Table 3.

The pros and cons of using sheep as an experimental animal model for translational research compared to other animal models.

Factors To Consider	Pros	Reference
Accessibility for research	Greater acceptability to animal ethics committees cf. companion animals	[26,53]
	Easily available, reasonably outbreed, less expensive to buy cf. other large species	[10,29,53,70]
	Long living mammal (10–20 years) with body size, weight and brain comparable to the human	[19,29,57,58,70,71,72,73]
	Easy management, Surgical manipulation	[14,29,70,74,75]
Body system specific advantages	Brain: higher degree of white matter and gyrencephalic structure, strong cerebellar tentorium cortical organization	[19,57,58,70,72,73]
	Excellent animal model to study HD due to HTT gene	[69]
	Long bones with dimensions suitable for the deployment of implant systems	[14,29,58]
	Excellent animal model to study osteoporosis due to long bones, early brain development	[14,29,70]
	Suitable to study the main physiological systems: cardiovascular, orthopedic, endocrine, respiratory, renal, nervous and reproductive systems, host organisms for virus infection	[10,14,29,58,70]
Others	Environmental enrichment not required as they live in their natural pasture	[58]
	Increased clinical translation and more accurate indication (as the dosage, drug distribution, and safety of potential therapies trialed)	[66]
	Ability to use clinically relevant technology to provide clinically translational measures, such as MRI, CT, and PET; ability to use clinical equipment such as anesthesia, physiological monitoring, surgical equipment	[53,76]
	Strong, can carry a backpack with transmitting devices	[58]
	Natural model for human infections such as parainfluenza, E.Coli.	[77]
	Cons
Accessibility for research	Higher ethical considerations than small animals	[29,53]
	Higher costs for maintenance and larger facilities required to perform procedures than small animals	[10,29,53,70]
Body system-specific advantages	Longer gestation time compared with small animals; Uniparous in breeding, difficulty scaling up the number of offspring	[19,29,57,58,70,71,72,73]
	Not suitable for studying neurobiology of fine motor control and binocular eye movements	[14,29,70,74,75]
	Transgenic selection and production of transgenic strains limited	[69]
	Poor availability of physiological databases for mapping to humans including atlases	[14,20,70]
Others	Vital sign monitoring needed by a veterinary practitioner during all surgical procedures	[19,57,58,70,72,73]
	Unlike, rodents, no standard behavioral testing protocol	[14,29,58]
	Limited access to antibodies	[10,14,29,58,70]