Why is the SPCA having Gwen charged with cruelty?

Why only charge Gwen under the PCA Act?
The SPCA only asked Crown to charge Gwen under the Prevention of Cruelty to Animals Act, not (as it sometimes does), under the Criminal Code of Canada also.

If the SPCA had had Crown charge Gwen under the Criminal Code, Gwen would have been able to get legal aid, which we have been told is not available to those only charged under the PCA Act.

Abuse of power warned of
The SPCA sometimes offers deals to owners of seized animals if the owner has a lawyer who will fight them.  (Remember - the SPCA sometimes seizes healthy animals, and even though it uses the media to convict owners in the court of public opinion, painting the owners as monsters of depravity, and even as mentally ill (as it is doing to Gwen), that does not necessarily mean that the animals were being cruelly treated. The abuses of power that were warned of in the BC Legislature in 1994 have come only too true.)

Gwen has been treated especially harshly
When the Hope Standard wrote so supportively  of Gwen and negatively of the SPCA about the seizure of happy animals from Gwen, a well-known and highly regarded animal-lover, many people rushed to Gwen's defense, $3,800 was raised and paid to the SPCA so Gwen could get her healthy dog, Dakota back (being kept in miserable depression in an SPCA cell), two days before she went into hospital for cancer surgery.

The SPCA already got the Act's penalties against Gwen.  What more does the SPCA want?
When Gwen's cats were seized, the SPCA told her that she was never going to get them back and she might as well sign them over.  Knowing that she had no money for a lawyer, she did, in the hope that the SPCA would find homes for them.  Later she came to believe that they probably killed them. 

Gwen had to sign a legal agreement with the SPCA that limited her to the number of animals she currently still has, and the SPCA  demanded, and was paid, $4,000 by Gwen.  The PCA Act's sentencing penalties are both those things: a fine: $2,000 maximum; and a prohibition on owning animals: from no animals to a named number of animals, for any period of time the judge decides (based on what Crown asks for) including forever. In other words, the SPCA already got from Gwen probably as much, or more, than a judge would sentence her.  It seems highly unlikely that a judge would sentence such a clearly decent person - not the least bit a criminal danger to society - to jail.

Why isn't that enough to leave alone a kind-hearted woman, doing her best for animals, and suffering from cancer? 

The SPCA offers deals to people who can afford lawyers. Gwen is not wealthy enough to stop the SPCA from having it recorded in the courts and in the media that she is an "animal neglector" and a mentally-ill "hoarder".