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Background Lowering the dose of desoxycorticosterone pivalate (DOCP) for the treatment of dogs with primary hypoadrenocorticism (PH) decreases costs and could lead to increased owner motivation to treat their affected dogs. Objective To evaluate the efficacy of a low-dose DOCP treatment protocol in dogs with PH. Animals Prospective study, 17 client-owned dogs with naturally occurring PH (12 newly diagnosed, 5 previously treated with fludrocortisone acetate [FC]). Methods Dogs with newly diagnosed PH were started on 1.5 mg/kg DOCP SC; dogs previously treated with FC were started on 1.0-1.8 mg/kg DOCP SC. Reevaluations took place at regular intervals for a minimum of 3 months and included clinical examination and determination of serum sodium and potassium concentrations. The DOCP dosage was adjusted to obtain an injection interval of 28-30 days and to keep serum electrolyte concentrations within the reference interval. Results Median (range) follow-up was 16.2 months (4.5-32.3 months). The starting dosage was sufficient in all but 2 dogs and had to be significantly decreased after 2-3 months to a median dosage (range) of 1.1 mg/kg (0.7-1.8). Dogs 3 years of age or younger needed significantly higher dosages compared to older dogs. None of them, however, needed the 2.2 mg/kg DOCP dosage, recommended by the manufacturer. Conclusions and clinical importance A starting dosage of 1.5 mg/kg DOCP is effective in controlling clinical signs and serum electrolyte concentrations in the majority of dogs with PH. An additional dose reduction often is needed to maintain an injection interval of 28-30 days. Young and growing animals seem to need higher dosages.

Background Clinicians alter dosing for desoxycorticosterone pivalate (DOCP) to mitigate costs, but this practice has not been critically evaluated in a prospective clinical trial. Hypothesis/Objectives The duration of action of DOCP is longer than 30 days in dogs with primary hypoadrenocorticism (PH). Animals A total of 53 client-owned dogs with PH. Twenty-four dogs with newly diagnosed PH (Group 1) and 29 dogs with treated PH (Group 2). Methods Prospective, multicenter, clinical trial. For phase I, DOCP was administered and plasma sodium and potassium concentrations were measured until the dog developed hyponatremia or hyperkalemia at a planned evaluation, or displayed clinical signs with plasma electrolyte concentrations outside of the reference interval independent of a planned evaluation, thus defining DOCP duration of action. Plasma electrolyte concentrations then were assessed at the end of the individualized dosing interval (IDI; i.e., DOCP duration of action minus 7 days, phase II and at least 3 months after concluding phase II, phase III). Results The duration of action of DOCP in dogs in phase I with naive PH (n = 24) ranged from 32 to 94 days (median, 62 days; 95% confidence interval [CI], 57, 65) and previously treated PH (n = 29) from 41 to 124 days (median, 67 days; CI, 56, 72). Overall, the final DOCP dosing interval for all dogs that completed phase II (n = 36) ranged from 38 days to 90 days (median, 58 days; CI, 53, 61). No dog that completed phase III (n = 15) required reduction in the IDI. The DOCP duration of action, independent of group, was not significantly associated with several baseline variables. The median drug cost reduction using IDI was approximately 57.5% per year. Conclusion and Clinical Importance The duration of action of DOCP in dogs with PH is >30 days, and plasma sodium and potassium concentrations can be maintained with an IDI >30 days long term.

