Nurm

15/11/2019

Great article by Mark

We are all looking for that perfect feed for our horses, particularly one that is low in sugars and starch and high in fermentable fibre. There have been a few products found to fit into these categories and have been gi...

16/10/2019

Considered deworming for bot? Now is a good time.

It's not uncommon for untreated horses to have hundreds of the larvae in their stomach that spend seven to 10 months growing and absorbing nutrition from the passing flow of food the horse has eaten. When spring and warm weather arrives, the orange-red botfly grubs that are just under an inch in length detach from the stomach lining and are passed out in the horse's manure where they are easily recognized. Once on the ground, they burrow in and pupate for two to four weeks before emerging as adult flies.

A small number of bot larvae in the horse's mouth or stomach usually do not cause much damage, but large numbers can make the horse's mouth sore, create damage to the stomach lining and block passage of food from the stomach into the small intestine.

Control should be a two-pronged approach, at both the adult and larvae. First of all, remove or destroy the bot eggs on the horse's hair before they have a chance to hatch. Bot knives work well, as do sandpaper or a stone grooming block. Rubbing the horse's legs down with baby oil suffocates the eggs. Sponging the horse off with a warm water/vinegar mixture encourages the eggs to hatch, and the larvae are then carried off with the sponge or water rinse.

These procedures need to be repeated at least twice weekly to prevent the new eggs from hatching and infecting the horse. Deworming is the best defense against the botfly larvae in the horse's mouth and stomach. Make sure the dewormer you use contains either moxidectin or ivermectin, as they are the only active ingredients that are effective against bots.

It's best to wait until the first killing frost (May, June) to administer the dewormer because the cold weather will eliminate the adult botflies and their laying of eggs. To catch survivors of the autumn deworming, a second treatment is recommended in early spring before the grubs detach from the horse's stomach wall and pass out of the horse to start their life cycle.

25/09/2019

Small Stongyles:
Life Cycle of the Small Strongyles (cyathostomins)
Adult female small strongyles live in the lumen of the large intestine of the horse. They shed eggs which are found in the horse’s faeces. The eggs hatch and develop sequentially into various larval stages (L1, L2, etc). Development of L1 to L3 occurs in the faeces, then the L3 (the only stage capable of infecting a horse) migrate from the faeces onto the pasture and are ingested by the horse. Egg survival and hatching, and larval survival and development depend on climatic conditions (temperature and moisture). Dry conditions kill eggs and larvae. Larvae, but not eggs, will tolerate freezing. Temperatures below about 7°C do not support hatching or larval development. With adequate moisture, the rate of larval development increases proportionally with temperature up to about 30°C.

Eggs and larvae can survive for considerable periods in cool weather with adequate moisture, but survival of larvae is reduced at warmer temperatures due to rapid depletion of limited energy reserves (with adequate moisture, the optimum temperature for survival is about 15°C, while above 30°C, larvae will die). Larvae can survive for 12 months on pasture under favourable conditions, but generally survive < 3 months in summer and < 6 months in winter. In winter rainfall areas in Australia, larval populations will be high in autumn, winter and spring, while in summer rainfall areas, larval populations will be high in spring, summer and autumn.

When L3 are consumed by the horse, they burrow into the mucosal tissue of the caecum and colon and become encysted (the cyst wall protects them from most drugs). These larvae either develop (within the cysts) into L4 or become arrested (development stops).

L4 ‘excyst’ (exit the cysts) and return to the lumen of the large intestine where they develop into L5 and then into mature worms which complete the life cycle with the females producing eggs. Arrested larvae remain encysted for varying periods of time before emerging from the cysts. Often the period of encystment is long (up to a year or more). Emergence of large numbers of arrested larvae, often in late winter/early spring in cooler climates, causes larval cyathostomosis, a clinical disease associated with intestinal mucosal damage, which can be fatal. Encysted larvae are usually present in much greater numbers than the adults in the intestinal lumen. The length of the life cycle varies from about 6 weeks to 2.5 years, depending on the amount of time that the larvae remain arrested.

08/09/2019