The effect of neutering on the risk of mammary tumours in dogs--a systematic review

A commonly-stated advantage of neutering bitches is a significant reduction in the risk of mammary tumours, however the evidence for this has not previously been assessed by systematic review. The objectives of this study were to estimate the magnitude and strength of evidence for any effect of neutering, or age of neutering, on the risk of mammary tumours in bitches. A systematic review was conducted based on Cochrane guidelines. Peer-reviewed analytic journal articles in English were eligible and were assessed for risk of bias by two reviewers independently. Of 11,149 search results, 13 reports in English-language peer-reviewed journals addressed the association between neutering/age at neutering and mammary tumours. Nine were judged to have a high risk of bias. The remaining four were classified as having a moderate risk of bias. One study found an association between neutering and a reduced risk of mammary tumours. Two studies found no evidence of an association. One reported "some protective effect" of neutering on the risk of mammary tumours, but no numbers were presented. Due to the limited evidence available and the risk of bias in the published results, the evidence that neutering reduces the risk of mammary neoplasia, and the evidence that age at neutering has an effect, are judged to be weak and are not a sound basis for firm recommendations.     

Efficacy, tolerance and acceptability of Incontex in spayed bitches with urinary incontinence

A clinical study about efficacy and acceptance of Incontex in spayed bitches with urinary incontinence was performed. In a randomised, double-blinded study the efficacy and acceptance of Incontex (Dr. E. Gr?ub AG, Bern, Schweiz) in bitches with urethral sphincter incompetence due to spaying was evaluated under field conditions. The active ingredient of the Incontex Syrup is phenylpropanolamine (PPA), an alpha1-adrenergic agonist. The study was performed using 24 spayed, incontinent bitches. Over a first period of treatment of 30 days the bitches received either Incontex, at 1.5 mg/kg twice per day, or a placebo. In the second period of 30 days all 24 bitches were treated with Incontex at the recommended dose. Any changes in the incontinence compared with the situation before the study were evaluated. RESULTS: Of 24 bitches 21 (88%) became continent and in 2 bitches (8%) urinary incontinence improved. In only 1 bitch (4%) the medication did have no effect. Five bitches (21%) showed side effects. The acceptance of Incontex was good. CONCLUSION AND CLINICAL RELEVANCE: Incontex can be recommended as an efficient and well-tolerated medication for the treatment of bitches with urinary incontinence after spaying. The oral application of 1.5mg/kg BW phenylpropanolamine twice daily has been approved.     

Treatment of urethral sphincter mechanism incompetence in 11 bitches with a sustained-release formulation of phenylpropanolamine hydrochloride

Between 1995 and 1999, urethral sphincter mechanism incompetence was diagnosed in 11 bitches. They had been treated with phenylpropanolamine hydrochloride at the recommended dose rate, but had shown no response or had become refractory to treatment. They were treated with phenylpropanolamine hydrochloride in a sustained-release formulation combined with diphenylpyraline hydrochloride. The urinary incontinence resolved fully in six of the bitches, two of which remained continent after the treatment was withdrawn; two showed a marked improvement on daily treatment, but the other three bitches failed to respond and underwent colposuspension.     

Phenylpropanolamine: an alpha-adrenergic agent for the management of urinary incontinence in the bitch associated with urethral sphincter mechanism incompetence

Ten bitches with urinary incontinence due to incompetence of the urethral sphincter mechanism were treated with phenylpropanolamine hydrochloride at a dose of either 1 mg/kg orally three times daily or 2 mg/kg orally once daily in a prolonged release formulation. The signs of incontinence resolved in all the bitches, and improvements were maintained over periods ranging from one to more than two years, except in one bitch which became refractory to treatment after three months. One bitch which was inadvertently treated at a dose rate of 2.5 mg/kg showed signs of lethargy and inappetence but returned to normal when the dose rate was reduced.     

Urethropexy for the management of urethral sphincter mechanism incompetence in the bitch

Urethropexy was performed on 100 bitches for the management of urethral sphincter mechanism incompetence (SMI). The dogs ranged in age from 12 months to nine years (mean 4.5 years). Diagnosis of the condition was based upon clinical, laboratory and contrast radiographic examinations, and clinical response to medical management. In all bitches, incontinence developed in the adult individual and in the majority (89 bitches) after spaying. Radiographic findings were unremarkable in 22 bitches, apart from the presence of an intrapelvic bladder neck. Follow-up periods ranged from 12 months to seven years (mean 2.9 years). Fifty-six bitches were completely cured by surgery, 27 became less incontinent and 17 either failed to respond (nine animals) or showed an initial improvement in urinary function, but then relapsed (eight animals). Nine of these 17 animals underwent a second urethropexy procedure, resulting in a cure in six and an improvement in three cases (follow-up 12 to 41 months, mean 22.2 months). A deterioration in the response rate was observed over time. Postoperative complications were seen in 21 bitches and included an increased frequency of micturition (14 bitches), dysuria (six bitches) and anuria (three bitches).     