ADDISON'S disease or hypoadrenocorticism generally results from immune-mediated destruction of the adrenal glands and particular dog breeds appear to be overrepresented; for example, West Highland white and wheaten terriers, Portuguese water dogs, duck-tolling retrievers and great danes. Candidate genes for the disease have been identified in several breeds, although at this time the exact contribution of these genes is unclear (Short and others 2014). In most cases of ‘typical’ hypoadrenocorticism there is a lack of production of both mineralocorticoid and glucocorticoid, whereas in the rarer ‘atypical’ Addisonian only glucocorticoid deficiency manifests itself. Mineralocorticoid deficiency results in hyponatraemia and hyperkalaemia, as well as hypovolaemia, whereas glucocorticoid deficiency can lead to weakness, hypoglycaemia and gastrointestinal signs. Once typical hypoadrenocorticism has been diagnosed, both mineralocorticoid and glucocorticoid supplementation is needed. Mineralocorticoid deficiency is generally treated with either fludrocortisone or desoxycorticosterone pivalate (DOCP). There is an example of a large study of 205 dogs where 95 per cent were initially treated with fludrocortisone. Some of these dogs (14 per cent) were eventually switched to DOCP for a variety of reasons (Kintzer and Peterson 1997). In a paper summarised on p 98 of this issue of Veterinary Record , Roberts and others (2016) were also able to successfully stabilise 90 per cent of their patients with fludrocortisone. There are significant differences between both medications, including cost, and in most countries DOCP is sparingly used, because it is considerably more expensive than fludrocortisone; however, in a small number of countries …

Background Measurement of plasma renin activity (PRA) is the gold standard for monitoring mineralocorticoid treatment in humans with primary hypoadrenocorticism (PH). Objectives To compare PRA in dogs with newly diagnosed PH, dogs with diseases mimicking PH, and healthy dogs, and evaluate measurement of PRA to monitor therapeutic effects in dogs with PH treated with different mineralocorticoids. Animals Eleven dogs with newly diagnosed PH (group 1), 10 dogs with diseases mimicking PH (group 2), 21 healthy dogs (group 3), 17 dogs with treated PH (group 4). Methods In group 1, PRA was measured before treatment and at different times after initiating treatment. In groups 2 and 3, PRA was measured at initial presentation only. In group 4, no baseline PRA was obtained but PRA was measured once or every 1–6 months during treatment. Mineralocorticoid treatment consisted of fludrocortisone acetate (FC) or desoxycorticosterone pivalate (DOCP). Results Plasma renin activity before treatment was increased in dogs with PH compared to normal dogs and dogs with diseases mimicking PH with median activity of 27, 0.8, and 1.0 ng/mL/h, respectively. In dogs with PH, PRA decreased and normalized with mineralocorticoid treatment using DOCP but not with FC. In dogs treated with DOCP, PRA was lower than in dogs treated with FC. Plasma sodium concentrations were higher and potassium concentrations were lower with DOCP treatment compared to FC treatment. Conclusion and Clinical Importance Plasma renin activity is a reliable tool for monitoring mineralocorticoid treatment. DOCP treatment more effectively suppresses PRA compared to FC in dogs with PH.

The efficacy of a microcrystalline desoxycorticosterone pivalate (DOCP) injection in the management of canine hypoadrenocorticism (CHAC) was investigated in 21 dogs. On day 0 dogs previously diagnosed with CHAC were given a physical examination and an injection (2.2 mg/kg) of DOCP. This was repeated on days 25 and 50. On day 75 of the study a final physical examination was performed and the success of therapy was evaluated. Blood samples were obtained for serum chemical analysis (Na+, K+, Cl−, BUN & creatinine) on day 0 and day 75. Body weight increased steadily from a mean (± sd ) of 25.5 ± 14.2 kg on day 0 to 27.1 ± 14.8 kg on day 75. The mean serum biochemistry values on day 0 were outside normal limits for Na+ (139.3 ± 9.2 mEq/l), K+ (5.4 ± 0.9 mEq/l), and Na + K + ratio [ (26.4 ± 4.8) 1 ]. On day 75, after three injections of DOCP, the values for Na+ (148.2 ± 5.2 mEq/l), K+ (4.9 ± 0.6 mEq/l), and Na + K + [ (30.8 ± 4.2) 1 ] were normal and significantly (P All dogs in the study did well on DOCP therapy. The few side effects observed resolved with concomitant administration of prednisolone and/or adjustment of the DOCP dose. All clients elected to continue DOCP therapy after the trial ended, and the dogs continue to do well.