60 Parasitic diseases (2).pptx

Parasitic diseases (2)
EQUINE
Dr. Munguti E.M
A.H.I.T.I NDOMBA

Habronemiasis (“summer sores”)
 It occurs as a result of nematode
infestation of the skin and typically
manifests as granulomatous erosions
and/or masses.
 Its caused by;
 Habronema muscae,
 Habronema majus (H. microstoma) and
 Draschia megastoma
28/12/2023 Munguti/DIPL2/VRD& PARA DSES 2

Clinical findings
 1) Conjunctival Habronemiasis
 produces granulomatous lesions caused by
invasion by Habronema larvae occurring on
the third eyelid, the eyelid proper, or on the
conjunctiva of the medial canthus.
 Excessive tearing and squinting often
accompany these lesions

2) Cutaneous Habronemiasis
 Manifested by granulomatous lesions caused
by the invasion of skin wounds or excoriations
by the larvae of Habronema spp. and
Draschia megastoma
 Presents as ulcerative skin nodules in the
spring and summer, with regression in winter
months

Effects.
 Commonly affected areas include legs, penis,
preputial sheath, eyes, and any open skin
wounds.
 Geldings and stallions that have infestation of
the penis or sheath may exhibit dysuria
(difficulty urinating).

Clinical signs.

3) Gastric Habronemiasis
 Causes large granulomatous masses in the
stomach mucosa due to the invasion of
Draschia megastoma larvae.
 These lesions usually go unnoticed (i.e. are
sub-clinical) until stomach wall perforation
occurs
 The larvae of H. Majus and H. Muscae only
cause mild gastritis

Lifecycle.
 Common house flies and stable flies are
intermediate hosts for these parasites & ingest &
harbour the larval stages
 the immature larval stages are deposited into
the skin while biting or around the muzzle,
thereby facilitating ingestion by the horse.
 Adult stages of the nematode live in the stomach
and produce larvae which are subsequently
passed in manure
 larvae in the manure are ingested by maggots
(immature flies).

Diagnosis.
 based on the clinical appearance of the
lesions.
 Pruritis (itchiness), swelling and excessive
granulation are typically evident and occur
secondary to the horse’s own immune
hypersensitivity to the larvae.
 In many cases, tiny yellow granules are
visible within the granulomatous reaction(s).
 Biopsy is required to make a definitive
diagnosis

TREATMENT
 1) Ivermectin; one full dose orally repeated 2
weeks later.
 2) Topical and/or Systemic Steroid Therapy to
reduce swelling, granulation, and pain.
 3) Fly Control. (fly repellents, fly strips and fly
masks/sheets, particularly those that cover the
underside of the belly).
 4) Topical Wound Care. Using a thick ointment
to cover open wounds may help to discourage
flies from landing and depositing larvae into the
tissue.

Hair Worms
(Trichostrongylus axei, Stomach Hair Worms)
 Effects: Hair worms in small numbers usually
do not cause the horse any medical
problems, but a heavy worm burden can lead
to watery diarrhea and severe weight loss.
 Control:
 Ivermectin-based wormer for broad-spectrum
control

Threadworms
(Strongyloides, Strongyloides westerii)
 Life Cycle: Mostly a concern in foals, larvae
are ingested in the mare's milk or by
threadworm larvae present in the bedding,
which can penetrate the foal's skin.
 Larvae migrate through the lungs and small
intestine.
 Effects: The main effect is diarrhoea.
 Control: An Ivermectin-based wormer
 Foals become immune by 3 months

Onchocercosis
 O. cervicalis is found in the ligamentum
nuchae and possibly other sites in Equidae.
 Adults are associated with connective tissues;
they are very thin and 3–60 cm long.
 Microfilariae are found in the dermis and on
rare occasions circulating in peripheral blood.
 Culicoides spp are the intermediate hosts for
O cervicalis,

Clinical Findings
 O. cervicalis has been associated with
fistulous withers, poll evil, dermatitis, and
uveitis in horses.
 Adults in the ligamentum nuchae induce
inflammatory reactions ranging from acute
oedematous necrosis to chronic
granulomatous changes, resulting in marked
fibrosis and mineralization.
 Mineralized nodules are more common in
older horses

Cl/s,…
 Microfilariae concentrate in the skin of the ventral
midline
 Large numbers can be found in horses without
dermatitis as well as in horses with dermatitis of
the face, neck, chest, withers, forelegs, and
abdomen.
 Lesions may be pruritic and often include areas
of scale, crusts, ulceration, alopecia, and de-
pigmentation.
 dermatitis may be due to immunologic reaction to
dead and dying microfilariae.

