Genetic welfare problems of companion animals

 

Ectropion

 

Breed: Dogue de Bordeaux (ddB)

 

Condition:  Ectropion

Related terms:

Outline: Dogues de Bordeaux are prone to ectropion – a condition in which the edges of the eyelids are everted – rolled outwards. This disrupts the functions of the lower lid in protecting the eye and in the normal drainage of tears. It predisposes to chronic conjunctivitis causing episodes of varying degrees of discomfort and pain throughout life unless eyelid conformation can be surgically corrected (which may be difficult). Animals should be chosen as pets or for breeding only if they have normal eyelid conformation, otherwise these diseases are likely to be perpetuated.

 


 

Summary of Information

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1.           Brief description

Eyelids are vital for the health of the surface of the eyes. They provide physical protection, help spread the tear film that keeps the surface of the eye moist, and remove debris during blinking. They also contain the drainage system for tears (the lacrimal ducts) (Renwick 2007). In order to perform these jobs successfully they need to have a smooth edges that stay in constant contact with the surface of the eyeball (Renwick 2007). This is often not the case in dogues de Bordeaux (DDB) because of the abnormal outwardly rotated edge of the lower eyelid (ectropion).

Dogs with ectropion are prone to conjunctivitis (inflammation of the conjunctiva), with or without secondary bacterial infection, and, if the corneal exposure is prolonged, then keratitis (inflammation of the cornea) or keratoconjunctivitis sicca (dry eye) will occur (Bedford 1988, http://www.upei.ca/cidd/Diseases/ocular%20disorders/ectropion.htm, Renwick 2007). Tear wetting of the face may also occur because of the displacement of the lacrimal duct and obstruction of the tear drainage system. Dogs of the mastiff type, like the dogues de Bordeaux, may be prone in general to having ectropion in the central part of their lower eyelids but with entropion (inward rolling of the edges) at each side of the eyelids (http://www.upei.ca/cidd/Diseases/ocular%20disorders/ectropion.htm).

Dogues de Bordeaux with ectropion may require surgery to correct this anatomical defect.

 

 

2.           Intensity of welfare impact             

Depending on the severity of the facial and eyelid abnormalities, the welfare effects can vary from mild to severe. Ectropion alone may cause some discomfort but if there is inflammation and infection of the conjunctiva, this may cause severe discomfort or pain. If the disease processes progress, vision can become permanently impaired.

 

3.           Duration of welfare impact

 

The condition of ectropion is life-long (unless successfully surgically corrected), often starting soon after the affected pups eyes open at two weeks of age (Bedford 1988, Yaphé 2005). The welfare effects may vary from mild to severe during periods of infection.

 

4.           Number of animals affected

 

Dogues de Bordeaux are predisposed to ectropion (ACVO 2007). A small survey suggests that around 15% of these dogs may be affected and that ectropion is the commonest eye disease with genetic causes seen in this breed (ACVO 2007).

 

5.           Diagnosis

Diagnosis is confirmed by examination of the eyes and face.

 

6.           Genetics

 

The eyelid abnormalities are thought to be due to multiple genes (ie to be polygenic). The eyelid abnormalities are linked to the exaggerated facial features of this breed (Rubin 1989).

 

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

Ectropion is common in dogues de Bordeaux. Prior to the purchase of a puppy, it and its parents and siblings should be examined carefully and individuals chosen on the basis of absence of signs of this condition (ACVO 2009).

 

8.          Methods and prospects for elimination of the problem

 

As far as we are aware there are no breeding schemes aimed at tackling eyelid problems in dogues de Bordeaux. It seems very likely that avoiding breeding from any animals that have had ectropion would be effective in reducing the prevalence of these welfare problems (Stockman 1983, Herring 2007).

