News

Case Summary

A Thoroughbred X Australian Stock Horse colt presented to the Veterinary Clinical Centre (VCC), Charles Sturt University at 5hrs of age. Parturition was not witnessed and the colt was found recumbent in the paddock, unable to stand. The foal had not nursed. The mare is multiparous and had a history of placentitis diagnosed by the referring veterinarian. This had been treated with systemic antimicrobials (trimethoprim sulphonamide) for approximately 2 months prior to foaling. The mare had run milk for 7 days prior to foaling.

On presentation to the VCC, the foal was quiet but alert and responsive. A strong suck reflex was present and occasional attempts to stand were made. Cardinal signs recorded were within normal ranges with the exception of mild hypothermia (36.4°C). Initial haematological and blood biochemical examination revealed a mild leukopenia and neutropenia and hypoproteinemia. There was also a moderate hypercreatinaemia, however this resolved quickly over the first 48hrs of hospitalisation and was therefore most likely associated with placental insufficiency. Other results were not supportive of renal dysfunction and the colt was producing urine with an appropriate USG.

A blood sample was collected aseptically at the time of admission to hospital for blood culture and results revealed a heavy pure growth of Acinetobacter sp. (aerobic Gram-negative bacilli). The sensitivity of the organism was used to direct systemic antimicrobial therapy.  Intensive medical management of this colt included replacement intravenous fluid therapy with an initial bolus of Hartmann’s solution, followed by maintenance constant rate infusion (CRI) of polyionic crystalloid fluid (Plasmalyte 56 + 5% glucose). A separate glucose CRI was also commenced with regular monitoring of plasma glucose concentration. Other treatment included nasal oxygen insufflation and an indwelling nasogastric tube was placed to facilitate enteral assisted nutrition, initially with colostrum and then mare’s milk. The volume of each feed was started at 5% body weight/day as 2hrly feeds and gradually increased with close monitoring for signs of abdominal discomfort and/or diarrhoea.

IgG concentration measurement confirmed failure of passive transfer of maternal antibodies and 1L hyperimmune plasma was administered. Repeat IgG concentration measurement was >8g/L. 24 hours after admission, the foal’s mentation and clinical condition deteriorated despite intensive care. He was obtunded with minimal response to stimulation and short intermittent episodes of seizure activity were noted. This included stretching out of the head and neck, paddling with the forelimbs and bilateral nystagmus. This was initially managed with bolus doses of diazepam (0.1mg/kg) administered intravenously. The episodes increased in frequency despite this treatment and a total of 3 doses of diazepam were administered. A decision was made to commence treatment for refractory seizures with a midazolam CRI. A bolus (0.04 mg/kg IV) was administered initially, followed by a CRI, starting at 0.02 mg/kg/hr and gradually increased to 0.06 mg/kg/hr over the following 12 hours due to persistent intermittent seizure activity. A dobutamine infusion was also commenced due to persistent hypotension and there was good response to this.

There was very good response to treatment with midazolam in this case and seizure activity resolved. The infusion rate was gradually decreased and discontinued approximately 60 hours after it was commenced. The dobutamine infusion was also discontinued. There was ongoing improvement in the foal’s mention and clinical condition overall and it was eventually able to stand with assistance. Intravenous fluid therapy was gradually discontinued as the foal was tolerating increasing volumes of mare’s milk via the nasogastric tube. The foal was intermittently assisted to nurse from the mare and was eventually able to nurse without assistance. Serial haematological and blood biochemical examinations confirmed resolution of systemic inflammation and antimicrobial therapy was discontinued. The mare and foal were discharged from hospital 16 days after admission.

Clinical relevance

It is assumed the neonatal encephalopathy (NE) and seizure activity developed as a consequence of perinatal asphyxia syndrome (PAS) in this case. Conditions associated with PAS in foals include dystocia, caesarean section, placentitis, premature placental separation (‘red bag’ delivery), severe maternal illness, maternal surgery. Many foals have no known peripartum period of hypoxia. Foals with PAS and NE may appear healthy at birth but develop central nervous system abnormalities from within a few hours of birth to 1-2 days of age.

