: 161 cases (2000-2006)

OBJECTIVE: To determine complications and neurologic outcomes associated with dexamethasone administration to dogs with surgically treated thoracolumbar intervertebral disk herniation, compared with dogs not receiving dexamethasone. DESIGN: Retrospective case series. ANIMALS: 161 dogs with surgically confirmed thoracolumbar disk herniation. PROCEDURES: Medical records from 2 hospitals were used to identify dogs that had received dexamethasone < 48 hours prior to admission (dexamethasone group dogs), dogs that received glucocorticoids other than dexamethasone < 48 hours prior to admission (other-glucocorticoid group dogs), and dogs that received no glucocorticoids (nontreatment group dogs). Signalment, neurologic injury grade, laboratory data, and complications were extracted from medical records. RESULTS: Dexamethasone group dogs were 3.4 times as likely to have a complication, compared with other-glucocorticoid or nontreatment group dogs. Dexamethasone group dogs were 11.4 times as likely to have a urinary tract infection and 3.5 times as likely to have diarrhea, compared with other-glucocorticoid or nontreatment group dogs. No differences in neurologic function at discharge or recheck evaluation were detected among groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that treatment with dexamethasone before surgery is associated with more adverse effects, compared with treatment with glucocorticoids other than dexamethasone or no treatment with glucocorticoids, in dogs with thoracolumbar intervertebral disk herniation. In this study population, no difference in outcome was found among groups. These findings suggest that the value of dexamethasone administration before surgery in dogs with thoracolumbar disk herniation should be reconsidered.     

Prognostic value of magnetic resonance imaging in dogs with paraplegia caused by thoracolumbar intervertebral disk extrusion: 77 cases (2000-2003)

OBJECTIVE: To determine whether magnetic resonance imaging findings in dogs with paraplegia caused by thoracolumbar intervertebral disk extrusion were predictive of clinical outcome. DESIGN: Retrospective case series. ANIMALS: 77 dogs. PROCEDURE: Medical records and magnetic resonance images were reviewed; clinical outcome was classified as successful (regained ability to walk with no more than mild neurologic deficits) or unsuccessful (severe neurologic deficits persisted). The prognostic value of magnetic resonance imaging was compared with prognostic value of deep pain perception, duration of clinical signs, and rate of onset of clinical signs. RESULT: 33 (43%) dogs had areas of hyperintensity of the spinal cord greater than or equal to the length of the L2 vertebral body on T2-weighted magnetic resonance images. All 44 dogs without areas of hyperintensity on T2-weighted images had a successful outcome, but only 18 of the 33 (55%) dogs with an area of hyperintensity did. Only 5 of 16 dogs with an area of hyperintensity that had also lost deep pain perception had a successful outcome. The odds ratio for an unsuccessful outcome for a dog with an area of hyperintensity (29.87) was higher than the odds ratio for a dog that had lost deep pain perception (5.24). Duration and rate of onset of clinical signs were not associated with clinical outcome. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggest that results of magnetic resonance imaging can be used to predict clinical outcome in dogs with paraplegia caused by intervertebral disk extrusion.     

Evaluation of electroacupuncture treatment for thoracolumbar intervertebral disk disease in dogs

OBJECTIVE: To evaluate use of electroacupuncture combined with standard Western medical treatment versus Western medical treatment alone for treatment of thoracolumbar intervertebral disk disease in dogs. DESIGN: Prospective controlled study. ANIMALS: 50 dogs with signs of thoracolumbar intervertebral disk disease. PROCEDURES: Dogs were randomly allocated to 1 of 2 treatment groups and classified as having grade 1 to 5 neurologic dysfunction. Dogs in group 1 received electroacupuncture stimulation combined with standard Western medical treatment; those in group 2 received only standard Western medical treatment. A numeric score for neurologic function was evaluated at 4 time points to evaluate effects of treatments. RESULTS: Time (mean +/- SD) to recover ambulation in dogs with grade 3 and 4 dysfunction in group 1 (10.10 +/- 6.49 days) was significantly lower than in group 2 (20.83 +/- 11.99 days). Success (able to walk without assistance) rate for dogs with grade 3 and 4 dysfunction in group 1 (10/10 dogs) was significantly higher than that of similarly affected dogs in group 2 (6/9 dogs). Dogs without deep pain perception (grade 5 dysfunction) had a success (recovery of pain sensation) rate of 3 of 6 and 1 of 8 in groups 1 and 2, respectively, but the difference was not significant. Overall success rate (all dysfunction grades) for group 1 (23/26; 88.5%) was significantly higher than for group 2 (14/24; 58.3%). CONCLUSIONS AND CLINICAL RELEVANCE: Electroacupuncture combined with standard Western medical treatment was effective and resulted in shorter time to recover ambulation and deep pain perception than did use of Western treatment alone in dogs with signs of thoracolumbar intervertebral disk disease.     