In tackling such polygenic disorders, Bell (2010) recommended the use of breeding values which take into account all genetic and phenotypic information available for the individual and its close relatives (including siblings). Healthy individuals with healthy relatives are likely to be the best animals to use for breeding (Bell 2010). However, developing a breeding strategy based on breeding values requires the cooperation of the majority of breeders in providing the information from which breeding values of potential breeding animals can be estimated. Progress towards breeding a population with normal eyelids may not be quick and opinions differ as to whether it is ethically acceptable to breed animals whose welfare is likely to be compromised.

 

 

 


 

For further details about this condition, please click on the following:

 

 

 

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1.           Clinical and pathological effects

 

The eyelids are formed of three layers of tissue. The outer layer is of skin with eyelashes (in dogs only the upper lids have eyelashes), hair and sebaceous glands. The middle layer is of muscle, meibomian glands and fibrous connective tissue, and the inner layer is the conjunctiva (Renwick 2007). The conjunctiva lines the inner surfaces of the eyelids and part of the outer surface of the eyeball itself. Dogs also have a third eyelid, or nictitating membrane, at the inner corner of the eye and which is also lined by the conjunctiva.

Eyelids are vital for the health of the surfaces of the eyes. They provide physical protection, help spread the tear film that keeps the surface of the eye moist and remove debris during blinking. They also contain the lacrimal ducts that drain away excess tears (Renwick 2007). To perform these functions effectively, the edges of the eyelids need to be in constant contact with the surface of the eye (Renwick 2007). Dogues de Bordeaux are prone to outward rotation (ectropion) of the edge of the lower eyelid. Having a brachycephalic head shape (with shortened facial and nasal bones), they tend to have excessive facial skin, both above and below the eyes and the weight of this skin tends to cause the lower lids to be pulled – to droop - away from the eye. These abnormalities encourage ectropion – the outward rotation (eversion) of the lower eyelids, leading to abnormal exposure of the conjunctiva, nictitating membrane and cornea (the clear surface at the front of the eye) (Bedford 1988). As a result the eyes are not adequately protected and are therefore prone to conjunctivitis (inflammation of the conjunctiva) and to bacterial infections. If the corneal exposure is prolonged, keratitis (inflammation of the cornea) or keratoconjunctivitis sicca (dry eye) tend to develop (Bedford 1988, http://www.upei.ca/cidd/Diseases/ocular%20disorders/ectropion.htm; ACVO 2009, Renwick 2007).

Wetting and staining of the face with tears may also occur in individuals with ectropion because the entrance to the lacrimal duct, through which tears normally drain, is pulled away from the surface of the eye and its is therefore unable to drain tears.  As a result they overflow and run down the face and the constant wetting of the skin can lead to skin irritation and infection. Ectropion is often not judged to require surgical correction, but the associated conjunctivitis has to be treated when it arises. However, when there is entropion – inward rotation of the edges of the eyelids - as well, the effects on the eyes are more serious. Dogs of the mastiff type, like the dogues de Bordeaux, may be prone in general to having ectropion in the central part of their lower eyelid with entropion to each side of these eyelids (http://www.upei.ca/cidd/Diseases/ocular%20disorders/ectropion.htm).

Surgical correction is often necessary when both ectropion and entropion arepresent (Herring 2007, Renwick 2007). These surgical treatments are complex and have to be based on specialist assessment of each individual, as further problems can be caused by inappropriate treatment (Renwick 2007). Various forms of surgery to the eyelids and, in severely affected individuals, major facelift surgery may be necessary (van der Woerdt 2004, Renwick 2007).

 

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2.               Intensity of welfare impact

The welfare effects depend on the severity of the eyelid abnormalities present and the knock-on disease conditions that arise because of these. The effects of ectropion alone may be relatively mild, causing some discomfort but, when inflammation and infection of the conjunctiva are present, affected individuals will experience greater discomfort and pain. If keratitis is present then the discomfort is likely to be greater still (Herring 2007, Renwick 2007).

Treatments may have adverse welfare implications in themselves, through the stress associated with travel for veterinary therapy, applications of eye medication and surgery of the face and eyelids.

 

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3.           Duration of welfare impact

 

Ectropion usually appears soon after the eyes open at two weeks of age (Bedford 1988). It may lead to recurrent bouts of conjunctivitis lasting from a few days to a few weeks through life. Surgical treatment is not always successful.

