Application of tenotomy on Korean native cattle (Hanwoo) with spastic paresis symptoms in the field

Abstract

Bovine spastic paresis (BSP) is a neuromuscular disorder characterized by hypertension and stiffness of hindlimb. Two Korean native cattle (Hanwoo) calves developed BSP or BSP-like symptoms, and a tenotomy of superficial tendon of medial head and deep tendon of lateral head of gastrocnemius muscle was performed for treatment. A cast was applied postoperatively to prevent muscle rupture and was removed three weeks later. The prognosis was evaluated at 3 weeks, 6 and 18 months postoperatively. Neither calf showed any other postoperative sequelae. This is the first case study to report the diagnosis, treatment, and prognosis of BSP in Hanwoo.

INTRODUCTION

Many diseases including lameness, neurological diseases and inherited diseases in cattle can lead to economic losses to farms due to the cost of treatment, increased early slaughter rate and reduced growth rate [1,2,3]. Especially inherited or neurological diseases are difficult to prevent or predict and these types of diseases outbreak at a younger age [4,5]. Bovine spastic paresis (BSP) is a neuromuscular disease that causes sudden lameness, mainly at three to eight months and rarely up to 1 year of age [4,5,6,7,8,9,10,11]. The cause of BSP has not been clearly identified; however, the possibility of genetic factors or abnormality in the gamma pathway related to the nervous system has been raised [3,4,5,6,7,12]. BSP is characterized by the sudden onset of symptoms of spastic paresis in the hindlimbs, bilaterally or unilaterally, without any apparent accident or trauma [10,13]. The primary symptoms include hypertension of the affected limbs and pendulum-like swinging motion while standing up [4,14]. Similar symptoms in cattle over three years of age are classified as a bovine spastic syndrome (BSS), in which symptoms usually occur recurrently in the hindlimbs, unlike BSP [13].

BSP has been reported since the 1920s in several breeds, including Friesian, Jersey, Brown Swiss, Holstein-Friesian, Romagnola, Charolais, Gelbvieh, Belgian White Blue, and Japanese Black Cattle [5,7,8,11,12,15]. According to previous studies, the symptoms of spastic paresis including hyperextension of the hindlimb and typical pendulum movement of the affected limb begin mildly and worsen gradually after the onset of symptoms [4,7,13,14,16]. There has been no reports on the occurrence and treatment of BSP in Korean native cattle (Hanwoo). In this report, we treated two Hanwoo calves with BSP symptoms. The first calf was diagnosed with BSP, but in the second calf, symptoms including the pendulum movement and hyperextension of the hindlimb developed after an accident. We applied the same surgical method to two calves for treatment, and the prognosis was identical. This study is significant because it is the first case study in the Republic of Korea to report the diagnosis, treatment, and prognosis of BSP in Hanwoo.

CASE PRESENTATION

Two Hanwoo calves from different farms were referred to the Farm Animal Medical Teaching Hospital of Seoul National University for BSP. The first patient was a female calf aged four-months with about 70 kg of body weight. Characterized symptoms of BSP developed suddenly in the left hindlimb without an accident or injury history. There was no evidence of an accident on physical examination (Fig. 1). In the second case, a two-month-old male calf, which weighed about 50 kg, developed symptoms after its leg was trapped in a fence. After the accident, a local veterinarian used a cast as a treatment for three weeks. BSP symptoms were not noted just after cast removal, but were recurred within a few days. Then, the calf was referred for further treatment (Fig. 2A). Radiographic diagnosis revealed no fractures at that point; however, the left calcaneus showed deformity with cranially angled, and the calcaneus seemed increased in opacity and thickened compared to the right hindlimb (Fig. 2B and C). We assumed that the present BSP-like symptoms developed due to bone and muscle damage and recovery following an accident involving the fence.

Fig. 1. Stiffness and hypertension of left hindlimb (yellow arrow) in a 4-month-old Hanwoo calf affected with bovine spastic paresis.

