⚠️ Not veterinary advice. General educational information gathered from university extension services, USDA and veterinary associations. Conditions vary farm to farm. Always contact your veterinarian before deworming, supplementing minerals or changing feed, and call your vet immediately if you suspect poisoning.
Illinois livestock guide
Region: Midwest & Great Lakes – Cold winters, warm humid summers; transmission spring–fall.
Horses in Illinois
Common parasites
- Small strongyles (cyathostomins) – The main worm of adult horses; resistance to common dewormers is widespread. Use fecal egg counts with your vet rather than rotating on a calendar. (source)
- Large roundworms (ascarids) – Mainly foals and weanlings; heavy loads can cause impaction colic. (source)
- Tapeworms – Linked to some colics; usually treated once or twice a year. (source)
- Ticks – Lyme disease and anaplasmosis occur in the upper Midwest.
Toxic plants & feeds
- Black walnut shavings – Native tree here; never use walnut in bedding. (source)
- Red maple (wilted leaves) – Fall danger. (source)
- Alsike clover – Can cause sun sensitivity and liver disease in horses. (source)
- Yew (Taxus) – Ornamental shrub; a few mouthfuls can kill a horse within hours. Never toss hedge clippings into a pasture. (source)
- Ionophore feeds (monensin, lasalocid) – Cattle/poultry feeds and some mineral tubs are deadly to horses and donkeys. (source)
- Blister beetles in alfalfa hay – Crimped alfalfa can trap beetles (cantharidin); buy hay from a known source. (source)
- Lawn clippings – Ferment quickly and can cause colic or laminitis. (source)
Minerals
- Selenium & vitamin E – Much of the Great Lakes area soils/forages are often LOW in selenium. Deficiency causes muscle disease (white muscle disease in foals). Supplement only with your vet – too much is toxic. (source)
- Salt – Free-choice plain or trace-mineral salt for every horse.
- Balance to the forage – Grass hay alone often runs low in some trace minerals; a ration balancer is commonly used. Have hay tested if possible.
Donkeys in Illinois
Common parasites
- Small strongyles and tapeworms – Same worms as horses; donkeys can carry heavy loads while looking fine. Use fecal egg counts. (source)
- Lungworm (Dictyocaulus arnfieldi) – Donkeys often carry it without coughing and can pass it to horses grazing with them. (source)
- Ticks – Lyme disease and anaplasmosis occur in the upper Midwest.
Toxic plants & feeds
- Red maple – Same risk as horses. (source)
- Yew, ionophore feeds – As deadly to donkeys as to horses. (source, source)
- Rich feeds and lush grass – Not a poison, but a major risk: donkeys easily become obese and develop laminitis or hyperlipemia.
Minerals
- Selenium & vitamin E – Much of the Great Lakes area forages are often low in selenium; ask your vet about a blood test before supplementing. (source)
- Salt and a low-calorie balancer – Donkeys usually need straw/low-sugar hay plus a vitamin–mineral balancer, not grain.
Goats in Illinois
Common parasites
- Barber pole worm (Haemonchus contortus) – Blood-sucking stomach worm and a leading cause of goat deaths. Watch eyelid color (FAMACHA) and bottle jaw; resistance to all dewormer classes exists. (source, source)
- Coccidia – Kids 3 weeks to 6 months; diarrhea and poor growth, worse in crowded or wet pens. (source)
- Meningeal worm – Common where goats share land with white-tailed deer. (source)
- Barber pole worm – Still a major summer problem despite cold winters. (source)
Toxic plants & feeds
- Water hemlock – Wet ditches and pond edges. (source)
- Rhododendron, azalea, mountain laurel – Ornamental and wild shrubs that cause vomiting and collapse in goats. (source)
- Yew and cherry (wilted leaves) – Yew is deadly; wilted wild-cherry leaves release cyanide. (source)
- Avocado leaves – Toxic to goats (heart damage). (source)
- Excess grain – Overeating grain causes rumen acidosis (bloat, collapse).
Minerals
- Selenium – Much of the Great Lakes area is selenium-deficient; white muscle disease in kids is a known risk. Vets often give Se/vit E around kidding. (source)
- Use a GOAT mineral, not a sheep one – Goats need much more copper than sheep; sheep minerals are copper-restricted and can leave goats deficient (rough coat, swayback in kids). Never feed goat mineral to sheep – copper can poison them. (source, source)
- Loose mineral, free choice – Goats generally eat loose minerals better than blocks.
Cattle in Illinois
Common parasites
- Brown stomach worm (Ostertagia ostertagi) – The most damaging cattle roundworm; Cooperia is also common. Young stock suffer most. (source)
- Flies and lice – Horn flies on pasture in summer; lice in winter. (source)
- Liver fluke (wet areas) – Present in low, wet pastures around the Great Lakes. (source)
Toxic plants & feeds
- White snakeroot – Wooded pastures in late summer–fall. (source)
- Nitrates in drought-stressed corn – Test drought-stressed corn silage or stalks. (source)
- Yew – A leading cause of sudden death in cattle from tossed clippings. (source)
- Nitrate and prussic acid forages – Drought-stressed or frosted sorghum, sudangrass and johnsongrass, and some weeds; test suspect forage. (source)
- Excess grain – Grain overload (acidosis) or sudden diet changes.
Minerals
- Selenium – Much of the Great Lakes area is selenium-deficient; use a selenium-fortified mineral (legal US limits apply) and discuss injections for calves with your vet. (source)
- Free-choice trace-mineral salt – Match the mineral to your forage and region; ask your extension agent or vet.
- Magnesium on lush pasture – Grass tetany risk in early spring on lush grass, especially older cows nursing calves; high-magnesium mineral is often used. (source)
Help in Illinois
- Cooperative Extension service
- State Department of Agriculture
- State veterinarian / animal health office
The state veterinarian link goes to the national directory of state animal health officials.
Suspect poisoning?
Remove the animal from the source, keep a sample of the plant or feed, and call your vet now.
- ASPCA Animal Poison Control Center – (888) 426-4435. 24/7, covers livestock and horses; a consultation fee may apply.
- Pet Poison Helpline – (855) 764-7661. 24/7; a fee applies.
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Last reviewed 2026-10-18. Regional summaries; your county extension office knows your area best.