1) Statistically What Are The 10 MOST common conditions/reasons DOG
Owners Take Their DOG to a vet?

2) Same question for CAT owners?

Hello miramo,

Thank you for your interesting question. Here is the research I could
find on the matter. Veterinary Pet Insurance releases data on this
annually.

The parentheses denote the placement of the condition the year before.

2005 Top 10 Claims by Incident -- Dogs (ranking in 2004)

1.  Skin allergies (2)
2.  Ear infections (1) 
3.  Stomach upsets (3)
4.  Bladder infections (5)
5.  Benign tumors (4)
6.  Osteoarthritis
7.  Sprains (7)
8.  Eye infections (8)
9.  Enteritis
10. Hypothyroidism 

2005 Top 10 Claims by Incident -- Cats (ranking in 2004)

1.  Urinary tract infections (1)
2.  Stomach upsets (2)
3.  Kidney disease (10)
4.  Skin allergies (5)
5.  Respiratory infections (3)
6.  Diabetes
7.  Ear infections (4)
8.  Colitis (8)
9.  Eye infections (6)
10. Wound infections (7)

Source:
http://www.petville.com/pet_community/2006/10/top_10_reasons_.html

Search terms:
"top 10 reasons" + dog + vet

If you need any additional clarification of my answer, feel free to
ask and I'll be happy to help.

--keystroke-ga

Fleas and infections for starters ... I guess.

Well, most people take their pets to the vet for annual shots. I'm
surprised that wasn't mentioned.....

Steph53

O No Stepho

'Annual shots' are NOT an illness.

Please read the question again!

The question said "conditions/reasons." The subject line said "illnesses."

Ooops....

My mistake...

I musta been having a "blonde moment" :(

Steph53