# Joint Fluid Analysis in Dogs: Diagnosing Septic Arthritis vs Immune-Mediated
## Key Takeaways
- Joint fluid analysis is the definitive diagnostic tool to differentiate septic arthritis (bacterial infection) from immune-mediated polyarthritis (IMPA) by evaluating cell counts, cell types, and the presence of bacteria. Septic arthritis typically presents with very high total nucleated cell counts (>50,000 cells/µL) dominated by degenerate neutrophils, often with visible bacteria or positive culture, whereas IMPA shows elevated counts (>10,000 cells/µL) with neutrophils (nonerosive) or mononuclear cells (erosive) and negative bacterial cultures.
- Septic arthritis requires immediate broad-spectrum antibiotic therapy and often joint lavage to remove bacteria and inflammatory debris, aiming to prevent permanent joint damage; early intervention is critical for a good prognosis. IMPA, conversely, is managed with immunosuppressive drugs, primarily corticosteroids like prednisolone, to suppress the immune system's attack on joint tissues, with adjunctive therapies considered for refractory cases.
- While both conditions can cause lameness, joint swelling, pain, and fever, septic arthritis is typically monoarticular (affecting one joint) and has a sudden, severe onset, whereas IMPA is often polyarticular (affecting multiple joints) and can have a more gradual or shifting presentation.
- Diagnostic procedures include physical examination, baseline bloodwork (e.g., CRP for inflammation), and imaging (radiographs to assess bone damage), but arthrocentesis (joint fluid sampling), potentially guided by ultrasound for improved accuracy, is essential for definitive diagnosis.
- Untreated septic arthritis can lead to rapid joint destruction and systemic sepsis, making prompt veterinary intervention paramount; delaying treatment for IMPA can result in chronic joint damage and potential relapses.
---
When a [dog](/knowledge/veterinary-medicine/clinical-methods/dog) arrives at the clinic with a sudden limp, swollen joints, or a fever, the list of possible causes is long. Trauma, tick-borne disease, osteoarthritis, and cancer can all look similar at first glance. But when multiple joints are painful or when the lameness shifts from one leg to another, the veterinary team must quickly separate two very different conditions: septic arthritis, caused by bacteria inside the joint, and immune-mediated polyarthritis (IMPA), caused by the dog's own immune system attacking the joint lining.
The single most useful test for making this distinction is joint fluid analysis, also called synovial fluid analysis or arthrocentesis. This procedure examines the fluid that lubricates the joint, looking at cell counts, cell types, and the presence of bacteria or abnormal proteins. The results determine whether the dog needs antibiotics, immune-suppressing drugs, or both.
This article explains what joint fluid analysis involves, how veterinarians interpret the results, and why the distinction between septic arthritis and IMPA matters for treatment and recovery. It also covers what owners can expect during the diagnostic process, including newer techniques that improve accuracy.
## At a Glance: Septic Arthritis vs Immune-Mediated Polyarthritis
| Feature | Septic Arthritis | Immune-Mediated Polyarthritis (IMPA) |
|--|--|--|
| **Cause** | Bacterial infection within the joint space | Immune system attack on joint tissues |
| **Typical onset** | Sudden, often severe lameness | May be sudden or gradual; can shift between legs |
| **Number of joints** | Usually one joint (monoarthritis) | Often multiple joints (polyarthritis) |
| **Joint fluid appearance** | Cloudy, yellow to green, sometimes bloody | Cloudy, yellow to orange |
| **Total nucleated cell count (TNCC)** | Very high, often >50,000 cells/µL | High, often >10,000 cells/µL |
| **Predominant cell type** | Neutrophils, often degenerate | Neutrophils (nonerosive) or mononuclear cells (erosive) |
| **Bacteria on cytology** | May be visible | Absent |
| **Bacterial culture** | Often positive | Negative |
| **Treatment** | Antibiotics, joint lavage | Immunosuppressive drugs (corticosteroids, etc.) |
| **Prognosis** | Good with early treatment | Good to guarded; relapses possible |
## Why Joint Fluid Analysis Matters
Joint fluid analysis is not a home diagnostic test. It requires a veterinary visit, sedation or anesthesia, and a laboratory equipped to handle cytology. However, understanding what the test does and why it is ordered helps owners make informed decisions when their dog is limping or showing signs of joint pain.