Fig. 2. The two-month-old calf with the characteristic symptom of bovine spastic paresis after the accident. (A) hypertension in the left hindlimb (yellow arrow); (B) radiographic lateral view of the bilateral tarsal joint in a calf; (C) radiographic craniocaudal view of the bilateral tarsal joint in a calf. The left calcaneus shows deformity with cranially angled or displaced, and the distal portion seems increased in opacity and thickened compared to the opposite leg (white arrow) and is seen as a more heterogeneous opacity superimposed on the craniocaudal view (white dotted arrow).

To diagnose BSP, confirmation of symptoms including hyperextension of the hock joint, increase in the tibiotarsal angle, pendulum-like swinging, and contraction of tendon in the affected limb is mostly used [4,7,10]. Also, we can use the nerve block or anesthesia to differentiate the BSP from a neurological problem, but the applicable treatment is consistent, which is tenotomy or tibial neurectomy [7]. BSP is generally treated using tibial neurectomy or tenotomy of superficial tendon of medial head of gastrocnemius muscle (ST) and deep tendon of lateral head of gastrocnemius muscle (DT) [9]; in this case, we used tenotomy of ST and DT to relieve BSP symptoms because the surgeries had to be performed on a farm, not a hospital. After treatment, the prognosis was evaluated 3 weeks, 6 months and 18 months after surgery in the two calves.

Surgery was performed within a week after the onset or recurrence of BSP symptoms, and the affected limb was the left hindlimb in both calves. Antibiotics (G.C. GPS inj., Green Cross Veterinary Products, Korea) and anti-inflammatory drugs (New Procop Inj., SB SHINIL, Korea) were administered to prevent postoperative infection and inflammation for three days after surgery. Before surgery, xylazine (Rompun; Elanco, Argentina) was injected intramuscularly at a dose of 0.2 mg/kg for sedation, and the surgical site was locally anesthetized using 2% lidocaine (DAI HAN PHARM Co., Korea). Total of 20 mL of 2% lidocaine was infused into the subcutaneous and muscular area, around the incision line. The tendons including ST, DT and superficial digital flexor tendon were approached by incising the upper lateral area at the hock point. After the skin incision, we confirmed a bunch of tendons including ST, DT and superficial digital flexor tendon, and tenotomy of ST and DT of the gastrocnemius muscle was performed by bending and stretching the fetlock joint (Fig. 3). In this process, a surgeon took care not to cut the superficial digital flexor tendon as well as the blood vessels and nerves running along the tendon. In both calves, the tension on the tendon disappeared after cutting ST and DT. The fascia, subcutaneous and intradermal sutures were performed using an absorbable suture (VICRYL 2; ETHICON, USA) after the tendon section. A cast was performed from tiptoe to about half of the tibia to prevent muscle rupture caused by excessive weight load on the remaining tendon postoperatively.

Fig. 3. Surgical procedure of tenotomy. (A) Local anesthetization of the surgical site with 2% lidocaine; (B) Incision line in the upper lateral side of the hock; (C) Exposure of the tendon; (D) Cutting of the tendon after confirming tendon stiffness (white arrow, superficial tendon of medial head of gastrocnemius muscle; white dotted arrow, deep tendon of lateral head of gastrocnemius muscle).

The BSP-like symptoms in both calves relieved immediately after tenotomy. The outcome of both calves was evaluated at 3 weeks, 6 months and 18 months after surgery, and both calves showed a normal gait without recurrence of symptoms within this time period. At the time of writing this case report, the first calf is 44 months old and has been calved twice. And the second male calf is 22 months old and is being raised normally for fattening, the average body weight of these ages is about 560 kg. Both patients were raised with no significant difference from other cattle on each farm. It was confirmed that the lameness improved after surgery and postoperative casting, the stiffness of the hindlimb was also alleviated, and there were no sequelae following treatment. In the calf with BSP-like symptoms after the accident, pus in the incision site was confirmed after cast removal, which recovered with repeated washing and sterilization of the affected site. In previous studies, the surgically treated calves with BSP recovered without difficulty, though the postoperative cast treatment was not performed [11]. Also, if the cast is performed for a long time in calves that grow fast, compression of the muscles may occur, and infection may worsen in the patient with a wound. Accordingly, the cast in calves should be maintained for up to 3 weeks and the new casting should be performed again if the further casting is necessary. In this case report, both calves withstood the weight after the first cast removal and thus did not need further casting.