Recurrence of thoracolumbar intervertebral disk extrusion in chondrodystrophic dogs after surgical decompression with or without prophylactic fenestration: 265 cases (1995-1999)

OBJECTIVES: To evaluate a population of chondrodystrophic dogs treated for Hansen type 1 intervertebral disk (IVD) disease by surgical decompression with or without prophylactic fenestration and determine the rate and location of surgically confirmed recurrence of intervertebral disk extrusion. ANIMALS: 265 dogs. STUDY DESIGN: Retrospective study. PROCEDURES: Medical records of dogs that underwent spinal decompression between 1995 and 1999 were reviewed. RESULTS: 3 (4.9%) dogs were euthanatized or died prior to discharge. Fenestration was performed in 252 dogs, including 37 (14.7%) at the site of decompression only, 48 (19%) at 3 to 4 disk spaces, and 167 (66%) at 5 to 7 disk spaces. There were 12 instances of recurrent disk extrusion confirmed by removal of disk at a second surgery 3.5 to 33 months after the first surgery. Recurrence was always at a new disk space, and rates did not significantly differ between dogs that underwent single or multiple fenestrations. Two recurrences were at a previously fenestrated disk space. Seven recurrences were at a site immediately adjacent to a fenestrated disk space, and 5 recurrences were at L4-5. CONCLUSIONS AND CLINICAL RELEVANCE: Prophylactic fenestration is generally successful in preventing future disk extrusions at fenestrated disk spaces. Prospective evaluation is still required to determine whether fenestration decreases the overall rate of recurrence. Prophylactic fenestration could promote disk extrusion at adjacent, nonfenestrated disk spaces. This could have a substantial clinical impact if recurrence develops at L4-5.     

Characteristics of dogs admitted for treatment of cervical intervertebral disk disease: 105 cases (1972-1982).

Case histories of 105 dogs that were treated for cervical intervertebral disk disease (IVDD) were studied retrospectively. To compare with previous data, dogs were grouped by age, gender, and breed. Dogs were also grouped by clinical signs of disease, and by presence and location of radiologic change. The age range of cases of cervical IVDD was 1 to 13 years (mean, 6.3 years). Fifty-nine percent of dogs treated for cervical IVDD were females, but the proportion of diseased females was similar to females in total hospital admissions. Twenty-eight breeds of dogs were treated for cervical IVDD. Dachshunds and Beagles were significantly over represented (P less than or equal to 0.001). However, gender-breed interaction was not observed. Prevalence of radiologic evidence of disk disease was detected at the following levels of the vertebral column: C2-3, 29%; C3-4, 24%; C4-5, 21%; C5-6, 15%; C6-7, 9%; and C7-T1, 2%. Significant difference was not observed in prevalence of cervical IVDD affecting the first 4 disk spaces. However, prevalence of cervical IVDD at C7-T1 was significantly less than that involving the first 4 disk spaces (P less than 0.02), and the space at C6-7 was significantly less affected than were the first 3 spaces (P less than 0.08). Significant association was not evident between clinical signs (pain and neurologic deficits) and radiologic signs of IVDD, although neurologic deficits were more likely to be observed in association with radiologic signs than with signs of pain.     

