Genetic Welfare Problems of Companion Animals

An information resource for prospective pet owners

Scottish Terrier

Scottish Terrier (Scottie)

Dystocia due to Foetal-Pelvic Disproportion

Related terms: foetal-maternal disproportion, dorso-ventrally flattened pelvic canal

Outline: Because of abnormalities in the shape of the pelvis, altering the birth canal dimensions, it is common for female Scottish terriers to be unable to give birth naturally and require delivery of the pups by caesarean. If this is not done the birth will end in the painful death of the mother.


Summary of Information

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1. Brief description

Dystocia is the term used to describe any difficulties in giving birth. Dystocia can lead to suffering in both the bitch and puppies during attempts to give birth and frequently requires veterinary intervention. It has been found that 60% of Scottish terrier pregnancies end in delivery through caesarean section (Evans & Adams 2010). Many of these caesareans are due to dystocia but some are probably performed electively to prevent it. Birth problems are common in Scottish terriers due to bitches often having an abnormally shaped pelvis, characterised by a flattened birth canal (Jones & Joshua 1988, Eneroth et al 1999).

2. Intensity of welfare impact   

Dystocia causes severe pain and distress. Without intervention it leads to the death of the puppies and often of the mother.

3. Duration of welfare impact

Dystocia can result in attempts to give birth lasting for hours, and possibly days, if veterinary intervention is not sought.

4. Number of animals affected

Scottish terriers have the highest rates of dystocia of all non-brachycephalic dog breeds (Bergström et al 2006), ie all those breeds with head shapes that have not been abnormally shortened by selective breeding, such as is seen in the English bulldog and Pug. Many pregnant female Scottish terriers would suffer dystocia if allowed to give birth naturally and if elective caesareans were not carried out. Currently 60% of Scottish terrier births are by caesarean in the UK (Evans and Adams 2010).

5. Diagnosis

A diagnosis of dystocia is made if a mother fails to produce live young within defined time periods after the onset of parturition. Radiographs can be used to confirm whether there is any foetal-pelvic disproportion (excessive size of the foetus in relation to the mother's birth canal) and radiographic pelvimetry (using pelvic radiographs [x-rays] to make specific, comparable measurements) can be used to assess the potential for dystocia in Scottish terriers (Eneroth et al 1999).

6. Genetics

No specific genes responsible for the abnormally flattened pelvic canal common in many Scottish terriers have been identified. The breed is highly predisposed to this problem (Freak 1948, 1962, 1975, Jones & Joshua 1988, Eneroth et al 1999, Linde-Forsberg ND). Pelvic shape has been shown to have a strong tendency to be inherited in Boston terriers (Linde-Forsberg ND) and it is likely that this is the case in Scottish terriers also.

7. How do you know if an animal is a carrier or likely to become affected?

It is common for Scottish terriers to have this problem and this may be related to the achrondroplasia (abnormally short limb bones) which is one of the characteristics of this breed (Jones &Joshua 1988). Radiographs of the pelvis of a mature bitch can give some indication of the pelvis being abnormally shaped (Eneroth et al 1999). Eneroth et al (1999) also found that larger Scottish terrier bitches, which were heavier, longer-bodied and taller at the shoulders, were less likely to suffer dystocia than their smaller counterparts.

8. Methods and prospects for elimination of the problem

Currently 60% of Scottish terrier births involve surgical intervention. It is very likely that this problem could be addressed by breeding only from those animals that are born by normal delivery and also by excluding any that have had to have had a caesarean to give birth themselves. If excluding these animals from the breeding population results in reducing the size of the breeding population such that there may be risks of other genetic diseases occurring, then this could be avoided by out-crossing with dogs of other breeds that do not have a high incidence of dystocia.

It has been suggested that radiographic pelvimetry may be helpful in the selection of females less likely to suffer dystocia (Eneroth et al 1999).


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1. Clinical and pathological effects

Dystocia (difficulty in giving birth) can have many causes and these are generally categorised into factors that relate to the mother and factors that relate to the foetus (Jones & Joshua 1988). A recent report indicated that 60% of Scottish terrier litters, in the UK, are delivered by caesarean section rather than naturally, via the birth canal (Evans & Adams 2010). It appears that, in this breed, the cause is mainly maternal, and related to an abnormal shape of the pelvis.

