Tag Archives: desexing

08/17/17
dog bites who gets bitten by which dogs

Which people get bitten by which dogs?

dog bites who gets bitten by which dogs

Dog bites are one of my niche areas of interest, so I when I came across this 2008 bite study, I was keen to read. The overall objective of this study was to work out the similarities between biting dogs and people injured by them, to be able to understand dog bites in such a way that public health could be influenced.

And dog bites are a bit public health problem. In 1986, dog bites were among the top 12 causes of nonfatal injury in the US. in 2005, an estimated 800 000 dog bites needed medical attention in the US. On average, 18 people die per year in the US as a result of dog bites. The number of reported dog bites is going up each year, suggesting this is a growing problem. (Though, personally, I think the number is probably going up to growing intolerance of dog bites in the community.)

So this study was a retrospective cohort study, looking at data for incidents that occurred in the 2002/2003 financial year in Multonomah County, Oregon. In this study period, 636 dog bites were reported to Animal Control Services, while there were 47, 526 dogs licensed in the county.

What followed was a whole lot of number crunching that I don’t entirely understand. From where I’m sitting, it looks like a fair bit of extrapolation went into the figures seen below, but without sampling every single household for dogs and other aspects, I’m not sure if there’s a much better way to go about it.

But regardless, onto the results…

The Biters

From this study, dogs were more likely to bite if:

  • They were of particular types (terrier, working, herding, and nonsporting),
  • They were sexually intact and male, and
  • They were purebred.

Instead of using dog breed, they used dog type, to try to avoid problems in identification. (For example, the general public has a hard time determining between a border collie and coolie, but they do know it’s some kind of herding dog.) The breeds listed above were more likely to bite than dogs that were sporting breeds, hounds, non-AKC breeds, and toy breeds. This study suggested that the dogs in the ‘problematic’ groups have instincts they’re likely to revert to if left untrained (which doesn’t ring true to me for the nonsporting group), and threat they are a ‘size and strength’ to cause damage (which doesn’t seem right considering the size of most terriers).

More intact male dogs bit than any other neuter/sex ratio. This is different to other studies I’ve reviewed.

It’s really perplexing that purebred dogs were more likely to bite in this study. I guess this goes to the breeding practices, but it’s curious to think that crossbreed dogs, presumably bred by people who are ‘accidental’ breeders, end up with less-bitey temperaments. Something for breeders to think about. While these dog factors existed, there was also a range of other elements to a dog bite.

“Factors that determine whether a dog-human interaction will result in a bite are complex and involve characteristics of the dog, the injured person, the owner, and the dog’s environment.”

The Owners of the Biters

Biting dogs were more likely than nonbiting dogs to live in neighbourhoods where the residents’ median incomes were less than the county median income value. If controlling for breed category and controlling for sex, “dogs living in census block groups that had incomes less than the county median were 1.5 times as likely to be reported as a biting dog than reported as a nonbiting dog”. When dog owner data was compared to population density, percentage sex by age, percentage nonwhite race, and percentage without high school diploma, there was still not an association with biting. It was correlated just with income!

So what’s going on here? What’s different in areas were less income? Less money spent on training? On fences? Different attitudes towards child raising? This study suggests that people in these areas may be inclined to select particular breeds (i.e. especially those with reputations for aggressive behaviours). (Though this study didn’t look at whether some breeds were more likely to be owned by different groups.) They also suggest that low income areas may socialise their dogs in a different way, and therefore change the bite potential of the dog, or perhaps they’re not trained or supervised in a way that minimises dog bite risk.

“In another study examining dog bite injuries in St Louis, Mo, bite injuries occurring in low income areas were attributed to large numbers of children playing outdoors, few homes with adequate fencing, poor dog control, and a high proportion of large-breed dogs owned for protective purposes.”

As a personal comment, in my experience, crossbreed large dogs are cheaper than small dogs or purebred dogs. This means low income areas are likely to own bigger dogs, and we know bigger dogs are more likely to have their bites reported. While studies of the past have looked at breed and sex-neuter status, this study reveals a new area for further research: block group income levels.

But there’s more: It’s not just about the dog and who owns it, but also where the bite took place.

