Issues

Immunodeficiency Disorders

Diminished ability to mount an effective immune response due to heritable defects in the immune system.

PATHOPHYSIOLOGY

• Defects in the cell-mediated, humoral, complement, and phagocytic systems have all been described in the veterinary literature.
• Defects involving the humoral immune response—associated with a high susceptibility to bacterial infection.
• Defects involving the cell-mediated immune response—associated with a high susceptibility to viral, fungal, and protozoal infections.
• Defects in the phagocytic or complement system—associated with disseminated infection.

 

SYSTEMS AFFECTED

• Hemic/Lymphatic/Immune—defect in a specific cell population in lymphoid tissue.
• Skin/Exocrine/Respiratory/Gastrointestinal—chronic or recurrent infections.
• Other organ systems—dissemination of infection, failure to thrive.

 

GENETICS

Typically breed-specific with variable modes of inheritance.

 

INCIDENCE/PREVALENCE

Rare

 

SIGNALMENT

Species

Dog and cat

 

Breed Predilections

• X-linked severe combined immunodeficiency—basset hounds, Cardigan Welsh corgis.
• Severe combined immunodeficiency disease—Jack Russell terriers.
• IgA deficiency—beagles, German shepherds, and Chinese Shar-Peis.
• IgM deficiency—Doberman pinschers.
• Thymic hypoplasia—dwarfed Weimaraners.
• Cyclic hematopoiesis—gray collies.
• Chediak-Higashi syndrome—Persian cats.
• Leukocyte adhesion deficiency—Irish setters.
• Complement deficiency—Brittany spaniels.
• Bactericidal defect—Doberman pinschers.
• Transient hypogammaglobulinemia—Samoyeds.

 

Mean Age and Range

Primary immunodeficiency diseases typically expressed in the first year of life.

 

Predominant Sex

X-linked recessive severe combined immunodeficiency disease of basset hounds—males affected and females are carriers.

 

SIGNS

General Comments

Depends on the level at which the immune response is defective; ranges from chronic respiratory and gastrointestinal signs and skin infections to life-threatening conditions.

 

Historical Findings

• High susceptibility to infection and failure to respond to appropriate, conventional antibiotic therapy.
• Lethargy.
• Anorexia.
• Skin infection.
• Failure to thrive.
• Signs often appear when maternal antibody concentrations decline.
• Vaccine-induced disease by modified live virus preparation.

 

Physical Examination Findings

• Hallmark—failure to thrive.
• Clinical signs attributable to infections.

 

CAUSES

Congenital

 

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS

Patients must be rigorously evaluated for underlying disease process that may cause secondary (acquired) immunodeficient state (e.g., hyperadrenocorticism, FeLV, and FIV).

Patients are typically young with recurrent infection that fails to respond to conventional treatment.

 

CBC/BIOCHEMISTRY/URINALYSIS

CBC may indicate deficiencies in specifically affected cell lines or chronic inflammation.

 

OTHER LABORATORY TESTS

• Serum protein electrophoresis—demonstrate gross deficiency in immunoglobulin concentration.
• Serum immunoglobulin quantitation—evaluate humoral immune system, identify selective immunoglobulin deficiency, support diagnosis of agammaglobulinemia.
• The lymphocyte transformation test—evaluate the cell-mediated immune system and identify animals with T-lymphocyte deficiency.
• Bactericidal assays—evaluate neutrophil function.
• Serum concentration of complement components—diagnose complement deficiency.
• Enumeration of lymphocyte subsets by immunofluorescence with monoclonal antibodies—identify deficiency of specific cell lines.
• Other more specific tests to evaluate immune function in veterinary species are available, but obtaining reliable results generally requires access to research laboratories that perform these tests.

 

DIAGNOSTIC PROCEDURES

In some patients, bone marrow and lymph node biopsy aids in classifying the type of immune deficiency.

 

PATHOLOGIC FINDINGS

• Lesions vary; depend on the specific defect; most are the result of recurrent or opportunistic infection involving the skin, ear canal, and respiratory and gastrointestinal systems.
• Lesions of septicemia common in animals with severe defects.
• T-lymphocyte defects—hypoplastic or dysplastic lesions of the thymus and T-lymphocyte-dependent areas of secondary lymphoid tissues.
• B-lymphocyte defects—hypoplastic or dysplastic lesions of the bone marrow or B-lymphocyte-dependent areas of secondary lymphoid tissues.
• Lymphoid hypoplasia or hyperplasia may be seen, depending on the overall defect and the occurrence of infection.

 

TREATMENT

APPROPRIATE HEALTH CARE

• Hospitalization may be necessary to control life-threatening infection.
• Outpatient management possible for some patients.

 

NURSING CARE

Supportive care appropriate to the nature of the infection.

 

ACTIVITY

Determined largely by the severity of the defect and the occurrence of infection.

 

DIET

• Dietary management may be required to ensure that the patient is maintained at an adequate level of nutrition.
• Potential sources of infectious agents such as raw meat must be avoided.

 

CLIENT EDUCATION

• Inform client that the animal cannot be cured.
• Discuss why the patient has high susceptibility to infection.
• Discuss and advise as to the heritability of the disease.
• Discuss the possibility of littermates being affected.
• Avoid exposure to ill animals.

 

MEDICATIONS

DRUG(S) OF CHOICE

• Antibiotics to control infections
• γ-Globulin or plasma preparations can be used in conjunction with antibiotics to control infection in patients with humoral defect.
• Symptomatic treatment for secondary disease states.

 

CONTRAINDICATIONS

γ-Globulin or plasma preparations should not be administered to patients with selective IgA deficiency because many affected patients have high concentrations of anti-IgA antibodies and may develop anaphylaxis.

 

PRECAUTIONS

Modified live virus vaccines should not be administered to patients with suspected T-lymphocyte deficiencies because they may induce disease in these patients.

 

FOLLOW-UP

PATIENT MONITORING

• For clinical signs of secondary infection.
• Routine physical examination to assess efficacy of antibiotic therapy.

 

PREVENTION/AVOIDANCE

• Do not breed affected animals.
• Pedigree analysis to determine the mode of inheritance and prevent propagating the defect.

 

POSSIBLE COMPLICATIONS

Infection

 

EXPECTED COURSE AND PROGNOSIS

The severity of the defect determines the course and prognosis.

Patients with minor defects can be successfully managed.

 

Visit your veterinarian as early recognition, diagnosis, and treatment are essential.

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