Hemosemen due to habronemiasis 

Keywords: habronema, habronemiasis, hemosemen,stallion, equine

Image size: 1500 x 1991px

This image shows semen that appears to be almost pure blood as a result of habronemiasis in Quarter horse stallion. In this case (as in most cases of hemosemen) hemorrhage was only seen during ejaculation. This is usually a transitory condition and resolves after appropriate treatment for habronemiasis.

Most cases of hemosemen are not due to habronemiasis. In fact, the etiology often remains unknown and the ejaculate returns to normal with sexual rest alone. Despite some recommendations to the contrary, only a brief period of sexual rest is required in most cases; perhaps a week to 10 days. In that regard, it is important for veterinarians to realize that hemosemen (even severe hemosemen such as that shown here) does not necessarily signal the end of the breeding season for a particular stallion.

Although blood in the semen has been reported to decreased fertility, anecdotal reports suggest that some stallions maintain their fertility despite the regular presence of blood in their ejaculates.

Habronemiasis

Keywords: Habronema, penis, stallion

Image size: 1650 x 1746px

Habronemiasis on the penis of a Quarter Horse stallion. This is due to infestation by the fly-borne larvae of Habronema muscae, H. microstoma and Draschia megastoma. The lesions these larvae cause are intensely pruritic and may occasionally cause hemosemen. Habronemiasis should be differentiated from squamous cell carcinoma by biopsy. A diagnosis is based on the presence of larvae in scrapings of the lesion.  Oral ivermectin Rx is an effective treatment for habronemiasis when two treatments are given one month apart.

Note: Habronema spp. lay their eggs in manure piles and their larvae are ingested by the larvae of the housefly (Musca domestica) or Stable fly (Stomoxys calcitrans) which also develop in manure. The habronema larvae then emerge from adult houseflies or stable flies as they alight on horses. Fly control is therefore of great importance in the control of habronemiasis.