Urinary incontinence in spayed female dogs: frequency and breed disposition

A follow up study was performed in 412 spayed bitches in order to determine the incidence of urinary incontinence. The period between the operation being performed and the survey being made varied between 3 and 10 years. 83 animals (20.1%) were incontinent independent of the surgical procedure (ovariectomy versus ovariohysterectomy). The onset of incontinence varied between immediately to 12 years with an average period of 2.9 years after surgery. 57 of these incontinent bitches were treated with ephedrine or estrogen. In 73.7% a good response was achieved with ephedrine and a further 23.7% showed some improvement. Generally ephedrine was more successful than estrogen in the treatment of incontinence. There appears to be a strong connection between body weight and the incidence of incontinence. Of bitches with a body weight of less than 20 kg only 9.3% were incontinent. Whereas in bitches with a body weight of more than 20 kg the incidence was 30.9%. Of the breeds Boxers showed a high incidence of incontinence (65%) while breeds such as German Shepherds (10.6%) or Dachshunds (11.1%) showed a low incidence in relation to the average incidence rate (20.1%).     

Acquired urinary incontinence in bitches: its incidence and relationship to neutering practices

A five-year cohort study was conducted on bitches chosen by a sample of 233 randomly selected practising veterinary surgeons in the UK, to estimate the incidence of acquired urinary incontinence (AUI) in neutered and entire animals, and to investigate possible risk factors associated with neutering practices. Information was collected using questionnaires, and data on 809 bitches, of which 22 developed AUI, were obtained. The estimated incidence rates in neutered and entire animals were 0·0174 and 0·0022 per animal-year, respectively (95 per cent confidence intervals: 0·0110, 0·0275 and 0·0009, 0·0058, respectively). The relative risk, neutered vs entire, was 7·8 (95 per cent confidence interval: 2·6, 31·5). The attributable proportion_exposed and population attributable proportion were 87·1 per cent and 63·1 per cent (95 per cent confidence intervals: 61·9 per cent, 95·6 per cent, and 28·3 per cent, 88·5 per cent, respectively). An increased risk, significant at the conventional 5 per cent level, was not demonstrated in animals neutered before, vs after, first heat (relative risk: 3·9, 95 per cent confidence interval: 0·8, 10·4), although the result was significant at the 10 per cent level. Removal of the cervix was not shown to be a risk factor in neutered dogs.     

Opinions of veterinarians about the age at which kittens should be neutered

The mean age recommended by veterinary practices for neutering kittens is 22.6 weeks, with only 28 per cent of veterinarians considering it appropriate to neuter 12- to 16-week-old kittens. Multivariable logistic regression was used to identify variables associated with veterinarians' opinion that 12 to 16 weeks is an appropriate age at which to neuter kittens. Significant risk factors included time since graduation, perception of the problem of there being too many unwanted domestic cats and their practice's policy on the recommended neutering age. Veterinarians who thought that neutering eight- to 11-week-old rescue kittens before homing was justified and veterinarians who had neutered 12- to 16-week-old domestic kittens within the previous year were more likely to consider that neutering 12- to 16-week-old kittens was appropriate. Veterinarians who thought that surgical complications, anaesthetic complications and lower urinary tract disease were, or might be, more likely to occur in kittens neutered at 12 to 16 weeks than in those neutered at six months of age, were significantly less likely to think that neutering 12- to 16-week-old kittens was appropriate.     

Treatment of urinary incontinence in bitches by endoscopic injection of glutaraldehyde cross-linked collagen

Thirty-two spayed bitches with urinary incontinence due to urethral sphincter incompetence, non-responsive to phenylpropanolamine administration, were treated by urethral submucosal injection of glutaraldehyde cross-linked collagen. Urinary incontinence resolved after a single injection in 19 of the bitches. Additional medication with phenylpropanolamine was necessary in five of these dogs, however. Of the 13 bitches that remained incontinent, the injections were repeated in nine. This resulted in a return to continence in five dogs, although two of these required additional medication for complete continence. The cure rate due to collagen injections alone is 53 per cent (17 of the 32 cases). A total of 41 injections were performed and no postoperative complications were observed.     

