Selected Seasonal Livestock Health Concerns

Author: Dr. Susan Kerr, WSU-Klickitat County Extension Director

Publish Date: Summer 2009

Coccidiosis -This parasitic disease can happen year round, but it mostly affects young animals and these are usually born in the spring. Coccidia organisms are generally species specific, which means that they don’t spread between pigs and cattle, for example. Sheep and goats can share a few species. Coccidia are extremely hardy, which means that once a premise experiences a case of coccidiosis, the premise should be considered perpetually infected through both contaminated environment and carrier animals.

Signs of coccidiosis vary between species. Typical signs include poor growth, rough hair coat, pot-bellied appearance, failure to thrive, loose to bloody stool and even death. Diagnosis is by fecal sample examination.

Animals can be affected from about one to 12 months but most typically those showing signs of illness are animals about weaning age. Affected animals may be permanently stunted and become poor do-ers. Clinical coccidiosis is rare in adults due to immunity they eventually develop.

Coccidia are protozoa and therefore not killed by routine dewormers. Clinically ill animals need treatment either through a water source or by oral drenching for several days in a row. The good news is that clinical disease can be prevented. Medications can be added to grain mixes, salt source or minerals to provide a low-level of coccidiosis prevention during the period of concern. Good manure management and sanitation practices also have a place in control of coccidiosis. NOTE: Do not feed medications with coccidiosis preventative medication (e.g. monensin) to any members of the horse or poultry families.

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White Muscle Disease

This nutritional disorder can also happen at any time of the year, but again it mostly affects young animals and these are usually born in the spring.

In most parts of the U.S., soils are deficient in the mineral Selenium. One of Selenium’s roles is as an antioxidant to help stabilize cell membranes, particularly muscle cell membranes. If animals do not ingest enough Selenium, either through grazing or supplements, they can exhibit signs of Selenium deficiency.

Signs of deficiency vary with age. In adult animals, signs are subtle and may include poor reproductive performance, retained placentas, chronic infections and poor immune system function. The signs are much more dramatic in young stock: poor growth rates, weakness, pneumonia and/or death. Animals with in utero deficiency may be premature, lightweight, weak or stillborn.

Selenium deficiency is diagnosed through physical examination, blood testing, liver biopsy, response to treatment or necropsy. At necropsy, hamstring, tongue, heart and throat muscles lack their healthy red color and are instead soft and pale (hence the name “White Muscle Disease”); this is because the cell membranes have been damaged and the muscles have degenerated. If cardiac muscles are affected, the disease can be fatal.

All livestock in our area need some sort of Selenium supplementation. Supplementation through mineral or grain mixes may be sufficient for adult animals at maintenance. Growing and pregnant animals will probably need at least one injection of a Vitamin E/Selenium product. Ask your veterinarian for advice about how, when, how often and how much to give your animals.

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Laminitis (“founder”) is inflammation of tissues connecting an animal’s hoof to the underlying bone. Although this disease could happen in any hoofed species, it is most common in horses and dairy cattle.

The sensitive layers of tissue connecting the hoof to bone can become inflamed whenever an animal has a high fever, overeats carbohydrates, is exposed to a toxin or experiences strong and repetitive concussive forces to the feet. In horses, too rapid cooling of a hot animal is another predisposing factor. Sources of excess carbohydrates include high-grain rations, molasses tubs, tree fruit falls, grain spills, unlimited access to grain or unlimited lush spring pasture.

Affected animals walk with a slow and hesitant gait but they usually do not favor one leg over another. They may lie down and be reluctant to move. Their hooves will be hot and the arteries serving the feet will throb.

A veterinarian should be consulted immediately for the best long-term outcome for the animal. Recommended treatments include removal or cessation of the causative factor, cold water soaks for the affected feet and administration of anti-inflammatories and other medications. More extreme treatment measures may be needed in individual cases. For horses, corrective shoeing methods can aid recovery and animal comfort.

To prevent founder, monitor animal health closely; control carbohydrate consumption; control access to lush spring grass; provide sufficient bedding; do not force horses to travel on hard surfaces; feed bicarbonate with high-grain diets; and cool horses slowly after work. Some horses are perpetually prone to founder and may need to be kept on a dry lot and only fed hay.

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Grass tetany

Grass tetany (“grass staggers”) is another common springtime disease of livestock, especially cattle. The cause is debatable. For simplicity, this condition will be described here as low blood levels of magnesium in affected animals due to low levels or low availability of magnesium in feed or poor absorption by the animal.

Lush spring forage may have low magnesium content and therefore be associated with this disease. However, grass tetany can occur if cattle are ingesting too much potassium, are deficient in salt or the diet is changed rapidly from hay to lush pasture.

Animals with abnormally-low blood magnesium levels may appear fine until stressed by calving, movement or transportation. Mildly affected animals will twitch their face and ears, carry their tail up, walk with a stiff “goosestep” and act more wary or wild than usual. As the condition worsens, animals become more excited. They may bellow`, stagger and appear blind. Without treatment, affected animals go down and begin a repetitive, stiff-legged paddling motion with all four legs. Death is likely without prompt treatment and down animals may do serious secondary injury to themselves. Indeed, most livestock producers realize they have an “outbreak” of grass tetany when they find dead animals that have paddled into the dirt before they died.

Treatment consists of intravenous magnesium preparations. Due to potentially-fatal cardiac complications, treatment should be administered by a veterinarian. Restraint is critical because unlike the near-coma induced by milk fever, grass tetany cows can be hyperexcitable and dangerous.

To prevent grass tetany, supplement winter hay and early spring pasture with magnesium oxide in salt, mineral or grain mixes. Make sure every animal ingests about two ounces of magnesium oxide each day. Molasses magnesium blocks are specifically made to prevent grass tetany; they are handy but expensive. Also feed hay before animals are let out on lush spring pastures to transition them over to pasture slowly.

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