EQUINE VETERINARY EDUCATION / AE / JANUARY 2020


41


a)


b)


Fig 4: a) Ultrasonographic image obtained from right caudoventral abdominal wall in a case of abdominal wall tearing. Intestine is visible external to the abdominal wall (AW). b) Ultrasonographic image obtained from right caudoventral abdominal wall in a case of abdominal wall tearing. The tear is outlined in arrows.


demonstrating many or all of the features of prematurity; low body weights, hypoglycaemia (associated with low body glycogen stores), hypothermia, a poor suck reflex, inability to digest enteral feeds, pulmonary and renal dysfunction, incomplete ossification and deficient musculoskeletal development (Ousey 2008). Should the mare suddenly deteriorate whilst attempting to


maximise gestational length and foal survival, intervention will be required; a caesarean (C section) or induction of parturition. Induction is usually preferable over C section, as the mares are often systemically compromised and pronounced oedema makes incisional complications common. Whilst an elective C section is beneficial in a few cases (when fetal maturity is suspected, it may allow the mare to have a reduced role in delivery [MacPherson 2012]), it is also indicated if the condition is terminal. There is a lack of data in the literature to help guide


treatment. One retrospective study (Ross et al. 2008) of a group of 13 mares showed a higher foal survival rate in mares that were managed conservatively vs. those in which interventions (euthanasia, elective C sections or induced parturitions) were performed. Whilst this


is valuable


information, it is a retrospective study where mares were not randomly allocated; for example, euthanasia with no attempt to save the foal was performed in two of the more severely affected mares (Ross et al. 2008). Nonetheless, although the exact number of foals surviving was not clearly outlined in this study, it certainly seems higher than many previously documented cases. Thus, wherever possible, conservative treatment should be the initial treatment regime of choice to allow more time for fetal maturation and therefore increased chance of a viable neonate. Finally in severe cases (requiring intensive monitoring and


treatment) in which neither the mare nor fetus has significant value, euthanasia is a justifiable alternative.


Supportive care


Supportive management consists of stall rest and abdominal support to prevent progression of the tear. Abdominal support will further control the oedema and makes mares more comfortable. Support can be achieved through homemade bandages (e.g. Tensoplast1), homemade slings (Fig 5) or commercial abdominal support (Fig 6) such as the CM Hernia Belt2. Mares should be monitored for pressure


necrosis developing along the spine; frequent repositioning and alterations in padding should be performed to allow redistribution of pressure and air movement around the skin. Diet should be modified to improve mare comfort by


reducing the bulk of the diet; minimise hay intake, feed a balanced high protein hard feed designed for the pregnant broodmare, and consider periodic nasogastric intubation with paraffin oil to maintain a soft faecal consistency. Analgesia is critical in these painful mares. Nonsteroidal


anti-inflammatories (NSAIDs) and opioids are often the backbone of treatment but a multimodal approach should be used, where possible to capitalise on synergistic if not additive effects of drugs without additional toxicity (provided drugs are metabolised and excreted by different routes). As well as systemically administered NSAIDs and opioids, consideration should be given to transdermal opioids, continuous rate infusions (CRIs) of lidocaine (0.05 mg/kg bwt/min), butorphonal (0.013 mg/kg bwt/h) and ketamine (0.4–0.8 mg/kg bwt/h) and potentially gabapentin. This latter drug is most commonly advocated for neuro- pathic pain and chronic pain states, but its use will likely be explored for other types of pain in equine patients.


Fig 5: Homemade canvas sling: design made to distribute weight evenly along the back, with adequate padding along the spine and with mesh to allow breathing of the skin. Image and design courtesy of Dr Angus McKinnon.


© 2018 EVJ Ltd


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