The midazolam infusion was an effective treatment for the intermittent seizure activity in this case. Diazepam and midazolam are benzodiazepines. The mechanism of action of benzodiazepines is through potentiating the activity of endogenous gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter of the central nervous system. The initial use of diazepam in this case was appropriate as diazepam is used preferentially over other benzodiazepines for the treatment of seizures as there is rapid distribution to the CNS following intravenous administration. Repeated doses may be required to achieve adequate seizure control, however if there is minimal response to treatment, alternative medications should be considered. Midazolam has relatively greater lipid solubility than diazepam, resulting in a more rapid onset of action. It is also approximately 3-4 times more potent than diazepam. The lowest effective dose should be used to avoid hypotension and respiratory depression. A CRI is recommended when there is inadequate response to single bolus doses and/or if more than 2 seizure episodes occur.

This case highlights the clinical efficacy of a midazolam CRI for the management of refractory seizures in equine neonates. No major adverse effects were noted with the use of midazolam in this case. The hypotension was effectively managed with a dobutamine infusion. Although negative haemodynamic and neurologic effects have been reported in human neonates, it is unknown if critically ill equine neonates experience these effects. In humans, the duration of treatment is often longer than that used in equine neonates and this may be associated with an increased risk of adverse effects. The pharmacokinetics of midazolam have not yet been published in equine neonates.

Photographs taken on days 4 and 5 of hospitalisation. The foal was maintained in a sternal support and was regularly turned while recumbent. Constant rate infusions of polyionic crystalloids, glucose, midazolam and dobutamine were administered. The foal also has a nasal oxygen tube and indwelling nasogastric tube in place.  Photographs taken on days 4 and 5 of hospitalisation. The foal was maintained in a sternal support and was regularly turned while recumbent. Constant rate infusions of polyionic crystalloids, glucose, midazolam and dobutamine were administered. The foal also has a nasal oxygen tube and indwelling nasogastric tube in place.

Photographs taken on days 4 and 5 of hospitalisation. The foal was maintained in a sternal support and was regularly turned while recumbent. Constant rate infusions of polyionic crystalloids, glucose, midazolam and dobutamine were administered. The foal also has a nasal oxygen tube and indwelling nasogastric tube in place.

Photograph taken on Day 16, prior to discharge from hospital.

Photograph taken on Day 16, prior to discharge from hospital.

If you have any questions regarding this case, or cases you would like to share, we welcome you to send them to: secretaryequine@anzcvs.org.au

Equine Online Scientific Series Review

Although the cancellation of Science Week on the Gold Coast due to COVID-19 restrictions was very disappointing, the Equine Chapter was excited to present an interactive series of four presentations as part of the ANZCVS Online Scientific Series earlier this year. Sessions were presented by experienced veterinarians from Australia, New Zealand and North America, thanks to the generous support from Bova Equine.

Dr. Steve Zedler, a specialist equine surgeon at The University of Queensland presented a series of challenging arthrodesis cases.  He provided some very interesting case material including photos, radiographs and CT images and talked through the important aspects of decision making in each case and when the option for arthrodesis may be warranted.

Dr Michelle Logan, a registered specialist in Equine medicine from New Zealand presented on practical approaches to fluid therapy in the field. The presentation highlighted some specific case examples including foals, colitis and ponies at risk of hyperlipaemia. Key physiology principles were succinctly explained, providing a logical approach to fluid type selection and administration rates and volumes. Practitioners working in field settings may not always consider the various options for providing fluid therapy to their patients, however this presentation will likely encourage them to include it as part of the management of certain cases.

Dr Edwina Wilkes, a registered specialist in Equine Medicine at Charles Sturt University (CSU) presented some of the challenging aspects of the management of horses that were injured during the Australian Bushfire crisis in early 2020 and hospitalised at CSU. Many different aspects of case management were discussed including pain management, nutrition, wound care and the potential complications which can arise. This presentation highlighted the difficulty in the initial assessment of the severity and extent of a thermal injury and provided practical advice for when referral to a hospital facility is warranted.

Dr Rana Bozorgmanesh, an associate and specialist in Equine medicine at Hagyard Equine Medical Institute in Kentucky, USA presented on colic in post-foaling mares. We were very lucky to have Rana present in the Online Series and her presentation highlighted the extent of her knowledge and experiences in a very busy referral hospital in the horse breeding capital of the world! She presented on a range of differential diagnoses, highlighting the number and diversity of cases that present to Hagyard. The presentation provided a practical approach to the diagnostic workup of these cases with very helpful discussion on how to accurately differentiate between different causes of colic in post-foaling mares. Rana made reference to the importance of regular re-assessment and when surgery may be indicated. The presentation included multiple photos, ultrasound images and videos and clinical pathology results and clearly described her interpretation of these and how it contributed to her assessment and treatment of each case. We hope to see Rana at Science Week in the future!

