Internal parasites in horses Flashcards

Question

Describe Parascaris spp.

Answer 1

Parascaris univalens (most prevalent) and P.equorum which Cannot be distinguished by appearance. Primarily affect horses less than 2 years old. Most common under 1 year of age. Adults develop an immunity. Largest nematode parasite of equids. 4 mm in diameter and 25 cm long! Eggs stay in the environment for a very long time (months, years) even in Dry and freezing conditions. The Eggs are sticky so they can adhere to perineum, udder and to objects.

Answer 2

Severe infestation causes severe damage: - Coughing, nasal discharge during migration through the lungs. - Damage to the intestine, and colic (small intestinal blockage, rupture).

Answer 3

Affects Foals with large burdens of Parascaris equorum. Median age of 5 months. Usually occurs when Foals have often received anthelmintic treatment within 24 h (Ivermectin, pyrantel. Dead worms mechanically obstruct the small intestine. Presents with gastric reflux and shock. Nasogastric tubing is needed for alimentary decompression. Deworming is contraindicated! Give Supportive therapy. + Often need surgical intervention. Guarded prognosis!

Answer 4

In order to prevent parascaris disease, Regular anthelmintic treatment of horses from 2 months of age onwards is needed. Benzimidazoles are preferred (so fenbendazole 10 mg/kg PO). Is safer than ivermectin, pyranthel and Less resistance. Fenben. May also lessen the risk of a post-treatment impaction. Definitely favor fenbendazole if: - No prior history of deworming - Very high P. equorum egg counts - Abdominal enlargement

Answer 5

The key is Management. Anthelmintic treatment for foals 60-70 days of age. Thereafter should be repeated at the greatest interval that minimizes environmental contamination with ascarid eggs. So, Three-month interval (approx. every 90 days). More frequent intervals intensify selection for resistance. Monitor the efficacy of all drug classes against P. equorum populations on each farm! to avoid using an ineffective drug on a resistant population

Answer 6

Horse tapeworm Require intermediate host (mites)! Horses ingest infective mites while grazing, Adult cestodes develop 2 to 4 months after infection. Attach to the cecal mucosa near the ileocecal valve. Segments pass distally with the ingesta, break apart and eggs are released into feces. These are only a problem of grazing horses. Increased infection risk at the end of grazing season.

Answer 7

Horse tapeworm Endemic in many herds. A.perfoliata (most common); found in cecum (ileocecal junction). A.magna and Anaplocephaloides (uncommon): found in SI. Less than 50% prevalence in adult horses in UK. In Finland (2022): 7% of horses infected; previously found in 1/3 of horses in post-mortem. More in young horses. ## Footnote Serum or saliva antibody testing or treatment 1x year (autumn) if endemic!

Answer 8

Ulceration of the cecal mucosa, local inflammation and development of fibrous connective tissue. Small numbers are not pathogenic though. Large numbers increase the risk for colic. Ileal impaction Spasmodic colic Ileocecal intussusceptions Cecal rupture

Answer 9

Ideally, tx in autumn. Use either: Praziquantel 1 mg/kg PO Pyrantel embonate 13.2 mg/kg PO (double the “normal” dose) Both are very effective but Praziquantel preferred. No resistance reported. Activity of both compounds is fairly rapid, 24-48 h. Colic has been reported after tx. ## Footnote Serum or saliva antibody testing or treatment 1x year (autumn) if endemic!

Answer 10

Female bot flies lay eggs onto the hair of a horse. Initial parasitic stages (L1 and L2) develop in oral cavity before they migrate to the stomach. 2nd and 3rd -stage larvae of Gasterophilus intestinalis are found attached to the nonglandular mucosa of the horse stomach. G. intestinalis often form very large dense mats. Larvae of G. nasalis occupy the duodenal ampulla. In one layer, luminal compromise is minimal. Bot infections are highly prevalent.

Answer 11

In some herds very prevalent. Often occur in more than 90% of herd members during the autumn and winter months. Probably not pathogenic at all but Some exceptions. Ivermectin (and moxidectin) are effective. Initial parasitic stages (L1, L2) develop in oral cavity then migrate to the stomach, then L2, L3 attach to the epithelial part of the stomach or the duodenal ampulla.

Answer 12

Horse pinworm Ingestion of larvated eggs from the environment. Low pathogenity. Adults live in the large intestine. After mating: males die, females migrate to the end of rectum to Lay eggs on the peri-anal skin causing Perineal pruritus and tail rubbing. Younger horses used to be more susceptible but now Increasing affect among all age groups.

Answer 13

horse pinworms Tail-rubbing behavior, brokwn tail hair, and FEC are not diagnostic alone. Also do a Tape-test + microscopy. Adult female parasites occasionally seen around the anus.

Answer 14

Anthelmintic use for treatment is actually questionable. Ivermectin/moxidectin, fenbendazole, pyrantel all work but there's a Resistance question. Definitely don't do repeated use of different drugs as they wont Likely be effective for long. Decontamination of the environment is important. Perineal region cleaned 1-2 times a day to remove eggs – break the life cycle. Apply Vaseline so new eggs won't stick.

Answer 15

Horse threadworm Reside in the Duodenum and jejunum and Affect foals up Until 6 months old. Larvae come in via the dam’s milk or from the environment through the skin. Easily diagnosed by fecal flotation. Eggs easily distinguishable from Strongylid eggs. May cause local mucosal damage, Diarrhea, lethargy, reduced weight gain. Deaths are reported with severe infections Clinical signs more common if >2000 epg. Presence of S.westeri in a foal with diarrhea is not diagnostic. Treatment only reserved for cases of enteritis. Usually ivermectin or Fenbendazole.

Answer 16

Not a very common problem in horses but prevalent among donkeys (4% vs 35%). Risk group: horses grazed with donkeys Not detected with regular FEC, needs the Baermann method. Strong eosinophilia in blood and BAL. The adult lungworm lives in the lung and releases larvae into the lung tissue which Causes cough, then are swallowed and pooped out.

Answer 17

Uncommon problem of horses, prelevance unknown. Horses are more resistant than ruminants. Consider liver flukes if wet soil (cause snails are intermediate hosts) and/or if the horses are grazed with ruminants. No good testing method: - Fecal samples unreliable - Increased liver enzymes can help Treatment: ticlalbendazole 12mg/kg which is Not licensed, but is efficient and safe. Some others used in cattle are toxic to horses.

Internal parasites in horses Flashcards

(42 cards)