Incidence of seizures associated with iopamidol or iomeprol myelography in dogs with intervertebral disk disease: 161 cases (2000–2002)

Objective – To compare the incidence of seizures in dogs with intervertebral disk disease after iopamidol or iomeprol myelography, and to assess whether the incidence of seizures differed between the 2 agents when severity of neurological deficits, location of cord compression, duration of anesthesia, site of myelogram, volume of contrast, and concentration of contrast were evaluated. Design – Retrospective study. Setting – Veterinary teaching hospital. Animals – One hundred and sixty‐one client‐owned dogs with intervertebral disk disease. Interventions – Subarachnoid injection of contrast medium. Measurements and Main Results – One hundred and sixty‐one dogs with intervertebral disk disease were subjected to myelography using iopamidol (n=74) or iomeprol (n=87). Cranial myelography was performed in 31 dogs, caudal myelography in 125 and both cranial and caudal myelography in 5. Seizures occurred in 23 of 161 (14%) dogs. There was no significant difference overall between iopamidol and iomeprol myelography. However, in dogs with thoracolumbar disk extrusion and paraplegia, seizures occurred more frequently after caudal myelography using iopamidol compared with iomeprol. Conclusions – Both iomeprol and iopamidol are suitable for myelography in dogs. Iomeprol is recommended for caudal myelography in paraplegic dogs with thoracolumbar disk extrusion due to the higher incidence of seizures in this group when iopamidol was used.     

Evaluation of sensitivity and specificity of cytologic examination: 269 cases (1999-2000)

OBJECTIVE: To determine sensitivity and specificity of cytologic examination used in a clinical setting. DESIGN: Retrospective study. ANIMALS: 216 dogs, 44 cats, 4 horses, 2 ferrets, 1 llama, 1 rat, and 1 mouse. PROCEDURE: Records were reviewed of cases in which a cytologic diagnosis was followed by a surgical biopsy or postmortem examination within 3 days with subsequent histopathologic diagnosis. Diagnoses were compared for agreement at various levels, including complete agreement, partial agreement, no agreement, or no comparison possible because of insufficient or incorrect cytologic specimen. Levels of agreement were compared for different categories of lesions, including neoplastic, inflammatory, dysplastic-hyperplastic-other, and normal tissue. Additionally, levels of agreement for neoplastic lesions were categorized with regard to cell type, degree of malignancy, and location. Sensitivity and specificity of cytologic examination were calculated. RESULTS: At the level of general agreement (complete and partial agreement), the sensitivity of cytologic examination ranged from 33.3 to 66.1%, depending on the location of the lesion. Cytologic examination was most accurate when used to diagnose cutaneous and subcutaneous lesions and least accurate for diagnosis of liver lesions. Cytologic examination was most effective in diagnosis of neoplastic disease and least effective in diagnosis of dysplastic or hyperplastic conditions. CONCLUSIONS AND CLINICAL RELEVANCE: Cytologic examination is a valuable diagnostic tool, although our results indicated lower accuracy than previously reported. False-negative results (missing a diagnosis) were far more common than false-positive results (categorizing a healthy animal as diseased): therefore, if the clinical index of suspicion is high, cytologic examination should be repeated or another technique should be selected to rule out the suspected condition.     

Liposarcomas in dogs: 56 cases (1989-2000)

OBJECTIVE: To determine the biological behavior of liposarcomas in dogs and identify clinical signs, the effect of treatment on survival time, and potential prognostic factors. DESIGN: Retrospective study. ANIMALS: 56 dogs with histologically confirmed liposarcoma. PROCEDURE: Information was obtained on signalment, tumor size, location of the tumor, stage of disease, remission duration, overall survival time, cause of death, type of surgery (incisional biopsy, marginal excision, or wide excision), and any additional treatments given. RESULTS: Surgery consisted of incisional biopsy in 6 dogs, marginal excision in 34, and wide excision in 16. Twenty-five dogs had histologic evidence of tumor cells at the surgical margins and 28 did not (status of the margins was unknown in 3 dogs). Twelve of 43 dogs had local recurrence. Median survival time was 694 days, and the only factor significantly associated with survival time was type of surgery performed. Median survival times were 1,188, 649, and 183 days, respectively, for dogs that underwent wide excision, marginal excision, and incisional biopsy. Factors that were not found to be significantly associated with survival time included tumor size, status of the margins, tumor location, and histologic subtype. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that in dogs, liposarcomas are locally invasive neoplasms that rarely metastasize and occur primarily in appendicular or axial locations and that wide excision is preferred to marginal excision when feasible.     