The synovial fluid that fills a healthy joint is a clear, viscous liquid that serves two purposes: it lubricates the cartilage surfaces and it nourishes the cells within the joint. In a healthy dog, this fluid contains very few cells, usually fewer than 3,000 nucleated cells per microliter, and the cells present are mostly mononuclear cells (lymphocytes and macrophages) [1]. When disease strikes, the composition of this fluid changes dramatically.
Inflammatory joint diseases, whether infectious or immune-mediated, cause white blood cells to flood into the joint space. The type and number of these cells, along with the presence of bacteria or other markers, tell the veterinarian what kind of inflammation is happening. Without this analysis, treating a septic joint with immunosuppressive drugs would be dangerous, and treating IMPA with antibiotics alone would be ineffective.
## Understanding the Anatomy and Physiology of the Joint
Joints are complex structures where two or more bones meet. The ends of the bones are covered with smooth cartilage, and the entire joint is enclosed in a capsule lined by a membrane called the synovium. This membrane produces synovial fluid, which fills the joint space.
The synovium is highly vascular and responds quickly to inflammation anywhere in the body. This is why joint disease can accompany systemic conditions like tick-borne infections or immune disorders. The synovial membrane also acts as a barrier, keeping bacteria and other pathogens out of the joint under normal circumstances. When this barrier is breached, either by direct trauma, blood-borne spread, or immune dysfunction, the joint becomes inflamed.
The composition of synovial fluid reflects the health of the synovium and the joint as a whole. In health, the fluid is thick and stringy due to the presence of hyaluronic acid. In disease, enzymes released by inflammatory cells break down this hyaluronic acid, making the fluid thin and watery. This change, along with the cellular changes, forms the basis of joint fluid analysis [1].
## Causes of Inflammatory Joint Disease in Dogs
Inflammatory joint disease in dogs falls into two broad categories: infectious (septic) and noninfectious (immune-mediated).
### Septic Arthritis
Septic arthritis occurs when bacteria enter the joint space. This can happen through:
- **Direct penetration**: Wounds, bites, or foreign bodies that breach the joint capsule
- **Iatrogenic introduction**: Contamination during joint surgery or injection
- **Hematogenous spread**: Bacteria traveling through the bloodstream from an infection elsewhere in the body
Common bacterial isolates include *Staphylococcus*, *Streptococcus*, and *Escherichia coli*. In some regions, tick-borne organisms like *[Anaplasma phagocytophilum](/knowledge/bacteria/pet-bacteria/anaplasma-phagocytophilum)* can cause joint inflammation that mimics septic arthritis, although these are technically not "septic" in the classic sense [2].
### Immune-Mediated Polyarthritis (IMPA)
IMPA is the most common inflammatory joint disease in dogs and results from the immune system mistakenly attacking the synovial membrane [3]. The exact trigger is often unknown, but it can be:
- **Primary (idiopathic)**: No underlying cause identified
- **Reactive**: Triggered by an infection elsewhere, a drug reaction, or a vaccination
- **Associated with other immune diseases**: Such as systemic lupus erythematosus
IMPA is generally divided into two forms based on joint radiographs and fluid analysis:
- **Nonerosive IMPA**: The most common form, characterized by neutrophilic inflammation in the synovial fluid and no bone damage on radiographs [4]
- **Erosive IMPA**: A less common but more destructive form, characterized by bone erosion visible on radiographs and a predominance of mononuclear cells in the joint fluid [4]
A 2026 case report described a miniature dachshund with erosive IMPA whose synovial fluid contained mostly mononuclear cells, with a significant expansion of CD8+ cytotoxic T cells [4]. This finding suggests that different immune mechanisms drive erosive versus nonerosive forms of the disease, which may have implications for treatment [4].