DISCUSSION

Generally, the first onset of BSP symptoms manifests at the age of three to eight months after birth and is characterized by the sudden onset of mild symptoms without any accidents or trauma and the progressive aggravations of symptoms [4,5,6,7,8,9,10,11,16]. In the first case from this report, the symptom suddenly developed at the age of four months and showed the characteristic symptoms of BSP. However, the second calf showed lameness after an accident in which the left hindlimb was trapped in a fence at two months of age. After the accident, the characteristic symptoms of BSP, such as stiffness and hypertension of the hindlimb, were confirmed; however, lameness due to fracture or luxation was not observed when referred. In a radiographic examination of the left leg of the second calf, some bone lesions including the calcaneus deformity with cranially angled and increased opacity and thickened calcaneus were confirmed. Therefore, it was determined to be symptoms similar to BSP rather than a general BSP.

Tenotomy or neurectomy is indicated to treat BSP, and the surgical method is determined according to the surgeon's convenience or skill [4,7,8,12,14,15]. To perform a neurectomy, it is necessary to identify the tibial nerve to be cut through stimulation using an electropuncture stimulator [9,12,14,15]. Therefore, when performing a neurectomy, the supply of electricity in the clinical field is essential to use the surgical equipment, and the prognosis of surgery may vary depending on the surgeons’ skill [6,12,14]. If a nerve branch is cut incorrectly because of a mistake during the surgical procedure, recovery may be challenging because nerve regeneration is rare. In addition, since the second calf was a case of BSP-like symptoms caused by damage to the muscle and calcaneus bone where the muscle was attached, not by nerve damage, only tenotomy was indicated. For these reasons, tenotomy of ST and DT was performed in this report. However, it should be noted that tenotomy has disadvantages. In a neurectomy, only the nerve is cut; therefore, the possibility of muscle damage after surgery is low. However, since the hyperextended tendon is cut during a tenotomy, postoperative care is required to prevent muscle or tendon rupture, which is the primary adverse outcome that may occur postoperatively. When tenotomy is performed for BSP treatment, among the three tendons that organize the Achilles tendon, the deep tendon of lateral head of gastrocnemius muscle and superficial tendon of medial head of gastrocnemius muscle are cut off, leaving only the superficial digital flexor tendon [7,12,14]. The remaining superficial digital flexor tendon bears the entire weight of the hind part. If an excessive load is applied to the remaining tendon, the risk of tendon and muscle rupture increases [9]. Therefore, in such cases, the load applied to the muscles and tendons is reduced by applying a cast to the affected limb immediately after surgery. In both cases, the cast was removed after three weeks, and calves recovered without complications and could rear within the herd.

Since this is the first report of the occurrence and treatment of BSP in Republic of Korea, it appears that BSP is relatively rare to be considered a major clinical case in Hanwoo. Though in other countries, BSP has been outbreak common, and they estimate the genetic factor as one of the causes of BSP [3,4,6]. For this reason, those countries have suggested that cattle with BSP should be culled without treatment or not used for breeding even if treated [6,11]. Considering the livestock circumstances in the Republic of Korea, however, it seems that surgical treatment of BSP is worth attempting because of the relatively simple method, especially in the case of tenotomy, as well as the adequate prevention of postoperative sequelae compared to other neuromuscular disorders.

In conclusion, this study is the first report on the diagnosis, surgical treatment, and prognostic evaluation of BSP in Hanwoo, and it is meaningful that this clinical sign was improved through partial tenotomy in the field condition.