The Place of the Bites

Dog bites occurred:

  • 35.1% of bites happened in the dog’s home or yard.
  • 23.4% of bites happened in ‘neutral territory’
  • 17% of bites happened in dog/victim household (i.e. the parties lived together)
  • 10.1% of bites happened in household of victim (not dog’s place)
  • 7.1% bites unknown place
  • 3.8% at “place of employment” – e.g. vet clinic, rooming facility, MCAC
  • 3.6% “Neighbour’s Property” (which could be grouped with the 35.1%)

This reinstates the idea that parents need to be extra vigilant when they are visiting houses with dogs.

Other Statistics

Other tid bits of interest:

  • Boys and girls aged 5-9 years had highest rate of injury, boys a bit higher (but not significantly so).
  • Of the 636 biting dogs, 49% had a license number. There are some estimates that less than half of all dogs are registered. (I really wonder what this kind of statistic would look like in Australia.)
  • 36% of dog bite victims didn’t know the dog that bit them. (The largest portion.)
  • But: Among children, 46% were bitten by the family dog.
  • More dog bites in summer months.
  • No significant difference between male and females being bitten.

Limitations

Like all studies, there are a number of problems. In this study, the results are limited by.

  • Not all dog bites will be reported. Dog bites are a reportable incident in Oregon, but the records are incomplete. There’s a problem with recording of dog bites. A previous study, referenced in this one, suggested that only 17% of bites are reported to any authority. (And while this may be the case, how else should we be analysing dog bites except through dog bite records? This model is probably the best we have.)
  • We know members of the public are not very good at reporting dog bites by breeds.
  • Dog license data can only be used as an estimate of breed-populations – especially because we know perhaps only half of all dogs are registered. Further, if owners of some breeds are less likely to license their dogs, the breed specific bite rates are further skewed.
  • When a large-breed bites, that bite is more likely to be reported and more likely to need medical care, meaning that there is a reporting bias that can increase the number of these dogs seemingly involved in incidents.

 

Conclusion

This study made recommendations for reducing dog bites:

  • Combined approaches from human medical communities, veterinary communities, and animal control to help foster healthy relationships between people and pets.
  • Focus on low income neighbourhoods.
  • Paediatricians to counsel parents (dog owning and not) on dog safety during routine medical visits.
  • Low cost spay neuter.
  • Education programs (perhaps through animal control).

“Innate tendencies dictated by breed, sex-neuter status, and size play a role in the potential of a dog to bite, but owners are ultimately responsible for their dogs’ action[,]… and need to make every effort to minimisze their dogs’ bite potential through obedience training; neutering; and supervision, especially around children.”

Source:

Shuler, CM, DeBess, EE, Lapidus, JA, and Hedberg, K 2008, “Canine and human factors related to dog bite injuries”, JAVMA, vol 232, no 4.

06/14/16

New Research on Early Neutered German Shepherds and Joint Disorders

New Research on Joint Disorders in German Shepherds

 

ResearchBlogging.orgIt’s very exciting how there is growing research on desexing in dogs, including age of neutering, and its implications on health. In the past, I have blogged on how desexing in German Shepherds is linked to reactivity. The latest study, published last month, looks at bone disorders, cancers, urinary incontinence, and pyometra in German Shepherds.

Many of the arguments for desexing dogs has been around population control instead of health matters – but obviously health does matter. We want dogs to be healthy.

This retrospective study looked at the health of 1170 German Shepherds. It included the analysis of vet records over 14.5 years (2000-2014). For each incidence of disease, the dogs’ records were followed for eight years, except in the case of mammary cancer, which was followed for eleven years. The data on the incidence of joint disorders and cancers in the German Shepherds was compared beside their sexes, and their neuter-age.

 

Joint Disorders

The biggest problem with early aged desexing in this breed, according to this study, is an increased risk of joint disorders. For example:

  • 6.6% of intact males had one or more joint disorders, but for dogs that were desexed before 6 months, 20.8% had one or more joint disorder. So joint disorder incidence was three times greater in dogs desexed before 6 months than intact dogs. For dogs that were desexed between 6-12 months, the incidence of at least one bone disorder was 16.4%.
  • Similarly, 5.1% of intact female had one or more joint disorders, but for bitches that were desexed before 6 months the incidence was 12.5%, and for bitches that were desexed at 6-11 months the incidence was 17%.
  • Of the joint disorders considered, Cranial Cruciate Ligament Tear was most highly correlated with early desexing. In entire dogs, hip dysplasia was most commonly seen.
  • For desexed dogs, rates of hip and elbow dyplasia was greater than entire dogs, but this difference was not statistically significant.
  • There was no difference between the body condition scores (i.e. fatness) between entire and neutered populations – so it’s not obesity that has caused these problems.