### Other Causes of Joint Inflammation
Not all joint inflammation is septic or immune-mediated. Osteoarthritis, while primarily a degenerative disease, does have an inflammatory component. The synovial fluid in osteoarthritic joints typically has a lower cell count than in septic arthritis or IMPA, but inflammatory markers may still be elevated [5][6].
Infectious diseases such as canine visceral leishmaniasis can also cause joint inflammation. A study of 89 dogs with leishmaniasis found that over half of the joints sampled had inflammatory infiltrates, although the severity varied [7].
## Clinical Signs: When to Suspect Joint Disease
Dogs with inflammatory joint disease typically present with one or more of the following signs:
- **Lameness**: May affect one leg or shift between legs
- **Stiffness**: Especially after rest
- **Joint swelling**: Visible or palpable effusion
- **Pain on joint manipulation**: Reluctance to move or vocalization when touched
- **Fever**: Often present in both septic arthritis and IMPA
- **Lethargy and reduced appetite**: Common in systemic inflammation
- **Difficulty rising or climbing stairs**
A 2025 study of 81 dogs with elevated C-reactive protein (CRP) and gait abnormalities found that 25% were diagnosed with polyarthritis [8]. Half of these dogs did not show obvious gait-related signs, highlighting the importance of considering joint disease even when lameness is not the primary complaint [8].
## The Diagnostic Approach: From Physical Exam to Arthrocentesis
When a veterinarian suspects inflammatory joint disease, the diagnostic workup typically proceeds in stages.
### Step 1: Physical Examination and History
The veterinarian will perform a full physical examination, paying close attention to each joint. They will palpate for swelling, heat, and pain, and assess the range of motion. A history of tick exposure, recent illness, vaccination, or medication use may provide clues.
### Step 2: Baseline Bloodwork and Imaging
Blood tests can reveal systemic inflammation, as indicated by elevated CRP or white blood cell counts. Radiographs (X-rays) of the affected joints can show joint effusion, soft tissue swelling, and in erosive IMPA, bone destruction [4]. However, radiographs are often normal in early nonerosive IMPA.
### Step 3: Arthrocentesis (Joint Fluid Sampling)
Arthrocentesis is the definitive diagnostic step. The veterinarian inserts a needle into the joint space and aspirates a small amount of synovial fluid. This procedure is typically performed with the dog sedated or under brief anesthesia to ensure safety and comfort [9].
Ultrasound guidance is increasingly used to improve the accuracy of arthrocentesis, particularly for deep joints like the hip and shoulder [9][10]. A 2025 video tutorial from the *Journal of the American Veterinary Medical Association* demonstrated that ultrasound guidance helps avoid surrounding blood vessels and soft tissue structures, maximizes fluid yield, and reduces the number of needle attempts [9]. This is particularly valuable when only a small amount of fluid is present or when the joint is difficult to access [10].
Multiple joints are often sampled, even if only one appears painful. This is because IMPA frequently affects multiple joints, and sampling several joints increases the chance of obtaining diagnostic fluid. A 2025 study on coagulation status in dogs with IMPA noted that multiple joints were routinely sampled for synovial fluid analysis [11].
### Step 4: Synovial Fluid Analysis
The collected fluid is sent to a laboratory for analysis, which includes:
- **Gross examination**: Color, clarity, and viscosity
- **Total nucleated cell count (TNCC)**: The number of white blood cells per microliter
- **Differential cell count**: The percentage of different white blood cell types (neutrophils, lymphocytes, macrophages, etc.)
- **Cytology**: Microscopic examination of cells to look for bacteria, abnormal cells, or other findings
- **Bacterial culture and sensitivity**: Attempting to grow bacteria from the fluid and determine which antibiotics will be effective
Traditional manual cell counting methods are labor-intensive and can be imprecise. A 2026 study investigated whether pretreating synovial fluid with hyaluronidase and using an automated analyzer could improve accuracy [1]. The study found that hyaluronidase-treated automated cell counts showed the strongest agreement with manual counts for TNCC, with the highest precision [1]. For differential counts, the automated method performed well in samples with high cell counts but was less reliable in samples with low cell counts [1]. The hyaluronidase-treated manual method, however, provided consistent accuracy across all cell count levels and produced superior smear quality [1].