Gonadectomy in immature dogs: effects on skeletal, physical, and behavioral development

In a 15-month study, the effects of prepubertal gonadectomy on skeletal growth, weight gain, food intake, body fat, secondary sex characteristics, and behavioral development were investigated in 32 mixed-breed dogs. Male and female pups from 5 litters were randomly allotted to 3 groups: group I, neuter at 7 weeks (n = 14); group II, neuter at 7 months (n = 8); and group III, sexually intact dogs (n = 10). Growth plate closure was delayed (group I vs group III; P less than 0.000001; group II vs group III, P less than 0.000001) in all neutered dogs, as compared with sexually intact dogs. Growth plate closure was delayed longer (group I vs group II, P less than 0.000045) in dogs neutered at 7 weeks old, compared with dogs neutered at 7 months old. The rate of growth was unaffected by gonadectomy, but the extended growth period resulted in greater final radial/ulnar length in all male dogs and bitches neutered at 7 weeks. Gonadectomy did not influence food intake, weight gain, or back-fat depth. Penile development was immature in the adult group-I males (mean +/- SEM diameter of pars glandis = 11.1 +/- 1.0 mm), compared with adult group-II (16.3 +/- 0.5 mm) and group-III (21.0 +/- 2.2 mm) males. Subjectively, the prepuce and os penis of the group-I males were immature, compared with those of group-II and group-III males. Vulvar development in group-I and group-II bitches was less mature than vulvar development in the sexually intact bitches. Of 7 behavioral characteristics assessed, only general activity and excitability rated differently among treatment groups. All neutered dogs were judged to be more active (group I, P less than 0.004) than sexually intact dogs. Group-I males were judged to be more excitable (P less than 0.02) than group-III males. It was concluded that with respect to skeletal, physical, and behavioral development, the effect of neutering pups at 7 weeks old was similar to that of neutering pups at 7 months old.     

Urinary incontinence in the dog due to accidental vagino-ureteral fistulation during hysterectomy

The paper reports urinary incontinence in three bitches caused by vagino-ureteral fistulation during or soon after hysterectomy. Diagnostic radiological features are described and the possible causes are discussed.     

When to neuter dogs and cats: a survey of New York state veterinarians' practices and beliefs

Practicing veterinarians in small-animal or mixed-animal practice in New York state were surveyed about their beliefs and practices regarding the age at which dogs and cats should be neutered and their attitudes toward early neutering (at 4 months of age or younger). The majority of veterinarians routinely recommended neutering for all client animals (70.6%) and supported the routine neutering of shelter animals before adoption (90.3%). More veterinarians in this study reported at least one perceived benefit (91.3%) for early neutering than reported at least one perceived risk (84.4%). Veterinarians with experience neutering early were less likely to believe that the procedure was associated with one or more risks.     

Prostatopexy as a treatment for urethral sphincter mechanism incompetence in male dogs

OBJECTIVES: The incidence of urinary incontinence due to urethral sphincter mechanism incompetence (USMI) in male dogs is relatively rare compared with the incidence in bitches, but the medical management of USMI in male dogs is less rewarding than in bitches. Attempts have been made to manage this condition surgically using either urethral bulking agents such as Teflon or by relocating the intrapelvic bladder neck to an intra-abdominal position by vas deferentopexy. This paper reports the response to prostatopexy in male dogs with USMI. METHODS: The response to prostatopexy was determined in nine severely incontinent male dogs with USMI that were followed up for periods ranging from 10 months to five years (mean 2.3 years). RESULTS: One dog was cured, four were improved, and no improvement in the frequency or degree of urinary incontinence occurred in the remaining four animals. No complications were seen in any of the dogs. CLINICAL SIGNIFICANCE: Prostatopexy may provide a further method of treating male dogs with USMI that do not respond to medical therapy.     

Clinical and radiographic findings compared with urodynamic findings in neutered female dogs with refractory urinary incontinence.

Possible correlations were investigated between the clinical and urodynamic findings in 77 neutered female dogs with urinary incontinence refractory to standard medical management. The clinical data used in the analysis were age, bodyweight, breed, the characteristics of the dribbling of urine and whether it developed before or after neutering, the type of response to previous treatments, signs of polyuria/polydipsia, and the results of urinalysis and culture. In 50 of the dogs, a standardised contrast radiographic examination was made to locate the neck of the bladder and to assess the morphology of the bladder. These findings were analysed for their correlation with the results of multichannel urethral pressure profilometry and diuresis cysto-urethrometry. Logistic regression analysis revealed that neither the clinical nor the radiographic findings could predict any of the abnormal urodynamic findings. Functional abnormalities of the bladder, such as a low compliance, detrusor instability, or a low bladder capacity may therefore be particularly difficult to detect in dogs with urinary incontinence.     

