Swellings and Enlargements in Ruminants

Sarel R. Van Amstel • Jan K. Shearer

Swellings and enlargements can originate from soft tissue (muscle or tendons) or hard tissue (bone). Those associated with lameness usually occur on the limbs.

Approach to Swellings and Enlargements in Ruminants

History

History will indicate whether it is congenital or acquired, as well as the duration. Historical information should also include type of pasture, presence of lameness, and progression of the lameness signs, possibility of trauma, vaccination history, appetite, and presence of systemic signs, as well as the number of animals affected.

Examination Including Palpation

The anatomic location of the swelling may give an indication as to its origin. Palpation will provide information about the nature and possible cause of the swelling. Soft fluctuant swellings on the upper leg are usually due to abscess formation following a small penetrating wound, or they may occur after an intramuscular injection. Cattle on sweet clover may develop hematomas due to the presence of warfarin sodium, which inhibits vitamin K and thus vitamin K-dependent factors.^2,7,9,10 Fluid effusion into a joint capsule will result in a soft fluctuant swelling. Those associated with septic joints are usually less fluctuant and warm and painful on palpation. Joint swelling associated with degenerative joint disease may be hard on palpation due to new bone formation and nonpainful. Fluid effusion into the joint space is usually present. Degenerative joint disease may be hereditary, typically incited by abnormal conformation. Acquired degenerative joint disease is common after traumatic injury to supporting ligaments or menisci. Unilateral swelling of the foot is often associated with sepsis of the distal interphalangeal joint and sheath of the flexor tendons. Bilateral swelling of the foot is typically associated with foot rot.

Radiology, Ultrasonography, and Cytology

CARPAL JOINT. Ultrasound carried out in the longitudinal plane over the dorsal surface of the joint will facilitate arthro- centesis. Individual joint recesses that can be visualized include the radiocarpal, intercarpal, and carpometacarpal joints. In the absence of ultrasound, joint fluid can usually be obtained from the radiocarpal pouch with the carpus in slight flexion. A high white cell count in the presence of degenerate neutrophils confirms septic arthritis. Bacteria may not always be visible on cytologic examination. In chronic cases of septic arthritis, the joint looks and feels thicker with a reduced range of motion. In such cases, chronic degenerative changes will be visible radiographically. These changes can first be detected over the cranial surfaces of the proximal carpal row. The radiocarpal joint space is widened, and subchondral bone destruction may be present, which is eventually followed by new bone formation.

COXOFEMORAL JOINT. Ultrasound-guided arthrocentesis can be carried out in cases where an increase in joint fluid can be visualized. Radiographs are useful in establishing the cause of lameness and may be accomplished by anesthetizing the animal and positioning it in dorsal recumbency for a ventro­dorsal radiograph. The size of the musculature will greatly influence the detail visible in the radiograph.

STIFLE JOINT. The following should be considered with arthrocentesis of the stifle. There is communication between the femoropatellar and medial femorotibial joint cavities. These compartments do not always communicate with the lateral femorotibial space. To enter this compartment, a needle is introduced behind the lateral patellar ligament and directed caudally. To enter the femoropatellar and the femorotibial compartments, the needle is inserted between the medial and middle patellar ligaments and directed slightly down and toward the medial lip of the trochlea. Use of ultrasound will confirm the presence of increased joint fluid and facilitate collection.