Active Chiropractic Clinic
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I am a graduate of Northwestern College of Chiropractic. After graduation I practiced in southeast Minnesota before relocating to the La Crosse area. I have been practicing in the Coulee Region for more than 30 years. I am a member of Rotary, Onalaska Area Business Association and have been on the Onalaska School Board for 18 years.

My certification in Nutritional Counseling was earned in 2008. I am a member of the Wisconsin Chiropractic Association, serving as District President several years. Additionally I am licensed to practice in South Dakota and Minnesota. I have over 30 years of experience working at various medical receptionist positions.
Services
Active Chiropractic Clinic in Onalaska offers Wisconsin Department of Transportation (DOT) Physicals, Federal DOT Physicals, DOT Drug Testing, NON-DOT Drug Testing, Alcohol Screens and Rapid testing with results in 10-15 minutes. Consortium; Small employers can be added to our consortium for random drug and alcohol testing at no additional costs.
Reviews (7)
Devin Rowan
Devin Rowan
Nov 18, 2021
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Went in for a new employee drug screening. Dr. Cassellius was very polite and gave instructions well! Was in and out in 10 minutes. The waiting room was really nice too.
Stacey Nikolay
Stacey Nikolay
Oct 05, 2021
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My experience was similar to several that I’ve since read. If I could give him a zero, I would. One of the most condescending, rude professional “dr” that I’ve ever dealt with. I went In for a new employee drug screening and he set the tone immediately…… what a positively miserable, belittling experience.
Willseyd
Willseyd
Aug 25, 2021
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Terrible customer service and RUDE!! Receptionist was nice but “so called Dr” absolutely not. Arguing to me about how I wanted my receipt. Seriously get over yourself. Don’t go here unless you want to be belittled. Terrible!!!
Mary Tschumper
Mary Tschumper
Mar 25, 2021
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Excellent, professional and very kind with my complicated pain related to pinched nerve/herniated disk in neck. Extremely knowledgeable about the spine/nerves/muscles and pressure points to relieve pain. Uses current and innovative research based methods to treat severe pain and works collaboratively as a team with other doctors to determine best care. I could not have survived this acute pain experience without him. God Bless You Dr Mark!!
Kinley M.
Kinley M.
Oct 31, 2020
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Extremely extremely rude. Very unwelcoming. He tried to say I refused to two drug tests when I stayed for 2 hours chugging water because each sample that was taken was “insufficient”. He had made me empty my pockets 3 times and to take my sweatshirt off and I had show him my necklace. I arrived at 4:30pm and was not able to leave until a little past 6:30pm. He claimed it was protocol when I confronted him of accusing me of refusal and him being rude. I had told him that I was not refusing anything. He claimed I did not follow directions and I was refusing which was not true. He said I could
Jared Laravia
Jared Laravia
Aug 29, 2020
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Honestly I wouldn't even give this guy one star. Completely unprofessional. I failed my DOT physical because of my eye exam And I went and got a prescription. Once I got that sorted out I went back to him to get my medical card. Not only did he decline me But told me I had to take the whole physical again. You couldn't even pay me to go back never well.
Josh Wallin
Josh Wallin
Aug 18, 2019
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The man i saw was extremely rude and extremely intrusive in his comments and making his oppinion known about things that are not his business wouldn't recommend