The warm embrace of summer often brings with it a range of outdoor activities and adventures for both humans and animals. However, for our equine companions, summer also heralds the arrival of a troublesome ailment known as Cutaneous Habronema, or more colloquially, “summer sores.” In this blog, we’ll dive into the world of Cutaneous Habronema, exploring its causes, symptoms, and potential complications.

The Culprits: Habronema Microstoma, Habronema Muscae, and Draschia Megastoma

Cutaneous Habronema is a parasitic disease found worldwide, caused by three specific nematodes: Habronema microstoma, Habronema muscae, and Draschia megastoma. These tiny troublemakers can wreak havoc on a horse’s skin and mucous membranes, causing discomfort and distress.

The Parasitic Lifecycle

The life cycle of these parasites is quite intricate. Adults and larvae reside in the horse’s stomach, where they can coexist without causing apparent harm. However, it’s when the larvae are shed in the feces that trouble begins. These larvae can survive outside the host for up to seven days under suitable conditions.

The Role of Flies: House and Stable Flies

House flies (Muscid) and Stable flies (Stomoxys) play a crucial role in the transmission of Cutaneous Habronema, acting as intermediate hosts. House flies tend to feed on the horse’s eyes, nose, and mouth, while Stable flies are blood-feeding insects that attack mostly on the horse’s legs and flanks. During the summer months, these flies contribute to the spread of the parasite, making it a seasonal concern for horse owners.

Seasonal Peaks and Lesions

Unsurprisingly, the prevalence of “summer sores” tends to follow the fly season, peaking in the summer. The lifecycle of Habronema larvae takes a particularly distressing turn when flies deposit them on the lips of the horse. Once ingested, these larvae mature into adults within the horse’s stomach.

The Nasty Consequences

Cutaneous Habronema can manifest as painful and unsightly lesions, frequently appearing around the mouth, eyes, and genital mucosa. These lesions may vary in number and characteristics, ranging from bloody and ulcerated to itchy and granulomatous. Some may even contain necrotic, caseous, or calcified granules. In cases where lesions form around the eyes, horses may exhibit squinting and tearing due to the pain.

Diagnosis and Biopsy

Veterinarians often diagnose Cutaneous Habronema through a combination of clinical signs and biopsy results. Biopsies typically reveal the presence of eosinophils, macrophages, lymphocytes, and sections of larvae, confirming the parasitic origin of the lesions.

Complications and Beyond

Cutaneous Habronema may also become complicated by other underlying issues, such as sarcoids or other neoplasia like squamous cell carcinoma. These additional challenges can make the management and treatment of “summer sores” even more complex.

In conclusion, Cutaneous Habronema, or “summer sores,” serves as a stark reminder of the intricate relationship between horses and the environment in which they live. While the seasonal nature of this condition may bring temporary relief, diligent horse owners must remain vigilant year-round. Regular veterinary check-ups, fly control measures, and prompt treatment of any suspicious lesions are essential components of keeping our equine friends healthy and comfortable, even in the midst of summer’s challenges.