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A positive outcome was reported in a case report of


presumed parasitic encephalitis, in which recovery was observed after treatment with dexamethasone at 0.1 mg/kg bwt i.v. once daily for 5 days, along with anthelmintic and antimicrobial medications (Wilford et al. 2013).


Head trauma The use of glucocorticoids in horses with head trauma remains controversial, and effects such as reduction of cerebral oedema, improvement in brain perfusion and membrane stabilisation, are the main suggested purposes of their use (Nout 2010; Hurcombe 2015). The effect of treatment with glucocorticoids in cases of head trauma remains unclear, and it is no longer recommended in human patients, based on clinical trials showing an increase in short- and long-term mortality in adults treated with steroids after traumatic head trauma (Czekajlo and Milbrandt 2005; Edwards et al. 2005). There is no evidence that glucocorticoids improve the outcome or reduce human intracranial pressure (Bullock and Povlishock 2007). In horses, the use of dexamethasone, prednisolone, and methylprednisolone is reported in cases of head trauma, and a retrospective study showed that dexamethasone was the most commonly used at a dose ranging from 0.03 to 0.08 mg/kg bwt administered i.v. (Feary et al. 2007). In this study, there was lack of evidence to support the use of this treatment in horses, where associations between treatments and nonsurvival were not performed (Feary et al. 2007). Another source suggests the use of dexamethasone at a dose of 0.1–0.2 mg/kg bwt i.v. every 6 to 8 h for the first 24 h after the head trauma, and then once daily for 2–3 days; however, the value of this treatment protocol is uncertain in horses with a noninflammatory cerebral injury (Divers 2008).


Spinal cord injury The use of glucocorticoids is controversial in cases of acute, severe human spinal cord injury; only small neurological improvements have been demonstrated with methylprednisolone used shortly after the acute onset of clinical signs (Bracken et al. 1992). Methylation increases the lipophilic characteristics of methylprednisolone, enhancing cell penetration. It has been observed in man that plasma concentrations are linear and proportional to the dose, and not determined by plasma protein binding as it occurs with prednisolone; even though the chemistry of both drugs is the same, these characteristics give methylprednisolone increased efficacy in the face of plasma protein variations (Rohatagi et al. 1997). Similarly in horses, the use of glucocorticoids for spinal trauma remains controversial, and if they have any benefit, it is likely in the acute stage and should be given early (Hurcombe 2010). The use of methylprednisolone sodium succinate, 10–30 mg/kg bwt i.v. within 1 hour from trauma, has been described; however, its use is rare and there are no reports describing the efficacy (Divers 2008). Another source described the use of methylprednisolone sodium succinate as a bolus of 25 mg/kg bwt i.v. shortly after the spinal cord trauma, followed by a constant rate infusion at 5–8 mg/kg bwt/h i.v. for 23 h (Hurcombe 2015). Reported dosages of dexamethasone for spinal cord trauma range from 0.1 to 0.3 mg/kg bwt i.v. every 6–24 h for 2–4 days (Divers 2008; Nout 2010). The main purpose of the therapy with dexamethasone is to reduce


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inflammation, thereby decreasing cytokine release and free radicals (Nout 2010). Based on a pharmacokinetics study comparing


dexamethasone and prednisolone after i.v. and i.m. administration in horses, it was determined that dexamethasone has a higher volume of distribution and longer half-life, which are desired characteristics when trying to reach therapeutic drug concentrations in tissues (Toutain et al. 1984). It is then inferred that dexamethasone will be the drug of choice if glucocorticoid administration is elected to treat head or spinal cord trauma, followed by methylprednisolone. For cases of cervical vertebral stenotic myelopathy


(CVSM), glucocorticoids may reduce the oedema associated with spinal cord compression, and provide transient improvement of the clinical signs; however, full recovery, if feasible, will not be achieved without dietary or surgical intervention (Rush 2009). In one retrospective study, there was a report of horses treated with flunixin meglumine at 1 mg/kg bwt orally every other day alternated with dexamethasone at 0.02 mg/kg bwt orally every other day for 30 days; and when compared to other types of treatments such as vitamin E supplementation, dimethyl sulfoxide, dietary changes, osteoarthritis medications, and exercise restriction, there was no significant effect on prognosis (Hoffman and Clark 2013). Another retrospective study showed clinical improvement in 3 out of 5 horses with CVSM treated with glucocorticoids by referring veterinarians; a total of 22 cases of CVSM were analysed, but neither the name of the medication, dosages nor duration of therapy was provided (Levine et al. 2007).


Other systemic uses of glucocorticoids


Immune-mediated haemolytic anaemia Immune-mediated haemolytic anaemia is associated with the production of autologous antibodies directed against the animal’s own red blood cells. It can occur as a primary idiopathic disorder, but it is more often associated with another primary disease process. Secondary autoimmune haemolytic anaemia in horses has been associated with conditions such as purpura haemorrhagica, lymphoma, chronic bacterial infections and medications, especially procaine penicillin (Weiss and Moritz 2003; Carlson 2009; Cottle and Hughes 2010; Johns et al. 2011). Glucocorticoids are often used to disrupt the immune


response, and a suggested therapy is the use of dexamethasone at an initial dose of 0.05–0.1 mg/kg bwt every 24 h for a 450 kg horse, given parenterally. This dose can be continued for 3–5 days, then decreased gradually over 7–14 days (Carlson 2009). If there has been no response in 5–7 days, the diagnosis should be reviewed. Once the haemolytic process is under control, treatment can be transitioned to orally administered prednisolone at a dosage of 0.8–1 mg/kg bwt once daily (Carlson 2009). Dexamethasone at 0.04–0.06 mg/kg bwt i.v. given once daily has been reported to be effective in cases of immune- mediated haemolytic anaemia secondary to Rhodococcus equi pneumonia in foals, together with antimicrobial treatment and supportive care; and once the clinical condition improved, the dexamethasone was tapered over a 25 day period (Johns et al. 2011). It is important to determine if the cause of the immune-mediated process is the use of a medication that needs to be discontinued, or an infectious


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