NEUROLOGY
on the field, I would say probably 99% of the cases that you are going to see with vestibular disease are going to be ipsilateral to the site of the injury,” Dr. Aleman said. Ipsilateral vestibular disease usually affects 1 side of the brainstem; paradoxical, the caudal cerebellum. Vestibular disease that is affecting the peripheral nerves is ipsilateral. She offered some tips to tell central versus peripheral disease: Looking at nystagmus will be helpful, she said. If the head is moved to different positions, it changes in central disease, but not in peripheral disease. The state of consciousness is another indicator, she said. “Even if the animal is bright and alert, it doesn’t rule out a central problem, but if it's obtunded, has stupor or coma, there is central vestibular disease.” Although facial nerves could be affected by either because the facial nerve and vestibular nerve pathways are close, if there are multiple cranial nerve abnormalities, it’s going to be associated with central vestibular disease. Signs of spinal cord dysfunction could be sensory or motor, depending on what parts of the spinal cord are affected. Sensory deficits include proprioceptive ataxia or proprioceptive deficits; motor issues include dysmetria, paresis and paralysis and weakness. Motor
deficits can be caused by an upper motor neuron injury or a lower motor injury. Another spinal problem are compressive myopathies, which can occur at various areas along the spinal cord. Unfortunately, proprioceptive deficits can be affected by every brain region, she said. “So that means that proprioceptive deficits alone cannot help you to localize the disease. You have to see what other signs you have,” she said. The neuromuscular junction can be involved in many functional and physical deficits, including paresis, paralysis, dysphagia, dysphonia, dyspnea, proprioceptive deficits, gait deficits, reflex deficits and muscle atrophy, she said. Once a neurological problem has been determined, the animal requires a complete diagnostic work up, which should be tailored toward the specific signs the foal is having. Full blood work, urinalysis, electrolyte analysis and other tests will be required. Cerebrospinal fluid might be needed for certain problems. Imaging will also be helpful, radiography and ultrasonography can be easily performed in the field, she said, but advanced tests such as electroencephalography will need to be done at a large academic institution. MeV
Ethanol Useful for Aseptic Distal Limb Prep Ethanol can be used to prepare the skin before performing immediate, short procedures in horses, according to a recent study. This randomized trial aimed to determine whether ethanol-based antisepsis reduces bacterial counts on the equine distal limb comparable to a current chlorhexidine scrub method and determine the most effective application technique for the product. They studied 41 horses, and each horse had a 5 x 5 cm patch clipped over the distal interphalangeal joint of 3 limbs. By horse, each limb was randomly assigned to a treatment group: 1. 5-minute scrub using 4% chlorhexidine gluconate to a clipped site (CHG); 2. 90-second scrub using 80% ethanol to a clipped site (ETC); 3. 90-second contact with 80% ethanol applied as a spray to a clipped site (ETS); and
4. 90-second scrub using 80% ethanol to an unclipped site (ETUC). Samples were collected pre- and post-treatment and plated in duplicate. Bacterial counts were log10 transformed and averaged between duplicates. Mean log10 colony forming units (CFU) reduction was compared among the groups. There was no significant difference in mean log10 CFU reduction between CHG and ETC in either fore- or hindlimbs. In forelimbs, there was no significant difference in mean log10 CFU reduction among any groups. In hindlimbs, CHG had significantly greater mean log10 CFU reduction than ETUC and ETS. A 90-second wet contact time using gauze sponges was recommended. In addition, the researchers noted that the study did not investigate the efficacy of other alcohol-based antiseptics such as isopropanol or n-propanol. MeV
For more information: Doyle AJ, Saab ME, Lewis KM, et al. Comparison of chlorhexidine and alcohol-based antisepsis of the distal limbs of horses. Equine Vet J. 2020 Dec. 31 https://doi.org/10.1111/evj.13417 https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.13417 8
Issue 3/2021 | ModernEquineVet.com