## Interpreting the Results: Septic Arthritis vs IMPA
The key to distinguishing septic arthritis from IMPA lies in the cell counts, cell types, and the presence or absence of bacteria.
### Total Nucleated Cell Count (TNCC)
- **Normal**: Less than 3,000 cells/µL
- **Osteoarthritis**: Mildly elevated, typically 3,000 to 10,000 cells/µL
- **IMPA**: Elevated, typically 10,000 to 50,000 cells/µL
- **Septic arthritis**: Markedly elevated, often exceeding 50,000 cells/µL
While a very high cell count suggests sepsis, there is overlap between septic arthritis and IMPA. A 2026 study on synovial fluid CRP found no significant difference in CRP levels between bacterial infective arthritis and IMPA groups, and synovial neutrophil counts were positively associated with CRP in both conditions [5]. This means that neither CRP nor cell count alone can reliably differentiate between the two [5].
### Differential Cell Count
- **Neutrophilic inflammation**: Both septic arthritis and nonerosive IMPA typically show a predominance of neutrophils, often exceeding 90% of the total cells [4]. In septic arthritis, these neutrophils may appear "degenerate," meaning they show signs of cell death and fragmentation.
- **Mononuclear inflammation**: Erosive IMPA may show a predominance of mononuclear cells (lymphocytes and macrophages) rather than neutrophils [4]. This was demonstrated in the 2026 case report of the miniature dachshund with erosive IMPA [4].
- **Mixed inflammation**: Osteoarthritis and other degenerative conditions may show a mix of cell types with a lower overall count.
### Bacteria on Cytology
The presence of visible bacteria within neutrophils or free in the fluid strongly supports a diagnosis of septic arthritis. However, bacteria are not always visible, especially if the dog has already received antibiotics. This is why bacterial culture is essential.
### Bacterial Culture
Culture of synovial fluid is the gold standard for diagnosing septic arthritis. However, culture results can take several days, and false negatives are possible, particularly in dogs that have received antibiotics. A 2024 study on leflunomide treatment for IMPA noted that synovial fluid microbial culture was performed as part of the diagnostic workup, but the study did not report positive cultures in the included cases [3].
### Additional Biomarkers
Research is exploring additional biomarkers to aid in diagnosis. Synovial fluid CRP has been studied as a potential discriminator between osteoarthritis, IMPA, and bacterial infective arthritis. A 2026 study found that synovial CRP was significantly lower in osteoarthritis compared to IMPA or bacterial infective arthritis, but it could not differentiate between the latter two conditions [5]. This means that while elevated synovial CRP confirms inflammation, it does not distinguish septic from immune-mediated disease [5].
## The Challenge of Overlapping Findings
The overlap between septic arthritis and IMPA creates a diagnostic challenge. A dog with a high neutrophil count and elevated CRP could have either condition. In some cases, the initial diagnosis is uncertain, and the veterinarian may need to start treatment for the more dangerous condition (septic arthritis) while waiting for culture results.
In rare cases, joint fluid analysis can reveal unexpected findings that mimic other diseases. A 2025 case report described a dog with acute anaplasmosis whose joint fluid cytology raised concern for large cell lymphoma [2]. Flow cytometry identified an aberrant population of CD4+ T cells, and PCR for antigen receptor rearrangement (PARR) confirmed clonal expansion [2]. However, the dog's clinical signs and joint fluid abnormalities resolved completely after treatment with doxycycline, confirming that the clonal T cell proliferation was a reactive response to the infection rather than true lymphoma [2]. This case highlights the importance of considering infectious causes before committing to a diagnosis of cancer or immune-mediated disease [2].
## Evidence-Based Management
Once the diagnosis is established, treatment differs dramatically between septic arthritis and IMPA.
