5 Common Autoimmune Diseases in Elderly Dogs

Autoimmune diseases occur when a dog's immune system mistakes healthy cells for harmful ones and launches an attack. These conditions can appear at any age but are common in middle-aged dogs. Elderly dogs are also at risk since they're more likely to contract illnesses that weaken their immune systems. Some breeds are predisposed to autoimmune diseases.

There are 2 types of autoimmune diseases in dogs: primary and secondary. Primary autoimmune diseases have no apparent or underlying cause. Secondary autoimmune diseases are the result of another condition.

Let's take a look at the symptoms, causes, and treatments for the 5 most common autoimmune diseases in dogs.

Pemphigus foliaceus is a type of pemphigus, a group of autoimmune diseases that affect the skin. Pemphigus foliaceus is the most common autoimmune condition in dogs.

This disease causes ulcers, blisters, and sores that are typically localized to the face, ears, and paw pads. Over time, the sores can spread across the body. Although it's common in middle-aged dogs, it can occur at any age.

Symptoms

• red patches
• skin ulcers
• lethargy
• loss of appetite
• fever
• excessive scratching

Causes

Pemphigus foliaceus occurs when the immune system attacks the bonds that hold together skin cells called keratinocytes. These cells form most of the epidermis, the outermost layer of skin. Keratinocytes are essential for:

• skin repair
• protecting the body from UV radiation
• warding off infections and foreign bodies
• regulating body temperature
• preventing water loss

There are 2 main types of pemphigus foliaceus: natural and drug-induced.

Natural pemphigus foliaceus occurs in dogs predisposed to the disease due to their breed or genetic makeup. Border Collies, Akitas, Chow Chows, and Newfoundlands are predisposed to the natural form.

The drug-induced form of pemphigus foliaceus is often a side effect of certain drugs, namely antibiotics. Doberman Pinschers and Labrador Retrievers are more prone to the drug-induced form.

Some cases of pemphigus foliaceus have no apparent cause.

Diagnosis

First, your vet will examine your dog's ulcers. Tell your vet if your dog has experienced other symptoms or is taking any medications (including over-the-counter drugs). Your vet can confirm pemphigus foliaceus using 2 methods: taking a biopsy or examining skin cells under a microscope.

Treatment

Suppressing the body's immune response is key to treating pemphigus foliaceus in dogs. Corticosteroids and other immunosuppressants are often the first line of defense. Your vet may prescribe prednisone, cyclosporine, azathioprine, or other drugs. If your dog is diagnosed with a drug-induced form, your vet will recommend that your dog discontinues the drug. They may also suggest an alternative.

Most dogs typically require long-term treatment for pemphigus foliaceus. Your vet will schedule follow-ups to monitor your dog's condition.

Average cost of treatment: $300–$2,000

Immune-mediated hemolytic anemia (IMHA) occurs when a dog's immune system starts attacking its own red blood cells. The dog's body continues to produce red blood cells, but they don't survive as long as red blood cells in healthy dogs. Certain breeds and middle-aged female dogs are predisposed to IMHA.

Symptoms

• blood in the urine or feces
• pale gums
• lethargy
• exercise intolerance
• jaundice
• fainting
• rapid heartbeat
• shallow breathing
• vomiting
• loss of appetite

Causes

The main cause of hemolytic anemia is an overactive immune system. This disease can be primary, with no underlying cause, or secondary to other conditions, including neoplasia, infections, snakebites, and reactions to drugs and vaccines. The primary form of IMHA is most common, accounting for up to 75% of cases.

In dogs with secondary hemolytic anemia, another disease typically changes the surface of the red blood cells, causing the body to view them as foreign invaders. The immune system then launches an attack on the altered red blood cells. Neoplasia and cancer are the most common causes of secondary hemolytic anemia.

Diagnosis

Your vet can confirm immune-mediated hemolytic anemia using several methods:

• Coombs test
• full biochemical profile
• complete blood count
• urinalysis
• x-rays
• other tests to identify potential causes

A positive Coombs test will show antibodies located on the surface of your dog's red blood cells. These antibodies form as part of the immune response.

The blood sample may show abnormally shaped red blood cells, clumps of red blood cells, or elevated levels of bilirubin, a byproduct of red blood cell breakdown.

Treatment

Treatments for IMHA will vary depending on the underlying causes and severity of the disease. Dogs with primary IMHA usually respond well to corticosteroid therapy. Severe cases of IMHA will typically require blood transfusions.

For secondary hemolytic anemia, other treatments can address the underlying cause. Chemotherapy, radiotherapy, and surgery are common treatments for dogs with cancer.

Your dog's prognosis will vary based on the presence and severity of underlying disease. The prognosis is worse for dogs with certain signs, including high levels of bilirubin, leukocytes, or blood urea nitrogen.

Average cost of treatment: $500–$8,000

Immune-mediated polyarthritis (IMPA) occurs when the body's immune system attacks the lining of multiple joints, causing pain and inflammation. Commonly affected joints are located in the legs and elbows.

There are 2 main types of IMPA in dogs: non-erosive and erosive. In erosive IMPA, the immune response destroys the bones and cartilage. Erosive IMPA is extremely rare, accounting for less than 1% of cases.

Symptoms

• reluctance or inability to walk
• loss of coordination
• changes in gait
• swollen joints
• limping
• fever
• pain
• lethargy
• loss of appetite
• vomiting
• diarrhea

Causes

The causes of IMPA are split into 4 main groups:

• Type I: Idiopathic (no apparent cause)
• Type II: Secondary to an infection elsewhere in the body
• Type III: Secondary to a gastrointestinal condition (like inflammatory bowel disease)
• Type IV: Secondary to neoplasia

Primary non-erosive IMPA (type I) is most common, accounting for up to 83% of all cases. While certain breeds, including Shar-Peis, Beagles, and Akitas, are predisposed to IMPA, experts note that some breeds are overrepresented in studies.

