Dogs: Health, Disease and Physiology- Reproductive and urinary system, including incontinence


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Spaying-related urinary incontinence and oestrogen therapy in the bitch

Risk factors affecting spay-related incontinence, its prevalence in bitches, and effectiveness of treatment with oestrogen therapy

source: Veronesi MC, Rota A, Battocchio M, Faustini M, and Mollo A.
Acta Veterinaria Hungarica vol 57 no 1, March 2009
starts p171, 12 pages long

Spaying has been linked to urinary incontinence in bitches, but not enough is known about why this can happen. Studying a large sample of spayed bitches can help clarify the issues. The sample in this study comprised 750 bitches which had undergone either ovariectomy or ovariohysterectomy, of which 5% were affected by urinary incontinence. Incontinence did not appear to be linked to the type of surgery, though other factors were found to be important. Larger bitches were more likely to be affected, and this was true whether they were mongrels or pedigree dogs. Affected bitches also tended to weigh more than 20 kg when they were operated on. There also appears to be a link between tail docking and spay-related incontinence. Bitches that were older when they were operated on appeared to show signs of spay-related incontince earlier than those operated on at a younger age. Oestrogen therapy can help affected bitches, and does not appear to have harmful side effects, though owners and vets need to co-operate for it to be effective.


Exploring mechanisms of sex differences in longevity: lifetime ovary exposure and exceptional longevity in dogs

Links between longevity and longer retention of ovaries in Rottweiler bitches

source: David J Waters, Seema S Kengeri, Beth Clever, Julie A Booth, Aimee H Maras, Deborah L Schlittler and Michael G Hayek
Aging Cell vol 8 no 6, December 2009
starts p752, 3 pages long

Studying pet dogs can help in understanding sex differences in human longevity, and it is worth looking at pet dogs to see whether retaining ovaries is linked to longevity. A high proportion of pet dogs have their ovaries removed at varying ages, while young women tend not to have ovaries removed, so it is easier to study dogs to work out the effects of removal at a young age on longevity in mammals. A database was set up for the medical histories of 119 of the oldest Rottweilers (both male and female) in North America. Questionnaires and telephone interviews with vets and owners were used to collect data on the medical history, cause of and age at death. The bitches were spayed, with removal of the ovaries (ovariectomy) carried out at different times in their lives. Rottweilers which survived to age 13 were compared with a group of Rottweilers from the same area which died between 8.0 and 10.8 years, which is more normal for the breed, which has an average expectancy of living to 9.4 years. American Kennel Club records were used to check the date of birth.

More bitches than dogs survived to age 13, though bitches that had had their ovaries removed in the first four years of their lives were no more likely to achieve longevity than were males. In contrast, females who kept their ovaries for over four years were more than three times likely than males to achieve longevity. We looked in depth at 83 exceptionally long-lived bitches, and 100 bitches with more usual longevity and asked whether the length of time bitches kept their ovaries during the first eight years of their lives was linked to better chances of exceptional longevity. We found that bitches which kept their ovaries the longest (between 6.1 and 8.0 years) were 3.2 times more likely to achieve exceptionally long lives than bitches which kept their ovaries for the shortest period. This link between longevity and ovaries was evident even after taking into account other characteristics with a possible influence on longevity, like weight, height, and the age at death of the bitch's mother. The benefits of intact ovaries do not appear to be explained by ovaries protecting bitches against a particular disease. The main cause of death in Rottweilers with normal longevity was cancer, and when we excluded cancer deaths, there was still a strong link between exceptional longevity and retaining ovaries; bitches retaining their ovaries up to the age of seven had a ninefold better chance of achieving exceptionally long lives than bitches retaining their ovaries for the shortest period of time.

This study is backed by results from another group of rottweilers that we have studied, 237 female Rottweilers who died at between 1.3 and 12.9 years. Those retaining their ovaries for the first 4.5 years of their lives showed a 37% lower mortality than bitches undergoing ovariectomy before they were 4.5 years old. We focused on one breed, and took into account how long bitches retained their ovaries rather than simply classing dogs as spayed or entire, in order to pinpoint the role of ovaries in aging, including the importance of how long ovaries were retained. Our results show both that bitches are more likely than dogs to achieve exceptional longevity, and that longevity is linked to the length of time a bitch retains her ovaries.


