🚀 Quick Summary
- The Conflict: Some dewormers (Moxidectin - Quest) are harsh on an inflamed gut lining.
- The Risk: A massive die-off of Encysted Small Strongyles can cause severe inflammation (Larval Cyathostominosis) mimicking colic.
- The Protocol: For active ulcer cases, use Fenbendazole (Panacur/Safe-Guard) first. Save Moxidectin for when the gut is healed.
- The Support: Always give Probiotics (Paste) and Sucralfate before/during deworming to buffer the die-off.
Table of Contents
Open Table of Contents
1. Why Parasites Cause Ulcers (The Mechanical Damage)
Parasites (Bots, Roundworms, Tapeworms) physically attach to the gut wall.
- Bots (Gasterophilus): Larvae attach to the stomach lining, causing focal ulcers.
- Tapeworms: Attach to the ileocecal valve, causing inflammation and blockage.
- Small Strongyles: Burrow into the intestinal wall (Encysted). When they emerge, they explode the tissue -> Massive Inflammation.
Result: A high worm load = Chronic Colic, Weight Loss, and Ulcer symptoms.
2. Dewormer Safety Ranking: Panacur vs. Ivermectin vs. Quest
If your horse has active gastric ulcers, choose wisely.
A. Safest: Fenbendazole (Panacur / Safe-Guard)
- Class: Benzimidazole.
- Pros: extremely safe margin. Gentle kill.
- Cons: High resistance in some areas. Doesn’t kill bots/tapes.
- Usage: First choice for ulcer/sick horses.
B. Moderate: Ivermectin (Zimectrin / Equell)
- Class: Macrocyclic Lactone.
- Pros: Kills almost everything (Bots, Rounds).
- Cons: Can cause mild colic in heavy burdens due to rapid die-off.
- Usage: Standard rotation.
C. Harshest: Moxidectin (Quest)
- Class: Macrocyclic Lactone (Lipophilic).
- Pros: Kills Encysted Strongyles (The hidden killer). Lasts 12 weeks.
- Cons: Absorbs into body fat. Lower safety margin. Can cause neuro signs in emaciated/foal horses.
- Usage: Avoid in active ulcer flare-ups if possible.
D. The Bomb: Praziquantel (Zimectrin Gold / Quest Plus)
- Target: Tapeworms.
- Warning: Can cause spasmodic colic. Use with caution in sensitive guts.
3. The “PowerPac” Debate: Is it too harsh?
Panacur PowerPac (Double dose for 5 days).
- Goal: Kill encysted strongyles.
- Gut Impact: It is a LOT of paste. The sheer volume/carrier can upset a sensitive stomach.
- Ulcer Horse:
- Better Option: Use Moxidectin (Single Dose) after the ulcers are healed, or stick to a single Panacur purge to lower the load first.
4. Managing the Die-Off Reaction
When worms die, they release toxins. This causes inflammation (Leaky Gut). Protocol for the Sensitive Horse:
- Day -1: Start Probiotic Paste (Succeed/Probios) daily.
- Day 0: Give Dewormer with food (Never on empty stomach).
- Day 0-3: Continue Probiotics + Sucralfate (to coat the lining).
- Monitor: Watch for colic or loose manure.
5. Fecal Egg Counts: Stop Guessing
The 80/20 Rule: 20% of horses carry 80% of the worms. You might be deworming a “Low Shedder” for no reason, damaging his gut microbiome.
- Low Shedder (< 200 EPG): Deworm only 2x/year (Spring/Fall).
- High Shedder (> 500 EPG): Needs 4x/year treatment.
Action: Spend $25 on a FEC before buying the $15 tube.
6. FAQ: Can I deworm a colicking horse?
Q: My horse is colicking. Should I deworm him “just in case”? A: NO! If the gut is already inflamed/twisted, adding a chemical poison + dead worms is gasoline on the fire. Stabilize first. Deworm later.
🏆 Final Verdict
Ulcers and Parasites go hand in hand.
- Test First (FEC).
- Use Panacur if he is actively flaring (Gentle).
- Use Quest only when he is stable and healthy (kills the encysted ones).
- Always Provide Gut Support during the kill. Don’t let the cure be worse than the disease.