 

But why do German Shepherds have an increased incidence of joint disorders when they’re desexed before one year of age?

If a dog is desexed before one year of age, the growth plates of the dog are unlikely to have closed. (That is, the bones are still growing.) With the removal of hormone cues through the removal of gonads, the bones are likely to grow longer than they ‘should’, which disrupts joint alignment. This disruption leads to joint disorders such as those found in this and similar studies.

However, this research did not just look at bone disorders.

 

Cancer

Unlike previous studies on cancer in other breeds, there was no statistically significant differences between neutered and entire animals. However, in terms of mammary cancer (which was only considered in bitches), 4% of intact females got mammary cancer, but <1% got mammary cancer if desexed before one year of age. The paper notes that mammary cancer seems to be uncommon in German Shepherds and refers to a recent meta-analysis that found the protective factor of neutering in terms of mammary cancer to be weak.

In terms of other cancers there was no significant differences. (My own note though: This study found that only 14% of the entire bitches were used for breeding. Lactating is a protective factor against mammary cancer, so I would suspect that if more of these bitches were breeding bitches, the rate of mammary cancer may have been lower again.)

 

Bitch-Specific Conditions

Urinary incontinence was seen at a rate of 7% in neutered bitches, but was not seen at all with entire bitches. (Urinary incontinence was not considered in males.) The mean age of onset of urinary incontinence in early neutered females was 5.2 years.

Pyometra in intact females was seen as a rate of 2.5%.

How does this compare to other research?

It’s important to note that this new data adds to our growing understanding of desexing implications. This study references:

  • A 2014 study saw that Golden Retrievers and Labrador Retrivers were, generally, more likely to have a joint disorder the earlier they were desexed.
  • A 2013 study saw that Golden Retrievers that were early desexed had more hip dysplasia, cranial cruciate ligament tears, and lymphosarcoma. Desexing, regardless of time, increased the rate of at least one cancer by 3-4 times.
  • Another 2013 study found that, in Vizslas, the incidence of cancers was high in desexed dogs (except mammary cancer – where incidence was low).
  • Another 2013 study found that neutered male and female dogs were more likely to die of cancer than intact dogs.
  • A 2011 study that found that, in several breeds, the incidence of mast cell tumours was four times greater in spayed females as opposed to intact.
  • A 2008 study that saw that desexing before 12 months of age saw joint disorders (such as hip dysplasia, cranial cruciate ligament tears, and elbow dysplasia) occuring at 2-3 times higher rates than in intact dogs.
  • A 2007 study linked early desexing with risk factors for cranial cruciate ligament tears.
  • A 1999 study found that cardiac hemangiosarcoma was four times more common in spayed females than those intact.
  • A 1998 study, looking at several breeds, saw that osteosarcoma was two times more likely in neutered dog compared to intact dogs.
  • A 1988 study that found that splenic hemangiosarcoma was two times more likely in spayed females than intact.

The researchers involved with this study have been adding great data to the neutering/spaying discussion. They have previously published articles on Labrador vs Golden Retrievers and Golden Retrievers, and these articles had similar findings. (Though German Shepherds did not seem to be as cancer prone as the Golden Retrievers.) As all these studies are using vet clinic data, it is not known how similar or dissimilar the strains/lines are – so the sample could be genetically diverse despite being the same breed.

But it seems that, for German Shepherds, it is far better to wait until dogs are twelve months or older before desexing, if desexing is chosen at all. I’ll end on a quote from the paper:

As shown in this study, delaying neutering until the dog is at least a year of age appears to avoid the increase in risks of joint disorders is associated with neutering. This is a consideration for joint disease control that is immediately available.

 

Reference:
Hart, B., Hart, L., Thigpen, A., & Willits, N. (2016). Neutering of German Shepherd Dogs: associated joint disorders, cancers and urinary incontinence Veterinary Medicine and Science DOI: 10.1002/vms3.34

 

Further Reading:

Early Neutering Poses Health Risks for German Shepherd Dogs, Study Finds

A Link Between Desexing and Reactivity

Labs and Goldens: Goldens Get Cancer Better

Desexing: It’s bad for Vizslas, too

But Mammary Cancer!