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4.           Number of animals affected

 

Dogues de Bordeaux are predisposed to ectropion (ACVO 2009). A small survey suggests that around 15% of these dogs may be affected and that ectropion is the commonest eye disease with genetic causes seen in this breed (ACVO 2009).

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5.           Diagnosis

 

Diagnosis is made by examination of the face and eyes using specific ophthalmological equipment and tests.

 

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6.           Genetics

The eyelid abnormalities are thought to be due to the effects of mulitiple genes (ie to be polygenic). The eyelid abnormalities are linked to the exaggerated facial features of this breed – the brachycephalic head shape and the excessive, heavy skin (ACVO 2009). The genes involved have not been identified.

 

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

Ectropion is common in dogues de Bordeaux. We are unaware of any information about whether they can be carriers of this condition (ie able to pass it on to their offspring) without themselves being affected. Prior to purchase of a puppy, it and its parents and siblings should be examined carefully and animals chosen on the basis of absence of signs of these conditions (ACVO 2009).

Prospective owners should look for any inclination of the puppy to excessive blinking, for signs of any discharge from the eyes (there should be none) and for any gap between the lower eyelid and the surface of the eye (there should be no gap). Buying affected animals is likely to increase the likelihood of this welfare problem being perpetuated.

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8.          Methods and prospects for elimination of the problem

As far as we are aware there are no official programmes in place aimed at controlling this problem in the dogues de Bordeaux. In tackling such polygenic disorders, Bell (2010) recommended developing breeding strategies based on the breeding values of individuals. These take account of all genetic and phenotypic information available for the individual and its close relatives (including siblings). Healthy individuals with healthy relatives are likely to be the best animals to use for breeding (Bell 2010). However, developing a breeding strategy based on breeding values requires the cooperation of the majority of breeders in order to provide the information necessary for estimating the breeding values of all potential breeding animals. Progress towards breeding a population with normal eyelids may not be quick and opinions differ as to whether it is ethically acceptable to breed animals whose welfare is likely to be compromised.

 
 

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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

ACVO (American College of Veterinary Ophthalmology) (2009) Ocular disorders presumed to be inherited in purebred dogs. American College of Veterinary Medical Database/Canine Eye Registry Foundation, http://www.vmdb.org/BlueBook%20Order%20Form.pdf pp 344

 

Bedford PGC (1988) Conditions of the eyelids in the dog. Journal of Small Animal Practice 29: 41-28

 

Bell JS (2010) Genetic Testing and Genetic Counseling in Pet and Breeding Dogs. 35th World Small Animal Veterinary Association World Congress Proceedings. 2-5th June 2010, Geneva, Switzerland. http://www.vin.com/Members/Proceedings/Proceedings.plx?CID=wsava2010&PID=pr56159&O=VIN accessed 12.9.2011

 

Herring I (2007) Ectropion. VIN Associate. http://www.vin.com/Members/Associate/Associate.plx?DiseaseId=1208. Accessed 12.9.2011

 

Renwick P (2007) Eyelid surgery in dogs. In Practice 29: 256-271

 

Rubin LF (1989) Inherited Eye Diseases in Purebred Dogs. Williams and Williams; Baltimore, USA

 

Stockman M (1983) Inheritable defects in dogs: 3. In Practice: 202-206

 

van der Woerdt A (2004) Adnexal surgery in dogs and cats. Veterinary Ophthalmology 7: 284–290

 

Yaphé W (2005) Lecture 2 - Eyelid and Third Eyelid Disease VIN Associate. http://www.vin.com/Members/CMS/Misc/default.aspx?id=6799. Accessed 28.3.11

http://vision4pets.com/web/images/pdf/BlueBookReport2009.pdf Accessed 12.9.2011

http://www.upei.ca/cidd/Diseases/ocular%20disorders/ectropion.htm; Accessed 12.9.2011

 

 

© UFAW 2011

 

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