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Biomedical subjects

G R Johnston

Publications and source records attributed to G R Johnston.

At least 19 recordsLinked to original sources
PubMed2001

Effects of finasteride on size of the prostate gland and semen quality in dogs with benign prostatic hypertrophy.

OBJECTIVE: To determine the effect of the 5alpha-reductase inhibitor finasteride on prostatic diameter and volume, semen quality, and serum dihydrotestosterone (DHT) and testosterone concentrations in dogs with spontaneous benign prostatic hypertrophy (BPH). DESIGN: Double-blind placebo-controlled trial. ANIMALS: 9 dogs with BPH. PROCEDURE: Five dogs were treated with finasteride for 16 weeks (0.1 to 0.5 mg/kg [0.05 to 0.23 mg/lb] of body weight, PO, q 24 h); the other 4 received a placebo. Prostatic diameter, measured radiographically, prostatic volume, measured ultrasonographically, semen quality, and serum DHT and testosterone concentrations were evaluated before and during treatment. After receiving the placebo for 16 weeks, the 4 control dogs were treated with finasteride for 16 weeks, and evaluations were repeated. RESULTS: Finasteride significantly decreased prostatic diameter (mean percentage decrease, 20%), prostatic volume (mean percentage decrease, 43%), and serum DHT concentration (mean percentage decrease, 58%). Finasteride decreased semen volume but did not adversely effect semen quality or serum testosterone concentration. No adverse effects were reported by owners of dogs in the study. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that finasteride can be used to reduce prostatic size in dogs with BPH without adversely affecting semen quality or serum testosterone concentration.

Animals↗
PubMed2000

Prostatic disorders in the dog.

Common canine prostatic disorders include benign prostatic hypertrophy (BPH), prostatitis, prostatic cysts and prostatic adenocarcinoma. BPH is a spontaneous and age-related disorder of intact male dogs, which occurs in more than 80% male dogs over 5 years of age, and which is associated with clinical signs of sanguinous prostatic fluid, constipation and dysuria. BPH signs respond to castration or to finasteride treatment (0.1-0.5 mg/kg per os once daily), as finasteride inhibits conversion of testosterone to dihydrotestosterone, causing prostatic involution via apoptosis. BPH often occurs concurrently with prostatic infection, abscessation, cysts and neoplasia in the intact dog, and finasteride-induced prostatic involution may be beneficial in treatment of all of these conditions except neoplasia. Two studies suggest that risk of prostatic adenocarcinoma is increased in neutered, compared to intact male dogs. Although canine prostatic neoplasia, unlike human prostatic neoplasia, usually does not respond to androgen deprivation, recent reports of prostatic intraepithelial neoplasia (PIN) in a high percentage of older male dogs, with and without prostatic adenocarcinoma, suggests that PIN may be a precursor to adenocarcinoma in the dog as it is believed to be in man.

Adenocarcinoma↗
PubMed1997

Long-term results of treatment of traumatic coxofemoral joint dislocation in dogs: 64 cases (1973-1992).

OBJECTIVE: To determine long-term results of various treatments for traumatic coxofemoral joint dislocation in dogs. DESIGN: Retrospective case series. ANIMALS: 64 dogs that underwent closed reduction and bandage stabilization, extracapsular suture stabilization, transacetabular pinning, toggle pinning, DeVita pinning, or femoral head and neck excision. PROCEDURE: Follow-up evaluations included owner evaluation (64 dogs), physical evaluation (23), and radiography (19). Follow-up time ranged from 8 to 156 months. RESULTS: Owner evaluation scores after closed reduction were significantly better than scores after DeVita pinning, extracapsular suture stabilization, and femoral head and neck excision. On physical examination, 6 of 23 dogs were lame on the side of the previous dislocation. Signs of pain and crepitation were evident during palpation of 12 and 8 of 25 joints, respectively. Thirteen of 21 joints had radiographic evidence of degenerative joint disease. There was a greater progression of degenerative joint disease in previously dislocated joints than in unaffected joints. There were not any significant differences between treatments in regard to results of physical and radiographic evaluation. Time between trauma and treatment and existence of concomitant injuries did not influence follow-up results, but there was a significant association between body weight and radiographic evaluation score. CLINICAL IMPLICATIONS: Concomitant injuries do not appear to justify a worse prognosis in dogs with traumatic coxofemoral joint dislocation, nor does a delay in treatment of > 3 days. Gait abnormalities and degenerative joint disease might develop in the long term. Proper body weight should be maintained regardless of treatment.