Why would you NOT desex your dog?

06/24/15

My Say: Mandatory Desexing

(This is the last post in a four part series on dog and cat reforms in South Australia. See post one here, post two here, and post three here.)

Screen shot of the YourSAy website.The YourSay website invites submissions to a citizen’s jury. While we could discuss the validity of allowing (quote) “32 ordinary South Australians” to decide on whether various animal species should undergo the medical procedure of a gonadectomy… Unfortunately, this process has already been decided on, and hence we must make a submission according to this format.

When accessing the site, you will need to download a word document to make a submission. It is only on this document do we get the date that submissions are due in by: Friday 10th July 2015

This form also asks the question:

Last year in South Australia over 10,000 unwanted dogs and cats were put down.
The State Government recently announced some reforms to dog and cat laws.
What further measures can we introduce or trial to reduce the number of unwanted pets?

While the downloaded word document doesn’t explicitly mention desexing, the site does with the comment:

The government has also sought a specific verdict from the Jury on the matter of whether de-sexing should be mandatory.

The form also specifies that the your submission should not be more than two pages, and yet asks for examples to be provided… It’s an impossibility to provide ample compelling evidence in these narrow frames.

However, my response (which you are, as always, welcome to use in shaping your own) is below:

I am adamantly opposed to mandatory desexing. The reasons for this opposition are:

 

Mandatory desexing has not been shown to reduce the incidence of euthanasia in animal shelters. In areas where it has been implemented, often there is a subsequent increase in the number of animals entering the facility, as people are financially unable to desex their pets and, to avoid risk of prosecution, they choose to relinquish them. Internationally this affect has been seen Los Angeles and, more locally, in Western Australia. Mandatory desexing has actually been demonstrated to increase euthanasia, and therefore should not be an option for South Australia on this basis alone.

 

However, mandatory desexing is a move that is rejected by the Australasian Veterinary Association (AVA). The AVA represents veterinarians across Australia, and so it would be sensible for policy makers to develop legislation that corresponds with statements made by this peak body. Additionally, it is anticipated that veterinarians would be responsible for performing desexings (mandatory or otherwise), and so their support is crucial for successful implementation of mandatory desexing. Considering that veterinarians have significant financial gains to be made from such a policy, yet choose to reject it is, is an indicator of the lack-of-support for mandatory desexing.

 

Finally, and crucially, there is evidence that desexing in dogs can pose some health risks to animals. These risks include:

  • Increased incidence of some cancers (including mast cell tumours, hemangiosarcoma, lymphoma, osteosarcoma, and lymphosarcoma),
  • Higher incidence of joint disorders (including hip dysplasia and cranial crucial ligament tears), and
  • Increased incidence of behavioural problems (including reactivity, aggression, and anxiety, storm phobias).

Studies that indicate these problems have been published in peer-reviewed academic journals, illustrating that this is not ‘sensationalised’ content, but the results of real research on dog populations. Considering the available evidence, it seems immoral and contradictory to animal welfare goals to obligate pet owners to subject their animals to such risks.

 

As alternative means to reducing the number of unwanted pets, there are a number of approaches that could be trialled. The most obvious would be requiring improvements in reclaims. For many animals entering shelters, they have homes that want to get them home. Unfortunately, the large shelters in Australia are not proactive in listing impounded animals. This makes it difficult for owners to know where their pet is to bring them home. Further, if they do visit a facility to reclaim their pet, many times there are large fees that they are required to pay to get the impounded animal out. This is a barrier to individuals getting their pets home, while if they stay at the shelter they may be at risk of euthanasia. An additional barrier is poor opening times of this facility, meaning in many cases animals have to stay in the shelter longer due to their owner’s inability to access the facility. In summary, the procedure for individuals reclaiming animals needs to be improved by:

  • Impound facilities clearly listing all impounded animals online.
  • Legally enforceable guidelines regarding the scanning of microchips and the use of the information to find the owner.
  • Fees and charges for the release of impounded animals being reduced, waived, or available on a payment plan.
  • Impound facilities having opening times that make them highly accessible to the public.