### Treatment of Septic Arthritis
Septic arthritis is a medical emergency. Treatment involves:
- **Antibiotics**: Broad-spectrum antibiotics are started immediately, then adjusted based on culture and sensitivity results. The route (oral or injectable) and duration depend on the severity of the infection.
- **Joint lavage**: Flushing the joint with sterile saline to remove bacteria, inflammatory debris, and destructive enzymes. This is often done under anesthesia, sometimes repeatedly.
- **Pain management**: Nonsteroidal anti-inflammatory drugs (NSAIDs) or other analgesics to control pain and inflammation.
- **Surgery**: In severe cases, surgical debridement may be necessary to remove infected tissue.
Early and aggressive treatment is essential to prevent permanent joint damage. With prompt therapy, the prognosis for septic arthritis is generally good.
### Treatment of Immune-Mediated Polyarthritis
IMPA is managed with immunosuppressive drugs to dampen the immune system's attack on the joints.
- **Corticosteroids**: Prednisolone is the mainstay of initial therapy. Most dogs respond within days to weeks.
- **Adjunctive immunosuppressants**: Drugs like leflunomide, mycophenolate mofetil, or azathioprine may be added to allow a lower corticosteroid dose or to treat refractory cases.
A 2024 retrospective study of 93 dogs with IMPA in Australia compared treatment with prednisolone alone versus prednisolone plus leflunomide [3]. The study found no difference in relapse rates, mortality rates, time to relapse, or time to discontinue prednisolone between the two groups [3]. The authors concluded that adding leflunomide did not improve outcomes in this cohort [3]. This finding is important because leflunomide is frequently used as an adjunctive therapy, and the study suggests it may not provide additional benefit over prednisolone alone [3].
A 2026 case report described successful treatment of erosive IMPA in a dog with mycophenolate mofetil [4]. The dog's activity improved and synovial fluid leukocyte counts decreased, although bone erosion slowly progressed [4]. This suggests that mycophenolate may be a useful option for erosive IMPA, but it may not halt all disease progression [4].
### Monitoring and Prognosis
Dogs with IMPA require close monitoring, including repeat joint fluid analysis to assess treatment response. The goal is to find the lowest effective dose of immunosuppressive medication to minimize side effects while keeping the disease in remission.
The prognosis for IMPA is variable. Many dogs achieve remission and live comfortable lives, but relapses are common. A 2025 study on coagulation status in dogs with IMPA found that most dogs (84.2%) were normocoagulable, suggesting that routine anticoagulant therapy may not be necessary in all cases [11]. However, individual risk factors should be considered [11].
## The Role of C-Reactive Protein (CRP) in Monitoring
C-reactive protein is an acute-phase protein produced by the liver in response to inflammation. It is elevated in many inflammatory conditions, including joint disease.
A 2024 study examined sex differences in serum and synovial fluid CRP concentrations in healthy dogs [12]. The study found that synovial fluid CRP was consistently lower than serum CRP in both sexes, and there were significant differences between males and females for both measurements [12]. These findings suggest that sex-specific reference ranges may be needed when interpreting CRP results [12].
In dogs with joint disease, CRP can be used to monitor treatment response. A 2025 study on pentoxifylline in dogs with osteoarthritis found that serum CRP levels were lower in the pentoxifylline group on days 15 and 30 compared to the meloxicam group [13]. This suggests that CRP may be a useful biomarker for comparing treatment efficacy [13].
However, as noted earlier, CRP cannot distinguish between septic arthritis and IMPA [5]. It is a marker of inflammation, not a specific diagnostic test.
## Unsafe Home Remedies and What to Avoid
Owners may be tempted to try home remedies for their dog's joint pain, but some can be harmful or delay proper diagnosis.
- **Human NSAIDs**: Medications like ibuprofen or naproxen are toxic to dogs and can cause gastrointestinal ulcers and kidney failure. Never give human pain medication to a dog without veterinary approval.
- **Corticosteroids without a diagnosis**: Giving prednisone or other steroids before a definitive diagnosis can mask signs and interfere with diagnostic testing. It can also worsen a septic joint by suppressing the immune system.