Animals↗
PubMed1996

Feline perineal urethrostomy: a potential cause of feline lower urinary tract disease.

Perineal urethrostomies are associated with complications that may mimic primary causes of feline lower urinary tract disorders. Though postoperative urethral strictures may be minimized by proficiency with an effective surgical technique, removal of the distal urethra may result in bacterial urinary tract infections in 25% to 30% of patients after surgery. Urinary tract infections caused by urease-producing microbes may induce struvite urolith formation. Thus the prophylactic benefits of minimizing recurrent urethral obstruction by urethrostomy must be weighed against a long-term predisposition to recurrent bacterial urinary tract infection and urolith formation.

Animals↗
PubMed1996

Medical management of iatrogenic rents in the wall of the feline urinary bladder.

Surgical closure may not be necessary to successfully manage all patients with ruptured urinary bladders. If the margins of the walls of tears in the bladder wall are not devitalized, and if they remain in close apposition via maintenance of the bladder lumen in a nondistended state for an appropriate period, these conditions may simulate those created by use of surgical sutures. This is not advocating an all-or-none choice. Because the clinical status of patients with ruptured urinary bladders can range from that characterized by only hematuria and dysuria to life-threatening postrenal uremia, a range of surgical and medical options should be considered.

Animals↗
PubMed1996

Percutaneous needle biopsy of the kidney. Indications, applications, technique, and complications.

During the past three decades, percutaneous renal biopsy has evolved as a valuable method of clinical evaluation of patients with various forms of glomerular proteinuria and primary renal failure. The advent of automated core biopsy needles and ultrasound guidance has substantially improved the safety of needle biopsy techniques and almost eliminated the need for surgical wedge biopsy.

Animals↗
PubMed1996

Diagnostic imaging strategies in small animal nephrology.

The diagnostic imaging methods most readily available to the private practitioner are survey radiography, radiographic contrast procedures, and ultrasonography. Nuclear medicine imaging techniques are available at referral centers. The advantages and disadvantages of these methods as well as the favored strategies of the authors in their utilization for the diagnosis of renal disorders in the cat and dog are discussed.

Animals↗
PubMed1996

Diagnostic imaging of the feline lower urinary tract.

Survey radiography, double contrast cystography, and antegrade urethrocystography are valuable imaging tools available to the clinician for evaluation of cats with lower urinary tract disease. However, to be cost effective during patient evaluation, diagnostic radiographic procedures should be used only when needed. An algorithm is presented that describes when radiographic imaging techniques may be most cost effective in providing useful information during the clinical workup of cats with lower urinary tract disease.

Algorithms↗
PubMed1995

Vaginal septa in dogs: 15 cases (1983-1992).

Medical records of 15 dogs with vaginal septa, examined between April 1983 and December 1992, were reviewed. Overall prevalence of vaginal septation at the hospital during the study period was 0.03%. Thirteen breeds were represented; mean age at the time of initial examination was 2.4 years. Owners' original complaints included inability to breed naturally, dysuria, urinary incontinence, infertility, recurrent vaginitis, ambiguous external genitalia, and dystocia. One dog did not have clinical signs associated with the vaginal septum. In 11 of the 15 dogs, the septum could be palpated during digital vaginal examination. The septum could be seen in 6 of the 7 dogs in which vaginoscopy was performed. Twelve of the 15 dogs underwent positive-contrast vaginography; in all 12, the septum could be easily seen. Four of the 15 dogs underwent removal of the septum, with or without episiotomy, and 4 others were ovariohysterectomized. One dog was bred by means of artificial insemination and became pregnant. The remaining 6 dogs were lost to follow-up.

Animals↗
PubMed1995

Efficacy of radioprotective agents in preventing small and large bowel radiation injury.

