What Are the Causes of Weakness in the Hind Limbs of Dairy Cows?

Lameness in the hind limbs affects between 10 percent and 50 percent of milk cows annually. The more obvious signs of lameness in cows include an arched back when the animal walks and an abnormal gait. These cows favor one or both hind limbs. Lame cows eat less, exhibit lower sexual activity and lose weight. It can take months for them to recover, depending on the cause of weakness.

  1. Abnormally Large Udders

    • Weakness in the hind limbs of cows can be due to abnormally large udders, which distort the posture and gait. The huge udders cause foot damage and subsequent lameness in dairy cows. According to Professor Christine Nicol from the Bristol University in the United Kingdom, modern dairy cows are bred to have disproportionately large udders, permanently splaying their hind legs.

    Inappropriate Housing and Feeding

    • Modern dairy cows breeds, although larger than their predecessors, are frequently still housed in stalls that were built for much smaller cattle. Dairy cows often have to stand with their hind feet in the service passage. These cows stand in their own manure, which softens the animals' hooves and causes infection. This problem is compounded by the fact that silage, which is frequently fed to dairy cows in the place of hay, produces wetter feces. These cows also urinate more frequently, both of which contribute to a continual wet slurry in passages.

    Botulism

    • Botulism in cows is caused by the same group of bacteria that cause diseases such as tetanus and blackleg. These bacteria form spores which contaminate the soil. Affected cows become weak one to seven days after ingesting the toxin produced by the bacteria. Weakness is typically seen first in the hind limbs. The toxins affect nerve impulses to the cow's muscles and symptoms of the disease vary greatly. Cows frequently drool and are unable to hold food in their mouths. A number of affected cows will die within a day, while others exhibit a moderate weakness that persists for weeks.

    Northern Cattle Grubs

    • These grubs are the larvae of the heel fly. Female northern grubs lay eggs, which hatch in two to six days, on the legs of cattle. Larvae migrate to areas next to the cow's spinal cord, where they cause swelling. The larvae create a hole in the animal's hide to breathe and double in length after molting twice. Calves, yearlings and malnourished cattle are more susceptible to the grubs than adult cows. Larvae cause inflammation and tissue damage as they migrate toward the cow's back, while those that die in the region of the spinal cord cause paralysis or weakness in the hind limbs.

    Mechanical and Metabolic Causes

    • Toe ulcers, sole ulcers, sole fractures, white line lesions and heel horn erosion represent mechanical causes of lameness, as do slippery floors, non-yielding and sloped walkways. Laminitis, a condition that develops when tissue between the cow's pedal bone and hoof wall becomes inflamed, represents a metabolic cause of lameness.