External-beam Co-60 radiotherapy for canine nasal tumors: a comparison of survival by treatment protocol.

A retrospective analysis of survival times in dogs with intranasal tumors was performed comparing those treated using hypofractionated or full course Co-60 radiotherapy protocols alone or with surgical adjuvant therapy and those receiving no radiation treatment. One hundred thirty-nine dogs presented to the University of Minnesota Veterinary Medical Center for treatment of histologically-confirmed nasal neoplasia between July 1983 and October 2001 met the criteria for review. Statistically analyzed parameters included age at diagnosis, tumor histologic classification, fractionation schedule (number of treatments, and number of treatment days/week) (classified as hypofractionated if 2 or less treatments/week); calculated minimum tumor dose/fraction; calculated total minimum tumor dose (classified as hypofractionated if less than 37 Gy in six or fewer fractions); number of radiotherapy portals, a treatment gap of more than 7 days in a full course (3-5 treatments/week, 3-3.5 week treatment time) radiotherapy protocol, the influence of eye shields on survival following single portal DV fields, the survey radiographic extent of the disease, and the presence or absence of cytoreductive surgery. There was a significant relationship only between protocols using 3 or more treatments/week and at least 37 Gy cumulative minimum tumor dose and survival. However, there was no significant relationship between either total minimum tumor dose or dose/fraction and survival and there were no significant relationships between survival and any of the other variables analyzed including tumor histologic type.

Case-control study of canine malignant lymphoma: positive association with dog owner's use of 2,4-dichlorophenoxyacetic acid herbicides.

A hospital-based case-control study of companion dogs examined the risk of developing canine malignant lymphoma associated with the use of chemicals in and about the home. Information from a self-administered owner questionnaire and/or a telephone interview of about 491 cases, 466 nontumor controls, and 479 tumor controls indicated that owners in households with dogs that developed malignant lymphoma applied 2,4-dichlorophenoxyacetic acid (2,4-D) herbicides to their lawn and/or employed commercial lawn care companies to treat their yard significantly more frequently than control owners (odds ratio = 1.3). In addition, the risk of canine malignant lymphoma rose to a twofold excess with four or more yearly owner applications of 2,4-D. The findings in this study are consistent with occupational studies in humans, which have reported modest associations between agricultural exposure to 2,4-D and increased risk of non-Hodgkin's lymphoma, the histology and epidemiology of which are similar to those of canine malignant lymphoma. The present study suggests that human health implications of 2,4-D exposure in the home environment should receive further investigation.

Quantitative evaluation of spinal cord lesions in canine globoid leukodystrophy.

Lesion distribution in the spinal cord was investigated by sampling an average of 26 spinal cord segments in each of ten dogs severely affected by canine globoid leukodystrophy (GLD). GLD lesions were quantified by subdividing spinal white matter into small unit areas and judging the quartile extent of lesion involvement for each unit area. Along the length of the spinal cord, lesions declined from cranial to caudal, decreasing precipitously in the midlumbar region. The lumbosacral region had the least amount of lesion, and, based on lesion per unit area, the thoracic region was most severely involved. The dorsal funiculus had the greatest concentration and the least dispersion of lesion generally amoung the three funiculi. White matter at the periphery of the spinal cord was involved earlier and more severely than white matter adjacent to gray matter. Amount of lesion per spinal cord could be estimated adequately by sampling one segment from each of five regions. Dogs could be divided into two groups based on rate of lesion development. Clinical signs did not correlate closely with total amount of lesion per spinal cord. Of the total amount of variability among dogs in amount of spinal pathologic involvement, 78% could be accounted for by a mathematical model expressing spinal cord pathologic involvement as a quadratic function of age at onset and duration of the clinical syndrome.

Effects of urinary bladder distension on the length of the dog and cat urethra.

Urethral lengths were determined in male and female cats and in female dogs from positive contrast retrograde urethrocystograms at 2 levels of urinary bladder distension. Urethral lengths were longer on urethrograms obtained after urinary bladder distension in female cats and in 7 of 8 female dogs. The intrapelvic and penile urethra were longer after bladder distension in 4 of 6 male cats. In female cats, urethral lengths significantly increased (P less than 0.05) after urinary bladder distension.