Normally, the front of the pelvis is pear shaped, with the vertical axis longer than the horizontal axis (Jones & Joshua 1988). In achrondroplastic breeds (those selected to have abnormally short limb bones (Ruppin 2010)), which includes the Scottish terrier, this ratio is typically reversed, with the pelvic inlet often having a vertical dimension equal to or shorter than the horizontal dimension (Jones & Joshua 1988, Eneroth et al 1999). This makes it difficult, or impossible, for the head and body of the puppy to pass through during the birth process.

It has been suggested that, in the UK, some cases of dystocia in Scottish terriers are due to uterine inertia in which the uterus fails to contract adequately to expel the foetuses (The Kennel Club 2006). However, we are not aware of any data on the prevalence of uterine inertia in this breed.

It is not known what proportion of the large number of caesareans carried out on Scottish terriers are elective procedures, undertaken to prevent any chance of dystocia and its consequent complications for the bitch or puppies, and what proportion are carried out to treat dystocia once it has occurred.

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2. Intensity of welfare impact

Dystocia is a severe welfare problem for the affected bitch and if not dealt with, likely to rapidly lead to very severe complications associated with failure to give birth. These are likely to cause severe pain and malaise and usually lead to the death of the bitch. Even with treatment it results in a higher rate of death in the puppies, unless treatment is prompt (Jones & Joshua 1988). Treatment of a bitch that is having difficulty giving birth involves transportation of the dog to a veterinary practice for examination and imposes further stresses on the affected animal. Uterine contractions are painful and control of this pain is difficult in the home environment, so any delay to the birth process result in more prolonged and severe pain than usual. Caesarean section is usually required to treat a Scottish terrier with dystocia. Unplanned, emergency caesarean sections are likely to have a higher welfare impact than either natural birth or elective caesarean, and a higher death rate for the puppies. Caesarean sections are major surgical procedures for any bitch to undergo.

It is likely that the reason for the high proportion of caesarean sections carried out on Scottish terriers is that they are being performed electively to reduce the risks and welfare impacts of dystocia (Evans & Adams 2010).

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3. Duration of welfare impact

If not resolved, dystocia can last for up to 24-36 hours or more. As time goes on, progressive death of the puppies will occur and, after 36 hours, the survival of the bitch is at increasing risk (Jones & Joshua 1988). Death is very likely to occur in time as a result of painful consequences associated with the failure to give birth

If a caesarean is successfully performed, the female will be pain from the surgery for some days although effective analgesia should be available. A further issue is that if live puppies have been delivered and the bitch is to rear them normally then their sucking on a teat close to the surgical wound may cause her pain in the first week, or so, after the procedure.Return to top

4. Number of animals affected

It has been reported that, in the UK, 60% of Scottish terrier litters delivered by caesarean section rather than by natural birth (Evans & Adams 2010). Bergstrom et al (2006) found, from assessment of insurance claims in Sweden, that Scottish terriers, had the highest rate of dystocia of any of the breeds that can be insured for this condition (Boston terriers, English bulldogs and French bulldogs were excluded from this as they cannot be insured against dystocia because of their very high risk of it). There was found to be an incidence rate of 38.3 cases per 1000 dog years for Scottish terriers, as opposed to 5.7 cases per 1000 dog years for the overall insured population of dogs (Bergström et al 2006). That is, Scottish terriers were found to be six times more likely to have dystocia than the average insured dog.

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5. Diagnosis

A normal labour has three stages. In the first stage, the body prepares itself for birth with the cervix relaxing and dilating. During this stage, if left alone, the bitch in the wild would seek seclusion and dig a den. The second stage involves the loss of uterine fluids, progressively more vigorous straining and birth of the puppies. The third stage of labour is delivery of the foetal membranes. In dogs, the third stage can be concurrent with the second stage, as membranes are sometimes expelled with their puppy. In some cases of dystocia, the second stage never begins. Dystocia is diagnosed if there has been no progress  from stage one to stage two after about 24 hours, or if stage-two labour has been happening for about two hours without a puppy having been delivered (Jones & Joshua 1988). Radiographs can be used to investigate the cause and to assess foetal and pelvic dimensions. 

Radiographic pelvimetry, involving measurement of various dimensions from X-rays of the pelvis, can be used to assess the degree of dorso-lateral flattening of the pelvic shape in Scottish terriers and to detect bitches that are at particular risk of dystocia (Eneroth et al 1999). The relative size of the bitch also may give some indication of dystocia risk, with small bitches at higher risk.

