The gastrocnemius muscle and its tendon play an essential role in gait, standing, and weight-bearing (1,8). The muscle arises from twin heads on the caudal surface of the femur and forms a muscular swelling at the upper end of the leg before narrowing abruptly to the strong tendon that is inserted at the point of the hock (3). The gastrocnemius muscle is a flexor of the stifle and an extensor of the hock (3).

Gastrocnemius muscle rupture is a musculoskeletal disorder that is rarely reported in cattle but can occur in various animals, including horses, camels, llamas, and wild animals (1,2,6). In cattle, such rupture disturbs the weight-bearing ability of the affected limb and carries a hopeless prognosis, resulting in significant economic losses (8). Ruptures can occur in both cows and calves. In adult cattle, it can result from continuous and drastic movement in situations that make it difficult for cattle to rise, such as slipping and falling or suffering from hypocalcemia (2,6). In the case of young calves, this may occur when they become trapped in mud or deep manure or if they have other conditions that cause them to struggle excessively. Additionally, many accidents may result in traumatic gastrocnemius ruptures (2,8). In general, the rupture of the gastrocnemius muscle occurs unilaterally; in rare cases, both sides may rupture (2,8). Rupture can occur immediately after an injury, or the muscle may be weakened enough to rupture completely following a mild strain (2). In cattle, the musculoskeletal junction and the origin or insertion of the muscle are the most common sites of rupture (2).

Cattle with ruptured gastrocnemius muscles are typically described as having a “rabbit leg” posture with the tibia and metatarsus at a 90-degree angle (8). If the affected animal attempts to raise or bear weight on the affected limb, the hock remains flexed with the hock resting on the ground (2,8). Simultaneously, the plantar aspect of the metatarsus may contact the ground depending on the degree of rupture (2).

Partial or complete rupture of the gastrocnemius muscle may occur; in most cases, the muscles are completely ruptured (1,8). Centered around the ruptured area, the affected muscle may become firm and swollen following hematoma formation, and the gastrocnemius tendon may become tensionless (2,8). In cases of partial rupture, severe lameness of the affected limb, dropped hock, and firm swelling in the ruptured area may occur; such symptoms are more prominent in complete rupture cases (1-3). Less commonly, rupture can occur at the junction of the tendon and muscle belly, making the diagnosis more challenging because there are few or no signs (3). Accordingly, a thorough evaluation of the hind limb, including careful palpation and observation, may be helpful for diagnosis (1-3).

In this report, we diagnosed and performed surgical treatment of bilateral gastrocnemius muscle rupture in a Korean native cattle (Hanwoo) calf. This is the first report of gastrocnemius muscle rupture in Hanwoo cattle.

A 3-month-old Hanwoo calf from a farm in Hoengseong- gun, Gangwon-do, Republic of Korea was referred to the Farm Animal Medical Teaching Hospital, Seoul National University. The calf showed abnormal posture while standing and could not rise. While retrieving the medical history an accident was identified in which both hind limbs of the calf were trapped between a barn structure and a water bowl.

Based on the symptoms exhibited following the event, it was assumed that the gastrocnemius muscle was ruptured as the calf attempted to escape. When the local veterinarian visited the farm, the calf was unable to rise even with assistance and showed a “rabbit leg” posture along with trauma to the metatarsus (Fig. 1). Upon request from the owner, on-site treatment was decided; therefore, disinfection and an antibiotic dressing were administered to the traumatized area, and a cast was applied to both metatarsals by a local veterinarian. Two weeks later, the calf could rise and move around, relying on the cast, but it still had difficulty taking normal posture or maintaining balance. The calf was transferred for a definitive diagnosis, surgical treatment, and postoperative care. After hospitalization, the casts applied by local veterinarians were removed. The calf attempted to rise repeatedly, but this was impossible, even with assistance. For sedation, xylazine (Rompun^®, Elanco, Buenos Aires, Argentina) was administered intramuscularly at a dose of 20 mg per 100 kg of body weight, and then physical and radiographic examinations were performed. Physical examination revealed lacerated trauma of both metatarsi with exposed bone and pus. In addition, neither the tarsal (hock) joint could be extended completely, and knuckling of the metatarsophalangeal (fetlock) joints was observed. All the symptoms were more severe on the left side. Both hind legs were carefully evaluated for firmness behind the stifle joint, which was presumed to be the location of the rupture. Radiography revealed no other abnormalities, but an atypical circular structure with soft tissue density was found behind both stifle joints, which was assumed to be a deep popliteal lymph node (Fig. 2). For surgical treatment, the left hind limb was considered first, and surgery on the opposite leg was performed after evaluating postoperative improvements in the symptoms and conditions of the calf. Before surgery, 20 mg of xylazine was administered intramuscularly. After sedation, the calf was placed on its right side and appropriately restrained, and the surgical area was prepared aseptically. For anesthesia, 2% lidocaine (Daihan Lidocaine HCl inj., 2%, Daihan, Ansan, Republic of Korea) was administered via local and epidural injections, respectively, while tramadol (MARITROL Inj., JE IL PHARM. Co., Ltd., Daegu, Republic of Korea) was administered intravenously for analgesia.

