Does Contrast-Enhanced CT Add Value for Canine Elbow Imaging? New Study Says Yes—Sometimes
Research examining 326 elbow joints reveals when IV contrast actually changes what we see—and when it might be unnecessary
Computed tomography has become the gold standard for imaging canine elbow dysplasia, offering superior detail of bony pathology compared to radiographs. But should we be using intravenous contrast agents during these studies? A new study published in Frontiers in Veterinary Science by Bettina Rohr and colleagues examined 326 elbow joints to determine whether contrast-enhanced CT provides diagnostic information we'd otherwise miss.
The answer, as often happens in veterinary medicine, is nuanced: contrast enhancement can reveal soft tissue pathology—particularly flexor muscle involvement—that's invisible on standard CT. But whether that information changes treatment or prognosis enough to justify the additional cost, time, and (admittedly small) risk of contrast administration is a question each practice will need to answer for themselves.
Why This Question Matters
CT imaging of the canine elbow has become increasingly accessible to general practitioners, not just referral centers. Many of us now routinely recommend CT for dogs with elbow lameness, particularly when considering surgical intervention for elbow dysplasia or when radiographs are inconclusive.
The standard protocol involves non-contrast CT focused on evaluating bony structures: fragmented medial coronoid process (MCPD), ununited anconeal process (UAP), osteochondritis dissecans (OCD), humeral intracondylar fissure (HIF), incomplete ossification of the humeral condyle (IOHC), and secondary degenerative changes like osteophytes.
But elbows are complex joints with significant soft tissue components. The joint capsule, synovium, collateral ligaments, and flexor muscle entheses can all be involved in elbow pathology. Without contrast enhancement, we have limited ability to assess these structures on CT.
The question becomes: are we missing clinically significant pathology by skipping contrast? Or are we adequately diagnosing and treating elbow disease based on bony findings alone?
The Study Design
The researchers examined 163 dogs (326 elbow joints) presenting with unilateral or bilateral forelimb lameness attributed to elbow pathology. All underwent:
Radiography (standard elbow series)
Non-contrast CT (evaluated in bone window for primary lesions and osteophytes)
Contrast-enhanced CT (evaluated in soft tissue window for joint capsule and flexor muscle enhancement)
Twenty-one elbows without pathological findings, lameness, or contrast enhancement served as controls—normal joints that helped establish what "no abnormality" looks like.
The primary lesions evaluated included:
Medial coronoid process disease (MCPD)—the most common finding
Ununited anconeal process (UAP)
Osteochondritis dissecans (OCD)
Humeral intracondylar fissure (HIF) or incomplete ossification of humeral condyle (IOHC)
Epicondylar spurs
Calcified bodies (caudal or medial)
Periarticular osteophytes (secondary degenerative change)
After contrast administration, they specifically looked for enhancement in two key areas:
Joint capsule (synovium and capsular thickening)
Flexor muscles (indicating enthesopathy or muscle injury)
The Findings: What Contrast Revealed
Of the 326 elbows examined, 137 (42%) showed contrast enhancement of some kind:
94 elbows (29%): Enhancement limited to joint capsule only
16 elbows (5%): Enhancement limited to flexor muscles only
27 elbows (8%): Enhancement of both joint capsule and flexor muscles
This is significant: nearly half of lame elbows showed soft tissue pathology visible only with contrast enhancement.
Joint Capsule Enhancement: Correlating with Bony Disease
Joint capsule enhancement was most strongly associated with periarticular osteophytes—those secondary degenerative changes that indicate chronic inflammation and osteoarthritis. This makes biological sense: osteophytes develop in response to chronic synovitis and capsular inflammation. If the joint capsule is inflamed and thickened (enhancing with contrast), it's producing inflammatory mediators that stimulate new bone formation.
This finding, while interesting, probably doesn't change clinical management much. We already know that osteophytes indicate chronic degenerative disease and ongoing inflammation. Seeing capsular enhancement confirms what we suspected but doesn't typically alter treatment decisions.
However, the degree of capsular enhancement might correlate with pain severity or prognosis—something the current study didn't assess but that would be valuable in future research.
Flexor Muscle Enhancement: The Game-Changer
Here's where things get clinically interesting. Flexor muscle enhancement—indicating flexor enthesopathy (inflammation at the muscle/tendon attachment site) or muscle injury—showed specific patterns:
Epicondylar spurs were most strongly associated with flexor muscle enhancement. This makes anatomical sense: epicondylar spurs develop at the medial humeral epicondyle where the flexor muscle group originates. These spurs likely represent chronic traction injury or enthesopathy at the flexor insertion.
When we see an epicondylar spur on CT, we can reasonably infer flexor muscle involvement. But here's the critical finding: 14 elbows showed flexor muscle enhancement without any visible epicondylar spur or calcified body.
These cases could only be detected through contrast-enhanced imaging. Without contrast, we'd have diagnosed them as having whatever bony pathology was present (if any) but missed the flexor muscle component entirely.
