Postmortem biochemical markers of experimentally induced hypomagnesaemic tetany in sheep

Abstract

Hypomagnesaemic tetany was induced in non-lactating and lactating ewes by feeding them semi-synthetic low magnesium diets containing additional potassium chloride and citric acid. Aqueous and vitreous humour were sampled from one eye at the time of death (fresh) and from the second eye after the head had been stored at ambient temperature for 24 hours (24.hour). There were significant relationships between the concentrations of magnesium in cerebrospinal fluid and plasma and its concentrations in fresh aqueous humour and fresh vitreous humour. Magnesium concentrations of <0.33 mmol/litre in fresh aqueous humour and <0.50 mmol/litre in 24.hour aqueous humour were associated with severe hypomagnesaemia and tetany. However, the concentration of magnesium in aqueous humour is relatively unstable and, unless the time of death was known accurately, its interpretation would be difficult. Magnesium concentrations of <0.60 mmol/litre in fresh vitreous humour and <0.65 mmol/litre in 24-hour vitreous humour were associated with severe hypomagnesaemia and tetany in adult sheep. The concentration of magnesium in vitreous humour was relatively stable for up to 48 hours postmortem.

Postmortem diagnosis of canine diabetes mellitus and diabetic ketoacidosis via biochemical analysis of aqueous humour

“…In contrast, postmortem biochemical analysis of aqueous or vitreous humour for diagnosis of potential diabetes and DKA is more routinely carried out in human forensic investigations (Coe 1977, Khuu and others 1999, Osuna and others 2001, Osuna and others 2005, Felby and others 2008, Zilg and others 2009, Boulagnon and others 2011, Hockenhull and others 2012, Palmiere and Mangin 2012, Palmiere and others 2013). In animals, biochemical analysis of ocular fluid has most commonly been performed in sheep and cattle for diagnosis of hypomagnesaemia (Lincoln and Lane 1985, McLaughlin and McLaughlin 1988, McCoy and others 2001a, b, Nietfeld 2012), hypocalcaemia (Hanna and others 1990, Mearns 2009) and less commonly, ketosis in pregnancy toxaemia (Sargison 2007). Literature is lacking for a similar use of ocular fluid analysis in diagnosis of metabolic conditions in small animals.…”

“…The biochemical analysis of aqueous/vitreous humour for postmortem diagnosis of metabolic conditions is generally uncommon in small animals. However, it is used routinely in human forensic investigations (Coe 1977, Khuu and others 1999, Osuna and others 2001, Osuna and others 2005, Felby and others 2008, Zilg and others 2009, Boulagnon and others 2011, Hockenhull and others 2012, Palmiere and Mangin 2012, Palmiere and others 2013) and for postmortem diagnosis of hypomagnesaemia (Lincoln and Lane 1985, McLaughlin and McLaughlin 1988, McCoy and others 2001a, b, Nietfeld 2012), hypocalcaemia (Hanna and others 1990, Mearns 2009) and pregnancy toxaemia (Sargison 2007) in cattle and sheep. The authors wish to raise awareness of the potential use of aqueous/vitreous humour for postmortem diagnosis of metabolic conditions (in particular diabetes mellitus and diabetic ketoacidosis (DKA)) in dogs when the serum/blood samples are not suitable or are inadequate for use.…”

Biochemical changes induced by hypomagnesaemia in lactating cows and ewes

“…However, severe magnesium deficiency is common only in ruminants, and, to the best of the authors' knowledge, it is not known whether similar biochemical effects due to severe magnesium deficiency either occur or are important in these species. The aim of this study was therefore to investigate the biochemical effects of severe hypomagnesaemia in lactating ruminants by using tissues derived from previous studies of hypomagnesaermia in sheep (McCoy and others 2001a) and cattle (McCoy and others 2001b).…”

“…A heparinised blood sample and a sample of liver were taken from each ewe at death. Full details of the experimental procedure have been described by McCoy and others (2001a).…”

Valores de magnésio no humor vítreo de bovinos abatidos para consumo no sul do Estado Do Rio De Janeiro

“…Atualmente as possibilidades investigativas são inúmeras e incluem DNA (Belsey & Flanagan, 2016), anticorpos (Tormey, 2016), choque anafilático (Han et al, 2015), glicemia (Boulagnon et al, 2011), gestação (Han et al, 2015), álcool e drogas (Metushi et al, 2016). Em veterinária, a análise do vítreo é pouco empregada, havendo relatos de sua aplicação diagnóstica na hipomagnesemia (McDowell 1992;Ramírez et al, 1998;Mattioli et al, 2000;McCoy et al, 2001), alterações renais (Choo-Kang et al, 1983) e intoxicações (Lincoln & Lane, 1985).…”