What is Hypoderma Bovis spp Infestation?
Hypoderma Bovis spp, also known as the Warble fly, is a large, parasitic fly that is often a pest to cattle, deer, horses, many other animals, and even humans. These flies, once grown from the larvae stage, are hairy and almost resemble a flying bee. They are several different colors, mainly yellowish, orange, and brown. The adult fly has an extremely short life span of five days. These parasitic flies are found on every continent within the northern hemisphere, and mostly in North America, Africa, Europe, and Asia. Related pests can be found in Mexico, the United States, and Canada.
Warble flies lay their eggs and attach them on the hairs of a variety of animals, including horses and cattle. This occurs in the warmer months such as the spring or summer. The eggs are typically attached to the lower parts of the body or legs of the animals. Within 3 to 7 days, the eggs hatch, the larvae penetrate the skin of the animals, and then move within and between the muscles, the connective tissue, or along the pathways of the nerves. While doing so, they secrete enzymes that help them move more effectively.
As the seasons pass, fall and winter are the times the larvae moved to other regions of the body. Typically, Hypoderma bovis spp transport themselves to the spinal canal region and are found within the fat of the epidermis. They typically end up within subdermal tissues along the back of the horse or animal, creating tiny holes through the skin to help them breathe. Cysts are then formed around these larvae, which can be quite large and painful to the horse; this stage usually lasts 1 to 2 months. After this period, the larvae come out of the holes they formed to breathe and then pupate. Flies then come from the pupae.
Hypoderma bovis spp infestation in horses is caused by the larvae from the fly making its way into the horse’s skin and tissue. They live their life cycle within the horse’s skin.
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Symptoms of Hypoderma Bovis spp Infestation in Horses
If your horse is a host to Hypoderma bovis spp, he will exhibit typical symptoms to this condition. Symptoms can include:
- Swelling in the area
- Small breathing holes from the warble
- Difficulty with coordination in the limbs
- Weakness in the muscles
- Heavy bleeding or hemorrhage
- Damage to the tissue
There are several different names for this type of parasite, one being Warble fly. These flies not only affect cattle, as the larvae can come into contact with many animals. Other names include:
- Heel fly
- Bomb fly
- Cattle Grub (larvae)
- Wolves (larvae)
Causes of Hypoderma Bovis spp Infestation in Horses
Hypoderma bovis spp infestation is caused by the insect, also known as the Warble fly. Causes include:
- Environmental factors in which the horse lives
- The eggs of the Warble fly attaching to the hairs of the horse
- The hatching of the eggs within the horse’s hair
- The larvae settling into the base of the horse’s hair shaft
Diagnosis of Hypoderma Bovis spp Infestation in Horses
If you notice any signs of lumps within your horse and if your horse is exhibiting any of the above symptoms, contact your veterinarian. To begin, your veterinarian may choose to perform bloodwork including a biochemistry profile, and a urinalysis to take a closer look at your horse’s system. This will also prevent any differential diagnoses, which can be infectious granulomas, neoplasia, cysts that are epidermoid, and disorders of the spinal cord.
Your veterinarian will take a very close look at any lumps or bumps on your horse’s skin. He will take a closer look at the bumps to check for any small holes, which will signify a breathing hole which the warble created.
Your veterinarian may also perform an ELISA test, or enzyme-linked immunosorbent assay test, to determine any presence of an antigen or antibody. This will detect antibodies to any migrating larvae within your horse. He may also choose to take a skin biopsy and further look and investigate the cyst walls to be sure your horse’s cyst was caused by the parasite.
Treatment of Hypoderma Bovis spp Infestation in Horses
To begin treatment, your veterinarian will enlarge the breathing hole and gently remove the larvae. He will also look at other breathing holes your horse may have and do the same. Other treatments may include:
Your veterinarian may apply a topical ointment to the hole and cyst once the larva is removed. This will protect the nodular lesions which have been ruptured and help prevent any secondary infection. He may also choose to give antibiotics to prevent any infection.
The very early stages of infestation by larvae can be treated with specific dewormers as well. These are only to be used in the very early stages. Once the warble fly is mature, using dewormers may cause the release of toxins into your horse. The veterinarian will know to how to remove the parasite and to keep it intact while removing it from your horse.
Recovery of Hypoderma Bovis spp Infestation in Horses
Prognosis is good for horses that have suffered from Hypoderma bovis spp. Once your horse has been treated your veterinarian will communicate with you how to continue to care for your horse, such as applying ointment or giving antibiotics.
With this type of parasite, prevention is very important. The best method of prevention is to eliminate the exposure to these flies by using insecticides, netting, sprays or any method that your veterinarian recommends.
If your horse lives close to a pond, in a fly-infested environment, or with cattle, research ways to keep the pests under control. Talk to your veterinarian about all of your options for pest control that are safe, yet effective.