Canine optic nerve sheath diameter study

This is a PAST clinic study

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Comparison of ultrasonographic optic nerve sheath diameter before and after hyperosmolar therapy in dogs with presumed intracranial hypertension

Purpose of study

Increased pressure within the brain, called intracranial hypertension (ICH), can be caused by several neurological conditions, is highly detrimental and, if left uncontrolled, can be life-threatening. While we know that early recognition and treatment favors patient recovery, the most direct way to monitor IHC is expensive, technically challenging, and invasive. Because of this, direct monitoring is rarely performed in veterinary medicine.

In human medicine, a method called ONSD-US (optic nerve sheath diameter determined with ultrasound) has been shown to be a reliable, non-invasive, and less costly way to estimate intracranial pressure and monitor at-risk patients. We believe this method will be useful for our veterinary patients. The purpose of this study is to evaluate ONSD-US measurements in dogs with suspected intracranial hypertension and to use ONSD-US to evaluate the effects of our normal, standard of care treatment for these dogs.


This study will cover the cost of study-associated ultrasound scans of the eyes and the first dose of treatment for intracranial hypertension (either mannitol or hypertonic saline). Due to the nature of this study, participating dogs will be closely monitored for potential increases in pressure within the brain, which may allow for faster recognition and treatment of subsequent rises in pressure.

Enrollment requirements

For this study, we will be enrolling both dogs with clinical signs of ICH (treatment group) and dogs without ICH (control group). Dogs in the control group will be weight-matched with dogs in the treatment group.

Treatment group: Dogs that are 6 months or older that come to the WSU Veterinary Teaching Hospital (WSU VTH) for brain disease with clinical signs of ICH. 

Control group: Dogs in this group must 6 months or older, healthy, and have NO recent history of intracranial neurological disease.

Treatment methods

Treatment group: An ultrasound probe will be gently placed over the upper side of the eyelid and ultrasonographic images of the optic nerve sheath will be obtained for each eye. If treatment for increased brain pressure is needed, standard of care treatment will be administered. Repeat neurological re-evaluation and ultrasound will be performed at 30 and 60 minutes, post-treatment.

Control group: A neurological examination and ultrasound, as described above, will be performed for each eye.

Owner responsibilities

  • Owners are responsible for bringing their dogs to the WSU VTH for their neurology appointment or emergency visit.
  • Owners are responsible for the costs associated with standard diagnostic testing, treatment, and hospitalization of their dog.

Contact information

Dr. Carlos Valerio