What is Immune-Mediated Polyarthritis

What is Immune-Mediated Polyarthritis?

Of late, there has been a surge in dogs suffering from immune-mediated polyarthritis. This post defines the disease and lists the symptoms, causes, and treatment methods available.

Read on to learn more.

What is immune-mediated polyarthritis?

Canine immune-mediated polyarthritis, or simply (IMPA), is a form of arthritis that arises when a mutt's immune system becomes overly stimulated, resulting in inappropriate inflammatory responses in one or multiple joints.

The condition is also called idiopathic immune-mediated polyarthritis.

When a dog's joint's lining becomes inflamed, it increases the concentration of white blood cells inside the joint fluid. The excess white blood cells cause pain and swelling.

Like many other immune-related diseases, female dogs are at a higher risk of suffering from the disease.

Additionally, IMP can affect all dog breeds at different ages, but it primarily affects middle-aged pooch's.

Symptoms of canine immune-mediated polyarthritis

What makes IMP deadly is that it has symptoms similar to those of other diseases. Hence, it's not easy to identify. 

Even so, below are some common symptoms associated with IMPA.

  • Diarrhea 
  • Malaise
  • Anorexia
  • Lethargy
  • Difficulty standing or walking 
  • Lameness
  • Fever
  • Vomiting 
  • Enlarged lymph nodes

Types of dog Immune-mediated polyarthritis 

There are two primary types of IMPA, namely.

  • Erosive IMPA – indicates damage to a dog's cartilage or bones
  • Non-erosive IMPA – reveals zero damage to your furry friend's cartilage.

In addition, there are four other subtypes of IMPA, including Type 1, Type 2, Type 3, and Type 4.

Let's look at the features of each 

Type 1

Prevalent than all the other forms of IMPA. It is responsible for about 55% of the canine deaths caused by the disease.

Type 2

Usually arises when a dog suffers from diseases like;

  • Dermatitis 
  • Mastitis
  • Chronic salmonellosis
  • Pneumonia
  • Pleuritis 
  • Pharyngitis 
  • Diskospondylits 
  • Bacterial tonsillitis 
  • Pancreatitis
  • Endocarditis
  • Bacterial prostatitis

Type 3

It mostly appears alongside chronic stomach infections such as:

  • Bacterial overgrowth
  • Eosinophilic
  • Intestinal malabsorption
  • Ulcerative colitis
  • Lymphocytic – plasmacytic hepatitis

Type 4

Caused by abnormal or cancerous cells in a dog's body like:

  • Leiomyoma
  • Squamous cell carcinoma
  • Seminoma

Causes of canine immune-mediated polyarthritis

Type 1

It doesn't have a known cause and can affect any dog breed at any age.

Type 2

Studies show the IMPA mainly originates from:

  • Viral infections
  • Bacterial infections
  • Fungal infections

Type 3

Caused by stomach, intestinal, or liver failure issues. Studies have also shown that it's rare since out of 100% of dogs with IMPA, only 3 or 4 percent will have type 3 IMPA.

Type 4

Regarded by veterinary doctors as the rarest form of IMPA, its primarily caused by massive cell growth outside a dog's joints.

Other causes of IMPA

Dog breed

Numerous studies show that some dog breeds have a high chance of encountering IMPA at one stage in their lives.

These breeds include; Beagle, spaniel, Akita, Boxer, Chinese Shar-Pei, German shorthaired pointer, and Bernese Mountain.


Certain drugs given by veterinary doctors to treat different diseases could trigger IMPA in your canine as a side effect.

Often symptoms of IMPA may start appearing 10 or 20 days after administration of the drug.

These medications are;

  • Lincomycin
  • Penicillin
  • Cephalosporins
  • Erythromycin
  • Sulfonamides
  • Phenobarbital 

Furthermore, some vaccines can also cause IMPA, particularly if you unknowingly let your furry friend get the same vaccine twice.

Diagnosis of canine immune-mediated polyarthritis 

Once you notice your loyal friend has unexplainable discomfort, pain, or trouble walking, you should visit your veterinarian.

At the vet clinic, your vet will perform a comprehensive physical exam on your mutt to assess the exact places that are swollen or painful.

After the examination, doctors usually want to know your dog's health history, such as recent vaccinations, medicinal changes, injuries, or exposure to items that could cause such symptoms.

