Dimninazene aceturate concentration in plasma and residues in tissues of dogs treated with secnidazolediminazene aceturate combination and with diminazene aceturate alone was investigated in apparently healthy dogs. Fourteen apparently healthy dogs were randomly assigned to 3 groups. The first group consisted of 6 dogs pre-treated with 100 mg/kg secnidazole (SEC) orally 30 min before administration of 3.5 mg/kg diminazene aceturate (DA) im. The second group consisted of 6 dogs treated with 3.5 mg/kg DA im alone, while the third group had 2 dogs untreated and used to prepare the control tissues and standards. Blood samples were collected at 24, 48 and 72 h post-administration of DA and serum harvested for estimation of DA concentrations in the serum. For estimation of DA residues in tissues, 2 dogs were sacrificed in each group at 240, 360 and 480 h post-administration of the drugs. Ten grams of tissue samples (liver, kidney, brain, heart and skeletal muscle) were collected in triplicate. Intramuscular administration of DA, led to detectable and measurable levels of DA up to 72 h in the serum of both groups of dogs. However, there was no significant difference in the serum concentration of DA in both groups of dogs from 24 -72 h. The concentration of DA was significantly (p < 0.05) higher in the brain of SEC pre-treated dogs at 240 h. In the kidney and liver, DA concentration was significantly (p < 0.05) higher in SEC pre-treated dogs at 480 h. There was no significant difference in the DA concentration in the myocardium and skeletal muscles of both groups of dogs. We therefore concluded that DA persists in the tissues of treated dogs beyond 20 days post-treatment and that SEC alters the elimination pattern of DA in SEC pre-treated dogs.

Relapse parasitaemia is a major setback in the chemotherapy of a late stage Trypanosoma brucei brucei infection. An aberrant serum biochemical profile resulting from a T. b. brucei infection in dogs has been attributed to multiple organ injuries resulting from the invasive nature of the organism. Therapy with diminazene aceturate alone has not been satisfactory. This study evaluated the effects of a secnidazole-diminazine aceturate (SEC-DA) combination therapy on parasitaemia and the serum biochemical profile after the late treatment of a T. b. brucei infection in dogs. Eighteen dogs were randomly assigned to 6 groups (n = 3) as follows: Group A: uninfected nor treated; group B: infected without treatment; group C: infected and treated with DA (3.5 mg/kg) (DA-monotherapy) intramuscularly (i.m.) once; group D: infected and treated with SEC (100 mg/kg) and DA (3.5 mg/kg); group E: in-fected and treated with SEC (200 mg/kg) and DA (3.5 mg/kg) and group F: infected and treated with SEC (400 mg/kg) and DA (3.5 mg/kg). Secnidazole was administered orally for 5 days while DA was given i.m. once in groups D–F. The dogs were infected with 5 × 10⁵ trypanosomes intraperitoneally and treatment started 14 days post-infection. The parasitaemia was monitored daily while the serum biochemical indicators were monitored 14, 21, and 28 days post-infection. The total aparasitaemia was achieved in the SEC-DA treated dogs 72 h post-treatment and in 86 h in the DA-monotherapy dogs. A relapse parasitaemia occurred in the DA-monotherapy dogs 17 days post-treatment. The SEC-DA combination therapy caused a significant (P &lt; 0.05) decline in the hitherto elevated urea and creatinine concentrations, and the ALP, ALT, AST activities. Also, there was a significant (P &lt; 0.05) increase in the previously decreased serum albumin in the SEC-DA treated dogs. In conclusion, secnidazole-diminazene aceturate combination therapy prevented the relapse parasitaemia and ameliorated aberrant serum biochemical profiles of T. b. brucei infected dogs after late treatment.