 

Other changes that could be made at a shelter level to reduce euthanasia include:

  • Oreo’s Law – the requirement that animals are not euthanised if there is any individual or group who is willing to take them.
  • Mandated time for adoption – require facilities to offer all animals for adoption for a set period, perhaps 72 hours.

 

Finally, a big reason that animals end up in shelters is due to owner accommodation issues. This includes those who are renting, or fleeing their home due to violence.  If we deal with human issues, people will be more likely to retain their pets. Changes that encourage landlords to permit pets, and providing temporary accommodation that allow pets, are important to prevent animals being relinquished to shelters.

 

In summary, suggestions for reducing shelter euthanasia include:

  • Creating legislation that requires shelters to:
    • Do more to assist reclaims,
    • Allow adoptions for animals who have no choice but euthanasia, and
    • Allow all animals to be available for adoption for a minimum period of time.
  • And dealing with community issues surrounding owner accommodation issues.

 

Further reading:

“Just stop breeding until the pounds are empty”

Is desexing a cult?

Why would you NOT desex your dog???

Are you willing to be wrong about that?

 

 

 

02/18/15

But Mammary Cancer!

ResearchBlogging.org

A common justification for early neutering of bitches is that it protects against mammary neoplasia. However, many frequently cited references are over 40 years old, and this evidence has not been scrutinised with the benefit of recent developments in epidemiological methods and knowledge of potential confounders of the association between mammary masses and neutering, such as age, breed and treatment with synthetic derivatives of ovarian steroids.

One of the most frequently presented arguments for desexing is ‘mammary cancer’. It is commonly stated that desexing bitches reduces the risk of mammary cancer.

But as always, we must ask: What does the research say?

I love to answer questions like this, and so I have read quite a bit of research on mammary cancers in bitches. However, despite doing lots of reading, none of these research papers have made their way to my blog.

The reason? The research is very old and I am not compelled to review or examine such ancient research.

Why does old research matter? It’s easy to say that ‘biology doesn’t change’, and if it was so in the 1970s, then it must be so now. While that’s the case, our understanding on research methods and limitations is continuing to improve.

Regardless, even if we say that the research from the 1970s is as accurate as ever, compelling results are those that are replicated. While it’s nice to get one study that shows a link between mammary cancer and sex hormones, we need multiple studies with large sample sizes to prove this without doubt.

Using the studies considered in Beauvais et al’s 2012 systematic review, since the 1960s, there has been approximately fifteen (15) studies on mammary cancer in the bitch. That is, the last fifty-five (55) years, there has been one study on mammary cancer in dogs in ever four years. There are very few papers on mammary cancer, and those that do exist do not replicate past results.

So how old is the mammary cancer research? 

Beauvais et al.'s references in their systematic review on mammary tumours in bitches as affected by spaying.

Beauvais et al.’s references in their systematic review on mammary tumours in bitches as affected by spaying.

Again, if we use the studies considered in Beauvais et al’s 2012 systematic review, there were fifteen studies in all considered. Of those studies, only one (1) of those studies was completed in the last ten years. Further, eighty-six percent (86%) of the studies are more than fifteen (15) years old. So, basically: the research is old!

Nothing excites me like a review on literature. (You can imagine what I’m like at parties.) When I noticed a systematic review by Beauvais et al. on mammary cancer in dogs (published in 2012), I was excited as I hoped I would find some more recent studies. The study did not fulfil my hopes, and so I am left believing that more recent research simply doesn’t exist.

Interestingly, the researchers made comment that a systematic review (like they produced) had seemingly not been covered before. A systematic review is used to evaluate the strength of evidence and to consider bias. This type of research is common in medical literature, but not so much in veterinary.

The researchers considered the quality of the research for thirteen reports and found “Nine were judged to have a high risk of bias. The remaining four were classified as having a moderate risk of bias.” Indeed, some studies made claims (e.g. that neutering had a ‘protective effect’) but then failed to back up these claims with evidence.

Considering that only one study found an association between neutering and reduced risk of mammary tumours, and two studies found no evidence, there is not strong evidence that desexing reduces the risk of mammary tumours.

Check out the mammaries! My girl, Myrtle, is due to whelp in a week's time.

Check out the mammaries! My girl, Myrtle, is due to whelp in a week’s time.

What does the evidence say? 

