Senecio, more commonly known as ragwort, gifbossie or dunsiekte bossie is the name given to the toxic plant common in paddocks, that has yellow, daisy-like flowers.
It is highly toxic to horses but is difficult to identify, since there are at least five different species in South Africa . The toxic principle is a pyrrolizidine alkaloid and can affect the intestinal and neurologic system, the liver and skin.
Intestinal (Acute): colic and severe diarrhoea
Liver (Chronic): weight loss, depression, colic, diarrhoea, icterus, dark coloured urine
Neurologic (Chronic): depression, yawning, aimless wondering, head pressing, draggin hooves, difficulty swallowing, blindness, circling, abnormal gait, coma.
Skin (Chronic): photosensitivity (sensitivity to the sun), skin inflammation, itching, hair loss
All parts of the plant may be toxic.
Gastrodiscus is a type of fluke that has an indirect life cycle with freshwater snails as the intermediate hosts. The larvae survive in humid and wet conditions, especially in marshy or flooded fields. They swim and penetrate actively into the snails. The larvae then leave the snail, attach to the vegetation and produce cysts which are infective for the horse. The recent wet conditions in Cape Town are ideal for the snails to thrive and horses grazing along streams or on the Constantia green belt are at risk.
Most infestations don’t show any clinical signs and the pathogenic nature of Gastrodiscus has been undetermined for a long time, there are many reports of the absence of clinical disease in horses and it was originally considered to be non-pathogenic. However, it can cause weight loss, poor condition, starry coat and diarrhoea. Colic has also been reported in horses with severe infestations with caecal intussusception and typhlocolitis as a sequela. The degree of clinical signs may also not relate to the level of parasitic burden.
A special floatation test is required to test for Gastrodiscus and it will not be picked up on your routine worm egg counts. The test costs around R340 per horse, depending on sample numbers and is called a faecal sedimentation test. The R340 also includes the routine worm count for all other worms. A fresh faecal ball should be collected first thing in the morning and delivered to the shop in Meadowridge. Please remember to leave your name and horses details for the laboratory forms. The results take approx. 12-24 hours and high counts of strongylids or ascarids eggs (other species of worms) will also be noted on your test.
A positive test for Gastrodiscus will confirm a diagnosis in your horse and we recommend treating these horses. Horses that test negative, however, may still have immature parasites. The test is designed to detect worm eggs, so if your horse grazes in a high-risk area and shows clinical signs of a possible worm burden, we recommend retesting these horses in 6-8 weeks. We do not recommend treating horses with an undetermined worm burden as the product is not registered for use in horses, it is a ruminant medication.
There are no licensed products, we currently recommend Tramizan, which is an “Off label” or not licensed oral medication for use in equines. It contains the active ingredient Oxyclozanide which is effective for the treatment of Gastrodiscus positive horses. Please do not try and buy this product off the shelf, please get the required dose per horse from your vet. You need to retreat the horse after 72 hours horse, so you will need to pick up two doses per positive horse.
Controlling fluke infestations in your horse involves keeping horses away from areas where they may be contracting the cysts. Grazing on the green belt or drinking water from the streams where the snails live is obviously the origin of infestation in most horses. It is not practical to try and eradicate the snail or to not access some areas of the green belt. Our recommendation is to test your horses twice a year to determine the level of infestation and whether your horse needs treatment. This needs to be more focussed in the wet months as the fluke larvae will desiccate quickly under dry conditions. Be aware of your horse’s water source and dams or stagnant water should be fenced off where possible.
Please contact us should you have any further queries.
Urticaria or hives is the development of small lumps on your horse’s skin caused by an allergic reaction to a change in feed, midge bites, or reaction to certain chemicals or allergens. The episodes may be limited to one or two occurrences that respond to treatment or may become recurrent episodes that require further investigation.
Horses showing signs of Urticaria may have welts or lumps over limited parts of their body extending to the whole body, they may itch profusely, have swollen lips or eyelids, elevated temperature, rapid breathing and be hot to the touch.
Sweet itch is a common seasonal dermatosis that occurs mainly in summer due to a hypersensitivity to biting midges. These midges, called Culicoides midges are the same midges that carry African Horse Sickness.
How can I prevent midges biting my horse?
As many of you are probably aware, a large part of the prevention of horse sickness lies in vector protection. In other words the stringent use of midge repellents and control methods can deter midges and flies. Since midges are not flies however, common fly sprays are not adequate in warding off these little critters and the use of midge repellent substances are strongly recommended.
How can I treat sweet itch?
Since this is an allergic irritation, there is no cure. However; there are a number of ways in which to provide some relief for those very itchy, irritated horses. It is important to differentiate between midge bite hypersensitivity and other causes of Urticaria such as feed sensitivity and/or fynbos allergies.
The first step in controlling the allergy is to reduce the number of bites from the midges. This is done in a number of ways:
Severely itchy horses may require medical intervention in order to minimise scratching and rubbing and causing injury to the skin of the itchy areas. These treatments would include the use of systemic cortisone injections as well as topical creams, lotions and/or shampoos. Please consult your vet in this case.
Benzyl Benzoate is an effective remedy for mites that cause mange (see later), but can be used successfully to control sweet itch. It is a skin irritant however and should thus only be used in cases prior to the onset of hair loss and raw sores. If used on very irritated, sensitive skin it may worsen the condition and lead to skin sloughing.
The use of fly sheets is a very effective way in which to decrease midge attacks and eliminates the need for insecticides and oils or greases.
Effective management of Sweet Itch is difficult, frustrating and relies solely on the decline in midge numbers for resolution. However it is seasonal and if your horse has it one year it is likely to get it every year. Should you have any concerns regarding your horse’s condition please chat to one of our vets.
Sweet itch vs Grasss Mange
Mange refers to the infestation of the skin and hair by a biting mite. These mites are found during the dry summer months in the long grass and attach to the horses hair as contact is made. There are many species of mite that may cause a problem but the most serious is Sarcoptes spp. Because infestation often starts on the neck and face it is commonly confused with sweet itch. Itchy patches become hairless and if left untreated, the skin over time becomes bare, wrinkled and covered in crusts.
Treatment involves washing with an insecticidal shampoo; however in severe cases veterinary treatment may be required.