Dysautonomia in dogs: 65 cases (1993-2000)

OBJECTIVE: To determine signalment, history, clinical findings, results of autonomic function testing and other antemortem diagnostic tests, and pathologic findings in dogs with dysautonomia. DESIGN: Retrospective study. ANIMALS: 65 dogs with dysautonomia. PROCEDURE: Case records of 68 dogs with a diagnosis of dysautonomia were reviewed; inclusion criteria included histologic confirmation of dysautonomia or clinical signs and results of pharmacologic testing consistent with dysautonomia. RESULTS: 65 dogs fulfilled all criteria for dysautonomia. Dogs from rural environments were overrepresented, and cases of dysautonomia were reported for every month, although the highest number of cases was reported in February and March. Vomiting was the most common clinical sign, followed by diarrhea, signs of anorexia and depression, weight loss, and dysuria. The most common physical examination finding was decreased or absent anal tone, followed by absent pupillary light reflexes and elevated nictitating membrane. Results of pharmacologic testing were consistent with dysautonomia, although no single test was 100% sensitive. Histologic lesions consistent with dysautonomia were found in the autonomic ganglia, brainstem nuclei, and ventral horns of the spinal cord. CONCLUSIONS AND CLINICAL RELEVANCE: Dysautonomia is an endemic disease in Kansas, and a high index of suspicion of the disease can be made by combining clinical signs, physical examination findings, and results of pharmacologic testing.     

Quantification of the association between intervertebral disk calcification and disk herniation in Dachshunds

OBJECTIVE: To quantify the association between intervertebral disk calcification and disk herniation in Dachshunds. DESIGN: Longitudinal study. ANIMALS: 61 Dachshunds that had been radiographically screened for calcification of intervertebral disks at 2 years of age in other studies. Thirty-seven of the dogs had survived to the time of the present study and were > or = 8 years of age; 24 others had not survived. PROCEDURES: Radiographic examination of 36 surviving dogs was performed, and information on occurrence of disk calcification at 2 years of age were obtained from records of all 61 Dachshunds. Information on occurrence of disk herniation between 2 and 8 years of age was obtained from owners via questionnaire. Associations between numbers of calcified disks and disk herniation were analyzed via maximum likelihood logistic regression. RESULTS: Disk calcification at 2 years of age was a significant predictor of clinical disk herniation (odds ratio per calcified disk, 1.42; 95% confidence interval, 1.19 to 1.81). Number of calcified disks in the full vertebral column was a better predictor than number of calcified disks between vertebrae T10 and L3. Numbers of calcified disks at > or = 8 years of age and at 2 years of age were significantly correlated. CONCLUSIONS AND CLINICAL RELEVANCE: Number of calcified disks at 2 years of age was a good predictor of clinical disk herniation in Dachshunds. Because of the high heritability of disk calcification, it is possible that an effective reduction in occurrence of severe disk herniation in Dachshunds could be obtained by selective breeding against high numbers of calcified disks at 2 years of age.     

Arthroscopic evaluation of menisci in dogs with cranial cruciate ligament injuries: 100 cases (1999-2000)

OBJECTIVE: To determine prevalence of meniscal injuries by use of arthroscopic examination in dogs with cranial cruciate ligament (CCL) injuries. DESIGN: Retrospective study. ANIMALS: 94 dogs with 100 injured CCLs. PROCEDURE: Records for 94 large dogs (> 20 kg [44 lb]) with 100 naturally occurring CCL injuries that were examined arthroscopically were reviewed. Pathologic findings in the CCL (complete or partial tears), prevalence and type of meniscal injuries, and periarticular osteophytes were recorded. RESULTS: 77% of joints had tears of the lateral meniscus; most were a series of small radial tears of the cranial horn. Fifty-eight percent of joints had tears of the medial meniscus. Positive correlation between complete tears of the CCL and medial meniscal damage was found. No significant relationships were detected between periarticular osteophyte formation and meniscal injury, medial and lateral meniscal injury, or degree of CCL tear and lateral meniscal injury. CONCLUSIONS AND CLINICAL RELEVANCE: There is a strong association between CCL injury and lateral and medial meniscal injuries in dogs. Clinical importance of lateral meniscal lesions is not known; a much higher percentage of dogs had such injuries than has been reported previously, possibly because of use of arthroscopy.     