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6. Genetics

The genes responsible for the abnormal dorsolateral flattening of the pelvic canal in Scottish terriers, which is commonly the cause of dystocia in this breed, are unknown. This dystocia is thought to be linked, in some way, to the achondroplasia (abnormally short limb bones) which is one of the characteristics of the breed (Freak 1948, 1962, 1975, Jones & Joshua 1988).  Achrondroplasia is caused by a single, autosomal dominant gene (Ettinger 2001). All Scottish terriers have the gene and the condition.

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7. How do you know if an animal is a carrier or likely to become affected?

Scottish terriers are at greater risk of this condition than most other dog breeds and the smaller bitches, which are lighter, shorter-bodied and shorter at the shoulders seem to be at greatest risk (Eneroth et al 19990). It seems likely that puppies born from family lines in which there is a long history of giving birth via caesarean, may be more at risk of dystocia than those from lines in which births have, for generations, been natural. When acquiring a Scottish terrier puppy with the intention of subsequently breeding from it, it is sensible to ask about its family's previous breeding history. 

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8. Methods and prospects for elimination of the problem

Currently 60% of Scottish terrier births involve surgical intervention. It is very likely that this problem could be addressed by breeding only from those animals that are born by normal delivery and also by excluding any that have had to have had a caesarean to give birth themselves. If excluding these animals from the breeding population results in reducing the size of the breeding population such that there may be risks of other genetic diseases occurring, then this could be avoided by out-crossing with dogs of other breeds that do not have a high incidence of dystocia.

In pursuing the above strategy – breeding only from those which have been born naturally in order to select for a strain (population) able to give birth naturally in the future – it would be important not to risk allowing all births to progress naturally in order to maximise the number of pups born naturally, as this would be likely to endanger the health and welfare of the bitches and puppies in cases of dystocia. All births would need to be closely monitored, with prompt intervention occurring when required.

It may be possible to make progress through assessing the size and shape of the pelvises of prospective mothers; as has been described for Scottish terriers by Eneroth et al (1999). These authors found that bitches in which the internal vertical pelvic diameter was greater than the internal horizontal diameter were less likely to have suffered from dystocia. Breeding from such dogs, and those with the greatest pelvic measurements may be reasonable and could be helpful in reducing the incidence of dystocia. However, this idea would need to be further considered and developed before it could be used in practice. Radiographic measurements would require general anaesthesia.

Since it is likely to be very hard, if not impossible, to ensure that that timely veterinary intervention will always be available to manage dystocias, wherever and whenever these dogs may breed, and because of the stressors that can occur even with veterinary intervention, animal welfare will be best served by not breeding from animals that are unlikely to be able to give birth naturally.

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9. Acknowledgements

UFAW is grateful to Rosie Godfrey BVetMed MRCVS and David Godfrey BVetMed FRCVS for their work in compiling this section.

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10. References

Bergström A, Nødtvedt A, Lagerstedt A and Egenvall A (2006) Incidence and breed predilection for dystocia and risk factors for cesarean section in a Swedish population of insured dogs. Veterinary Surgery 35: 786-91

Eneroth A, Linde-Forsberg C, Uhlhorn M and Hall M (1999) Radiographic pelvimetry for assessment of dystocia in bitches: a clinical study in two terrier breeds. Journal of Small Animal Practice 40: 257-264

Ettinger SJ (2001) Pocket companion to Textbook of veterinary internal medicine. WB Saunders: Philadelphia, USA. pp430

Evans K and Adams V (2010) Proportion of litters of purebred dogs born by caesarean section. Journal of Small Animal Practice 51: 113–118

Freak MJ (1948) The whelping bitch. Veterinary Record 60: 295-301

Freak MJ (1962) Abnormal conditions associated with pregnancy and parturition in the bitch. Veterinary Record 74: 1323-1339

Freak MJ (1975) Practitioners'-breeders' approach to canine parturition. Veterinary Record 96: 303-308

Jones D and Joshua J (1988) Some problems of parturition. In: Reproductive Clinical Problems in the Dog, 2nd Ed. pp 87-112. Wright: London

Linde-Forsberg C (ND) Pelvimetry to Diagnose Dystocia in the Bitch. On-line http://www.vetlatranquera.com.ar/pages/wsava2002/Reproduction06.htm. Accessed 21.6.11.

Ruppin M (2010) Achrondroplasia. On-line http://sydney.edu.au/vetscience/lida/dogs/search/disorder/5/Achondroplasia.  Accessed 5.7.11.

The Kennel Club (2006) KC/BSAVA Purebred Dog Health Survey. On-line

http://www.thekennelclub.org.uk/item/549. Accessed 17 June 2009.

© UFAW 2011


Credit for main photo above:

By Walescot (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons