History
A 2.5-month-old female Angus calf was evaluated for an acute onset of hind limb paresis. The calf had been unable to rise for several hours and on initial evaluation was alert and responsive but sluggish. The calf was able to rise on its forelimbs and did attempt to suckle. The calf's rectal temperature was 39.2°C (102.5°F; reference range, 36.7° to 39.1°C [98.1° to 102.4°F]), heart rate was 120 beats/min (reference range, 60 to 80 beats/min), and respiratory rate was 24 breaths/min (reference range, 30 to 50 breaths/min). No rumen contractions were detected; however, increased respiratory effort and bruxism were noted. Normal withdrawal reflexes but severe deficits of conscious proprioception were noted bilaterally in the hind limbs. On palpation of the vertebral column, an area of crepitus was noted adjacent to T9 and T10.
The calf was treated with penicillin G procaine (2,010,000 U, SC), dexamethasone (4.6 mg, IV), butorphanol (1 mg, SC), and florfenicol (1,800 mg, SC) overnight, and a full neurologic examination was performed the following morning. At that time, the calf still had withdrawal reflexes but severe deficits of conscious proprioception bilaterally in the hind limbs. The remainder of the examination was unremarkable. Spinal trauma was suspected, and lateral and horizontal-beam ventrodorsal radiographs of the thorax were obtained (Figure 1).
Lateral (A) and horizontal-beam ventrodorsal (B) radiographic images of the thoracic region of the vertebral column of a 2.5-month-old female Angus calf evaluated for acute onset of hind limb paresis.
Citation: Journal of the American Veterinary Medical Association 254, 3; 10.2460/javma.254.3.343
Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →
Radiographic Findings and Interpretation
A sharply marginated, well-defined, ovoid, soft tissue opaque mass (7 × 5.5 cm) containing a focal, triangular gas bubble was evident ventral to T4 through T6 (Figure 2). In addition, an alveolar pulmonary pattern characterized by air bronchograms was present in the left cranial lung lobe, and several round, thin-walled, sharply marginated, gas-filled structures were visible in the region between the carina and diaphragm, obscuring the caudal vena cava on the lateral radiographic view and the vertebral column and diaphragm on the ventrodorsal radiographic view. A focal unstructured interstitial coalescing-to-alveolar pulmonary pattern surrounded these gas-filled structures and was characterized by focal border effacement of the diaphragm and faint air bronchograms.
Same radiographic images as in Figure 1. A—Notice the ovoid, sharply marginated, soft tissue opaque structure (white arrow) containing a focal area of gas (arrowhead) that is evident ventral to T5 and T6. There are several round, gas-filled structures (black arrow) in the lungs between the region of the heart base and diaphragm. Notice the alveolar pulmonary pattern surrounding the round, gas-filled pulmonary lesions that silhouettes with the diaphragm and obscures the caudal vena cava. B—An alveolar pulmonary pattern characterized by air bronchograms (black arrows) is present in the left cranial lung lobe, and the abnormal, gas-filled structures are superimposed with the vertebral column and extend into the right caudal region of the thorax.
Citation: Journal of the American Veterinary Medical Association 254, 3; 10.2460/javma.254.3.343
The radiographic findings of a mass with intralesional gas ventral to the vertebral column coupled with the findings from the neurologic examination were most consistent with a paraspinal abscess and secondary osteomyelitis or diskospondylitis, whereas granuloma or hematoma formation were considered much less likely. The radiographic findings of abnormal changes to the pulmonary parenchyma and presence of gas-filled structures between the carina and diaphragm were most consistent with pneumonia and pulmonary abscess formation.
Treatment and Outcome
A brief ultrasonographic examination was performed to evaluate the region adjacent to the vertebral column where crepitus and radiographic abnormalities had been detected. A structure containing echogenic fluid was present adjacent to vertebral bone, and a small pocket of gas was present in this structure (not shown). Similar fluid-filled, thin-walled structures were detected in the caudodorsal lung field caudal to the heart. Bronchopneumonia and a thoracic vertebral abscess with presumed spinal cord compression were diagnosed. Owing to a grave prognosis, the calf was euthanized.
On necropsy, the calf's lungs were dark purple to red, and the cranioventral aspects of the lungs were firm on palpation. Firm foci filled with thick yellow exudate were scattered throughout the lung lobes. Two firm, red, thin-walled abscesses measuring 2 × 1.5 cm and 5.5 × 5 cm were identified on the ventral surface of the vertebral bodies of T5 and T6, respectively. When explored, these abscesses were determined to have extended through the T5–6 intervertebral disk space into the spinal canal and severely compressed the spinal cord at that location. Bacterial culture of material from the spinal abscesses and the lung abscesses both yielded heavy growth of Trueperella pyogenes.
Comments
Trueperella pyogenes (also called Arcanobacterium pyogenes, Corynebacterium pyogenes, or Actinomyces pyogenes) is an opportunistic bacterium that can be found on the mucous membranes of the upper respiratory, genital, and gastrointestinal tracts of many domestic species; however, pathological infections are most often seen in livestock and ruminants.1,2 Although mastitis and liver abscesses are more common, vertebral abscesses have also been reported.2 In a study3 of 21 cattle, vertebral abscesses resulted in paraparesis or tetraparesis that tended to worsen in severity over time. Of those 21 cattle, 11 had lesions sampled for bacterial culture, and 5 had lesions from which T pyogenes was isolated. Other bacterial isolates included Sphaerophorus necrophorus, Streptococcus sp, Staphylococcus sp, Pseudomonas sp, and Escherichia coli.3 In addition, T pyogenes is frequently isolated from suppurative bronchopneumonia lesions in cattle, especially with chronic disease.4
Although the size of adult cattle can be a limiting factor, thoracic radiography has been shown to be useful in evaluating acute and chronic respiratory changes in cattle, especially in young animals.5Radiographic evaluation of vertebral bodies in large animal patients is possible but requires high-powered radiography equipment to penetrate the large amount of soft tissue adjacent to the thoracolumbar region of the vertebral column in large animal patients.6 Portable radiography units with the ability to obtain diagnostic thoracic images of adult cattle are not available for most ambulatory and large animal veterinarians; however, available portable units are often adequate for obtaining diagnostic radiographic images in young calves. The radiographic images obtained for the calf of the present report captured the characteristic appearance of an abscess as a discrete, thin-walled structure, containing a mix of soft tissue and gas opaque material.7
Ultrasonography can also be effective in detecting abscesses in various regions of the body, although again, the size of adult cattle limits visualization of deep structures.8 With ultrasonography, abscesses typically appear as well-demarcated, heterogeneous, anechoic to hypoechoic masses, with or without an associated gas pocket and reverberation artifact.8 In the calf of the present report, ultrasonography revealed a fluid-filled, hypoechoic pocket with intralesional gas, findings that supported the radiographic diagnosis of a paraspinal abscess. In larger calves, spinal and pulmonary lesions may be difficult to detect with ultrasonography because of the gas interface from the surrounding lungs and the shadowing from the adjacent vertebrae and ribs.
The case reported here further supported the use of radiography in diagnosing pulmonary lesions and thoracic spinal lesions in calves. Compared with that of older cattle, the smaller body size of the calf in the present report allowed adequate radiographic beam penetration through the thorax, and because of the distinctive appearance of the abscess on the radiographic images obtained, a traumatic cause of the paraparesis could be ruled out in this patient.
Acknowledgments
The authors declare that there were no financial or other conflicts of interest.
References
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