Veterinary doctors may also carry out extensive tests to find the exact cause of IMPA; these tests include

  • Biochemical profile
  • Culture and sensitivity urinalysis
  • Abdominal and chest x-rays
  • Complete blood test (CBC)
  • Xray of the painful joints 
  • Titers of infectious diseases like Ehrlichia, rocky mountain fever, and Lyme disease

Before you head out to the vet clinic, you must collect plenty of information on your dog to ease the vet's work.

Observe your dog's specific symptoms, how long they last and how often they appear. 

Also, tell your doctor when the symptoms become severe and what activities trigger them. 

When you provide detailed and accurate information, your vet doctor will know the measures to take to treat the condition.

How to treat immune-mediated polyarthritis

Unfortunately, immune-mediated polyarthritis isn't curable; instead, vet doctors provide medications to manage your mutts' symptoms. 

These drugs will help a dog live a pain-free, happier life when adequately utilized.

There are two categories of medications vets use to manage IMPA symptoms. 

  • Immunosuppressive drugs
  • Chemotherapeutic drugs

The immunosuppressive medications are typically anti-inflammatory, like corticosteroids (prednisone). 

Your vet doctor will administer these medications alongside chemotherapeutic drugs like cyclophosphamide, azathioprine, and leflunomide.

It's worth noting that long-term intake of corticosteroids is detrimental to a dog's health, for it may cause urinary tract infections, hyperadrenocorticism, and diabetes.

Furthermore, if your furry friend takes azathioprine, your doctor must conduct regular liver enzyme checks since the drug can cause cystitis.

Due to the drug cyclophosphamide's immense side effects, doctors will administer it for only four months, but they can put your dog on azathioprine for longer.

Even though immunomodulation drugs that regulate your puppy's immune system will lessen pain from IMPA, especially when the dog has a relapse. These drugs have serious side effects like 

  • Anemia
  • Constant agitation
  • Lethargy
  • Vomiting
  • Diarrhea 

Your vet doctor will recommend giving your canine immunosuppressive drugs for 2 or 4 months while she checks on the progress.

If your furry friend responds positively to the drugs, the vet will start cutting down the medications over the next 3 or 4 months.

Pay close attention to your pups' behavior when your vet lessens the medications.

That's because studies show up to 75% of dogs with IMPA tend to relapse after four or five months of medication.

It's not all sad news; some reports show that 54% of canines with IMPA live for up to 6 six years without developing severe complications.

Home care and recovery

Mutts usually respond quickly to treatment; however, relapses can occur significantly when your vet reduces the drug dosage.

Therefore, you must regularly monitor your pet for any deterioration or improvement.

If your canine is on immunosuppressive medication, you will need to schedule regular vet visits so he can check for any potential side effects.

Initially, doctors recommend that your dog gets mandatory rest so as not to stress the already aching joints, but as the symptoms lessen, the dog can resume usual activities.

Currently, experts are yet to identify measures that can prevent the occurrence of canine immune-mediated polyarthritis.

However, veterinary doctors say specific steps can fasten a dog's recovery and reduce the chances of relapse. For instance;

Healthy diets

A dog's immunity revolves around what it eats. That's because the food provides the minerals needed to fight diseases and infections.

Earlier, we learned that type 2 and 3 IMPA arise from bacterial infections and liver failure, respectively.

You prevent such by feeding your dog a wholesome diet containing all the essential nutrients. 

Additionally, it's good to keep off dog food containing artificial additives. Regular consumption of these chemicals strains your dog's liver as it's the primary detoxification organ.

Experts have also found that supplementing your pet's diet with medicinal mushrooms can offer plenty of benefits to dogs with IMPA.

For example, Immune Defense from Northern Cascades contains medicinal mushrooms that will

  • Relive pain
  • Enhance liver function, reducing chances of liver failure
  • Increase endurance 
  • Heighten immune system function. Consequently, your dog won't fall sick easily.
  • Improve digestion. A fast and efficient digestive system means more nutrient absorption and a robust immune system.
  • Balance blood sugar levels
  • Increase stamina and energy 
  • Provides antioxidants

For pet parents whose dogs are recovering from IMPA, the Immune Defense Supplement is a must-have.

Final word

It may be saddening when you notice your loyal furry friend has immune-mediated polyarthritis symptoms, and the vet confirms it.

Luckily, some drugs can help ease your dogs' symptoms and fasten recovery.

Ensure you administer the drugs exactly how your vet advised, feed a healthy diet and schedule regular clinic visits. After a few months, your dog will be jumping around solid and healthy.