Other causes of IMPA include vaccinations and medications (specifically sulfonamide antibiotics). Sometimes, IMPA occurs alongside other autoimmune diseases, including hemolytic anemia and thrombocytopenia. In this case, dogs are diagnosed with and treated for systemic lupus erythematosus.

Diagnosis

To confirm IMPA and identify the cause, your vet will conduct a series of tests, including:

• blood work
• urinalysis
• physical exam
• x-rays of the legs
• ultrasounds
• joint taps

An article in Today's Veterinary Practice noted that IMPA can be tricky to diagnose due to the variety of possible symptoms. Up to 25% of dogs don't experience joint pain or swelling.

Treatment

The treatment for IMPA will vary depending on the cause and type.

Immunosuppressants are usually prescribed to treat primary non-erosive IMPA (the most common type). However, your vet typically won't start immunosuppressive therapy until underlying causes are completely ruled out.

Opioids and other non-NSAID pain relievers will reduce pain in the short term until the test results come back. Fortunately, immunosuppressants usually work quickly and effectively, improving or even resolving symptoms in as little as 24 hours.

Dogs with IMPA that's secondary to a bacterial infection will require antibiotics and other treatments to eradicate the infection. Treatments for IMPA that's secondary to a gastrointestinal condition like inflammatory bowel disease include dietary changes, anti-inflammatory medications, and vitamin supplements. For cases that are secondary to medications or vaccinations, symptoms may clear up on their own.

Secondary erosive IMPA is also treated with immunosuppressants and pain relievers. However, treatment often continues throughout the dog's life. Some dogs may require physiotherapy or surgery.

Average cost of treatment: $800–$4,000

Keratoconjunctivitis sicca (KCS) occurs when the body's immune system attacks cells within the eye glands, causing chronic inflammation of the cornea and lacrimal gland. Dogs diagnosed with KCS don't produce as many tears as healthy dogs. The fluid layer that protects and lubricates the eye is also reduced. Like other autoimmune diseases, KCS can be primary, with no apparent cause, or secondary to another condition. Primary KCS is more common.

Symptoms

• red eye
• excessive blinking
• pawing or scratching at the eyes
• swollen eyelids
• sensitivity to light
• yellow discharge
• reduced vision
• a dark film covering the eyes (indicates corneal scarring)

Causes

Experts don't know much about what might cause a dog's immune system to attack the tear glands. Some breeds are more likely to develop KCS, including:

• Spaniel breeds
• Terrier breeds
• Shih Tzus
• Pugs
• Bloodhounds

Diagnosis

Dry eye is commonly misdiagnosed as bacterial conjunctivitis. Your vet may conduct the following tests to confirm the diagnosis and identify the cause:

• physical exam
• corneal staining
• Schirmer tear test
• intraocular pressure
• tear duct exam

Treatment

Dogs with KCS require long-term and even lifelong treatment to increase tear production and restore the eye's tear film. Cyclosporine ophthalmic ointment is effective in reducing inflammation and increasing tear production. Studies show that more than 80% of dogs respond well to cyclosporine, but those that don't may respond to tacrolimus eyedrops instead.

Tear film replacement medications can keep the eye lubricated until tear stimulants start working. A variety of tear replacement medications for dogs are available. Most will need to be applied frequently, every 2 to 6 hours. Some longer-lasting tear replacement drugs can increase the debris that accumulates in the eyes. Unfortunately, certain preservatives found in many tear film replacement medications for dogs can worsen pain. Your vet can recommend the right option for your dog's needs.

Average cost of treatment: $200–$2,000

Immune-mediated thrombocytopenia occurs when the immune system attacks the platelets (also called thrombocytes). Platelets are created in the bone marrow and assist blood clotting.

Certain breeds are predisposed to immune-mediated thrombocytopenia, including Cocker Spaniels, Toy Poodles, and Golden Retrievers. This condition is more likely to affect female dogs.

Symptoms

• low platelet count
• weight loss
• lethargy
• fever
• bruises on the skin
• nosebleeds
• blood in the urine or gums
• hemorrhaging of the eye

Causes

There are 2 types of thrombocytopenia: primary and secondary. The primary form has no apparent cause. Common causes of secondary immune-mediated thrombocytopenia include:

• cancer
• infection, specifically tick-borne diseases
• medications (including sulfonamide antibiotics)
• vaccinations
• bone marrow disorders
• other immune diseases, including hemolytic anemia and polyarthritis

Diagnosis

When making a diagnosis, your vet will examine your dog and consider their medical history. Several tests can confirm the diagnosis and identify (or rule out) potential causes, including:

• platelet count
• blood smear
• bone marrow aspiration
• urinalysis
• ultrasounds

Treatment

Immunosuppressants, namely prednisolone, are typically the first line of defense. Dogs that don't respond well to prednisolone may be prescribed other corticosteroids.

Adequate supportive care is essential — your vet may recommend placing your dog on bed rest, limiting their exercise, and avoiding activities that may cause bleeding.

Vincristine, a chemotherapeutic drug that can increase platelet counts, may be given to dogs with immune-mediated thrombocytopenia that's secondary to cancer. Intravenous therapy with immunoglobulin can increase platelet counts in dogs with severe symptoms. Blood transfusions may be required for dogs with significant blood loss or extremely low platelet counts.

Most dogs with idiopathic immune-mediated thrombocytopenia respond well to immunosuppressive therapy. However, the condition recurs in up to 31% of dogs.

Average cost of treatment: $2,000–$15,000