Fibrocartilaginous Embolic Myelopathy in a Calf

Abstract

Abstract.A 5-month-old Angus heifer with a history of acute hindlimb paresis that quickly progressed to lateral recumbency was necropsied. Gross lesions included a 6-cm segment of gray to brown discoloration and softening of the right ventrolateral spinal cord between T2 and T3. Microscopically, there was liquefactive necrosis of ventrolateral white and gray matter, and multiple intravascular emboli partially or completely occluded many intralesional and adjacent spinal and meningeal arteries and veins. Emboli were alcian blue positive, consistent with fibrocartilage of the nucleus pulposus of the intervertebral disk. No gross abnormalities were detected in the vertebrae or intervertebral disks. Fibrocartilaginous embolic myelopathy appears to be very rare in cattle; however, it should be considered in cases of acute, nonprogressive spinal cord dysfunction. Fibrocartilaginous embolism (FCE) of the spinal cord, or rarely the brain stem, is a relatively uncommon cause of acute, nonprogressive neurological dysfunction that has been previously described in humans, 15 dogs, 2,3,5,7,11 pigs, 1,8,10,14 horses, 6,13 cats, 2,16 and a lamb. 9 Spinal cord injury results from occlusion of the vasculature (arteries, veins, or a combination of both) within the cord parenchyma or the adjacent leptomeninges by masses of fibrocartilaginous material histochemically identical to fibrocartilage of the nucleus pulposus of the intervertebral disk. Consequent ischemia of dependent regions of spinal cord produces clinical signs with distribution and severity referable to the site and extent of infarction. Definitive diagnosis is reliant on histologic demonstration of intravascular fibrocartilaginous emboli and necrosis of associated spinal cord segments. Clinically, acute to subacute, nonprogressive, focal spinal cord dysfunction in the absence of hyperpathia is suggestive of fibrocartilaginous embolic myelopathy. 4,7,8 The following is a case report of fibrocartilaginous embolic myelopathy in a bovine.A 5-month-old Angus heifer calf was presented to the ambulatory service of the Virginia-Maryland Regional College of Veterinary Medicine Veterinary Medical Teaching Hospital (VMTH), Blacksburg, Virginia, with a history of being acutely down. The calf was found in lateral recumbency and was unable to rise with assistance. Once positioned, the calf could remain in sternal recumbency. The calf was admitted to the VMTH the following day for complete neurologic examination. On presentation, the calf was tetraparetic to the point of recumbency but was bright, alert, and responsive. Cranial nerve responses were within normal limits. Patellar reflexes were intact and normal bilaterally. Withdrawal responses were normal in the right hindlimb and both forelimbs and decreased in the left hindlimb; however, the heifer had been in left lateral recumbency for at least several hours before neurological evaluation. Tail and anal tone were within normal limits. No localized pain was identified. The panniculus reflex was absent caudal to T3/T4. Cervical r...

Clinical characteristics of canine fibrocartilaginous embolic myelopathy (FCE): a systematic review of 393 cases (1973–2013)

“…While primarily reported in dogs, the disease also occurs in cats, horses, cattle, tayras, swine, turkeys and human beings (Taylor and others 1977, Tessaro and others 1983, Renner and others 1998, Stedman and others 1998, Landoli and others 2004, Mikszewski and others 2006, Cuello and others 2014). The canine disease may serve as a spontaneous clinical animal model of ischaemic myelopathy in human beings (Davidovic and Illic 2014).…”

Pulmonary emboli of bone marrow associated with femoral fracture in a calf

“…Direct (mechanical theory) release of bone marrow into the bloodstream after trauma following elevated intramedullar pressure and the release of free fatty acids (biochemical theory) following the inflammatory response after trauma, have been proposed as mechanisms for the development of fat emboli (Ten Duis 1997; Landolfi et al 2004;Fernández et al 2005). Pulmonary and systemic fat emboli that develop after traumatic injury are typically considered a consequence of injury to fat deposits, bone fracture and increased bone pressure during orthopaedic procedures (Ten Duis 1997;Landolfi et al 2004;Oberst et al 2009). The presence in the current case of fat in small emboli and fat with haematopoietic cells in larger emboli support the hypothesis that both mechanical and biochemical mechanisms can be simultaneously involved.…”

“…Emboli were not found within the arteries of the central nervous system in spite that they are found during human trauma. In contrast to fibrocartilaginous material associated to ischemic myelopathy in humans and numerous animal species (Landolfi et al 2004), fat embolization occurs most frequently in the lungs and rarely in organs belonging to the area supplied by the systemic blood circulation, which may be due to the composition and the deformability of embolic material that influences the pulmonary filtering capacity (Byrick et al 1994), or due to that embolism in general affecting the cerebrospinal arterioles is very seldom observed in animals (Caswell and Williams 1997;Sierra et al 2007). …”

“…Embolized fat within capillary beds cause direct tissue damage as well as induce a systemic inflammatory response, known as fat embolism syndrome (Ten Duis 1997;Landolfi et al 2004;Fernández et al 2005). Syndrome is commonly seen following orthopaedic trauma, but bone marrow transplant, pancreatitis, and liposuction are also patients in risk.…”

Arterial lumbosacral spinal cord infarction in a 4-year-old post-parturient cow

“…It is speculated that the alteration of the subarachnoidal blood vessels which were probably the branches of the dorsal spinal arteries may have followed that of the dorsal spinal arteries several days later, presumably in a period corresponding with parturition, thereby giving rise to ischaemia due to decreased or arrested arterial blood supply and resulting in infarction of the watershed areas at the spinal cord. Fibrocartilaginous embolism derived from the nucleus pulposus of the intervertebral disc, the precise pathogenesis of which remains poorly understood, is an important risk factor for the development of spinal cord infarction or myelomalacia in several domestic or other animal species, such as the cat (Scott & O'Leary 1996;Mikszewski et al 2006), the dog (Cauzinille 2000), the pig (Haynes & Benson 1999), the horse (Fuentealba et al 1991), the bovine species (Landolfi et al 2004) and the lion (Ricci et al 2010). Other risk factors confirmed so far are limited to a small number, including necrotizing polyarteritis involving the leptomeniges of the spinal cord in dogs (Hoff & Vandevelde 1981), general anesthesia in a horse (Lerche et al 1993), an episode of hypotension associated with a surgical procedure in a monkey (Zeiss et al 2001) and aortic catheter implantation in a calf (Offinger et al 2011).…”