Effect of multiple excretory urograms on glomerular filtration of normal dogs: a preliminary report.

Study was made of the effect of a triiodinated radiopaque contrast agent, sodium iothalamate on glomerular filtration of ten normal dogs given the dosages commonly recommended for diagnostic studies--200, 400, and 800 mg of iodine/0.45 kg of body weight administered at 2- to 6-day intervals. Renal function was evaluated by determination of serum urea nitrogen and serum creatinine concentrations and endogenous creatinine clearance immediately before each urogram and at 2 to 5 days after the last urogram. Although no significant changes in serum urea nitrogen or creatinine concentrations were identified, a statistically significant reduction in endogenous creatinine clearance following urography was identified when the data from all the dogs were evaluated as a group. However, only 3 of the 10 dogs had successively decreasing values on serial evaluations of endogenous creatinine clearances and an additional 2 animals had final endogenous creatinine clearances further than 1 SD below the preinjection (base line) mean for that animal. Serial renal function studies will be required in dogs given a single dose of the radiopaque contrast to determine the reversibility of the decreased endogenous creatinine clearance and the significance of the decreased creatinine clearances when compared with those values in control dogs (not given radiopaque contrast medium). In addition, these studies may reveal whether the incidence, degree, and duration of reduced glomerular filtration are related to the dose rate of radiopaque contrast agent and are statistically significant were greater numbers of dogs given single and multiple doses of radiopaque contrast agent under laboratory conditions.

Effects of urinary bladder distention on location of the urinary bladder and urethra of healthy dogs and cats.

Evaluation of the anatomic location of the distended and empty urinary bladders and urethras of healthy adult male and female dogs and cats by retrograde urethrocystography revealed substantial variations. In 15 dogs in lateral recumbency with empty bladder lumens, the caudal portion of the urinary bladder was within the pelvic canal in 5 of 7 male and 5 of 8 female dogs. In female dogs examined in ventrodorsal recumbency, only 4 of 8 had the empty urinary bladders in part within the pelvic canal. After luminal distention, 3 of 7 male and 3 of 8 female dogs, while in lateral recumbency, had the urinary bladders in part intrapelvically. However, when female dogs were placed in ventrodorsal recumbency, only 1 of 7 urinary bladders was in part within the pelvis. The urinary bladders of 14 cats were consistently within the abdominal cavity, irrespective of whether the bladder lumen was distended or empty. Urethral flexures occurred in dogs with intrapelvic bladders that were distended or empty. Urethral flexures were not found in cats. The urethras of dogs and cats in lateral recumbency were generally closer to the floor of the pelvis after urinary bladder distention than when the bladder was empty. The urethra of the dogs and cats in ventrodorsal recumbency was to the left or right of or on the midsagittal plane, whether the urinary bladder was empty or distended. A greater degree of lateral displacement was encountered in ventrodorsal recumbency after urinary bladder distention.

Consecutive water provocative tests in normal and glaucomatous Beagles.

Water provocative tests were evaluated in normal and glaucomatous Beagles. Schiotz tonometry was performed before water was administered (50 ml/kg) by stomach tube and for the next 90 minutes. The mean increase in Schiotz tonometric values in normal dogs ranged from 3.1 to 8.6 mm of Hg and in glaucomatous dogs, 7.3 to 19.9 mm of Hg. Beagles with glaucoma had progressive, gradually increased responses to water provocative tests.

Orthovoltage radiation of normal canine nasal passages: assessment of depth dose.

Frozen heads of 9 clinically normal dogs were irradiated with orthovoltage x-rays. Surface doses and nasal cavity depth doses were measured, and the percentage of surface dose (depth dose) was calculated at random depths from the dorsal cutaneous surface in transverse planes through the medial and lateral canthi. Depth dose of 2 orthovoltage x-ray beams having half-value layers of 1.5 mm of Cu (96 keV) and 2.6 mm of Cu (134 keV) were compared with and found to resemble that reported in depth dose tables based on soft tissue equivalent material. Any differences (identified graphically) in depth dose, compared with that described using a uniform (soft tissue equivalent) phantom, were explained by the variations in tissue composition and the presence of air within the normal nasal and paranasal cavities.

