Page 247 - The Welfare of Cattle

224 the WeLfare of CattLe

cattle identified and assessed for lameness for the first time were severely lame and experienced
high relapse rates (between 8% and 13%).
The main infectious causes of lameness in feedlot cattle include foot rot, infectious arthritis
(Stokka et al., 2001), and more recently digital dermatitis (Döpfer et al., 1997; Marti et al., 2016).
Foot rot is the result of a bacterial (Fusobacterium spp.) infection resulting in swelling of the
interdigital tissue of the toes, coronary bands, and heels (Stokka et al., 2001), and is found more
commonly in finishing than backgrounding cattle (Tibbetts et al., 2006). Digital dermatitis is an
infection associated with spirochete bacteria that causes a raw lesion on the back of the heel just
above or at the coronary band (Döpfer et al., 1997) and is found more commonly in cattle >430 kg
(Marti et al., 2016). As implied, infectious arthritis is the result of a joint infection associated with
mycoplasma bacteria (Stokka et al., 2001). Marti et al. (2016) reported that that the incidence of foot
rot and joint infection was 71.77% and 19.25%, respectively. The above-described conditions are
highly contagious and can spread rapidly affecting a large percentage of animals within a pen which
greatly increases their significance as a welfare concern.
The most common noninfectious causes of lameness include toe-tip necrosis, laminitis, and
injuries. Toe-tip necrosis is characterized by necrosis of the distal part of the third phalanx (P3) bone
in the foot caused by trauma that allows bacteria to enter the claw as a consequence of white line
separation and is commonly seen in highly agitated receiving cattle (Jelinski et al., 2016). Laminitis
refers to inflammation of the connective tissue (corium) located between the pedal bone and hoof
horn and has strong associations with acidosis which causes bacteria and their toxins to enter the
blood stream resulting in inflammation of the corium (Stokka et al., 2001). Finally, injuries refer to
such conditions as sprains, fractures, and lacerations all of which can cause mild-to-severe lameness
and have a reported incidence of 3.51% (Marti et al., 2016). All of the previously listed conditions
are believed to be extremely painful in advanced stages as evidenced by severely modified gait
scores as well as weight loss and in some cases mortality (Greenough, 1997; Tibbetts et al., 2006;
Marti et al., 2016).
Wet pen conditions and constant moisture with manure contamination have been implicated
in softening and allowing bacterial organisms to penetrate the skin between the claws (Bergsten,
1997). This was confirmed by Marti et al. (2016) who found increased incidence of both foot rot and
digital dermatitis during the spring (41.3%) and fall (28.7%) when pen conditions were wet. Other
risk factors for both infectious and noninfectious causes of lameness include rough pen surfaces
associated with frozen manure, rocks, or other sharp objects: slippery or poorly maintained pens
and handling facilities and frequent or rough handling (Grandin, 1997; Stokka et al., 2001; Green
et al., 2012). Little is known about the relationship between the incidence of lameness and housing
on concrete or slatted floors although one study suggested that the claw health of beef cattle housed
on straw or deep litter was better than those house on slatted floors (Tessitore et al., 2009).
The most significant risk factors associated with increased lameness and lameness severity
reported in a recent Canadian feedlot study were as follows: being a yearling, being sourced from
an auction market rather than a ranch, having a greater number of days on feed, being housed with
a greater number of cattle within a pen, having reduced bunk space, having reduced forage content
in the diet, being exposed to a greater number of handling events, and being housed in pens with
increased mud depth (>5 cm) (Marti et al., 2016). The same study found that although the majority
of cattle were lame in the hind limbs (approximately 68% of all lame animals); the severity of lame-
ness was approximately 40% greater in cattle that were lame in the fore limbs.
Common mitigation strategies based on the risk factors listed above include improving pen
drainage, increasing pen cleaning, and or provision of bedding to reduce wet and slippery pen
conditions (Stokka et al., 2001; Marti et al., 2016); regular pen and handling facility maintenance
to reduce rough pen surfaces and eliminate sharp objects (Stokka et al., 2001); reducing handling
frequency and eliminating rough handling (Grandin, 1997; Lensink et al., 2000a, b; Green et al.,
2012); reducing pen density and increasing bunk space availability; purchasing ranch direct calves