Congenital Defects in Dogs

Introduction
Congenital defects can be defined as defects (hereditary or non hereditary) that are present from birth. The majority of congenital defects have no clearly defined cause, while others are caused by either genetic or environmental factors, or an interaction between these. Teratogens (other factors) that may cause congenital defects include toxic plants, viruses, drugs, trace elements, nutritional deficiencies, and physical agents. Infectious diseases, toxins, and nutritional imbalances however generally affect the entire litter, whereas hereditary disorders often involve only a few in a litter. Most genetic defects cause clinical signs early in life, but the signs are extremely variable. These signs are however progressive in nature and therefore once an animal shows signs it probably will not recover and death often occurs at an early age. Only a few hereditary defects result in intermittent or recurrent problems.

The domestic dog is second to humans in the number of reported hereditary disorders and because of an increased awareness of genetic defects; the number of reported hereditary disorders in small animals is rapidly growing. Approximately 400 hereditary disorders in dogs and 150 disorders in cats have been documented and every year approximately 12 additional disorders are being reported. Any genetic defect may occur in any animal, however many have been documented only in a particular family or particular breed.

Domestic dogs have been heavily selected for particular traits, such as body size, conformation, temperament and behaviour over a period of at least 15 millennia. Particular dog types became established through relative inbreeding. High levels of inbreeding contribute to the appearance of inherited disorders.

The control of genetic disorders is much more important than the treatment of these conditions. A reduction in the frequency or even an elimination of a genetic defect is possible by not breeding with affected animals.

Congenital defects are usually classified by the body system that is primarily affected. Some of the most common congenital defects & defects are listed below.

Eyes - PROGRESSIVE RETINAL ATROPHY (PRA), Cataracts, Entropion
Bones & Joints - Hip dysplasia, Elbow dysplasia
Digestive system - Cleft palate, Detition abnormal
Skin - Dermoid sinus, Alopecia X, Sarcoptic mange