Common congenital and hereditary problems in neonatal small animals (Proceedings)
• To familiarize practitioners with the common abnormal findings in neonates due to congenital and hereditary disease.
• To aid in the accurate recognition and diagnosis of congenital and hereditary conditions encountered in pediatric small animals.• To increase knowledge of the current information regarding genetic testing of dogs and cats.
• To promote knowledgeable genetic counseling of dogs and cat breeders.
General Key Points
• Neonatal pathology may involve a number of developmental malformations. A solid background in embryology and early development assists in understanding the pathogenesis of many of the conditions.
• The causes of many well described defects remain undefined.
• The rate of occurrence of congenital defects in neonatal puppies and kittens has been reported between 7% and 20%.
Causes of Congenital Defects and Disease
• Genetics, Heredity- Veterinary research is rapidly adding to the understanding and diagnosis of defects known to be genetic. Many genetic diseases are outwardly visible, but mutations may also cause disease at the biochemical level making diagnosis more difficult. The defect may cause disease that is incompatible with life resulting in death within the first few days. These cases are often classified as" faders". Other mutations may cause symptoms that may not become clinical for months or years, thus delaying their diagnosis. Metabolic screening is recommended for neonates displaying symptoms compatible with an inborn error of metabolism. Testing may be performed at the University of Pennsylvania's Metabolic Screening Laboratory. Detailed information on testing and sample submission may be found at http://www.vet.upenn.edu/penngen/.
• Toxins, Teratogens, Chemical agents- The developing fetus is most susceptible to teratogen insult during the first third of pregnancy, the period of organogenesis. Potential teratogens include a variety of environmental pollutants, plants, vitamins, minerals, hormones and drugs. Commonly implicated drugs usually fall into the categories of antibiotics, anticonvulsants, antineoplastics or anti-inflammatories.
• Infections- A variety of infectious organisms may induce congenital abnormalities. Infection with feline panleukopenia virus or vaccination with a modified live vaccine can induce cerebellar hypoplasia in kittens.
• Developmental anomalies may also be caused by other factors including ionizing radiation, temperature extremes, hypoxia, maternal metabolic disease and trauma.
• Anomalies affecting the central nervous, cardiovascular or respiratory systems may be incompatible with life resulting in resorption, stillbirth or death shortly after birth.
Breed Related Diseases
Certain breeds (such as the bulldog) have a plethora of defects that commonly occur within the breed. Knowledge particular breeds predispositions will greatly increase the ability to recognize all problems presented to the practitioner. The goal is diagnosing all obvious and subtle abnormalities on physical examination. Often the recognition of the mild outward clinical signs of a problem, along with cognizance of the breed related predispositions, aids in making diagnosis of less obvious problems such as megaesophagus, heart defects, hypoplastic trachea, metabolic defects or immunodeficiency.
Differentiating Genetic Defects from other Congenital Anomalies
• A problem is more likely to be a hereditary defect if it is known to be genetically transmitted in another breed or species. MEDLine and VIN are very useful tools for conducting searches of known genetic diseases.
• Genetic disease tends to occur in more than one litter produced by a dam or sire.
• The frequency of a genetic defect will increase with inbreeding.