Small animal practice team
Our small but very experienced and competent team consists of two veterinarians and three veterinary practice assistants EFZ as well as one practice assistant in training.
Veterinarians
Dr. med. vet. Michael Hiestand
Owner, Managing Director
Head of Dermatology, Surgery, Wound Healing and Orthopaedics
In daily practice, Dr. Hiestand runs part of the general consultation hours and takes special care of the Diseases of the musculoskeletal system and the skin. Surgery and imaging examinations (X-ray, ultrasound and endoscopy) are further focal points.
As a particular specialization, Dr. Hiestand deals with physical treatments such as cold plasma therapy, which is used especially in dermatology and wound healing, but also in pain therapy. is applied. Since 2025, it has also dhe new ultrasound surgery was introduced in practice to make tooth removal less invasive and faster. Patients benefit from shorter anesthesia times and less pain after the operation.
He grew up as a 'local' in Wollerau and studied and did his doctorate in Zurich. The residency years began in 1994 in Au on Lake Zurich followed by residencies in various practices and clinics in different regions of Switzerland. For the last 10 years before founding the Obersee practice, he was a partner and operations manager of a larger practice near Lucerne where he also worked as a surgeon.Â
In his free time, he is an avid skier and mountaineer. He certainly enjoys tackling a ‚4,000er‘ every now and then, which he then prefers to descend on skis through deep snow or by balancing his way along a beautiful ridge. But exploring the mountains with his three dogs—Enzo, Fiona, and Orso—is one of his absolute favorite things to do.
In addition to the three Cirneci dell' Etna, the two holy Burmese cats Caillou and Zsazsa and 4 Moorish tortoises complete the small 'zoo'.
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Dr. med. vet. Hanna Stamm
Specialist veterinarian FVH small animals
Head of Small Animal Medicine
Since August 2023 Dr. med. vet. Hanna Stamm, Veterinary Specialist FVH for small animals active in the Obersee practice. In addition to her excellent education, the small animal specialist also brings a lot of practical experience with her. For the past three years, she has been the head veterinarian at a VetTrust AG practice in Uster. Dr. Stamm continues to act as a consultant specialist advisor for the assistant veterinarians at VetTrust AG.
After graduating from the University of Vienna in 2014, she completed her doctorate at the Clinic for Small Animal Medicine at the University of Zurich on the ultrasound examination of cat kidneys. This was followed by various positions as an assistant veterinarian in Switzerland as well as an internship at the Basel Veterinary Clinic.Â
We are very pleased that Dr. Stamm has now decided to join the Obersee practice. She will be conducting consultations with us, doing medical evaluations including ultrasound exams, and also working in surgery. Within the next year, Dr. Stamm will also be European ESAVS Ophtalmology Training graduate with the Certificate of Advanced Studies (CAS). This means that we have our own eye disease specialist at the Obersee practice.
Privately, Hanna Stamm is married and has a little daughter (Maila). Of course she grew up in her family with dogs and cats . Besides animals, Hanna Stamm is interested in kite sports. This exciting hobby she pursues intensively on water and on land (snow).
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Veterinary anesthesia technician / VAT
Jasmin Härtsch, VAT/TPA
Jasmin Härtsch joined the Obersee-Praxis team on March 1, 2025. The likeable Grisons native completed her apprenticeship as a TPA in Sargans in 2016. She then worked at the Aarau West Veterinary Clinic in Oberentfelden until 2021, successfully completing the VASTA training course to become a veterinary anaesthesia technician. She then returned to her 'regular practice' in Sargans. We are very pleased that she has now moved to Altendorf and can perfectly complement our team.
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Veterinary Practice Assistants (TPA)
Melanie Beeler, TPA, medical and hospital secretary
joined the team in April 2018. After completing her apprenticeship as a TPA in a private practice in Meilen, she worked in small animal medicine at Zurich Veterinary Hospital for 7 years. She brings a lot of professional experience to the team. In 2023, Ms. Beeler completed her additional training as a medical and hospital secretary.
In 2024, Ms. Gloor became Ms. Beeler, and in June, she welcomed a new addition to the family! We’re all happy for her, especially since her next maternity leave is coming up soon (Fall 2026). After that, she’ll return to work with us part-time as soon as it makes sense to do so.
As a long-standing member of the team, she helps the senior vets to organize procedures and also plays a very special role on operation days. With a wealth of experience and expertise, she monitors the anesthesia patients in a team with our VAT.
She was an active ice hockey player for Rapperswil-Jona and also enjoys sports (snowboarding, swimming). How could it be otherwise? She also grew up with animals. Her cat Bartholomew is of course also perfectly looked after.Â
Shannon Grellmann, TPA
has been working with us since December 2024 as a broadly trained medical technician who changed careers.
Shannon has an extremely exciting CV: She grew up in Namibia with a German passport, where she also completed her degree in Animal Science (BSC Agriculture) and studied veterinary medicine for three years. Her mother tongue is therefore English. Unfortunately, she was unable to build on this due to an extended baby break. Instead, she repeatedly worked as an assistant in clinics and even wildlife parks. After moving to Ireland, she spent two years at Maynooth University looking after the inpatient animals in the Bio-Resources Unit until she joined us.