Figure 1. The Korean native calf with a typical posture of bilateral gastrocnemius muscle rupture (A) and a lacerated trauma on a metatarsal after lavage (B).

Figure 2. The X-ray image of the right hindlimb. The round structure with soft tissue density is assumed to be a deep popliteal lymph node (white arrow).

To identify the ruptured gastrocnemius muscle, a parabolic skin incision was made approximately 20 cm below the greater trochanter of the femur, and significant adhesions between the subcutaneous tissue and fasciae were confirmed. After detachment of the adhesions, the biceps femoris and vastus lateralis muscles were exposed; however, no specific gross lesions were observed. The movement and tension of each muscle were evaluated by operating the joint to precisely identify the ruptured area. The biceps femoris muscle was incised to obtain the visual field and space. Due to severe atrophy and adhesion of the ruptured muscles, careful dissection was performed to confirm the complete rupture of the medial head and partial rupture of the medial part of the lateral head (Fig. 3A). After trimming, the heads of the ruptured muscles were sutured with an absorbable suture (Vicryl 2; Ethicon Vicryl^TM, Somerset County, NJ, U.S.A.) using the locking loop technique. To reduce tension in the sutured area, the unaffected lateral head was anchored to the neighboring muscles (Fig. 3B). After suturing the gastrocnemius muscle, the biceps femoris muscle, fascia, and subcutaneous tissue were closed using Vicryl 2, and the skin was sutured using non-absorbable sutures (BLUE NYLON 2, AILEE CO., LTD., Busan, Republic of Korea). The trauma to both metatarsi was cleansed and treated with an antibiotic dressing. In addition, a cast was applied from the tarsal joint to the metatarsophalangeal joint, and a window was created to disinfect the wound. After surgery, atipamezole (ANTISEDAN; Zoetis Korea, Seoul, Republic of Korea) was administered intravenously to awaken the calf. Both the surgical site and wound were disinfected three times a day and once a day, respectively, and ketoprofen (New-Procop inj., SB shinil, Yesan, Republic of Korea) and a penicillin-G-streptomycin complex antibiotic (GREEN CROSS VETERINARY PRODUCTS, Yongin, Republic of Korea) were administered intramuscularly for 3 days. The calf could not rise on its own on the day of surgery but was able to raise itself, access fresh water, and feed ad libitum on the second day. Four days after the surgery, additional surgery was performed on the right hindlimb.

Figure 3. Identified ruptured heads of gastrocnemius muscles (A) and appearance after suturing muscles (B). Note the medial part (arrows) and lateral part (arrowheads) through the incised biceps femoris (asterisks).

The severity of the injury in the right leg was similar to that of the left leg. The heads of the ruptured gastrocnemius muscles were trimmed and sutured while anchoring the unruptured area of the lateral head to the surrounding muscles. Subsequent treatment was the same as that conducted on the left side, and no specific findings were observed.

The cast and sutures were removed approximately 2 weeks after each surgery. The usage of the right hindlimb increased, and the muscles were fixed well and moved satisfactorily, but the left hindlimb seemed difficult to support and collapsed gradually (Fig. 4). A new cast was applied to the left hind limb, which was judged to require more rehabilitation, and it was replaced with a new one every 2 weeks. After 3 weeks of follow-up, no complications were observed, and the calf was transferred back to the farm. On physical examination performed after removing the cast of the left hind limb at the farm, there were no problematic signs with the angle of the joint or tension of the muscle during movement. When visiting the farm again approximately 2 weeks later, no specific findings were observed, so the cast was removed. Follow-up was concluded 112 days after the first surgery, confirming normal posture and gait (Fig. 5).