Our results suggest that there is some evidence in one study that neutering is associated with a reduction in the risk of malignant mammary tumours (approximately 10-fold), amongst dogs from which samples and been submitted for histopathology, although there was no evidence that neutering after 2.5 years of age is associated with any change in the risk of malignant mammary tumours.

Basically, they concluded that there is weak evidence and there is “not a sound basis for firm recommendations“. There is some evidence that desexing before 2-5 years of age is beneficial, and also evidence that desexing before their first season may be beneficial.

The biggest faults in the existing research identified by Beauvais et al. included:

  • Research failed to control for age or breed.
  • No indication of age at neutering.
  • Little numerical data provided in publications (which limited this retrospective study).
  • Lack of consideration to bitches treated with ovarian steroids (and the effects this may have on research.)

When it comes to spaying bitches, it is important to recognise that the implications of a gonadecmomy on many aspects of the bitch. Not only does desexing affect the health and temperament of that bitch, there may be wider implications on the general population.

At the moment, vets vary in their opinion and recommendations, especially by country. I encourage owners to do their own research when making decisions for their pets.

 

 
Further Reading:Beauvais, W., Cardwell, J., & Brodbelt, D. (2012). The effect of neutering on the risk of mammary tumours in dogs – a systematic review Journal of Small Animal Practice, 53 (6), 314-322 DOI: 10.1111/j.1748-5827.2011.01220.x

09/3/14

A Link Between Desexing and Reactivity

ResearchBlogging.orgWhile desexing bitches is a common surgery, I was pleased to see Kim et al. take note that “the side effects of the operation, particularly any changes in behaviour, have been quantified in only few studies”.

That is to say, despite us commissioning vets to take the ovaries and uterus out of a great many bitches, we don’t really have much research about it. It’s a pretty scary state of play.

This particular study took 14 healthy German Shepherd bitches, between 5 and 10 months old. Half of these dogs were spayed, and the other half left entire. (The bitches were assigned to each group randomly, except for litter sisters, which were assigned opposite groups.)

After the spay, and having been given 4-5 months to recover from the surgery, the bitches were filmed in their kennel as a stranger and a dog approached. This footage was then scored based on how reactive the bitch was. A score of ’3′ indicated severe reactivity, and a score of ’0′ indicated no reactivity. The scorer was unaware of whether the bitch was spayed or not.

Photo courtesy of Rachel Willis.

Photo courtesy of Rachel Willis.

The reactivity of each bitch was recorded several times, and the reactivity of each bitch declined over the study. It’s likely that the bitches habituated to the novel stimuli. However, despite this affect, bitches in the ovary-hysterectomy group scored higher throughout the study.

Before generalising these results, there are some matters to consider:

  • Reactivity was only measured in a kennel setting, and how these dogs react in the ‘real world’ may be different. We can’t suppose that our pet dogs are going to respond in the same way as kennel dogs.
     
  • The reactivity of these dogs was not measured at the start of the study. While it is unlikely, perhaps more reactive dogs happened to fall into the treatment group by chance. Without a ‘before desexing’ score, we cannot be sure of this.
     
  • The authors make note that these results are for German Shepherd bitches aged 5-10 months old. We can’t assume dogs of all breeds and ages would respond this way to spays.
     
  • Further, the bitches in this study are working lined German Shepherds, which may be more reactive than the typical pet dog.

 

However, this study notes that other studies on bitch spays have shown that as a group spayed bitches are:

  • More likely to gain weight
  • More aggressive than prior to spay (if they were aggressive prior to spay)
  • More active
  • More likely to have urinary incontinence
  • More likely to be reactive after surgery

 

The authors recommend:

[V]eterinary practitioners should inform owners that a bitch may become more reactive after spaying either because they have lost the calming effects of progesterone or because elevated gonadotropins stimulate release of adrenal androgens.

 
Source:
Kim HH, Yeon SC, Houpt KA, Lee HC, Chang HH, & Lee HJ (2006). Effects of ovariohysterectomy on reactivity in German Shepherd dogs. Veterinary journal (London, England : 1997), 172 (1), 154-9 PMID: 16772140

Further reading:
Desexing: It’s bad for Vizslas too
Is desexing a cult?
Desexed dogs – 2.6 times less likely to bite!
Why would you NOT desex your dog??
Golden Retrievers: Cancer if you do, cancer if you don’t