By Chris Rademacher, Iowa State University Clinical Associate Professor and Swine Extension Veterinarian; Anna Johnson, Iowa State University Associate Professor Animal Behavior and Welfare; Locke Karriker, Iowa State University Professor and Swine Medicine Education Director and Ken Stalder, Iowa State University Professor Animal Science
Sow mortality has significantly increased in recent years in the U.S. swine industry. Most databases, including the Iowa Pork Industry Center Pelvic Organ Prolapse survey database of 124 sow farms, indicates that lameness is the No. 1 reported cause of sow mortality. Sow lameness is challenging to develop early interventions, because lameness has multiple causes. Most lameness mortality is due to euthanasia of lame gilts/sows that can no longer stand and have difficulty in reaching feed and water.
A team of researchers from Iowa State University attempted to look at sow lateral toe growth and the incidence of toe lesion presence when housed in gestation stalls. A total of 30 sows (10 sows each from parities 1-3) were selected. These females were cross-factored by their breed (11 Duroc, 11 Duroc x Yorkshire cross, eight Yorkshire) in order to look at the potential impact of breed. For the next four weeks, the length of the lateral claws was measured as well as the toe was evaluated for any lesions according to the Zinpro FeetFirst guidelines.
When evaluating lateral toe growth, Parity 2 females had the fastest toe growth compared to parities 1 and 3, growing 2 millimeters quicker. It was also discovered that lateral claws from purebred Yorkshire sows grew slowest compared to the cross-bred and Duroc sows. When evaluating toe lesion severity, the vast majority were Grade 1 — mild (out of a scale of 1-3) and the most common lesion type was a vertical crack in the hoof wall. Grade 1 cracks don’t extend down into the soft tissue underneath, therefore is not generally thought to be of great clinical significance. When comparing front and back legs, there tended to be more toe lesions on the front, compared to the back toes.
With lameness, a major cause of mortality in sow herds, more studies like this need to be conducted in order to better understand the potential link of these lesions to lameness. We understand that new toe growth tends to be softer and this may contribute to the greater likelihood of sows developing lesions that may ultimately lead to lameness.