Figure 4. The appearance of the calf 4 weeks after removing the cast from the left hind leg.

Figure 5. The calf with normal posture and gait at the end of the follow-up.

An accurate diagnosis is critical for treating cattle with difficulty rising and walking. Although there may be various causes for the inability of cattle to rise, rupture of the Achilles tendon is a representative disease that must be differentiated for the diagnosis of rupture of the gastrocnemius muscle (8). The Achilles tendon, also known as the common calcaneal tendon, consists of multiple tendons from several muscles of the hind limb (3). The main components of the Achilles tendon are the superficial digital flexor muscle and tendon, the gastrocnemius tendon, and the combined tendon of the biceps femoris, semitendinosus, and gracilis muscles (3,4). Cattle with Achilles tendon rupture may have a similar history and symptoms as gastrocnemius muscle rupture; therefore, it must be differentiated through careful clinical examination (4,6,8,9). In this case, the calf showed a “rabbit leg” posture with the tibia and metatarsus at a 90-degree angle, a typical sign of gastrocnemius muscle rupture, and the digits were knuckled downward like they were trying to grip the ground. This was considered a result of the superficial digital flexor tendon not being ruptured, but only the gastrocnemius muscle being ruptured; thus, the superficial digital flexor tendon bears all the full weight and strain, pulling the digits to flex (3,6,8).

While retrieving the history, it was identified that there had been an accident in which both hind limbs were trapped in a barn structure. After the event, the calf presented symptoms that can accompany a gastrocnemius muscle rupture. Physical examination revealed firmness behind the stifle joint and a reduction in the range of motion of the stifle and tarsal joints. Radiographic imaging did not show skeletal abnormalities such as fractures, but a round structure with soft tissue density was found behind both stifle joints, which was presumed to be a deep popliteal lymph node. These findings indicated that the gastrocnemius muscles of the calf had ruptured on both sides, and surgical treatment was considered.

The ruptured gastrocnemius muscle was sutured using the locking loop technique, and the unruptured lateral head was carefully pulled and anchored to the surrounding muscles to reduce tension in the sutured area. The locking loop technique is an effective method for suturing severed tendons where tension can occur (5). In this case, the rupture of the gastrocnemius muscle occurred perpendicular to the direction of the muscle. As general suturing can induce additional muscle damage, the locking loop technique was used to prevent such additional damage.

After surgery, a cast was applied from the tarsal joint to the metatarsophalangeal joint to prevent re-rupture and enhance rehabilitation. The cast is relatively easy to apply, does not require complex equipment, and can be used on various body parts (7,10). In addition, the cast can be periodically replaced for young calves that grow rapidly, making post-surgery management uncomplicated (7). A plaster cast was applied to prevent flexion contracture of the tarsal joint and to induce phase correction of the knuckled metatarsophalangeal joint by body weight pressure. Moreover, fixation and support of the hind leg prevent further damage to the affected muscle and simultaneously enable the calf to rise and move, aiding rehabilitation and functional recovery.

Generally, rupture of the gastrocnemius muscle has a poor prognosis in cattle and has not yet been reported in the Republic of Korea (1,6,8). This report describes the successful diagnosis and treatment of a Hanwoo calf with bilateral gastrocnemius muscle rupture, which is the first domestic case. Additionally, it is important to obtain radiological information, which is challenging for field clinicians because of cost and management difficulties, along with a thorough physical examination.

The gastrocnemius muscle rupture in cattle is generally known to be difficult to diagnose and treat in the field. Nevertheless, in this case, a bilateral rupture of the gastrocnemius muscle was diagnosed through a thorough physical examination, including radiography, which is difficult in the field. The ruptured gastrocnemius muscles were surgically corrected using the locking loop technique, and a cast was applied postoperatively for several weeks. The purpose of the cast was to prevent additional damage and simultaneously enable the calf to rise and move around, promoting functional recovery of both hind limbs. The postoperative monitoring was performed for approximately 4 months. During the follow-up period, the calf recovered normal posture and gait.

The authors have no conflicting interests.