Clinical signs and clinicopathologic abnormalities in dogs with clinical spirocercosis: 39 cases (1996-2004)

OBJECTIVE: To determine clinical signs and clinicopathologic abnormalities in dogs with naturally occurring clinical spirocercosis. DESIGN: Retrospective case series. ANIMALS: 39 dogs with spirocercosis. PROCEDURES: Medical records were reviewed, and information on signalment, residence (rural vs urban), owner complaints, physical examination findings, clinicopathologic abnormalities, radiographic and endoscopic findings, and concurrent systemic diseases was recorded. RESULTS: Hellenic hounds and mixed-breed dogs were overrepresented, compared with a group of 117 control dogs without spirocercosis that were examined because of gastrointestinal tract disease, and mean body weight of dogs with spirocercosis was significantly higher than mean body weight of control dogs. Odynophagia (34 [87%]), regurgitation (24 [62%]), and excessive salivation (14 [36%]) were the most common clinical findings. The most common radiographic abnormalities were a mass in the caudodorsal aspect of the mediastinum (15/35 [43%]) and spondylitis of the caudal thoracic vertebrae (10 [29%]). Parasitic nodules were seen during esophagoscopy in all 39 dogs. Normocytic, normochromic, nonregenerative anemia; neutrophilic leukocytosis; hyperproteinemia; and high alkaline phosphatase activity were significantly more common in dogs with spirocercosis than in a control group of 56 healthy dogs. Concurrent systemic diseases, mainly leishmaniosis, dirofilariosis, and monocytic ehrlichiosis, were documented in 14 (36%) dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that clinical spirocercosis occurs more often in young-adult, large-breed dogs. Nonregenerative anemia, neutrophilic leukocytosis, hyperproteinemia, and high alkaline phosphatase activity may be useful clinicopathologic indicators of this disease.     

Gallbladder mucocele in dogs: 30 cases (2000-2002)

OBJECTIVE: To determine long-term outcome of dogs with gallbladder mucocele. DESIGN: Retrospective study. ANIMALS: 30 dogs with gallbladder mucocele, including 23 that underwent cholecystectomy. PROCEDURE: Medical records were reviewed for signalment, history, and clinical, ultrasonographic, and surgical findings. Follow-up information was obtained for all dogs that survived the perioperative hospitalization period. RESULTS: 23 dogs had signs of systemic illness; 7 had no clinical signs. Median values for serum activities of alanine aminotransferase and alkaline phosphatase, serum total bilirubin concentration, and total WBC count were significantly higher among dogs with gallbladder rupture than among dogs without rupture. Sensitivity of sonography for detection of rupture was 85.7%. Overall perioperative mortality rate for dogs that underwent cholecystectomy was 21.7%; mortality rate was not significantly greater for dogs with rupture. Aerobic bacteria were isolated from the bile or gallbladder wall in 8.7% of dogs. All 18 dogs discharged from the hospital had complete resolution of clinical signs. In dogs that underwent in-hospital reexamination, serum liver enzyme activities were significantly decreased, compared with preoperative activities. Persistent increases in serum activities of 1 or more liver enzymes were detected in 9 of 12 dogs; 6 of 12 dogs had persistent abnormalities in hepatic echogenicity. Mean follow-up period was 13.9 months. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cholecystectomy is an effective treatment for gallbladder mucocele. Although perioperative mortality rate is high, prognosis after discharge from the hospital is excellent. Rupture of the gallbladder warrants emergency surgical intervention but does not preclude a positive outcome.     

Lung lobe torsion in dogs: 22 cases (1981-1999)

OBJECTIVE: To identify breed disposition, postoperative complications, and outcome in dogs with lung lobe torsion. DESIGN: Retrospective study. ANIMALS: 22 client-owned dogs. PROCEDURE: Information on signalment; history; clinical findings; results of clinicopathologic testing, diagnostic imaging, and pleural fluid analysis; surgical treatment; intra- and postoperative complications; histologic findings; and outcome were obtained from medical records. RESULTS: All 22 dogs had pleural effusion; dyspnea was the most common reason for examination. Fifteen dogs were large deep-chested breeds; 5 were toy breeds. Afghan Hounds were overrepresented, compared with the hospital population. One dog was euthanatized without treatment; the remaining dogs underwent exploratory thoracotomy and lung lobectomy. Eleven dogs recovered from surgery without complications, but 3 of these later died of thoracic disease. Four dogs survived to discharge but had clinically important complications within 2 months, including chylothorax, mediastinal mesothelioma, gastric dilatation, and a second lung lobe torsion. Six dogs died or were euthanatized within 2 weeks after surgery because of acute respiratory distress syndrome, pneumonia, septic shock, pneumothorax, or chylothorax. Chylothorax was diagnosed in 8 of the 22 dogs, including 4 Afghan Hounds. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that lung lobe torsion is rare in dogs and develops most frequently in large deep-chested dogs, particularly Afghan Hounds. Other predisposing causes were not identified, but an association with chylothorax was evident, especially in Afghan Hounds. Prognosis for dogs with lung lobe torsion was fair to guarded.     

