Eosinphilic Granuloma Complex in Horses

Several things cause these lesions, with insect bites being one of the most obvious. But pressure from the tack and saddle areas can cause these lumps to develop as well. Your horse may develop many of these lumps over its body while other areas remain smooth. Allergies may be a cause, and it is a problem when these lumps ulcerate. Other lumps can become very hard because of calcification and these are quite hard to treat.

Equine eosinophilic granuloma is really a common condition in horses with lesions of various sizes occurring on the neck body and back of your horse.

• Lumps or bumps forming on the otherwise smooth hide
• Lesions in various sizes from small to quite large, for example, 5 cms in diameter 
• These lumps form under pressure areas such as the saddle area 
• Some of these lumps are rock hard to touch 
• Can be patches of lumps in various areas of the body
• Not painful generally unless these lumps ulcerate
• Hair does not generally fall out although it may stand up in the bump

Types  

Usually these lumps are similar in sizes and shape and the lumps are not painful to your horse. Although too many may look a bit strange, they usually resolve themselves if left alone 

• Some lumps may be larger than others and it would pay to have these checked
• Insect bites from horse fly and mosquitoes causing lumps
• Food induced allergies
• They can be a pressure induced lump

• Pressure (often these lumps occur in high pressure areas like saddle and tack areas)
• More prevalent in the warmer season
• Allergies or environmental causes 
• Hypersensitivity
• Collagen degeneration
• Trauma or injury 
• Insect bites

You may notice these lumps forming and they may form quite a wide patch or occur singularly. They range in size but are usually round and sometimes hard. Examination by your veterinarian will confirm what these lumps are. He will give your horse a thorough examination and discuss the history of your horse’s health with you to see if there are any connecting factors. He may take a sample of the lump to test. Usually these lumps don’t cause your horse pain unless it is in the area where the tack affects them, or if your horse is rubbing itself. If they rub open and ulcerate they will need cleaning and medicating. 

If ulcerated they can take a few weeks to heal completely and if they occur in an area where the tack usually goes then your horse must be rested until these areas heal. Covering to prevent insect infections will assist your horse’s recovery and he may need to wear a light cover. Treating your property to remove any stagnant water that may attract insects can prevent excessive biting of your pet.

The simplest solution is to leave the nodules alone unless they are bothering your horse, such as when you ride him. As they can be a reaction to insect biting, using a veterinary grade insect repellent may help. Keeping your horse covered with a light cover may deter insects. If the bumps are bothering your horse or they continue to enlarge, an injection of a steroid can shrink them. It may take two or three injections to achieve this but it is worth a try. If they don’t shrink and they are in an area where they worry your horse, you can get them surgically removed. On occasion, they may rub open and cause ulceration. This will need cleaning and medicating by the veterinarian. After treatment, the dressing will need to be kept clean and covered until healing. This condition is usually harmless although it may affect the way your horse looks. If your horse competes in shows, then you will need to talk to your veterinarian to discuss how these can be cleared up.

If there are only a few nodules or lumps, then leaving them to heal themselves may be best. If your horse has had steroid injections to shrink them, he will recover easily at home. Your veterinarian may suggest keeping your horse covered against fly or biting insects, and may prescribe an insect repellent to use. Your horse’s diet may need adjusting and your veterinarian will be able to suggest some alternative feed; this may help your horse if it is having an allergic reaction. If you get the lesions surgically removed, at home care will include keeping the area covered and protected against insects and infection. Usually with this condition, healing or control is excellent.