Incidence of cryptorchidism in dogs and cats

Cats less likely to suffer cryptorchidism than dogs

source: D. Yates el al
Veterinary Record vol 152 no 16, April 19 2003
starts p502, 3 pages long

Testes start to descend after mid-gestation, and, in the case of dogs, they usually travel through the inguinal ring by the time a pup is five days old, being fully descended when a pup is from six to eight-weeks' old. The inguinal ring is usually partially closed by the time a dog is six months' old, preventing migration of any undescended testicles. When testicles to not descend in this way, the result is usually cryptorchidism, with the testicle either hidden in the abdomen, or in the inguinal region. This may affect one or both testicles. There have been different estimates of the incidence of cryptorchidism in cats and dogs. Two studies give estimates for cats of 1.7% and 3.8%, while other studies have given figures for dogs of between 0.8% and 9.7%. Dogs can inherit this condition as a recessive trait, and it has been linked to a higher incidence of testicular cancer. Castration may be carried out both to prevent affected pets from breeding, and to prevent or treat cancer.

This study examines the incidence of cryptochidism in cats and dogs castrated at an English RSPCA hospital from March 1997 to September 2001. Awareness of the owner that their pet might be cryptorchid could affect results, so this was recorded. There were 3,518 dogs castrated in this period, 240, or 6.8%, of which were cryptorchid. Owners believed 129 of them to be cryptorchid, and only 111 were found to be so at surgery. This gives a true incidence of from 3.3% and 6.8% for these dogs. Right-sided inguinal testicles were most commonly found, followed by right-sided abdominal cryptorchidism. There were 3,806 cats castrated, with 50 of them (1.3%) cryptorchid, with owners of 11 cats, or 22%, knowing about the condition in their cats. Inguinal testicles, both left and right side, were most common among the cats, with abdominal and bilateral cyptorchidism being uncommon.

Pedigree dogs accounted for 186 or 77.5% of the dogs, with certain breeds, Chihuahuas, boxers and German shepherds especially likely to be at risk. Other breeds that were overrepresented were Yorkshire and Staffordshire bull terriers, shih tzus, and miniature poodles. Border collies appeared to have a lower than average risk, with 5 of 172 showing this condition, or 2.9%, though the numbers may be too small to be significant. There were not enough dogs for some breeds to make useful estimates. Other studies have mentioned chihauhas, boxers, miniature poodles, and Yorkshire terriers as prone to cryptorchidism. The local population of Staffordshire bull terriers, German Shepherds and shih tzus may have had special characteristics due to inbreeding, or local breed distribution.

Cats showed an incidence of cryptorchidism of between 1% and 1.3%, which was not as high as in other studies where the proportion of pedigree cats was higher. Left testicles were affected in the cases of 29 cats and right testicles in the cases of 27 cats. Owners of only 22% of the affected cats were aware that their cats were cryptorchid, while the percentage for dogs was higher, at 53.8%. The lower level of awareness among cat owners may have been because their cats had not previously visited the clinic.


Urinary tract infections in small animals: therapeutic options and management of problem cases

Treating problem UTIs in cats and dogs

source: Mark Dunning and Jo Stonehewer
In Practice vol 24 no 9, October 2002
starts p 518, 7 pages long

The main way of treating urinary tract infections (UTIs) in cats and dogs is to use conventional antimicrobials, especially injections followed by oral treatments. The article provides a detailed discussion of selection of antibiotics and recommended amounts. Cephalexin or amoxycillin may be useful, but culture and sensitivity is indicated, and this should always be the case where infection recurs. The therapy should always be completed, even if the cat or dog appears to have recovered.

Underlying causes have to be investigated if the infection recurs or does not respond to antimicrobials. Low dose antibacterials may help if an underlying cause cannot be found. Infections may recur for a number of reasons, such as drug resistance, too low a dosage, factors that affect how the cat or dog absorbs the drug, or deep-seated infections. Reinfections can also occur for a number of reasons such as urine retention, or urethral disease.

Novel therapies include oestrogen replacement therapy (which can help women), prophylactic Lactobacillus administration (effective in mice), and regular consumption of cranberry juice, which is effective in reducing infections in some humans, though there is only anecdotal evidence that it may be effective in veterinary species. DO,HD


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

New sustained-release formulation helps some incontinent bitches that did not previously respond to treatment

source: N.J. Bacon et al
Veterinary Record vol 151 no 13, September 28 2002
starts p373, 4 pages long

Most adult bitches with urinary incontinence suffer from a faulty urethral sphincter mechanism. They tend to leak, especially when they are lying down. Spayed bitches, and medium-to large breeds are especially affected, as are bitches in middle age. Obesity and neutering are among predisposing factors. The usual treatment has been to prescribe drugs that help boost urethral resistance, like phenylpropanolamine hydrochloride, which is prescribed as Propalin in the UK.