PURPOSE: A variety of adjuvant treatments and cytoprotective agents have been proposed to lessen the toxicity of radiation therapy. The following study was designed to evaluate the benefit of six agents or combinations using anastomotic bursting strength as a measure of transmural radiation injury. METHODS: The 40-Gy study consisted of the following. Seventy-two male Sprague-Dawley rats were divided into eight equal groups: nonradiated control, radiated untreated control, and six radiated treated groups. The radioprotective treatments included ribose-cysteine (Rib-Cys), WR-2721, glutamine, vitamin E, MgCl2/adenosine triphosphate, and RibCys/glutamine in combination. Radiated animals received 40 Gy to the abdomen. Two weeks after radiation, all animals underwent small bowel and colonic resection with primary anastomosis. Animals were sacrificed one week postoperatively, at which time anastomoses were evaluated and bursting strengths determined. The 70-Gy study consisted of the following. The same protocol was repeated for five groups of nine rats divided into nonradiated, radiated untreated, and three radiated treated groups receiving RibCys (8 mmol/kg), RibCys (20 mmol/kg), and WR-2721. All radiated animals received 70-Gy doses. RESULTS: In the 40-Gy group, there were 10 radiation-related deaths and 6 anastomotic leaks among 70 rats studied. None of the differences between groups were significant. Nonradiated control group small bowel and large bowel anastomotic bursting pressures were significantly elevated compared with all radiated groups. Compared with radiated controls, there were significant improvements in small bowel bursting strength in the RibCys, WR-2721, RibCys-glutamine, and vitamin E groups and significant improvement in colonic bursting strength in MgCl2/adenosine triphosphate, WR-2721, and RibCys groups. In the 70-Gy group, all nine nonradiated control rats survived. All eight untreated radiated control rats died, four of eight WR-2721 animals died (P = 0.03), all RibCys (8 mmol/kg) animals died (P = 0.03), and three of nine treated with RibCys (20 mmol/kg) survived (P = 0.08). CONCLUSIONS: WR-2721 and RibCys gave consistent protection against large and small bowel radiation injury. The lower incidence of treatment-related toxicity and potentially equal or greater radioprotective effects may make RibCys more clinically useful than WR-2721.

Adenosine Triphosphate↗
PubMed1993

Protective effect of RibCys following high-dose irradiation of the rectosigmoid.

UNLABELLED: Ribose-cysteine (RibCys) is a prodrug of L-cysteine that stimulates glutathione biosynthesis. Increased glutathione levels have been shown to have a protective effect against radiation-induced injury and oxidative stress. Surface oximetry has previously been used successfully to predict anastomotic leakage. PURPOSE: The following study was done to evaluate the protective effect of RibCys and the predictive value of PtO2 determinations in a swine model. METHODS: Domestic swine were divided into three groups: Group A served as a nonradiated control; Group B received 6,000 to 6,500 rad to the rectosigmoid; and Group C received RibCys (1 g/kg) prior to receiving 6,000 to 6,500 rad. Radiated animals and controls underwent rectosigmoid resection after a three-week rest period. Intraoperative anastomotic PtO2 was checked with a modified Clark electrode. Anastomoses were evaluated radiographically at three and seven days; animals were sacrificed, and bursting strength was recorded at 10 days. RESULTS: Mean bursting pressures were 243.8 +/- 59.4, 199.5 +/- 37.8, and 209.5 +/- 54.9 mmHg (NS) for Groups A, B, and C, respectively. Anastomotic PtO2 ranged from 19 to 98 mmHg and could not be correlated with anastomotic leaks or bursting pressure. There were 11/15 radiation-related deaths and leaks (eight deaths and three leaks) in the radiated group and 4/12 radiation-related deaths and leaks (three deaths and one leak) in the group receiving radiation and RibCys (P < 0.04). CONCLUSIONS: 1) RibCys protected animals against radiation-related deaths and anastomotic leaks following high doses of pelvic irradiation; 2) anastomotic PtO2 levels did not correlate with anastomotic healing in this model.

Anastomosis, Surgical↗
PubMed1991

Clinical evaluation of cats with lower urinary tract disease.

