May sakit ang aso ko / <em>May sakit ang aking aso</em><em> </em><em>sounds more natural</em>

Malungkot ako kasi may sakit ang aso ko. May cancer ang tiyan siya/ <em>May cancer ang kanyang tiyan</em>. Pero hindi masyadong malungkot si Chase. <em> Tuwing siya ay napapagod nais niya kami makatabi sa pagtulog </em>at kumakain siya ng manok at kanin. Magiging masaya si Chase kung aalagain namin siya sa bahay. Mahal namin si Chase.

May s Sakit a Ang  a Aso k Ko

Malungkot ako, kasi may sakit ang aso ko. May canser kanser ng  siya sa tiyan siya. P pero hindi masyadong malungkot si Chase.  NapPagod siya, pero  kaya gusto niya matulog  na kasama kami, at kumakain siya ng manok at kanin. Kung  kaya masaya si Chase, . mag- inaalagaan kami namin siya kaniya sa bahay namin. dahil M mahal namin siya Chase.

Sorry about your dog :(

May sakit ang aso ko - Tama

Malungkot ako, kasi may sakit ang aso ko. –Tama

(Just for consistency though, you may want to decide if you should use “ko” (my) or “namin” (our).  Your title and first sentence use “ko”, but in your last 2 sentences, you used “namin”. 

May cancer ng tiyan siya. -  I think what you wanted to say here is, “He has stomach cancer”.   “Cancer ng tiyan”, does translate to “cancer of the stomach”, but we don’t say “cancer NG” (cancer of) in Tagalog.  We say instead, “cancer SA” (cancer in), e.g., cancer sa tiyan” (cancer in the stomach/stomach cancer), cancer sa balat (skin cancer).   You may state your sentence as:  “Siya ay may cancer sa tiyan” or “May cancer siya sa tiyan”.  Another, but less common way of saying it is, “May cancer ang tiyan niya” or “Ang tiyan niya ay may cancer”, which translates to “His stomach has cancer”.

Pero hindi masyadong malungkot si Chase. – Tama.

“Pagod siya, pero gusto niyaNG matulog kasama kami.” – This translates to, “He is tired, but he likes to sleep/sleeping with us,...”.   I am not sure if you really meant to use “but” in there.  If you’d like to use “and” instead, just replace “pero” with “at”.   I would also suggest that you use “namin” instead of “kami”.  With “namin”, the idea that “he likes to sleep with us” would be clearer.  With “kami”, it would sound more like, “he likes us to sleep with him”.  => “Pagod (na) siya at gusto niyang matulog kasama namin” =  He is (already) tired and he likes sleeping with us.

“Kumakain siya ng manok at kanin.”  - Tama.  This is better stated as a separate sentence because the idea of this phrase is independent of the previous part.  

“Kung masaya si Chase, mag-aalaga kami sa kaniya sa bahay namin.” = If Chase is happy, we will take care of him in our house/at home.  -  Grammatically, it is correct, but it does not sound right.  If what you meant was, “If it will make Chase happy, ...”, then that would be, “Kung ito ay ikasasaya ni/magpapasaya kay Chase...”.  The part, “...mag-aalaga kami sa kaniya sa bahay (namin)” is also grammatically correct, but I think “... aalagaan namin siya sa bahay (namin)” would be a better way to say it.  “Namin” is optional because it is understood that you are referring to your house/home.

Mahal namin si Chase. – Tama

Sana tumagal pa ang buhay ni Chase.