Complications of retrograde contrast urethrography in dogs and cats.

Urinary bladder lesions varying histologically from a focal hemorrhagic cystitis to a diffuse transmural fibrinonecrotic cystitis were encountered in 11 of 14 dogs and cats euthanatized 1 day after retrograde urethrography. Focal-to-diffuse hemorrhagic urethritis was histologically encountered in 14 of 14 dogs and cats euthanatized 1 day after retrograde urethrography. Lesions in the urinary bladder and urethra were not reversible within 14 days and were evident histologically in 10 of 15 urinary bladders and 11 of 15 urethras of dogs and cats euthanatized 14 days after retrograde urethrography. During urethrography, iatrogenic mural leakage of contrast media into the bladder wall or bladder wall rupture was encountered radiographically in 6 of 15 dogs and 3 of 14 cats. However, macroscopic evidence of bladder rupture was encountered in only 1 male dog at necropsy. Immediately after retrograde urethrography, macroscopic hematuria occurred in 12 of 15 dogs and 9 of 14 cats. Microscopic hematuria was not encountered in dogs or cats euthanatized 14 days after urethrography. Pyuria was encountered less frequently and was present in only 2 cats euthanatized 14 days after urethrography. One day after urethrography, urinary tract infection characterized by urine cultures with greater than 10(5) microbes/ml was encountered in 4 of 29 dogs and cats. All animals with urinary tract infection were female dogs or cats. At day 14, only 1 female cat had a positive urine culture. Seemingly, the technique of retrograde urethrography was the cause of the encountered lesions.

Effects of prolonged distention of retention catheters on the urethra of dogs and cats.

The effects of inflation of a balloon-tipped catheter in the distal part of the urethra of clinically healthy male and female dogs and cats were evaluated. Tissues were evaluated at 1 and 14 days after balloon inflation. Macroscopic and microscopic lesions were limited to the distal part of the urethra occupied by the inflated balloon in animals which were euthanatized 1 day after balloon inflation. The lesions were characterized by submucosal urethral hemorrhage. This investigation indicates that balloon inflation for 15 minutes duration in the distal part of the urethra of dogs and cats results in a mild reversible inflammatory reaction.

Malignant hyperthermia-triggering liability of selected inhalant anesthetics in swine.

Twenty pigs, known to be malignant hyperthermia (MH)-susceptible by previous MH-positive [MH(+)] reactions to halothane testing, were given 5 inhalant anesthetics. The number of MH(+) responses evoked by the different anesthetics varied. In response to halothane, isoflurane, and enflurane, MH(+) reactions were exhibited by 12, 11, and 7 pigs, respectively. The number of MH(+) reactions to nitrous oxide (0) and methoxyflurane (1) was significantly (P = 0.02) less. In the present study, all 4 halogenated-hydrocarbon volatile liquid inhalant anesthetics were capable of evoking a MH(+) reaction in susceptible pigs.

Evaluation of the morphologic characteristics and prevalence of canine urocystoliths from a regional urolith center.

