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2/2/13

Dog diseases : Kartagener Syndrome and L-2-hydroxyglutaric Acidemia

Kartagener Syndrome

Kartagener syndrome (KS), also known as Primary Ciliary Dyskinesia (PCD), Kartagener Triad, Kartagener's Syndrome, Kartagener's Triad, and Siewert Syndrome, is is a rare congenital condition associated with abnormal retention of mucus and bacteria in the respiratory tract. The syndrome is caused by mutations of genes encoding proteins which are components of sperm and cilia in the respiratory and the reproductive tracts. Cilia are hairlike structures found in various bodily tissues. Patients with KS may have exercise intolerance and chronic, thick, discharge from the nose. Nasal polyps and ear disease are commonly seen affected individuals. Males with KS may be infertile due to impaired sperm motility.

Ciliated epithelium covers most areas of the upper respiratory tract, including the nasal mucosa, nasal passages, middle ear, eustachian (auditory) tube, and pharynx (throat). The lower respiratory tract contains ciliated epithelium from the trachea to the respiratory bronchioles. Cilia propel overlying mucus via a 2-part ciliary beat cycle. 
Patients with KS exhibit a wide range of defects in ciliary ultrastructure and motility, which ultimately impairs ciliary beating and clearance of mucus. The disease has been reported in the Dachshund, Golden Retriever, English Springer Spaniel and Chow Chow.

The progression and severity of lung disease varies among individuals and can be slowed with appropriate therapy. Aggressive measures to enhance clearance of mucus and prompt antibiotic therapy for bacterial infections are required. The therapies are aimed at treating consequences of this disorder as there are no cure for ciliary dysfunction. The prognosis is usually poor because of complications.

L-2-hydroxyglutaric Acidemia

l-2-Hydroxyglutaric aciduria (l-2-HGA) is a hereditary neurometabolic disorder reported in human beings and dogs characterized by spongiform changes in the brain which affect the gray matter of the cerebral cortex, thalamus, cerebellum and brain stem. 

The disease is caused by increased L-2-Hydroxyglutaric acid concentration in cerebrospinal fluid (CSF) and to a lesser extent in blood plasma. L-2-Hydroxyglutaric aciduria (L-2-HGA) is characterized by progressive deterioration of central nervous system function including epilepsy and abnormal enlargement of the head and brain (macrocephaly) in many cases. In dogs, the disease has been described in the Staffordshire Bull Terrier.

Clinical signs include mild motor and neurological abnormalities in the first years of life, followed by progressive poor coordination of limbs, imperfect coordination of throat, tongue, or face muscles, tremors, seizures, and moderate to severe mental deterioration. 

Clinical signs are usually apparent between 6 months and one year, although they can appear later. The diagnosis is confirmed by the finding of an excess of L-2-hydroxyglutaric acid in urine, blood and cerebrospinal fluid (CSF). 

L-2-hydroxyglutaric aciduria should be considered as one of the alternative diagnoses of epilepsy. The canine disease shares many of the clinical and MRI features of the disease in humans. In one case report, a 6-month-old, female Cavalier King Charles Spaniel exhibited seizures that were difficult to control with standard anticonvulsants over a 12-month period. 

The diagnosis of an organic aciduria with excessive excretion of hexanoylglycine was determined when the dog was 20 months old. Recurrent and cluster seizures were eventually controlled with the addition of other medications.
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