What is Immunodeficiency?

The following are congenital diseases that cause immunodeficiency :

Canine Leucocyte Adhesion Deficiency / Canine Granulocytopathy Syndrome
Canine granulocytopathy syndrome (now called canine leucocyte adehesion deficiency) has been reported to be an inherited autosomal recessive trait in Irish Setters and the condition has been reviewed recently in a report (Trowald-Wigh G. et al Journal of Small Animal Practice (2000) Vol41 p211-217).

With this disorder neutrophils have impaired phagocytosis and have impaired ability to kill bacteria due to lack of adhesion proteins (integrins CD11b/CD18, b2-integrins). Deficiency of these proteins prevents leucocytes from leaving blood vessels - so poor numbers are found in tissues even though large numbers are present in the blood - and renders them unable to phagocytose bacteria opsonised by fragment C3b.

The age of onset of problems is 2-4 months and clinical signs reported include :

* Post-natal infection of the umbilicus (called omphalophlebitis)
* Inappetance (anorexia)
* Gingivitis
* Lymph node enlargement
* High white blood cell (neutrophil) count. Over 200,000mm3 has been reported.
* Metaphyseal osteodystrophy - radius and ulna
* Craniomandibular osteopathy
* Osteomyelitis
* Respiratory disease including interstitial pneumonia
* Poorly healing skin wounds

Unfortunately, these cases are difficult to treat and most animals are euthanased before they are 6 months of age.

Chediak-Higashi Syndrome
Chediak-Higashi Syndrome is caused by giant lysosomes forming in cells - including leucocytes. It has been reported to occur in blue Persian cats, Hereford cattle and other species. Clinical signs include :

* Dilution of hair color
* Albinism (coat and iris)
* Photophobia
* Haemorrhages - due to abnormal platelets.
* Increased susceptibility to infection - due to impaired chemotaxis, and reduced hexose monophosphate activity.

Combined Immunodeficiency
Combined B-cell and T-cell immunodeficiency is extremely serious and life-threatening. Combined immunodeficiency has been reported in long-haired dachshunds and in basset hounds. Clinical signs are:

* Severe respiratory tract infections
* Premature death
* Complement (C3) Deficiency
* Complement fragment C3b which is an opsonin that coats bacteria surfaces rendering them susceptible to phagocytosis. C3 deficiency results in affected individuals being unable to opsonize bacteria, making affected individuals susceptible to severe bacteraemias. Complement C3 deficiency has been reported to be an autosomal recessive trait in Brittany Spaniels. C3 concentrations in heterozygotes are about 50% of the normal amount, but individuals do not show clinical signs. Homozygous individuals have C3 concentrations of only 0.003% normal and show typical signs of immunodeficiency with bacterial infections, septicaemia, and death. Clostridia and gram-negative bacteria are usually involved.

Cyclic Haematopoiesis of Grey Collies
This is a cyclic disorder of the bone marrow resulting in low neutrophil counts, and these neutrophils also have impaired bactericidal activity due to altered intracellular biochemical activity including reduced myeloperoxidase activity and impaired iodination of ingested protein . The precise mechanism that causes this disorder is not known but it is an autosomal recessive trait.

Clinical signs include :

* Severe, recurrent bacterial infections
* Haemorrhages - due to low platelet counts
* Respiratory infections
* Gastrointestinal infections
* Infection of the umbilicus
* Death - neonatal or within 3 years.

Affected animals can be successfully treated with a normal bone marrow transplant and lithium carbonate has been reported to be a successful treatment restoring cell counts to normal ....but it must be given continually.

Growth hormone deficiency
Immunodeficiency has been reported in a litter Weimaraners which were deficient in growth hormone and had low T-cell lymphocytes. Clinical signs included :

* Recurrent severe infections
* Poor growth rate and condition
* Treatment with bovine growth hormone was successful.

A line of German Shepherd Dogs have also been reported to have a this disorder and it is an autosomal recessive inherited defect.

IgA Deficiency
A genetic defect resulting in IgA deficiency has been reported to occur in Beagles, Shar Peis and German Shepherd Dogs..

Clinical signs include :

* Recurrent respiratory tract infections (eg Bordatella bronchiseptica)
* Dermatitis (staphylococcal infections, demodex)
* Parvovirus infection (despite vaccination)
* Seizures
* Bacterial overgrowth in the intestine of German Shepherd Dogs ?
The defect occurs because in affected individuals B-cell lymphocytes fail to develop into plasma cells which synthesise and secrete IgA.

Lethal Acrodermatitis in Bull Terriers
In affected individuals impaired T-cell function results from an autosomal recessive trait for abnormal zinc absorption and metabolism. The zinc deficiency and immunodeficiency causes a variety of signs :

* Dilution of coat color
* Recurrent respiratory tract infections
* Skin disease - footpad cracks, paronechia, dermatitis with crusting of the feet and around mucocutaneous junctions.
This condition does not respond to zinc supplementation because the animal can not absorb or utilise it properly and affected puppies die by 15 months of age.

Pelger-Huet Anomaly
In this condition the neutrophils and eosinophils have round nuclei due to incomplete nuclear segmentation and they may be described as "juvenile" on laboratory examination.. The disorder is an autosomal dominant trait that has been reported to occur in foxhounds other dogs like Basenji.

Clinical signs include :

* Neonatal deaths
* Lower litter sizes surviving to weaning than normal dogs.

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