OBJECTIVE: To determine whether morphology of single-mineral urocystoliths and age, sex, or breed data could be applied to facilitate radiographic and clinical urocystolith mineral type prediction, respectively, in dogs. SAMPLE POPULATION: Database of 2,041 dogs with pure mineral composition urocystoliths. PROCEDURE: All uroliths were characterized according to geologic descriptive terminology and by breed, sex, and age of dog at time of sample submission. Summary statistics were used to compare features with specific mineral types. Observed trends were analyzed for statistical relevance between observed and expected frequencies for age, sex, color, size, shape, and surface, using the null hypothesis that differences by urocystolith mineral type did not exist. On the basis of expected breed occurrence derived by equations, the null hypothesis that urocystolith occurrence paralleled canine breed popularity was tested. RESULTS: Urocystoliths > 10 mm in any dimension were > 92% likely to be magnesium ammonium phosphate hexahydrate (MAP). Smooth, blunt-edged or faceted, and pyramidal urocystoliths were usually MAP. Jackstone shapes were almost always silica. Botryoidal (grape-like clusters) urocystoliths were likely to be oxalates. Breeds with high relative likelihood of urocystoliths included: English Bulldog, Pekingese, Pug, Welsh Corgi, and West Highland White Terrier. Breeds with low relative likelihood of urocystolith production included: German Shepherd Dog, Shar-Pei, and German Shorthaired Pointer. About 94% of urocystoliths produced in females or spayed females were MAP, whereas males and neutered males produced a greater assortment. CONCLUSIONS AND CLINICAL RELEVANCE: For pure mineral composition urocystoliths, trends in mineral type among breeds and between sexes can be exploited clinically in the diagnosis and management of urolith-related disease. Size and shape, used in conjunction with age, breed, and sex, can facilitate pure urocystolith mineral type prediction.

Effects of intravesical hydrostatic pressure and volume on the distensibility of the canine prostatic portion of the urethra.

Positive-contrast retrograde urethrocystograms were obtained serially on 12 male dogs weighing 11.4 to 23.2 kg before, during, and after the injection of contrast medium until the urinary bladder neck and prostatic and membranous portions of the urethra remained open and distended as viewed by fluoroscopy. Correlations of intravesical volumes and pressures required to achieve maximum distension of the midprostatic portion of the urethra with body weight and surface area were not significant. Because of the variability in intravesical volumes and pressures encountered at maximum distension of the prostatic portion of the urethra, a dose of contrast material expressed relative to body weight or surface area could not be determined for consistently providing maximum distension of the prostatic portion of the urethra.

Calibration of the Schiøtz tonometer for the normal canine eye.

The Schiøtz tonometer with 5.5-, 7.5-, and 10-g weights was calibrated for the normal canine eye, using a transducer with open and closed reservoir systems. The line of best fit for the observations was determined, and the equation of this line was utilized to derive a calibration table for the conversion of tonometer scale readings to mm of Hg intraocular pressure.

Effects of radiographic contrast media on results of urinalysis, with emphasis on alteration in specific gravity.

The effect of radiographic contrast medium on the urine specific gravity of ten clinically normal dogs was evaluated. Urinary excretion of different dosages of intravenously administered triiodinated contrast medium caused significant alterations of urine specific gravity. The magnitude of change was related primarily to preinjection urine specific gravity values rather than dosage of contrast medium. In general, preinjection urine specific gravities < 1.040 were increased 15 minutes after injection of contrast material, whereas preinjection urine specific gravities > 1.040 were decreased 15 minutes after injection of contrast medium. A linear relationship was identified between the concentration of radiographic contrast medium in either distilled water or urine and the specific gravity of these mixtures. This simulated the effects of radiologic contrast medium on urine specific gravity when used for retrograde urethrocystography. Results of the investigation indicated that urinary excretion of radiographic contrast media significantly alters urine specific gravity values in normal dogs and renders postinjection urine samples unsuitable for diagnostic evaluation of renal tubular concentrating capacity. In addition, previously reported errors in urine protein, glucose, and sediment evaluations attributed to radiographic contrast media were reviewed.

Nonneurogenic urinary incontinence in a canine female pseudohermaphrodite.

Nonneurogenic incontinence was observed in a 1-year-old Pekingese X Poodle with female pseudohermaphroditism. The dog had male external genitalia as well as a well-developed vagina, uterus, and ovaries. Urinary incontinence was caused by an anomalous communication of the prostatic urethra with the vagina. Ovariohysterectomy and surgical correction of the urethrovaginal fistula was followed by remission of urinary incontinence. Subsequently, the dog developed estrogen responsive urinary incontinence. Nonneurogenic incontinence to be a common finding in canine pseudohermaphroditism associated with abnormalities of the vagina or urethra (or both). Surgical correction should be considered to correct anomalous communications between the genital and lower urinary tracts.

Imaging canine urocystoliths. Detection and prediction of mineral content.

