|
Biodiversity |
THE HEALTHY PONY.
Indicators of Health:
First Stand back and look:
When to call the Vet:
Worming of the Exmoor Pony.
When considering the welfare of the Exmoor pony, you must take into account the possibility of external and internal parasites. (See codes of practice - All animals in conservation grazing should receive appropriate regular worming). However, treating the wild pony can present the Veterinary surgeon and owner with unique problems. Often the animals are not broken and are contained in very large, unfenced areas, running wild with many other ponies of varying ages, fitness and health. Thus the routine worming regimes of the average horse become difficult to implement. Even the management of picking up dropping becomes an overwhelming task.
First you must consider the various parasites you wish to control:
STRONGYLES;
LARGE STRONGYLES (LARGE RED WORMS): Strongylus and Triodontophorus
Members of this genus live in the large intestine of the horse and cause significant disease, often with mixed infections.
The Strongylus Spp live in the Caecum and colon of the horse and the adults eat the lining of the intestine and suck blood. They also have a migratory stage depending on the species (Vulgaris -Cranial mesenteric artery, most pathogenic, Equinus - Liver and pancreas, rare, Edentatus - Liver and Mesentery.
Triodontophorus Spp feed in "herds" round ulcers in the RDColon and don't have a migratory stage.
Both of the above produce eggs that are passed out in the faeces and undergo 3 larval stages. The eggs and the larvae can be washed away from the faeces by rain droplets and then are able to undergo the changes to the infective L3 stage. This can occur within 2 weeks if the climate is good. The pony then ingests this larval stage which can then undergo its migration and cause damage to the pony as they emerge through the gut wall and feed as young adults.
DISEASE:
SMALL STRONGYLES/ CYATHOSTOMES (SMALL RED WORMS): Trichonema Spp.
These are non-migratory worms and cause problems when they form nodules in the large intestinal walls and then hatch as adults. These parasites can cause the greatest problem as they can undergo HYPOBIOSIS - This is when the cycle in the host becomes arrested due to external factors such as climate in the autumn. Then in early spring all the arrested larvae suddenly hatch together and cause severe damage with perfuse D+, weight loss, colic and death. This is called Larval Cyathostomiasis.
Faecal egg counts of 150 eggs pg can still be significant as there may still be large number arrested.
Now very common - poss encouraged by poor husbandry.
Some resistance to Benzimidazoles, use 5day Fenbendazole (Panacur equine guard)
TREATMENT AND CONTROL:
IMMUNITY only occurs SLOWLY, due to EXPOSURE and is INCOMPLETE.
Benzimidazoles, Pyrantel(Strongid-P), Ivermectin(Eqvalan), all have good efficacy against lumen-dwelling adults, but less against migrating larvae. Fenbendazole (Panacur Equine Guard) is used against the small red worm
Hypobiosed Small Red Worms are very difficult to treat with ANY drug!
LARGE ROUND WORMS
PARASCARIS EQUORUM - THE HORSE ASCARID:
These are very common but usually only affect young animals. Following egg ingestion (the eggs being very resilient to environmental conditions), they migrate through the liver and pulmonary areas and can cause two different syndromes.
Resp. disease - Tracheal exudate with Cough and Nasal Discharge.
Intestinal signs - Ill thrift, wt loss, D+, pot bellied, occ intestinal obstruction/intersusception - colic resulting to sudden death of worms due to anthelmintics or immunity at 6m of age.
TREATMENT:
Double dose Benzimidazoles, single dose Ivermectins or Piperazine.
Alternate young stock grazing from year to year.
THE HORSE PINWORM
OXYURIS EQUI:
The adult worms are found in the Colon of the horse and the female migrates to the anus and lays her eggs around the perineum. The eggs can then develop in 4-5 days and are ingested.
Intestinal signs are very rare. Most commonly it is the irritation around the anus that causes a problem of the horse rubbing and causing bare patches and inflammation.
TREATMENT:
Routine anthelmintic use,
Good stable hygiene , with cleaning and then disposal of cloth.
THE HORSE LUNG WORM
DICTYOCAULUS ARNFIELDI :
This is really a parasite of the Donkey but can cause clinical disease in the horse, usually only young animals. The eggs are ingested after being laid in the donkeys faeces. Resp signs, cough +/_ limited exercise ability may occur.
TREATMENT:
Ivermectins, Levamisol.
TAPEWORMS
ANOPLOCEPHALA PERFOLIATA(Caecum) / MAGNA(Small intestine):
Life cycle involves the Orbatid mite which ingests the segments and then is ingested by the horse. The adults tend to collect around specific areas and may cause blockage resulting in colic. All ages of horse may be affected.
TREATMENT:
Pyrantel at a double dose. (Pyratape P or Strongid-P)
BOTS
GASTROPHILUS SSP:
The adult fly lays eggs on the horse during summer. These are then ingested by the horse and may remain in the stomach of the horse till the following year. They generally cause few problems, the adults being the most irritating to the horse.
TREATMENT:
Use of a Boticide during the winter e.g. ivermectins (Eqvalan)
WHICH ANTHELMINTIC AND WHEN?
"Good worm control consists of sound pasture management, SUPPLEMENTED by an effective worming programme."
(see pasture management)
Ideally:
Remove faeces from the pasture or break up the dung pile so as to expose the larvae to daylight and warmth so increasing their activity so reducing their reserves and thus period of survival.
The Exmoor Pony:
The natural balance between alterations in condition - weight loss in winter and spring and weight gain in summer and autumn can be severely affected by worms. Also the difficulties in treating and controlling worm populations in the large groups of semi-wild, mixed aged groups, on large, unfenced areas is obvious.
It can be impossible to round up large numbers and worm these in 1 day and so different strategies must be found.
There are 4 main groups of wormer and each year a worming programme should be based on just one of these.
However to treat certain parasites, specific wormers should be used at specific times of year.
BENZIMIDAZOLES
Fenbendazole (Panacur)
Mebendazole (Equivurm, Telmin)
Oxbendazole (Equidin, Equitac)
AVERMECTINS
Ivermectin (Eqvalan, Furexel)
MILBEMYCINS
Moxidectin(Equest)
TETRAHYDROPYRIMIDINES
Pyrantel Embonate (Strongid-P, Pyratape P)
WHO, WHEN WHERE?
Alert with ears pricking to and fro,