In a prospective study, 141 cats with hematuria, dysuria, urethral obstruction, or combinations of these signs were evaluated by contemporary diagnostic methods and compared with 26 clinically normal cats (controls). Specific diagnosis was established in 45% (64/141) of cats affected with lower urinary tract disease (LUTD). Crystalline matrix plug-induced urethral obstruction was diagnosed in 21% (30/141) of affected cats, uroliths were identified in 21% (30/141) of affected cats, uroliths with concomitant bacterial urinary tract infection (UTI) were identified in less than 2% (2/141) of affected cats, and bacterial UTI alone was identified in less than 2% (2/141) of cats with LUTD. Viruses, mycoplasmas, and ureaplasmas were not isolated from urine samples collected from affected or control cats. Bovine herpesvirus 4 (BHV-4)-neutralizing antibodies were not detected in any serum sample obtained from cats with LUTD or from control cats. In contrast, BHV-4 antibodies were detected by an indirect immunofluorescent antibody (IFA) test in sera obtained from 31% (44/141) of cats with LUTD and 23% (6/26) of control cats. The prevalence of positive BHV-4 IFA test results in affected cats was not significantly different from that observed in control cats. Significant association was not apparent between positive BHV-4 IFA test results and clinical diagnosis, abnormal laboratory findings, or cat age. However, the number of male cats with BHV-4 IFA titer was significantly (P less than 0.02, chi 2 test) greater than that of female cats. Detection of BHV-4 antibodies in approximately 30% of affected and control cats indicates prior virus exposure. Further investigations are warranted to clarify the specific role of BHV-4 in cats with naturally acquired LUTD.

Animals↗
PubMed1991

Ultrasonographic features of testicular neoplasia in dogs: 16 cases (1980-1988).

For 16 dogs with testicular neoplasia (n = 19 tumors), ultrasonography was performed to determine whether a correlation exists between ultrasonographic features of testicular tumors and cell type. The echogenicity of the tumors varied depending on the size of the tumor and whether the tumor had focal or diffuse distribution within the testis. The ultrasonographic characteristics of Sertoli cell tumors were variable, with no predominant pattern. This variation may be related to tumor size, because 6 of 7 Sertoli cell tumors were greater than 5 cm in diameter. Focal seminomas and interstitial cell tumors less than 3 cm in diameter had hypoechoic texture. Focal seminomas and interstitial cell tumors greater than 3 cm in diameter had mixed echogenicity. Tumors of multiple cell types were greater than 5 cm in diameter and had mixed echogenicity. In valuable breeding dogs with a small (less than 3 cm) focal intrascrotal lesion, testicular ultrasonography would be of benefit for localization of the mass to the testis or epididymis for subsequent biopsy. In dogs with intraabdominal neoplastic testes, ultrasonography may be of benefit in determining intra-abdominal metastases and invasion of contiguous structures.

Animals↗
PubMed1991

Ultrasonography of the kidney and prostate gland. Has gray-scale ultrasonography replaced contrast radiography?

Beginning in the late 1970s with the first reports of two-dimensional, gray-scale ultrasonography used to image small-animal abdominal organs, the question of whether to use contrast radiographic or ultrasonographic techniques for urogenital assessment has become increasingly important. In the last five to seven years, the volume of veterinary literature on ultrasonographic imaging equals or exceeds that on contrast radiographic imaging of the small-animal urogenital tract. While the advantages of ultrasonographic over contrast radiographic imaging are obvious for some situations (eg, renal failure or paraprostatic cyst), no overviews critically comparing these techniques have been published to our knowledge. With the increasing availability of ultrasonographic equipment in private veterinary practice, choices between these imaging techniques must be made. Imaging the kidney and the prostate gland are discussed because both techniques are applicable to these organs. Our intent was to determine which of these techniques would be appropriate for the common clinical conditions. This article addresses the advantages and disadvantages of both techniques for renal and prostatic imaging. The perspective provided is based on ten years of clinical experience with both techniques by each of the authors. Clinical scenarios and specific diseases are discussed and the consensus of the authors on the procedure(s) of choice for these situations are described.

Animals↗