3D printing comes to veterinary medicine

3D printing is a method of producing a physical object from a digital model by adding a succession of thin layers of material. In one type of 3D printing a filament of the material (the ink) is melted then deposited in a layer, then cooled rapidly. Another type of 3D printer uses a stereolithography (SLA) process, which begins with a liquid, typically a photosensitive thermoset polymer, and creates the object by using a UV laser beam to selectively cure the polymer resin layer by layer. Thermoplastics are commonly used in 3D printing but liquids, powders, metals, ceramics or living cells are also used. Major advantages of this method of manufacture are that it is accurate and repeatable with high speed and low cost.

3D printers are now used to create a wide range of products including toys, foods, jewelry, automobile parts and aircraft parts. Some 5 years ago massive 3D printers and quick drying concrete were used to build 10 houses in China in a single day at a cost of less than $5000 each.

The first applications of 3D printing in medicine occurred in the 1990s and involved the production of dental implants and custom prosthetics. Other areas in medicine in which 3D printing is having an impact include surgical planning, education and training, research and drug delivery (1).

The study of 3D printed patient-specific organ replicas substantially improves planning for complex surgeries by allowing exploration of various surgical approaches and permitting hands-on experience prior to the surgery (1). Use of these models shortens the duration of surgery and improves the outcome. Educators have used 3D printing to produce models of organs and structures that assist students in anatomy and physiology. Printing of human organs (organoids) from living cells is predicted to find a major place in drug screening, toxicology and oncology research. The combination of stem cell technology and 3D printing has led to the development of organoids that mimic the corresponding organ in structure and function and can play a role in regenerative medicine. A sheep model has shown the feasibility of using a hand-held device (biopen) to deposit cultured cells and a bioscaffold into a cartilage defect in vivo. In the future, printed organs or portions of organs will likely be used for transplantation into humans. There is considerable research on the use of 3D printing for drug delivery (1). The technique permits printing of specific doses for an individual, creating pills that contain immediate release and sustained release layers, and producing pills that incorporate several drugs with different release profiles in a single pill.

3D printing is also finding application in veterinary medicine. In late 2018, Dr. Michelle Oblak at the Ontario Veterinary College made news around the world because of her use of a 3D printed customized part of the skull of a dog with a massive brain tumor (2). Dr. Oblak remarked on how well-prepared she and her Cornell University colleague, Dr. Galina Hayes, were when they walked into the operating room — because they had been able to study the 3D model of the dog’s head and tumor and to have the 3D printed skull replacement on hand. Earlier this year a 3D printed indirect lens adapter was described as part of an inexpensive system for funduscopy in dogs and cats (3). The other parts of the system were a smart phone and an indirect ophthalmoscopy lens. This system is suitable for acquiring, archiving, and sharing images of the retina by veterinary ophthalmologists and general practitioners.

Other applications of 3D printing in veterinary medicine have been reported. Patient-specific drill guides have been shown to be effective in a variety of procedures including placement of pedicle screws in vertebrae and stabilization of fractures in dogs. 3D printing has also been used for making a customized implant for treatment of canine cruciate ligament by tibial tuberosity advancement, for producing a small animal immobilizer for radiotherapy, for creating rhino horns, and for producing custom ballistic vehicles for drug delivery to wildlife. Within a few years I expect that many veterinary practices will have a 3D printer in the office.