Shannon works part-time on our TPA team as a career changer with extensive knowledge of veterinary medicine. She handles the maintenance of our state-of-the-art lab and the daily sample analyses with exceptional expertise. But of course, she especially loves caring for our patients with tenderness. Her warm and friendly demeanor goes over well with our clients. The four-legged friends also notice right away that Shannon loves animals 🙂
The Grellmann family moved to Switzerland with husband Guilliam and their two children Lilly and Maya. Dachshund 'Max' was of course always with them as a world traveler! Shannon is also a talented singer and was known as such in Namibia, where she also took beautiful wildlife photographs.Â
Tanisha Bertenghi, TPA
Tanisha completed her medical assistant apprenticeship at the Obersee Clinic and continued working with us afterward. She helped launch our sister clinic: katzen-praxis.ch guided and provided extremely active support. Starting in August 2026, Tanisha will once again be working part-time as a member of the Obersee team, which of course makes us very happy.
Tanisha is a very experienced TPA with additional training as a dog trainer. She works intensively and with great joy with her own two dogs: Jolie, an Australian Shepherd, and Mr. Peanutbutter, a Golden Retriever.
In addition to working with us, she opened her own dog-sitting service on July 8, 2026:
Woof & Fluff
Services include a dog grooming salon and a dog training school with medical training.
Chilly Scherer, TPA
has been working for us as a TPA on a part-time basis since August 2026.
Chilly attended part of her elementary school in Altendorf and is now back in Altendorf. She successfully completed her TPA apprenticeship in Siebnen by 2024 and earned her vocational high school diploma in 2025.
In addition to her training as an elementary school teacher, Chilly now supports us part-time as a certified veterinary technician. With her cheerful and friendly demeanor, she’s very popular with both clients and the team. It’s more than obvious that she loves people and animals. She’s particularly fond of cats. After all, she lives in a ‚cat household‘ with three ‚velvety paws.‘ It goes without saying that she wholeheartedly supports our efforts to comply with the cat-friendly guidelines.
Trainee assistant
Siria Messina
has been continuing her apprenticeship as a veterinary practice assistant with us since 1.6.2026. Siria will complete the second and third year of her apprenticeship with us. The reason for the excellent student's move to us is to intensify her practical training.
Siria spent her entire school career in Freienbach, her hometown is Wollerau. As she grew up with animals, one thing was always clear to her: I'm going to be a TPA! Now she is well on the way to becoming one. With 3 native languages (Portuguese, Italian and Swiss German), she fits perfectly into our international team and our international clientele. Siria also enjoys being with people, especially her family and friends, of course.
In her free time, Siri has been riding for 15 years and keeps fit in the gym and outdoors by jogging.
Practice Tierli
Enzo
Cirneco dell' Etna, born in Sicily in November 2020, definitely brings a good mood to the team. With all his energy and lots of fun ideas 'between his ears', he keeps us on our toes behind the scenes. But he also has the potential for great alpine performances in his free time, as Cirnecos have climbing in their blood: they have been bred for more than 4000 years to track down wild rabbits on the steep and rocky slopes of Etna. They won't really be allowed to hunt here, at most they'll dig up a few mice, but they will scramble and climb much higher. Good prerequisites for continuing the tradition of our ultra-cool practice dogs with us!
Fiona
Cirneco dell' Etna, born on October 13, 2021 in Sicily, as the younger sister of Enzo. She came to us in Switzerland as a little puppy. She is extremely independent and yet affectionate at the same time, because she doesn't go for walks with anyone, that's for sure! Fiona is a stunningly beautiful dog and she knows it 😉 ...only when she has once again rolled in a fox poop, this well-groomed appearance suffers massively for a short time!
Orso
Cirneco dell' Etna, our youngest team member, born on May 12, 2025 in Sicily, is hard to beat in terms of cheekiness. But because of his stunning charm, you simply forgive him everything. Together with Enzo, he completes our infernal trio in the office, turning everything upside down in case people forget that there's more to life than work! If this is not observed, he simply shreds something important, which happens from time to time...
Caillou
Holy Birman, the tomcat is hard to beat in charm, perfect house cat, typical for this breed, but not boring at all! He provides a lot of entertainment around the clock! But also as a 'freelance practice employee' he is versatile as a photo model to the test eater!
Zsazsa
Holy Birman, maybe a little more cheeky than Fiona? At least when it comes to food for sure! The young queen has an amazingly strong voice and always asks for more. The self-confidence is also reflected in her striking facial markings.
Turtles, Moorish
four in number, are probably from Tunisia. They show us every day how we should actually live: Dosed sunbathing, enough sleep, no stress, eat healthy and in general: Enjoy the essentials in life! They are therefore only seasonally employed and retire in the winter in the refrigerator.Â
Your field of activity is limited to "green stuff reduction" and is supplemented by extended siestas. You bring some calm and serenity to the operation...aaaaow and again you hold a beak in the practice for demonstration purposes....