Occurrence of mammary neoplasms in bitches in relation to breed, age, tumour type, and geographical region from which reported

Of 2075 mammary neoplasms in bitches reported by 14 veterinary schools in the United States and Canada, 1187 were histologically malignant, 557 were benign, and 331 were in the 'malignancy not determined' category. There were 12 breeds at significantly high risk for one or more of the major mammary tumour types; 7 of the 12 were hunting breeds. Mixed breeds were at low risk for all tumour types and categories, and collies were at low risk for benign neoplasms. Neutered bitches were only one-third as likely to have neoplasms as were entire bitches. There was no clear difference in distribution of the various tumour types in relation to age at first diagnosis. Among the four geographical regions studied separately, there were more similarities than differences in the rates of mammary neoplasms, especially when adenocarcinomas and malignant mixed mammary tumours were combined for analyses. There was, however, a marked excess of benign neoplasms in the south and west of North America.     

Vaginal position and length in the bitch: relationship to spaying and urinary incontinence

A study was undertaken to determine if the vagina might be a suitable site for the measurement of intra-abdominal pressure during cystometry in the bitch. The position of the cranial vagina and vaginal length were measured radiographically and the effects of spaying and urinary incontinence on these variables were evaluated in 30 continent and 30 incontinent bitches. The study used retrograde vaginourethrograms which had been obtained from animals used in a previous study. The cranial vagina was intra-abdominal on 36 of the vaginourethrograms, being least commonly intra-abdominal in incontinent bitches (11/30). Vaginal position was related linearly to vaginal length and continence status (P < 0.01), while its length was related to bodyweight (P < 0.01). Allowing for bodyweight, neutered animals had significantly shorter vaginas than entire bitches (P < 0.01). Measurement of intra-abdominal pressure with concomitant measurement of intravesical pressure is essential if accurate assessment of detrusor pressure is to be determined during cystometry. The vagina is unlikely to be a useful location from which to measure intra-abdominal pressure since any pressure-measuring catheter inserted into it may fall outside the abdominal pressure zone. This is particularly true of neutered and/or incontinent bitches, the groups in which urodynamic investigations of urinary incontinence are most frequently indicated.     

An evaluation of positive contrast vaginourethrography as a diagnostic aid in the bitch

The contribution of vagino-urethrography to the diagnosis of disorders of the lower urogenital tract in 123 bitches was evaluated. It was found to be particularly valuable in animals with urinary incontinence, vaginal discharge, dysuria and physical vaginal abnormalities. Determination of vaginal volume in 69 bitches has enabled a dosage of contrast medium to be suggested.     

Estrogens metabolism associated with polymorphisms: influence of COMT G482a genotype on age at onset of canine mammary tumors

Catechol-O-methyltransferase (COMT) is an important enzyme participating in inactivation of carcinogenic oestrogen metabolites. In humans there is a single nucleotide polymorphism in COMT gene (COMT val158met) that has been associated with an increased risk for developing breast cancer. In dogs, there is a single nucleotide polymorphism in COMT gene (G482A), but its relation with mammary carcinogenesis has never been investigated. The aim of this study was to focus on the evaluation of such polymorphism as a risk factor for the development of mammary tumors in bitches and on the analysis of its relationship with some clinicopathologic features (dog's age and weight, number and histologic type of the lesions, lymph node metastasis) of canine mammary neoplasms. A case-control study was conducted analyzing 90 bitches with mammary tumors and 84 bitches without evidence of neoplastic disease. The COMT G482A polymorphism was analyzed by PCR-RFLP. We found a protective effect of the polymorphism in age of onset of mammary tumors, although we could not establish a significant association between COMT genotype and other clinicopathologic parameters nor with mammary tumor risk overall. Animals carrying the variant allele have a threefold likelihood of developing mammary tumors after 9 years of age in comparison with noncarriers. The Kaplan-Meier method revealed significant differences in the waiting time for onset of malignant disease for A allele carrier (12.46 years) and noncarrier (11.13 years) animals. This investigation constitutes the first case-control study designed to assess the relationship between polymorphic genes and mammary tumor risk in dogs. Our results point to the combined effect of COMT genotype with other genetic and/or environmental risk factors as important key factors for mammary tumor etiopathogenesis.     

Canine bacteruria

Urine from 237 dogs submitted for euthanasia was collected directly by needle aspiration from the urinary bladder. The bacteriological findings were correlated with the sex and age of the dogs. E. coli was the most frequent species found. The overall incidence of bladder infection was 6–2% for males and 26–6% for females. Bladder infection can be categorized on the basis of occurrence in either very young or in older dogs. The infection incidence increased linearly in bitches older than 4 years, ending at a 50% frequency in those more than 10 years old. Pyometra frequency also increased after 4 years of age and this pattern may indicate a common causative factor for urinary tract infection and pyometra. This investigation shows that subclinical urinary tract infection is common in dogs and is related to age in bitches.