Lice are external parasites that can affect horses, causing discomfort and potential health problems. A lice infestation is also known as pediculosis.
There are two main types of lice that affect horses: sucking lice and biting lice. The sucking louse, Haematopinus asini, feeds on the horse’s blood. Biting lice (Werneckiella equi or Damalinia equi) chew on skin debris.
If you own or care for horses, it’s important to understand how lice infestations happen, how to spot them early, and how to treat them. Early detection and appropriate treatment are key to minimizing the impact of lice on horses. Read on to learn more about lice on horses and how to manage them effectively.
Types of Lice: Sucking vs. Biting
There are two main types of lice that can affect horses: sucking lice and biting lice. They’re different sizes, they eat different things, and they tend to congregate in different spots on your horse.
Sucking Lice (Haematopinus asini)
Sucking lice are generally between 3 and 5 millimeters long, so they’re relatively easy to spot. They feed on blood, which they extract from your horse. You’ll often find them in areas where the skin is thinner, like the mane, tail, and flanks.
Biting Lice (Werneckiella equi or Damalinia equi)
Biting lice are smaller than sucking lice, usually only 1 to 2 millimeters in length. Instead of blood, they feed on skin debris and hair. You’ll often find them along your horse’s back and sides, and at the base of the tail.
Key Differences and Identification
The key differences between sucking and biting lice are their size, what they eat, and where they hang out on the horse. Sucking lice are bigger and feed on blood, while biting lice are smaller and feed on skin debris. They also tend to prefer different areas of the horse’s body.
The Lice Life Cycle
Lice go through three stages: egg (or nit), nymph, and adult.
The entire life cycle takes about 20-40 days. The eggs hatch in 5-20 days, and the nymphs (which look like smaller versions of adult lice) mature in 14-28 days.
Understanding the lice life cycle is key to getting rid of them. Because treatments only kill adult lice and nymphs, not the eggs, you’ll need to repeat treatments. This ensures you kill the newly hatched nymphs before they mature and lay more eggs. If you don’t, the infestation will just keep coming back!
How do horses get lice?
Lice most often spread through direct contact, like when horses stand close together in a pasture or stall.
But they can also spread indirectly. Think about all the things horses share: grooming tools, blankets, saddles and tack, even the stable itself. Lice can live on these objects (called “fomites”), and then jump to a new host.
That’s why it’s so important to disinfect anything that comes into contact with an infected horse. Otherwise, you could be setting up a never-ending cycle of re-infestation.
What makes a horse more likely to get lice?
Certain factors can make a horse more susceptible to lice infestations.
- Poor Body Condition: A horse with a compromised immune system is more likely to get lice. Sick, injured, or immunosuppressed horses are at higher risk.
- Overcrowded and Dirty Facilities: Overcrowding increases the likelihood of direct contact between horses, which can spread lice. Poor sanitation can also help lice survive and spread.
- Long Hair Coats: Longer hair provides a more favorable environment for lice to live in. Grooming is also more difficult on horses with long, thick coats, making it harder to detect and remove lice.
- Seasonal Factors: Lice infestations are often more common in the winter months because horses are often confined to close quarters and have longer hair coats.
What are the symptoms of lice on horses?
If your horse has lice, you will likely notice:
- Intense itching: This is usually the first sign. Your horse will likely rub, scratch, and bite at the affected areas.
- Hair loss: Constant rubbing and scratching can lead to patchy hair loss.
- Skin inflammation: You might see redness and irritation on the skin.
- Restlessness: The constant itching can make horses restless and agitated.
- Weight loss: In bad cases, the stress and discomfort can cause weight loss.
- Secondary infections: If your horse scratches so much that they break the skin, those sores can get infected.
How to diagnose lice on horses
The most common way to diagnose lice is to look closely at your horse’s coat. Focus on the areas where lice like to congregate, such as the mane, tail, and around the face. You’re looking for both the lice themselves and their eggs (nits).
Sometimes, a vet will want to do a skin scraping. They’ll gently scrape the skin and look at the sample under a microscope to confirm the presence of lice or nits.
If you see small, whitish or yellowish eggs attached to the base of the hair shafts, those are almost certainly nits.
How to get rid of lice on horses
If your horse has lice, there are several treatment options available. You’ll likely need to try a few things at once to get rid of an infestation.
Topical Insecticides
Many horse owners use insecticide shampoos with permethrin to kill lice. Be sure to follow the directions on the label. You’ll likely need to repeat the treatment to kill any baby lice that hatch after the first bath.
Oral Dewormers
Ivermectin and moxidectin can get rid of some types of lice. Talk to your vet before using these medications, as they can cause side effects.
Whole-Body Treatment
Make sure you treat your horse’s entire body, including those hard-to-reach spots. Lice can hide anywhere!
Environmental Treatment
Thoroughly clean and disinfect your horse’s stall, brushes, saddle pads, and any other tack. Treat any other horses that have been in contact with the infested horse, too.
Supportive Care
Help your horse’s immune system by providing good nutrition and plenty of water. If your horse has any underlying health problems, address those, too.
How to prevent and manage lice on horses
The best way to handle lice is to prevent an infestation in the first place. Here’s what experts recommend:
- Quarantine new horses. Keep new arrivals separate from your herd for a few weeks to monitor them for signs of lice or other parasites.
- Inspect new horses. Before introducing a new horse, carefully check its coat for lice and nits.
- Groom regularly. Regular grooming can physically remove lice and their eggs. Concentrate on areas where lice tend to congregate, like the mane and tail.
- Keep things clean. Clean and disinfect stalls, grooming tools, and tack to prevent the spread of lice.
- Support the immune system. A healthy immune system can help horses resist lice infestations. Feed a high-quality diet, reduce stress, and provide regular veterinary care.
To Conclude
Lice are common external parasites that can make life miserable for horses. They cause itching and discomfort and, in some cases, can even lead to more serious health problems. The good news is that lice infestations can be treated and prevented.
If you suspect that your horse has lice, it’s important to talk to your veterinarian to get a diagnosis and discuss treatment options. They can recommend the best course of action for your horse’s specific situation.
As a horse owner or caretaker, you play a crucial role in maintaining a healthy environment and taking steps to prevent lice infestations from occurring in the first place.