- **Heat or cold therapy without guidance**: While these can be helpful in some situations, improper application can cause burns or worsen inflammation.
- **Delaying veterinary care**: Joint disease is painful, and delaying treatment can lead to permanent joint damage.
If a dog shows signs of joint pain, lameness, or fever, the safest course is to contact a veterinarian promptly.
## Prevention and Risk Reduction
Not all cases of joint disease can be prevented, but some risk factors can be managed.
- **Tick control**: Many tick-borne diseases, including anaplasmosis and ehrlichiosis, can cause joint inflammation. Regular tick prevention is essential, especially in endemic areas [2].
- **Prompt wound care**: Any wound near a joint should be evaluated by a veterinarian to reduce the risk of septic arthritis.
- **Weight management**: Obesity increases the risk and severity of osteoarthritis. Maintaining a healthy weight reduces stress on joints.
- **Regular veterinary check-ups**: Early detection of joint disease allows for earlier intervention and better outcomes.
## Limitations and When to Contact a Veterinarian
This article provides general information about joint fluid analysis and the diagnosis of septic arthritis versus immune-mediated polyarthritis. It is not a substitute for professional veterinary advice.
The information presented here cannot predict how an individual dog will respond to treatment. Breed, age, overall health, and the specific cause of joint disease all influence outcomes. For example, a 2025 epidemiological study found that polyarthritis was more common in smaller breeds and older dogs, with a median age of 13.8 years at diagnosis [8]. However, this does not mean that large-breed or young dogs are immune to the condition [8].
**Contact a veterinarian immediately if your dog shows any of the following signs:**
- Sudden or severe lameness
- Swollen, hot, or painful joints
- Fever
- Lethargy or reduced appetite
- Difficulty standing or walking
- Shifting-leg lameness
Early diagnosis and treatment are critical for the best possible outcome.
## Frequently Asked Questions
### 1. What is joint fluid analysis in dogs?
Joint fluid analysis, also called synovial fluid analysis, is a diagnostic procedure where a veterinarian collects a small sample of fluid from a dog's joint using a needle and syringe. The fluid is then examined under a microscope to evaluate cell counts, cell types, and the presence of bacteria or other abnormalities.
### 2. How is joint fluid collected from a dog?
Joint fluid is collected via arthrocentesis, which involves inserting a needle into the joint space. The dog is typically sedated or anesthetized to ensure comfort and safety. Ultrasound guidance may be used to improve accuracy, especially for deep joints like the hip or shoulder [9][10].
### 3. What is the difference between septic arthritis and immune-mediated polyarthritis?
Septic arthritis is caused by a bacterial infection within the joint, while immune-mediated polyarthritis (IMPA) is caused by the immune system attacking the joint tissues. Septic arthritis usually affects one joint and requires antibiotics, while IMPA typically affects multiple joints and requires immunosuppressive drugs.
### 4. How can joint fluid analysis tell the difference between septic arthritis and IMPA?
Joint fluid analysis looks at the total nucleated cell count, the types of white blood cells present, and the presence of bacteria. Septic arthritis typically has a very high cell count with degenerate neutrophils and may show bacteria on cytology or grow bacteria on culture. IMPA also has a high cell count with neutrophils, but bacteria are absent and culture is negative [4].
### 5. Can joint fluid analysis be done at home?
No, joint fluid analysis is a veterinary procedure that requires specialized training, equipment, and laboratory support. It should only be performed by a licensed veterinarian.
### 6. Is joint fluid analysis painful for dogs?
Arthrocentesis is performed under sedation or anesthesia, so the dog should not feel pain during the procedure. Some soreness may occur afterward, but this is usually mild and temporary.
### 7. What is the treatment for septic arthritis in dogs?
Treatment for septic arthritis involves antibiotics, joint lavage (flushing the joint), and pain management. In severe cases, surgery may be necessary. Early treatment is essential to prevent permanent joint damage.
