私は犬を飼っています。
犬の名前はマキ。3歳です。
東京の八王子にある保護センターで彼女を引き取りました。
犬種はミックス犬です。　日本ではこの様な犬種の事を雑種犬と呼びます。
最近では雑種という呼び方は差別的な用語な為あまり使用しません。

カナダで生活しているとよく犬の種類を聞かれますが該当する犬種が分からない為
最初の頃はどの様に説明すれば良いのか分かりませんでした。

最近では、柴犬とのミックスであると説明してます。
実際の所柴犬とのミックスなのかは分かりませんが、それが一番伝わりやすいです。

I have a dog
My dog`s name is MAKI.  She is 3 years old.
I got to her from the animal shelter Hachioji in Tokyo.
My dog`s kind of MIX. There kind of call to mongrel dog.
But I think this word is discriminatory expression that these days don`t use it.
I`m often asked what kind of my dog but I don`t know correct kinf of my dog.
so, I didn`t know how to talk about it.
These days I have been explaining that it is a mix with a Shiba inu
Because shiba inu is very famous with dog lover  in the world
Actually, I dont` know mix with a shiba inu bt my dog.
But That's the easy to talking.

修正
I have a dog named MAKI, and she is 3 years old. 
I adopted her from the Hachioji animal shelter in Tokyo. 
She is a mixed breed, commonly referred to as a mongrel dog. 
However, I understand that this term is considered discriminatory these days and is not commonly used.

When people ask about my dog's breed, I often find it challenging to provide an accurate answer.
 To make the conversation easier, I have started explaining that she is a mix with a Shiba Inu, a popular breed among dog lovers worldwide.
 In reality, I am not certain about the specific mix with a Shiba Inu, but it makes the conversation more accessible.

以下に修正した部分を詳しく説明します。

I have a dog named MAKI, and she is 3 years old.

この部分は元のままで問題ありませんが、文の最初にカンマを追加して、「I have a dog named MAKI」と「she is 3 years old」を分けました。
I adopted her from the Hachioji animal shelter in Tokyo.

「got to her」の部分を「adopted her」に変更し、より一般的で自然な表現にしました。
She is a mixed breed, commonly referred to as a mongrel dog.

「They kind of call to mongrel dog.」を「She is a mixed breed, commonly referred to as a mongrel dog.」に変更し、より自然な英語表現にしました。

However, I understand that this term is considered discriminatory these days and is not commonly used.

「But I think this word is discriminatory expression that these days don't use it.」を「However, I understand that this term is considered discriminatory these days and is not commonly used.」に変更し、文の流れを繋げ、より自然な表現にしました。
When people ask about my dog's breed, I often find it challenging to provide an accurate answer.

「so, I didn't know how to talk about it.」を「When people ask about my dog's breed, I often find it challenging to provide an accurate answer.」に変更し、より具体的で明確な表現にしました。
To make the conversation easier, I have started explaining that she is a mix with a Shiba Inu, a popular breed among dog lovers worldwide.

「But That's the easy to talking.」を「To make the conversation easier, I have started explaining that she is a mix with a Shiba Inu, a popular breed among dog lovers worldwide.」に変更し、文の整合性を保ち、より自然な表現にしました。

修正後の文章はすこし難しいので
今後添削するときは具体的にレベルを指定して実施する。