Registration for the Online Series is still open until 30 November 2020 so make sure you don’t miss out on the opportunity to view these informative and entertaining presentations! Each presentation included a live Q&A session with each of the speakers and the recordings of these sessions are also available.


- By Edwina Wilkes, November 2020

Examinations Update

                                                                                                                

We extend a massive CONGRATULATIONS and welcome to those 10 new members who achieved Membership in Equine Medicine in 2019. We congratulate and welcome Dr Amy Williamson in attaining Fellowship in Equine Surgery in 2019. We wish those candidates who recently sat their Equine Surgery Fellowship examinations over the weekend of Nov 7th-8th 2020 the very best of luck.

Associate members: Associate members are those who have achieved equine specialist qualifications overseas with the American or European Colleges. Our most recent associate member is Dr Darien Feary. There are many overseas trained equine specialist veterinarians practicing in Australia and New Zealand, but we are still a relatively small group and we encourage those people to become members of the ANZCVS so that we may share resources and knowledge, particularly those that are involved in supervising veterinary students, equine interns and residents in Australia and NZ. If you know any specialists that are non ANZCVS members please encourage them to contact us to become members.

THANK YOU to Examiners: We extend a massive thank you to the 2020 examiners for Membership in Equine Surgery and Equine Practice, and Fellowship in Equine Surgery. These examiners have worked tirelessly through the disruption of COVID-19 pandemic to not only create a relevant examination of the highest standard, but to examine via a digital distance platform at Fellowship level. Thank you to examiners and to our candidates for negotiating these challenges, including postponing Membership examination to 2021.

Examinations in 2021: The Equine Chapter is pleased to be offering Membership examination in Equine Surgery, Equine Medicine, and Equine Practice in 2021. Please encourage your associates to consider undertaking these examinations.


- November 2020

Scone Equine Group Award for Excellence in Equine Surgery

Congratulations to Dr Ashley Vermeulen for successfully completing the membership examination in Equine Surgery. Ashley was awarded the Scone Equine Group prize for the best performed candidate in this year's examination.

Ashley graduated from the University of Sydney with an honors degree in Exercise and Sports Science and published on Equine Excercise Physiology and exercise testing in Thoroughbred racehorses. After several years working with racehorses throughout Australia and overseas, Ashley returned to study and completed a Veterinary degree at the University of Queensland. Ashley has worked as an Equine Veterinarian in Sydney, predominantly at Randwick, Rosehill and Warwick Farm racecouses. Ashley is now working at the Morphetville Equine Clinic.

 

Reg Pascoe Research Session prizewinner

Congratulations to Alexandra Jaarsma who was the inaugural winner of the Reg Pascoe ANZCVS Research session prize.

Alexandra presented her research entitled "Owner-reported respiratory disease in South Australian horses" and is currently working at the University of Adelaide veterinary hospital.


Equine Chapter Proceedings available

The Equine Chapter Proceedings are available for download from the link below

2018 Equine Chapter Proceedings


We look forward to seeing you all on the Gold Coast in a couple of days.


Regards

Equine Chapter Executive Committee


Equine Chapter Research session

The Equine Chapter Research session will be held again this year during our annual Science week program. It will be held on the 6th July 2018 and we encourage people to submit their abstracts for consideration. If selected to present your abstract, your presentation will be assessed by 2 independent assessors and if considered the best presentation will be awarded with a prize.


For more information please follow the link below:

Equine Chapter Research Session - Call for Abstracts


If any further information is required please email presidentequine@anzcvs.org.au


FACEBOOK

The Equine Chapter now has it's own Facebook page!

Visit us on our Facebook site (ANZCVS Equine Chapter) and "like/follow" us to keep up to date with any news and interesting posts

SCIENCE WEEK 2018

Join us for the Equine Chapter program at Science Week 2018.

We have an exciting program this year which has an Emergency theme. We are extremely happy to announce that our key-note speaker is Professor Chris Sanchez from the University of Florida. We also have excellent local speakers including two specialists in the human field discussing traumatic brain injury and sepsis.

 

The preliminary program can be seen when you follow the link below:

Equine Chapter Program 2018


Look forward to seeing you on the Gold Coast in July!