### 8. What is the treatment for immune-mediated polyarthritis in dogs?
Treatment for IMPA involves immunosuppressive drugs, primarily corticosteroids like prednisolone. Additional medications such as leflunomide or mycophenolate mofetil may be used in some cases [4][3]. Treatment is typically long-term and requires regular monitoring.
---
**References**
## References
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[2] Teichner SR, Powell LL, Mazepa AS. "Clonal T Cell Proliferation Induced by Acute Anaplasmosis in a Dog." *J Vet Intern Med*. 2025. https://pubmed.ncbi.nlm.nih.gov/40874640/
[3] Wilson R, Swift I, Groth-Semple M, et al. "Treatment with Leflunomide in Conjunction with Glucocorticoids for Dogs with Immune-Mediated Polyarthritis Is Not Associated with Improved Outcomes: A Retrospective Cohort Study of 93 Dogs from Australia (2017-2024)." *Vet Sci*. 2024. https://pubmed.ncbi.nlm.nih.gov/39591311/
[4] Murakami K, Kobayashi K, Kutara K, et al. "Increased Abundance of Cytotoxic T Cells in Synovial Fluid of a Dog With Erosive Immune-Mediated Polyarthritis." *Case Rep Vet Med*. 2026. https://pubmed.ncbi.nlm.nih.gov/42078331/
[5] Beer AJC, Edmunds GL, Meakin LB, et al. "Synovial Fluid C-Reactive Protein as a Biomarker in Osteoarthritis, Immune-Mediated Polyarthritis and Bacterial Infective Arthritis." *Vet Comp Orthop Traumatol*. 2026. https://pubmed.ncbi.nlm.nih.gov/41038244/
[6] Neumann S, Diekmann H, Lauenstein S. "Stage-dependent analysis of IL-6, TGF-β, osteocalcin, and sRANKL in the synovial fluid of dogs with osteoarthritis." *Sci Rep*. 2026. https://pubmed.ncbi.nlm.nih.gov/42265287/
[7] Silva ARS, Gomes AAD, Aquino MCC, et al. "Synovial fluid and radiographic evaluation of joints from dogs with visceral leishmaniasis." *Parasit Vectors*. 2022. https://pubmed.ncbi.nlm.nih.gov/36076242/
[8] Narita M, Hirano T, Naito E, et al. "Epidemiologic Insights on Polyarthritis in Dogs in Primary Care Populations." *J Vet Intern Med*. 2025. https://pubmed.ncbi.nlm.nih.gov/40864877/
[9] Miller A, Jennings C, Frye C. "Ultrasound-guided arthrocentesis and intra-articular injections of the elbow and stifle joint in the dog." *J Am Vet Med Assoc*. 2025. https://pubmed.ncbi.nlm.nih.gov/40882683/
[10] Miller A, Jennings C, Frye C. "Ultrasound-guided arthrocentesis and intra-articular injection of the hip and shoulder joints in the dog." *J Am Vet Med Assoc*. 2024. https://pubmed.ncbi.nlm.nih.gov/39111338/
[11] Packham LAF, Black V. "Coagulation status of immune-mediated polyarthritis in dogs." *J Small Anim Pract*. 2025. https://pubmed.ncbi.nlm.nih.gov/39995340/
[12] Carreira LM, Alves J, Inacio F, et al. "Sex diferences in serum and synovial fluid C-reactive protein concentration in healthy dogs." *Vet Res Commun*. 2024. https://pubmed.ncbi.nlm.nih.gov/38662317/
[13] Parlak K, Zamirbekova Erdogan N, Parlak TM, et al. "Pentoxifylline in Dogs With Osteoarthritis: Comparative Treatment and Efficacy Analysis With Meloxicam." *Vet Med Sci*. 2025. https://pubmed.ncbi.nlm.nih.gov/40434930/
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3. [Enhancing Accuracy and Efficiency of Canine Synovial Fluid Analysis with Hyaluronidase Pretreatment and Automated Analyzer.](https://pubmed.ncbi.nlm.nih.gov/42146917/)
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