The role of survey radiography, contrast radiography, and ultrasonography in the assessment of urocystolithiasis has been primarily one of detection. Information about the radiographic characteristics of uroliths (size, shape, radiopacity, surface characteristics, number detected) for characterization and diagnosis of urocystolithiasis is emerging; however, there are no studies on the accuracy or sensitivity of these techniques. In this article, the intent is to update knowledge about available imaging techniques used in the detection and characterization of urocystoliths based on recent studies designed to evaluate their accuracy in prediction of different urocystoliths mineral content.

Clinical features, intestinal histopathology, and outcome in protein-losing enteropathy in Yorkshire Terrier dogs.

BACKGROUND: A poorly understood protein-losing enteropathy (PLE) disorder has been reported in Yorkshire Terrier dogs. OBJECTIVES: To describe clinical features, intestinal histopathology, and outcome in Yorkshire Terrier dogs with PLE, and to identify variables predictive of outcome. ANIMALS: Thirty client-owned Yorkshire Terrier dogs with PLE. METHODS: Retrospective study. Records of dogs with a diagnosis of PLE were reviewed. Intestinal histopathology was interpreted using the World Small Animal Veterinary Association gastrointestinal histopathology classification system. Discriminate analysis techniques were used to identify variables predictive of outcome. RESULTS: Females outnumbered males (20/30). Median age was 7 years (range 1-12). Common clinical signs were diarrhea (20/30), vomiting (11), ascites and abdominal distension (11), and respiratory difficulty (8). Histopathologic abnormalities included villous lymphatic dilatation, crypt lesions, villous stunting, and variable increases in cellularity of the lamina propria. All dogs were treated with glucocorticoids. Of 23 dogs with long-term follow-up, 9 had complete, and 3 had partial, resolution of signs, and 11 failed to respond to treatment. Median survival of responders was 44 months and of nonresponders was 12 months, with 4 dogs experiencing peracute death. Vomiting, monocytosis, severity of hypoalbuminemia, low blood urea nitrogen concentration, and villous blunting were predictive of survival <4 months. CONCLUSIONS: In addition to classic GI signs, Yorkshire Terriers with PLE often show clinical signs associated with hypoalbuminemia and low oncotic pressure. Lymphatic dilatation, crypt lesions, and villous stunting are consistent histopathologic findings. Clinical outcomes are variable, but many dogs experience remission of clinical signs and prolonged survival.

Applicability of 3T body MRI in assessment of nonfocal bone marrow involvement of hematopoietic neoplasia in dogs.

BACKGROUND: The utility of whole body magnetic resonance imaging (MRI) in detecting bone marrow infiltration in dogs with cancer has not been investigated. OBJECTIVES: To assess the feasibility of 3T body MRI for bone marrow assessment in dogs with hematopoietic neoplasia. ANIMALS: Seven dogs with B-cell lymphoma, 3 dogs with myelodysplastic syndrome (MDS), and 2 clinically normal dogs. METHODS: A prospective study of dogs with hematopoetic cancer was conducted using T1W, T2W, In-Phase, Out-of-Phase and STIR pulse sequences of the body excluding the head prior to bone marrow sampling. The relative signal intensity of a midlumbar vertebral body and a midshaft femoral bone marrow was compared by visual and point region of interest analysis to regional skeletal muscle. RESULTS: Similarity of femoral diaphyseal and vertebral body marrow signal intensity to that of skeletal muscle on the Out-of-Phase sequence was useful in distinguishing the 3 dogs with hypercellular marrow because of MDS from the 7 dogs with B-cell lymphoma and from the 2 clinically normal dogs. 1/7 dogs with lymphoma had proven bone marrow involvement but normal cellularity and less than 5% abnormal cells. Unaffected midfemoral marrow had greater signal intensity than skeletal muscle and unaffected vertebral marrow had less signal intensity than skeletal muscle on the Out-of-Phase sequence. CONCLUSIONS AND CLINICAL IMPORTANCE: 3T, Out-of-Phase MR pulse sequence was useful in distinguishing diffuse bone marrow infiltrate (MDS) from minimally or unaffected marrow using skeletal muscle for signal intensity comparison on whole body MRI.