Calcified Bodies: An Unexpected Pattern
Interestingly, medially located calcified bodies were NOT associated with flexor muscle enhancement. This is somewhat surprising, as we might expect any calcified body in the region to indicate soft tissue mineralization and inflammation.
The location and nature of these calcified bodies matter. Medial calcified bodies may represent:
Chronic fragmented coronoid fragments
Dystrophic mineralization of joint capsule
Organized hematoma or synovial bodies
The lack of association with flexor enhancement suggests these structures may be more intra-articular than periarticular, and their presence doesn't necessarily indicate active flexor pathology.
Clinical Implications: When Does This Matter?
So what do we do with this information? The study reveals soft tissue pathology in a significant percentage of cases, but does it change management?
Scenario 1: Standard Elbow Dysplasia Cases
For the typical young dog with MCPD or UAP being evaluated for arthroscopic surgery, contrast probably doesn't change the treatment plan. We're already planning surgical intervention based on the bony pathology. Knowing there's capsular inflammation doesn't alter the approach—we're addressing that through surgical debridement and postoperative anti-inflammatories anyway.
Scenario 2: Chronic Lameness with Minimal Bony Changes
This is where contrast becomes more valuable. Consider the dog with persistent elbow lameness where CT shows only mild osteophytes or perhaps no obvious primary lesion. Non-contrast CT might leave you scratching your head about the source of pain.
Contrast enhancement revealing significant capsular thickening or flexor muscle involvement provides:
Confirmation that the elbow is indeed the pain source
Evidence of active inflammation warranting aggressive medical management
Potential explanation for why lameness persists despite minimal bony pathology
Justification for treatments targeting soft tissue inflammation (PRP, IRAP, etc.)
Scenario 3: The Hidden Flexor Enthesopathy
Those 14 cases with flexor muscle enhancement but no epicondylar spur represent the strongest argument for routine contrast use. These dogs have flexor enthesopathy that's completely invisible on non-contrast imaging.
Why this matters:
Flexor enthesopathy may require different treatment approaches than standard elbow dysplasia
Physical therapy and rehabilitation protocols might need modification
Prognosis discussions with owners might differ
Return-to-work or return-to-sport timelines may need adjustment
Medical management might be prioritized over surgical intervention
Flexor enthesopathy (also called "flexor enthesopathy syndrome" or informally "flexorenthesopathy") is increasingly recognized as a significant cause of forelimb lameness in working and sporting dogs. It's essentially overuse injury at the flexor muscle origin, similar to "golfer's elbow" in humans.
Without contrast-enhanced CT, we'd miss this diagnosis entirely in cases without obvious epicondylar spurs.
The Risk-Benefit Analysis
The authors appropriately note that we must weigh benefits against risks when deciding whether to use contrast. Let's break this down:
Risks of IV contrast:
Allergic/anaphylactoid reactions (rare but potentially serious)
Renal toxicity (minimal risk in healthy patients with adequate hydration)
Extravasation injury (rare with proper catheter placement)
Additional cost to client
Extended anesthesia time (typically 5-10 minutes)
Additional radiation exposure (usually minimal)
Benefits of contrast:
Detection of soft tissue pathology invisible on non-contrast CT
Better characterization of inflammation severity
Identification of flexor enthesopathy in cases without epicondylar spurs
More complete diagnostic picture for prognostication
Potential to guide medical management strategies
For most healthy young dogs undergoing elbow CT, the medical risks are quite low. The more significant considerations are cost and anesthesia time.
The Bottom Line
This study demonstrates that contrast-enhanced CT reveals soft tissue pathology in approximately 42% of lame canine elbows—pathology that's invisible on standard non-contrast imaging. Most significantly, it can identify flexor enthesopathy in cases where no epicondylar spur or calcified body provides a bony clue.
Key takeaways for practice:
Contrast enhancement is not necessary for all elbow CT studies, particularly straightforward dysplasia cases in young dogs
Contrast adds significant value in chronic lameness cases, working dogs, and situations where soft tissue involvement might change management
Flexor enthesopathy can be present without visible epicondylar spurs and requires contrast to diagnose
Joint capsule enhancement correlates with osteophytes but probably doesn't change treatment decisions in most cases
A selective approach—evaluating non-contrast images first, then deciding whether contrast adds value—makes clinical and economic sense
The decision to use contrast should be individualized based on clinical presentation, suspected pathology, treatment goals, and client resources. When in doubt, or when dealing with complex cases where soft tissue involvement might impact management, the relatively low risk and modest additional cost of contrast administration may be justified by the additional diagnostic information gained.
This isn't about making contrast-enhanced CT the new standard for every elbow—it's about understanding when that additional information matters and using it strategically to improve diagnostic accuracy and patient outcomes.
Full Text Link: Diagnostic value of contrast-enhanced CT for elbow joint disorders in dogs - Frontiers in Veterinary Science, PMCID: PMC12571617
