Severe lameness in feedlot

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A few days ago we have posted some pictures in our facebook site:

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Well, in this post we want to explain which have been the possible causes we have been discussing with different experts and with some of you in facebook; and which is the real cause.

Pictures are from a feedlot in a dry and hot climate area, altough before this peak of lameness there was the rain season. Thus, facilities had more humidity as usual. Lameness cases are between 40 and 120 animales depending on the barn.

Discussing about possible causes, our first option is chemical burn, probably made by formalin. But, lesions are not exactly like in burns by formalin: the skin folds have no lesions, neither the accessory digits. If this would have been the cause, footbaths protocol should have been cancelled for a while, until animal recover; some animals would have been slaughtered and new dosis of formalin and footbath protocol shouldhave been planned, to prevent the problem in the future.

The second option is Foot rot, or even Super fowl, which is a similar disease to foot rot, but it is much more agressive, lameness is hiperacute and severe in a fez hours. Necrosis in interdigital space appears after 12 hours and in 24 hours there is fistulization. Treatment for Superfowl is sistemic antibiotics, like in foot rot, but bigger dosis and for longer period NSAIDs are also recommended, to minimize pain and swelling.

Third option ir ergotism or fescue toxicosis (both are toxicosis from feed that cause metabolic disorders and diseases). Typical symptom of ergotism is arteriolar vasoconstriction. After a week, animals are lame and lost sensitivity at the hooves (mostly in hind feet). The main consequence of it is gangrene, in distal part of hind feet, ears and tail. But, gangrene appears usually in cold weather areas; in this herd, animals should have been feeded with a bigger amount to develop gangrene.

In fescue toxicosis symptons are similar as in ergotism, there is also hypersalivation and fever. In both toxicosis, female cattle would have fertility problems and sudden milk yield decrease.  Lame animals of this clinical case are males. One week later, with this three possible causes in mind, the herd was visited and some animals from every barn were examinated.

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Observations:

40,5ºC Temperature
No diarrhea
No hypersalivation
Animals walk like “drunk” leavinf the crush.
“Swelling” is really hard.
Typical foot rot lameness: 4-5 cases in every lot, as usual in this herd
Reviewing the feed amounts, a mistake was found: there were some changes in pre-mix amounts, mistakenly have caused that cattle have been feeded with bigger amount of β-agonistas (Zilpaterol). The overdose varied between 12 and 40% in lots.
References describe higher mortality in beef cattle at the end of feedlot because of β-agonists intake. In 2015, Thomson described the “fatigue syndrom” in beef cattle, related with using this drugs for feeding.
EFFECTS OF β-AGONISTS:

  • Protein deposition in muscle
  • Muscle hypertrophy
  • Lipolisis
  • Lipogenesis inhibition
  • Lower proliferation of preadipocits AGO

These affects digital cushion, impact absorber of the hoof, made of fat and elastic fibers. Some other effects that can be noticed in feet are:

  • Artery dilatation
  • Slow venous flow
  • Capillary Hyperpressure
  • Higher permeability
  • Edema
  • Dermic atrophy
  • Estasis
  • Hemorrhage
  • Ulcers

After removing β-agonists from feed, lameness cases reduce in 85% in lots which this pre-mexi have been used. The ambiental risk factors, such as cattle handling, low quality floors, overcrowded barns, humidity and high temperature; had a big influence in the development of this lesions.

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