Electrical impedance tomography (EIT) is used in lung physiology monitoring. There is evidence that EIT is linearly associated with global tidal volume (VT) in clinically healthy patients where no positive end-expiratory pressure (PEEP) is applied. This linearity has not been challenged by altering lung conditions. The aim of this study was to determine the effect of PEEP on VT estimation, using EIT technology and spirometry, and observe the stability of the relationship under changing lung conditions. Twelve male castrated cattle (Steer), mean age 7.8 months (SD ± 1.7) were premedicated with xylazine followed by anaesthesia induction with ketamine and maintenance with halothane in oxygen via an endotracheal tube. An EIT belt was applied around the thorax at the level of the fifth intercostal space. Volume controlled ventilation was used. PEEP was increased in a stepwise manner from 0 to 5, 10 and 15 cmH 2 O. At each PEEP, the VT was increased stepwise from 5 to 10 and 15 mL kg −1. After a minute of stabilisation, total impedance change (VT EIT), using EIT and VT measured by a spirometer connected to a flow-partitioning device (VT Spiro) was recorded for the following minute before changing ventilator settings. Data was analysed using linear regression and multi variable analysis. There was a linear relationship between VT EIT and VT Spiro at all levels of PEEP with an R 2 of 0.71, 0.68, 0.63 and 0.63 at 0, 5, 10 and 15 cmH 2 O, respectively. The variance in VT EIT was best described by peak inspiratory pressure (PIP) and PEEP (adjusted R 2 0.82) while variance in VT Spiro was best described by PIP and airway deadspace (adjusted R 2 0.76). The relationship between VT EIT and VT Spiro remains linear with changes in tidal volume, and stable across altered lung conditions. This may have application for monitoring and assessment in vivo.

Electrical impedance tomography (EIT) is a non-invasive real-time non-ionising imaging modality that has many applications. Since the first recorded use in 1978, the technology has become more widely used especially in human adult and neonatal critical care monitoring. Recently, there has been an increase in research on thoracic EIT in veterinary medicine. Real-time imaging of the thorax allows evaluation of ventilation distribution in anesthetised and conscious animals. As the technology becomes recognised in the veterinary community there is a need to standardize approaches to data collection, analysis, interpretation and nomenclature, ensuring comparison and repeatability between researchers and studies. A group of nineteen veterinarians and two biomedical engineers experienced in veterinary EIT were consulted and contributed to the preparation of this statement. The aim of this consensus is to provide an introduction to this imaging modality, to highlight clinical relevance and to include recommendations on how to effectively use thoracic EIT in veterinary species. Based on this, the consensus statement aims to address the need for a streamlined approach to veterinary thoracic EIT and includes: an introduction to the use of EIT in veterinary species, the technical background to creation of the functional images, a consensus from all contributing authors on the practical application and use of the technology, descriptions and interpretation of current available variables including appropriate statistical analysis, nomenclature recommended for consistency and future developments in thoracic EIT. The information provided in this consensus statement may benefit researchers and clinicians working within the field of veterinary thoracic EIT. We endeavor to inform future users of the benefits of this imaging modality and provide opportunities to further explore applications of this technology with regards to perfusion imaging and pathology diagnosis.

Background: Electrical impedance tomography (EIT) produces lung ventilation images via a thoracic electrode belt. Robust electrode design and material, providing low electrode skin contact impedance (SCI), is needed in veterinary medicine. The aim of this study was to compare three EIT electrode designs and materials. Methods: Simulations of cylindrical, rectangular and spiked electrode designs were used to evaluate electrode SCI as a function of electrode size, where skin contact was uneven. Gold-plated washers (E GW ), zinc-plated rivets (E ZR ) and zinc-galvanised spikes (E ZS ) were assigned randomly on two interconnected EIT belts. Gel was applied to the cranial or caudal belt and placed on 17 standing cattle. SCI was recorded at baseline and 3, 5, 7, 9 and 11 minutes later. Results: Simulations that involved electrodes with a greater skin contact area had lower and more uniform SCI. In cattle, SCI decreased with all electrodes over time (p < 0.01). Without gel, no difference was found between E GW and E ZS , while SCI was higher for E ZR (p < 0.03). With gel, SCI was lower in E GW and E ZR (p < 0.026), with the SCI in E GW being the lowest (p < 0.01). Limitations: Low numbers of animals and static electrode position may affect SCI. Conclusions: Electrode design is important for EIT measurement, with larger electrode designs able to compensate for the use of less conductive materials. Gel is not necessary to achieve acceptable SCI in large animals.

Four nulliparous, pet, merino ewes from the same property were evaluated at The Animal Hospital at Murdoch University, Western Australia, over a one-year period. The ewes presented with a history of chronic serosanguinous vaginal discharge. Age ranged from 5 to 11 years. Medical treatment with cloprostenol (Juramate, Jurox) and oxytocin (Syntocin, Ilium) failed in two ewes. A decision to surgically manage the cases was made. Midline laparotomy and surgical ovariohysterectomy resulted in permanent resolution of clinical signs. The first uterus and ovaries were submitted for histopathological examination and hydrometra was confirmed. Hydrometra is a known cause of infertility in sheep however more frequently noted as an incidental finding on abattoir specimens. It is an uncommon histopathological diagnosis. This case report expands the differentials for vaginal discharge in ewes, provides details of surgical correction of hydrometra and highlights the increased likelihood of unusual clinical presentations in older livestock kept as pets.

Sepsis of the distal interphalangeal joint is a commonly encountered problem in bovine practice. Treatments include conservative management, joint resection and digit amputation; however all of these options are associated with poor long-term outcomes. Referral for arthroscopic treatment may be an economically viable option for certain selected cases. This article describes such a case in detail.