Diagnosis
 The most effective method of diagnosis is by
skin biopsy, preferably a full-thickness biopsy
≥6 mm.
 The tissue is minced and macerated in
isotonic saline for several hours.
 Microfilariae are concentrated and stained
with new methylene blue after removal of skin
pieces

Treatment
 No treatment is effective against the adults.
 Ivermectin (200 mcg/kg) and
 moxidectin (400 mcg/kg) are efficacious
(>99%) against microfilariae

Ascarids in horses
 Parascaris equorum, the horse roundworm, is
a very large yellowish white parasite that may
pass out in the feces of foals and young
horses.
 Typically, adult horses develop an immunity
to this parasite; therefore, roundworms
primarily infect young horses less than 2
years of age.

Clinical signs.
 Include unthriftiness, potbelly, rough hair coat,
and slow growth.
 Some young horses develop nasal discharge
accompanied by a cough as a result of larvae
migration.
 Physical damage, such as inflammation and
scarring of liver and lung tissue, occur in the
horse during migration.
 Adult roundworms can cause physical damage
due to intestinal blockage or intestinal rupture.
 The damage ranges from mild digestive upset
and lower feed absorption to severe colic.

Strongyles in horses
 The three primary species of large strongyles
that infect the horse are;
 Strongylus vulgaris,
 Strongylus endentatus, and
 Strongylus equinus.
 The adult form of all strongyles (large or
small) live in the large intestine.
 The larvae of large strongyles migrate through
various parts of the body

Pathology.
 S. vulgaris, (the bloodworm), will burrow into
and migrate in the walls of the arteries that
are the primary blood supplier to the small
and large intestines.
 Migration can result in the formation of blood
clots, which can disrupt the blood flow to the
intestines and cause scar tissue formation in
affected arteries.

 Strongylus endentatus and Strongylus
equinus larval migration is primarily through
the liver.
 This migration results in damage to the liver

Stomach bots in horses

Stomach bots
 are not worms but, the larvae of the botfly,
Gasterophilus.
 Female botflies lay their eggs by attaching
them to the hairs of the horse.
 Gasterophilus nasalis lay between the jaw
bones.
 Gasterophilus hemorrhoidalis lay on the short
hairs of the lip.
 Gasterophilus intestinalis lay their eggs on
the forelimb and shoulder.

Pathology
 Effects: Although bots can cause damage to
the tissue of the horse's mouth and intestinal
tract, most horses do not show signs of
serious diseases from bots.
 However, very large numbers of bots have
been associated with gastric ulcers.
 Control: Use an Ivermectin-based wormer
for broad-spectrum control.

Tapeworms (cestodes)
 Life Cycle:
 require an intermediate host to mature.
 Tapeworm eggs are ingested by a tiny mite
called the orabatid mite that lives on the grass in
pastures.
 Horses ingest the mites while they graze.
 Inside the horse, the tapeworm eggs mature in
6-10 weeks into adult tapeworms that attach to
the intestinal lining, where they absorb nutrients.

Effects:
 Tapeworm infestations can lead to colic,
rough hair coat, slow growth, and other
conditions due to nutrient deficiencies.
 In addition, heavy tapeworm infestation is
considered to be a significant cause of colic.
 Control: regular use of an Ivermectin-based
wormer for broad-spectrum control is
combined with a specialized wormer
containing pyrantel pamoate.

Lungworms (Dictyocaulus arnfieldi)
 Life Cycle: Larvae are ingested while
grazing.
 They then migrate through the body to the
lungs where they mature into adults and lay
eggs
 Effects: Horses with lungworms may show
coughing or respiratory problems, especially
when exercising.
 Control: Frequent deworming is important.
Use an Ivermectin-based wormer for broad-
spectrum control.

Pinworms (Oxyuris equi)
 Life Cycle: Female pinworms lay their eggs in
the skin around the horse's anus where they are
often rubbed off onto the ground.
 They are then eaten by a horse and the life cycle
repeats.
 Effects:
 The egg masses are extremely itchy.
 Horses with pinworm infections will sometimes
rub their tails until all the hair is pulled off.
 Adult pinworms may be seen around the anal
area, along with a clear discharge.

Control.
 Ivermectin, fenbendazole, pyrantel pamoate,
 piperazine, moxidectin, and praziquantel can
help control pinworms

60 Parasitic diseases (2).pptx

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