This study assessed the effect of a sustained-release formulation of phenylpropanolamine hydrochloride, in combination with diphanylpyraline hydrochloride, an anti-histamine. The subjects were 11 bitches with urinary sphincter incompetence which had not responded to phenylpropanolamine hydrochloride in the form of an oral solution with immediate release. The study involved a review of cases of bitches seen from 1995 to 1999. Four cases involved weimeraners, and two involved boxers. Eight of the 11 bitches had initially responded well to the immediate-release product, but had then developed problems. Six of the 11 bitches improved to the extent of full continence using the sustained-release product, and two of these six remained continent after the treatment ended. Two bitches improved with the sustained-release formulation, without becoming fully continent, and three bitches did not show an improvement. The article also discusses reasons why the sustained-release product was effective in some cases when the immediate-release product was not.


Treatment of bitches with acquired urinary incontinence with oestriol

European study of oestriol as a treatment for incontinent bitches

source: P.J.J. Mandigers and T. Nell
Veterinary Record December 22 2001 vol 149 no25, December 22 2001

A study using 129 incontinent bitches from 48 vets in four European countries has found that 83% of the bitches treated with oestriol tablets had improved after 42 days. Incontinence occurs in between 11% and 20% of spayed bitches, and has been linked to lack of oestrogen, though the role that oestrogen plays is unclear. Bladder storage function and urethral closure can be improved with oestriol treatment, partly through an increase in the urethra's functional length. Some oestrogens have been links to bone marrow depletion, and reports of this side effect concern synthetic oestrogen. Oestriol that occurs naturally has been tested on dogs, and no significant haematological changes has been found.

The bitches in this study came from the Netherlands, Germany, France and Belgium, and were at least a year old, with no incontinence problems when they were under a year old. Spayed bitches accounted for 124 of the total. There was a range of breeds, with the most numerous being boxers, accounting for 21.8% of the sample, and dobermanns, accounting for 8.4%.

Twelve bitches did not respond to initial treatment, and did not complete the course. Continence was achieved in 61% of the bitches, an improvement was achieved for 24%, while 14% of the bitches showed no change, and 3% worsened. Dose rate schedules varied on an individual basis, and were unrelated to the severity of the bitches' incontinence or their bodyweight. Some of the bitches had side effects, such as swollen teats, especially at the start of the treatment. Short-acting oestriol appears to be a safer treatment than long-acting oestrogens, though there may be a risk of pyometra if this treatment is used on intact bitches. This treatment appears to be successful as well as safe, though more research is needed.

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When should bitches be neutered?

Debate between vets on the timing of neutering of bitches

source: Veterinary Record vol 148 no 16, April 21 2001
starts p 491, 3 pages long

The BSAVA congress held in April 2001 has discussed neutering of bitches. University of Wiscosin's Dale Bjorling argues that pre-pubertal neutering can be safe. US animal shelters are concerned about large numbers of strays euthanased annually, and want neutering to be carried out at between eight and 16 weeks. Some studies following dogs in their first year indicate that this may be safe. Peter Holt, from Bristol University, England, in contrast, is more concerned about health risks from early spaying. He argues that incontinent bitches should not be spayed at under six months, since incontinence is often resolved when a bitch has had her first season. He also cites a study showing bitches were almost four times as likely to be incontinent ten years afterwards if they were spayed before their first season, compared with bitches spayed after their first season.

Some breeds, like Old English Sheepdogs and Dobermanns, are especially at risk from incontinence. Infantile vulva and juvenile vaginitis could also be problems for bitches spayed early. Data on the extent to which pre-pubertal spaying may reduce risks from mammary tumours are inconclusive, and further research is needed, he argues. Meanwhile, small animal specialist, David Coffey, opposes spaying, arguing that owners should control dogs, or not keep them.