Mammary duct ectasia in dogs: 51 cases (1992-1999)

OBJECTIVE: To evaluate the clinical and pathologic characteristics of mammary duct ectasia in dogs. DESIGN: Retrospective study. ANIMALS: 51 dogs with mammary duct ectasia. PROCEDURE: Information regarding body condition, history, number and location of affected mammary glands, appearance of lesions, surgical treatment, nonsurgical treatment, and evidence of recurrence or development of mammary neoplasia was obtained from surveys sent to referring veterinarians. Results of information from examination of histologic sections and referring veterinarians were evaluated for all mammary duct ectasia biopsies performed between 1992 and 1999. RESULTS: Duct ectasia was the primary diagnosis in 51 of 1,825 (2.8%) mammary biopsy specimens and comprised 48% of nonneoplastic mammary diseases. Affected dogs were evenly distributed over a range of 1 to 13 years of age, with a mean age at the time of diagnosis of 6.1 +/- 3.1 years. All dogs were female (31 sexually intact, 20 spayed); 10 of 26 had whelped. Duct ectasia was described as nodular (26 dogs), cystic (13), and multiglandular (11) and located in caudal (31) more often than cranial (14) or middle glands (10). Ectasia recurred in 3 dogs. One dog had a history of previously excised mammary adenocarcinoma; another subsequently developed mammary carcinoma. CONCLUSIONS AND CLINICAL RELEVANCE: Duct ectasia affected mature, sexually intact and spayed female dogs over a wide age range. Certain breeds were affected more commonly than expected. Increased risk for mammary neoplasia was not evident. Duct ectasia should be considered as a cause for mammary enlargement, especially in young dogs or when its cystic nature is evident. Mastectomy is usually curative, and neoplasia should be ruled out in dogs with ectasia.     

5-Hydroxytryptophan toxicosis in dogs: 21 cases (1989-1999)

OBJECTIVE: To determine epidemiologic characteristics, clinical findings, and treatment outcome of 5-hydroxytryptophan (5-HTP) toxicosis in dogs. DESIGN: Retrospective study. ANIMALS: 21 dogs with evidence of accidental 5-HTP ingestion. PROCEDURE: Information was retrieved from the National Animal Poison Control Center database. Records of dogs ingesting 5-HTP between January 1989 and February 1999 were reviewed for information on signalment, dose ingested, clinical signs (onset, severity, duration), treatments administered, and outcome. RESULTS: Clinical signs of toxicosis developed in 19 of 21 (90%) dogs. Neurologic signs included seizures (9 dogs), depression (6), tremors (5), hyperesthesia (5), and ataxia (4). Gastrointestinal tract signs included vomiting or diarrhea (12 dogs), signs of abdominal pain (3), and hypersalivation (2). Other clinical signs were hyperthermia (7 dogs) and transient blindness (3). Three dogs died. No important clinical laboratory or necropsy findings were reported. The doses of 5-HTP ingested ranged from 2.5 to 573 mg/kg (1.1 to 260 mg/lb) of body weight; the minimum toxic dose reported in our study was 23.6 mg/kg (10.7 mg/lb), and the minimum lethal dose was 128 mg/kg (58.1 mg/lb). Onset of signs ranged from 10 minutes to 4 hours after ingestion, and signs lasted up to 36 hours. Of 17 dogs with clinical signs of toxicosis that received treatment, 16 recovered; treatment consisted of decontamination, seizure control, thermoregulation, fluid therapy, and supportive care. CONCLUSIONS AND CLINICAL RELEVANCE: Ingestion of 5-HTP in dogs can result in a potentially life-threatening syndrome resembling serotonin syndrome in humans, which requires prompt and aggressive care.