Congenital Conditions of the Skin
Eyes and Ears of dogs

SKIN

 

 

A dermoid sinus is a defect that occurs during embryonic development that results in an incomplete separation between the skin and the neural tube, the structure present during embryonic life which gives rise to the central nervous system (brain and spinal cord).  A sinus (blind infected tract) forms that may extend from the skin to the dura mater (the outermost, toughest and most fibrous membrane that covers the brain and spinal cord) of the spinal cord or may end as a blind sac in the tissue below the skin.

 

 

It has the highest incidence in Rhodesian Ridgebacks, but has also been reported as congenital defects in Shih Tzu and boxer breeds.

 

 

The sinus has single or multiple small openings that may have tufts of hair protruding from them and may be found anywhere along the midline of the back, but is most common over the cervical (neck) spine.  A cord may be clearly palpable.  The sinus may contain sebum, keratin, debris and hair, and sinuses may even become inflamed, infected , and drain.  Sinuses that extend to the the spinal cord may also lead to bacterial meningoencephalitis.

 

Draining tracts requires surgical removal of the sinus.

 

Alopecia X - Introduction

Clinical signs

Diagnosis

Treatment

 

 

The condition is mostly a cosmetic problem.  Hair regrowth is expected after castration of male dogs, but recurrence after one year is possible.  Melatonin has been reported to be effective, but Trilostane is regarded as the most effective and safe drug for the disease.

 

EYE

 

 

Entropion - Introduction

 

 

Entropion is the inversion of part or all of the eyelid margin, resulting in eyelashes making contact with the cornea.  Hereditary is the most common cause of entropion and it occurs as a congenital defect in many breeds.

Clinical signs

 

 

The overflow of tears, rolling in of the eyelid, inflammation of the conjunctiva as well as corneal ulceration may be present.

Treatment

 

 

Neonatal entropion in puppies may be corrected by means of eyelid tacking.  In puppies older than 3 months of age, surgical correction may be indicated.

Cataracts - Introduction

 

 

A catacract is an opacity caused by the disruption of the normal arrangements of the lens fibres or lens capsule.  Hereditary is the most common cause of cataracts in dogs, and it can be either congenital or develop up to 5 years of age.  Other possible causes include diabetes mellitus, milk replacements, chemicals, radiation, electric shock, trauma, ageing.

Clinical signs

 

 

Will vary depending on the maturation of the cataract(s) and may include no visual defects, varying degrees of vision and blindness.:

Treatment

 

 

Removal of the lens and its capsule as an intact unit, removal of the anterior capsule and lens contents, or the ultrasonic fragmentation and aspiration of the lens.

Progressive retinal atrophy - Introduction

 

 

Progressive retinal atrophy is also known as rod-cone degeneration and is the most common inherited cause of blindness in dogs.  In most cases it is transmitted as an autosomal recessive disease, and different dog breeds have different forms of the disease.  It has been reported as an inherited condition in the following breeds:  American and English Cocker Spaniels; Miniature and toy poodles:  Labrador Retrievers; Portuguese Water Dogs: Akita, Miniature Long Haired Dachshund; Papillon; Tibetan Terrier;; Tibetan Spaniel; Siberian Huskies; Miniature Schnauzer.

Clinical Signs

 

 

The age of onset varies.  The initial behavioural sign is usually loss of night vision.  the disease is progressive, invariably leading to blindness.

EAR

 

 

Deafness - Introduction

 

 

Congenital deafness can either be inherited, or result from damage to the developing foetus.  Merle and white coat colours are associated with congenital deafness in dogs.  Dog breeds that are commonly affected include the Dalmation, Australian Shepherd, Catahoula, English Setter, Australian Shepherd, Boston Terrier, Old English Sheepdog, Great Dane, West Highland White Terrier, and Boxer.  The list of affected breeds currently consists of over 48 breeds and it continues to expand and may change due to breed popularity and elimination of the defect through selective breeding.

Diagnosis

 

 

The primary signs of deafness is failure to respond to an auditory stimulus, but other signs include unusual behaviour such as excessive barking.  In congenital deafness, examination of the external ear, radiographs and neurologic examination are normal, but the animal shows evidence of a lack of hearing.

 

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For more information on other Congenital Defects in Dogs:

Deafness in Dogs

Canine Leukocyte Adhesion Deficiency  - CLAD

Dog Health Conditions

Congenital Portosystemic - Shunts in dogs

Return from Skin Eyes and Ears of dogs to Veterinary Articles

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Veterinary articles supplied by Dr S Strydom and published with kind permission of DIA Publishing - publishers of KUSA Dogs in Africa Magazine

Dr Sunelle Strydom qualified as a veterinarian in 2004 at the Faculty of Veterinary Science, University of Pretoria.  She has a passion for writing and the sharing of knowledge to promote animal health and welfare.  She has written several articles for KUSA Dogs in Africa as well as for Vra vir Faffa on the Landbouweekblad website at www.landbou.com

 

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References

1. Boden E 1998. Black's Veterinary Dictionary 19th Edition. A & C Black, London
2. Ettinger S J & Feldman E C. 2000. Textbook of Veterinary Internal Medicine 5th Edition. W.B. Saunders Company, USA. 2-5; 1983-1996
3. Hnilica K A & Medleau L. 2001.  Small Animal Dermatology A Color Atlas and Therapeutic Guide.  W.B. Saunders Company, USA
4. Iwasaki T. 2004. Non-inflammatory Alopecia.  Proceedings of the 29th World Congress of the World Small Animal Veterinary Association October 6-9, 2004, Rhodes, Greece
5. The Free Dictionary by Fralex (website).  Available from http://medical-dictionary.thefreedictionary.com as accessed on 30 September 2008.
6. Mausberg E.-M., Drogemuller C & Leeb T. 2007. Evaluation of the CTSL2 gene as a candidate gene for alopecia X in Pomeranians and Keeshonden. Animal Biotechnology 18: 291-296
7. Mausberg E.-M, Drogemuller C, Rufenacht S, Welle M, Roosje P, Suter M & Leeb T. 2007.  Inherited alopecia X in Pomeranians.  Deutsche tierarzliche Wochenschrift 114(4): 129-34
8. MedineNet.com (website). Available from http://www.medterms.com as accesed on 1 October 2008.
9. Merck Veterinary Manual (website).  Available from http://merckvetmanual.com/mvm?index.jsp?cfile=htm/bc/toc_508000.htm as accessed on 1 October 2008
10. Ofri R 2006.  Blindness in veterinary ophthalmology: examanation, causes and treatment.  International congress of the Italian Association of Companion Animal Veterinarians May 19 - 21 2006, Rimini, Italy.
11. BVSc lecture notes: Small Animal Clinical Studies 470.

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