Associations between age, parity, hormonal therapy and breed, and pyometra in Finnish dogs

Study of pyometra in dogs in Finland

source: M. Niskanen and M.V. Thrusfield
Veterinary Record vol 143 no 18, October 31 1998
starts p493, 6 pages long

Pyometra is pus in the womb, and is a common affliction of entire bitches, which can be fatal, though treatment has improved survival rates. Other studies have found that bitches may be more vulnerable to pyometra if they are given oestrogen at a time when they have high levels of progesterone. Bitches are most likely to suffer this condition when they are between six and eight years old, though younger bitches can also be afflicted, and this could be linked to their being given oestrogen to avoid pregnancy. Other studies have found some possible links between breed and vulnerability, with Collies and Chow Chows among vulnerable breeds.

This Finnish study took place in a country where spaying is uncommon, and is based on 953 bitches with the condition, and 10,660 unmatched controls. A total of 219 breeds were recorded, and pyometra affected 112 of them. The mean age of affected bitches was 8.5 years, and median age 9.0 years. Bitches that had never had puppies (nulliparous) were more likely to be affected, There were not enough data to assess fully the impact of progestin therapy, though there is some evidence of a link between oestrogen therapy and pyometra in younger dogs. Breeds found to be at risk from this condition, according to this Finnish study include Golden Retrievers, Miniature Schnauzers, Irish Terriers, Rough St Bernards, Leonbergers, Airedale Terriers, Cavalier King Charles Spaniels, Rough Collies and Rottweilers, while Wire Haired Dachshunds and mongrels appear to have a low risk of suffering the condition.


Urinary incontinence in spayed bitches. Part 1: significance, clinical features and aetiopathology

Risk factors and characteristics of incontinence affecting spayed bitches

source: S. Arnold European
Journal of Companion Animal Practice, vol IX(2) October 1999
starts p125, 5 pages long

Spayed bitches have had their ovaries, and normally their uterus removed. The risk of mammary tumours drops to some 0.5%, though side effects can include poorer coat quality, weight gain, and incontinence. Bitches that become incontinent usually do so within three years of surgery, though they may not be affected until some years later. Incontinence tends to affect bitches when they are asleep.

Larger dogs are more vulnerable than smaller dogs. Boxers appear to be especially vulnerable, Dobermanns and Giant Schnauzers appear to have a higher than average risk, while one study reported no cases among Bernese Mountain Dogs and Spaniels. The removal of the uterus does not appear to increase risk significantly. An English study reported incontinence in three of 14 bitches spayed before puberty, and only one case in 180 bitches spayed after puberty, or 21% compared with 0.5%. However, a US study reported 12 of 73 bitches spayed before puberty becoming incontinent, or 16%, compared with six of 23 spayed after puberty, or 26%. Oestrogen deficiency may contribute to the problem, since many bitches can be successfully treated using oestrogen therapy. Oestrogen deficiency is not the only cause, however; around 25% of affected bitches do not respond to oestrogen, and intact bitches treated with gestagens, which lower their oestrogen levels, are unaffected. The problem appears to be linked to urethral sphincter incompetence, and there seems to be a link between urethral closure and ovarian function.


Urinary incontinence in spayed bitches. Part 2: diagnosis and treatment

Treating and diagnosing incontinence in spayed bitches

source: S. Arnold
European Journal of Companion Animal Practice, vol IX(2) October 1999
starts p130, 4 pages long

The most common reason for bitches to be incontinent is an incompetent sphincter as a result of spaying, though there may be other causes such as bacterial cystitis, or congenital defects. Measurement of urethral pressure closure is a useful diagnostic tool, though it is expensive.

Alpha-adrenergic drugs such as Ephedrin or Phenylpropanolamine can be used to treat the problem by increasing urethral closure pressure through stimulating alpha-receptors in the wall of the urethra. Some 75% of affected bitches become continent with this treatment, with 25% showing some improvement. Raised arterial blood pressure may occur with some 10% of bitches given these drugs, and they are not recommended for dogs with glaucoma, cardia arrhythmia, or hypertension prior to treatment. Oestrogens are an alternative treatment, though oestrogen treatment may be linked to generalised bone marrow depression.

Teflon paste injections have been used successfully, though there have been complications such as rejection. Collagen injections have had a similar success rate, of some 75%, including dogs having second injections. Collagen does not involve the complications seen with Teflon injections. Collagen treatment is better than Teflon treatment, but it is too early to say whether Collagen treatment is risk free, and it is an expensive treatment.