Immune-mediated polyarthritis in dogs
In immune-mediated polyarthritis, the dog's defence system attacks its own joints. Several joints become inflamed at the same time, most often the wrists and hocks. The dog has fever, appears depressed, limps on one leg and then another, wa...
What is it?
In immune-mediated polyarthritis, the dog's defence system attacks its own joints. Several joints become inflamed at the same time, most often the wrists and hocks.
The dog has fever, appears depressed, limps on one leg and then another, walks stiffly or refuses to move.
The disease may appear on its own with no identifiable cause, or be triggered by an infection elsewhere in the body, a medication, chronic intestinal disease, or cancer.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Lameness that shifts from one leg to another day to day, or affects several legs at once.
Stiffness, shortened stride, especially when getting up.
Refusal to move, climb stairs, or jump; in severe cases, the dog remains lying down and will not stand.
Joint pain when bent, sometimes swollen and warm, particularly the wrists and hocks.
Fever, depression, loss of appetite.
Swollen lymph nodes in some dogs.
Weight loss if the disease persists.
Signs may come and go, with periods of improvement.
In some dogs, fever and depression are the main signs and limping is barely noticeable.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The disease results from an abnormal immune system reaction that causes inflammation in several joints.
Most often, no cause is found: this is called the idiopathic form.
In other cases, the reaction is triggered by an infection elsewhere (urinary, respiratory, dental, skin), by a medication, by chronic intestinal disease, or by cancer.
It may also be part of a more generalised autoimmune disease, such as lupus.
It is not an infection of the joint: the joints are inflamed, but no microbe is present in them.
Recent infection elsewhere in the body.
Recent administration of a medication, for example certain antibiotics from the sulfonamide family.
Known chronic intestinal disease or cancer.
The disease often affects young adult to middle-aged dogs.
Exposure to ticks or sand flies does not cause this disease, but it means tick-borne diseases and sand fly-borne diseases should be investigated first, as they produce very similar signs.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Your vet will examine each joint, take your dog's temperature, and palpate the lymph nodes.
The key examination is joint fluid sampling from several joints under sedation: the fluid is analyzed under a microscope and shows the inflammation.
Blood tests, urine analysis, and X-rays look for a triggering cause and check the condition of the joints.
Before any treatment that slows the immune system, your vet will screen for tick-borne diseases (ehrlichiosis, anaplasmosis) and leishmaniosis, which are present in Tunisia: these produce a very similar picture and are treated completely differently.
Your vet will also distinguish this condition from osteoarthritis, young dog panosteitis, and spinal pain.
Treatment
When a cause is found, treating it or stopping the responsible medication may be enough to make the signs disappear.
In the idiopathic form, treatment relies on medications that calm the immune system, prescribed by your vet. Treatment typically lasts from several weeks to several months, with very gradual reduction.
Other immunosuppressive drugs can be added if the response is insufficient or if side effects become troublesome.
Regular check-ups, sometimes with new joint fluid samples, guide how long treatment should continue.
Never stop treatment abruptly on your own, and never give human anti-inflammatory medication to your dog: some are toxic and they can be dangerous when combined with prescribed treatment.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
There is no specific prevention for the idiopathic form.
Regular protection against ticks and sand flies, tailored by your vet, reduces the risk of the diseases they carry, which are both possible causes and conditions to rule out.
Have infections treated, especially dental and urinary infections.
Tell your vet about any recent medication when your dog begins to limp with fever.
Possible complications
Relapses, which are frequent when treatment is stopped or reduced.
Side effects from prolonged immune-suppressing treatments, monitored by your vet.
Persistent joint damage in some cases, with lasting stiffness.
Muscle wasting in a dog that moves little for a long time.
When to see a veterinarian
Your dog has fever and refuses to get up at all: see your vet the same day.
Your dog limps from one paw, then another, or from several paws at once.
Your dog walks stiffly, in short steps, or refuses to climb stairs or jump.
Your dog's wrists or hocks are swollen, warm, or painful when bent.
Your dog is lethargic, eating less, and feels warm, with no obvious cause.
Your dog has had ticks recently and begins to limp with fever.
Your dog's signs return during treatment reduction.
Prognosis
Most dogs respond well to treatment and return to a normal life.
Relapses are frequent, which requires regular follow-up and sometimes prolonged treatment.
The prognosis also depends on the triggering cause when there is one, for example cancer.
Frequently asked questions
How do you distinguish it from osteoarthritis?
Osteoarthritis mainly affects the older dog, develops slowly, causes stiffness when rising that improves with walking, and does not cause fever. Immune polyarthritis can affect a younger dog, appears more rapidly, is often accompanied by fever and lethargy, and causes limping that shifts from one leg to another.
My dog had ticks and is limping with fever: is it this disease?
Not necessarily, and that's precisely what should be ruled out first. Ehrlichiosis, anaplasmosis, and leishmaniasis, which are present in Tunisia, can produce exactly the same signs. The veterinarian searches for them through a blood test before prescribing treatment that suppresses the immune system.
What about back or neck pain?
A herniated disc causes a hunched back, a dog crying out when lowering its head or when its back is touched, generally without fever or swollen joints. In polyarthritis, the pain comes from the legs, particularly the wrists and hocks.
Is the treatment for life?
Not always. Many dogs can stop treatment after several months by tapering it very gradually. But relapses are frequent, and some dogs require prolonged treatment.
References
Content reviewed by the TunisieVet editorial team · Updated 10 October 2026
Comments (0)
No comments yet.
AT A GLANCE
Need a veterinarian?
Find a practitioner near you on TunisieVet, with their specialities, hours and contact details.
Find a veterinarianCategories
Affected species
This information is provided for educational purposes only and is not a substitute for a veterinary consultation. If you have any concerns about your animal's health, consult a veterinarian.
Thinking of welcoming a pet? Dogs and cats are waiting for a family in Tunisia, and adoption is completely free.
Adoption listingsOn the TunisieVet marketplace
Food, hygiene and accessories for dog, sold by verified shops and delivered across Tunisia.
Buying advice, not medical advice: for a diagnosis or treatment, consult your veterinarian.
To discover
Related diseases and linked Animalia content.
Canine parvovirus
Viral · Vaccine available
Canine distemper
Viral · Vaccine available
Kennel cough
Viral · Vaccine available
Canine leishmaniasis
Parasitic
