The Prevention of Cruelty to Animal Act (PCA Act) defines causing or permitting an animal to be in distress a criminal offence punishable by fines and/or a prohibition on owning animals.

The Act says: 24 (1) A person responsible for an animal who causes or permits the animal to be or to continue to be in distress commits an offence.

Distress is defined as
(a) deprived of adequate food, water or shelter,
(b) injured, sick, in pain or suffering, or
(c) abused or neglected.
For the purposes of this Act, a person responsible for an animal includes a person who
(a) owns an animal, or
(b) has custody or control of an animal.

The SPCA is in contravention of the PCA Act every time it has custody or control of an animal that is sick, in pain or suffering and does not "promptly take steps to relieve the suffering".

Perhaps the SPCA feels that it cannot be charged with cruelty for ignoring sick animals in its "shelters" because Subsection (1) does not apply if the distress results from an activity that is carried on in accordance with reasonable and generally accepted practices of animal management, and since it has ignored sick animals in its custody or control for so many decades, ignoring sick animals is de facto "generally accepted practices of animal management"?

If it is, then on what grounds does the SPCA charge puppymillers?

If AAS won the lottery it would hire lawyers to prosecute the SPCA on the grounds of permitting distress.