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Ultrasound-guided histotripsy ablation of canine brain tumors through an acoustically transparent cranial window


To investigate the safety and antitumor activities of a new ultrasonic technology, called histotripsy, that can noninvasively destroy (ablate) tumor tissue using acoustic energy, in dogs with brain tumors.


Primary brain tumors (PBT) are a significant cause of illness and death in dogs. Surgery remains a common treatment for canine PBT, with the goal of removing as much of the tumor as possible. However, significant numbers of canine PBT are considered inoperable due to their location in the brain, and conventional, invasive surgical techniques can cause serious side effects. Even when surgery goes well, the tumor may regrow after surgery. New treatments, particularly for PBT that can’t be removed by surgery or that have regrown after surgical removal, are needed to improve quality and quantity of life of affected dogs.

This proof-of-concept of study will provide data necessary to refine histotripsy technology and explore new, non-invasive techniques. The techniques we are developing have the potential to allow precision image-guided, non-invasive treatment of PBT using ultrasonographic equipment and treatments that are currently in use in the majority of small animal veterinary practices, which may make treatment cheaper and more accessible. Please note that while our eventual goal is to be able to offer histotripsy as a non-invasive option, for this study we need to be able to surgically remove the patient's brain tumor and test it. This helps us ensure that the treatment works and is safe. 

This study is funded by the Focused Ultrasound Foundation and the American Kennel Club.


  • Dogs of any age, weight, sex, or breed who have a measurable (>10 mm in diameter), treatment-naive primary forebrain tumor documented with MRI that is able to be removed with surgery

Exclusion Criteria

  • Dogs with other serious illnesses or cancers
  • Dogs with cystic tumors (cystic component > 30% of tumor volume)
  • Dogs requiring transfrontal surgical approach to access tumor
  • Dogs who are not expected to survive for the duration of the study period (approximately 42 days)
  • Dogs that have received prior treatment for their tumor, including surgery, radiotherapy, chemotherapy, or immunotherapy
  • Dogs who have excessive neurological dysfunction or poorly controlled seizures

Study Design

The patient will undergo an initial brain surgery (craniotomy) and subsequent treatment with histotripsy. Immediately after the histotripsy treatment while the patient is still anesthetized, an MRI will be performed. Then, the mass will be removed and the acoustically transparent cranial window (ATW) will be placed, before recovering the dog from anesthesia. The ATW is a small piece of a plastic-like polymer that has been approved for medical use. The ATW will be inserted on the surface of the patient’s brain to allow sound waves to pass through. These procedures (craniotomy, histotripsy treatment, tumor removal, ATW placement)  typically take place on the same day. Dogs then recover in the hospital for 2-3 days before returning home.

The dogs will be then evaluated on scheduled recheck visits with physical and neurologic examinations on day 14 and 42 post treatment, and brain ultrasound and MRI scans will be performed on days 14 and 42. We will analyze the safety and effectiveness of the therapy using brain images and tests performed on the tumor tissue we remove. 


Once the dog is deemed eligible, the study will cover costs associated with tumor treatment and removal, as well as study-related imaging and clinical visits during the study period. The cost of the initial MRI to confirm diagnosis is not covered by the study.


Dr. John Rossmeisl, Neurology
Phone: 540-231-4621 | Email:

Mindy Quigley, Clinical Trials Coordinator
Office Phone: 540-231-1363 | Email:

If your query is urgent, please call the Small Animal Hospital on 540-231-4621