Overactive Immune System in Dogs

A dog’s immune system is made up of the innate immune system and the adaptive immune system.  The innate immune system is the first line of defense. The innate immune system helps to stop “intruders” from entering the body. The skin, mucous, stomach acids, phagocytes and monocytes cells form a physical barrier. The adaptive immune system is also known as the acquired system.  This system adapts and keeps “learning”. The adaptive immune system helps to fight off specific diseases, viruses and bacteria. Once this system encounters an “intruder”, it keeps a memory of the foreign body.  So, the next time the “intruder” enters the body, the immune system knows the best way to attack it.

An overactive immune system can cause autoimmune diseases and conditions to develop such as canine lupus, Addison’s disease, inflammatory bowel disease and rheumatoid arthritis.

An overactive immune system reacts to the body as if it is a threat.  It will attack the body’s healthy tissues, which then causes inflammation and damage to the tissue cells and organs.

Canine Discoid Lupus Erythematosus (DLE)

• Skin scaling
• Hair loss
• Skin sores
• Sunlight can irritate the dog’s skin

Canine Systemic Lupus Erythematosus (SLE) 

• Lameness
• Swollen joints
• Thickened foot pads
• Stiff gait
• Lethargy
• Weakness
• Depression

Addison’s Disease

• Lack of appetite
• Vomiting
• Lethargy
• Muscle weakness
• Imbalance of electrolytes can cause shock

Inflammatory Bowel Disease

• Diarrhea
• Vomiting
• Weight loss
• Depression 
• Fever

Rheumatoid Arthritis

• Lameness
• Fever
• Loss of appetite
• Stiffness
• Swollen painful joints
• Depression
• Decreased activities

The main cause of autoimmune diseases is an overactive immune system, which can be triggered by infections, nutrition, adverse drug reaction and other factors.

Canine Lupus

• Genetics
• Viral Infection
• Adverse drug side effect
• Chronic sunlight exposure

Addison’s Disease

• Genetics
• Breed disposition to the disease (Standard Poodle, West Highland Terriers, Great Danes, Bearded Collies, Portuguese Water Dogs and Soft Coated Wheaten Terriers)
• Metastatic tumor
• Adverse reaction to medications

Inflammatory Bowel Disease

• Genetics
• Infectious agents
• Nutrition

The veterinarian will want to go over your companion’s medical history.  Please inform the doctor if your pet is currently taking any medications.  The veterinarian will want to know what symptoms you have observed, when they began and what the progression has been.

The veterinarian will perform a physical examination on your dog.  He may take the patient’s weight, temperature, pulse and heart rate. He may palpate the limbs, lymph nodes and abdomen area.

He will recommend a complete blood count (CBC), serum chemistry panel, urinalysis and a fecal exam. He may also suggest x-rays and an ultrasound.  If lupus is suspected, a skin biopsy may be taken to be examined by the pathologist. A blood test called the ACTH stimulation test may be done to confirm Addison’s disease.

If the x-rays showed bone loss, the doctor may want to extract synovial fluid from the affected joint. If your dog has rheumatoid arthritis the fluid may be thinner and cloudier than normal synovial fluid. 

If inflammatory bowel disease is suspected the doctor may schedule an endoscopy or exploratory surgery. During the procedure, the doctor will also obtain a biopsy sample of the intestine.

Dogs that are diagnosed with autoimmune diseases will be prescribed immunosuppressive drugs such as corticosteroids.  Antioxidants may be recommended to help the patient lower free radicals and oxidative stress.

Dogs that have inflammation of the joints may be prescribed NSAIDs.  Patients with a severe onset of canine systemic lupus erythematosus may need to be hospitalized until their condition is stabilized. Dogs with systemic lupus may require chemotherapeutic treatments to help suppress the immune system and to help manage the pain of SLE.

Patients with inflammatory bowel disease will be placed on a low fat diet and may be prescribed probiotics.  Overweight dogs diagnosed with rheumatoid arthritis will need to lose weight.  Less weight will cause less stress on the joints.

Most diseases caused by an overactive immune system have no cure.  They can be treated to improve the quality of life of the dog.  Follow-up visits are required to monitor the patient’s condition. 

It is important to follow the veterinary team’s treatment plan for your dog.  Please call the veterinarian‘s office if your dog shows any adverse reactions to prescribed medication.