Administration: as with other methods of euthanasia, care should be taken not to excite the animal during preparation. Many authorities recommend that the procedure should be carried out in familiar surroundings avoiding harsh lights and sudden noises where possible. During the preparation and administration, it is often helpful to handle the animal carefully, but firmly, comforting it with gentle talk and coaxing as one would for the quiet induction of anaesthesia. This can also serve to calm apprehensive animals.

Perivascular administration of secobarbitone may delay the onset of effect and cause pain and result in excitement. Placement of a venous catheter is therefore recommended and care should be taken to ensure (by aspiration) that the injection is correctly placed in the vein. In horses and cattle the use of a preplaced 14 gauge jugular catheter is strongly recommended. In horses, the administration of detomidine, or suitable alternative, by slow IV injection is recommended to produce profound sedation prior to euthanasia. However, this may produce a slower onset of euthanasia.

N.B. The speed of injection is very important. Administer the full dose over 10– 15 seconds in order to minimise premature cardiac arrest. Additionally, an injection rate that is too slow may induce normal collapse, but prolong the period until death.

Do not use if solution is not clear or if any sediment is observed.

Adverse reactions

The recommended dose may be insufficient to achieve rapid euthanasia in some horses and this has been rarely reported. Excitation, muscle tremor and convulsion after injection has been very rarely observed in horses. Sedation prior to euthanasia is recommended in horses (see also section 4.9).

The frequency of adverse reactions is defined using the following convention:

- very common (more than 1 in 10 animals treated displaying adverse reaction(s))

- common (more than 1 but less than 10 animals in 100 animals treated)

- uncommon (more than 1 but less than 10 animals in 1,000 animals treated)

- rare (more than 1 but less than 10 animals in 10,000 animals treated)

- very rare (less than 1 animal in 10,000 animals treated, including isolated reports).