Last update: March 30, 2012 09:04:44 AM E-mail Print



EM van Tonder 


The symptoms of nenta poisoning are often more dramatic than fatal, especially in older animals, says Dr Marius van Tonder, Chief of the Regional Veterinary Laboratory at Middelburg Cape, apropos of concern expressed by Angora goat farmers about the incidence of nenta poisoning in their flocks.

Although symptoms mostly involve the nervous system, affected animals may also show signs of acute abdominal pain. The fact that these symptoms may occur concurrently, and are also features of other diseases, may often lead to confusion as to the actual cause of any so-called nenta-poisoning outbreak, he says.

A further complication in arriving at a correct diagnosis is sudden deaths, which may feature strongly in some outbreaks, especially in young goats. Sudden death is quite a common sequel to a large number of diseases other than plant poisoning.

Apart from Cotyledon spp., Tylecodon spp. and Kalanchoe spp. (all commonly referred to as plakkies or nenta), which are the more important causes of nenta poisoning, Crassula spp. And Adromiscus spp. (also called plakkies.) may also be responsible for this disease. In addition, a similar and indistinguishable type of syndrome may result from the ingestion of Cynanchum spp. (bobbejaantou, klimop, or dawidjies), Psilocaulon spp. (asbos, loogbos), Malva parviflora (kiesieblaar), Sarcostemma viminale (melktou) and Urginea spp. (slangkop).

Furthermore, certain infectious diseases, like chronic pulpy kidney and even bluetongue or organic phosphate poisoning, may give rise to similar nervous symptoms.

Dr Van Tonder goes on to say that farmers should not regard sudden deaths as a characteristic feature of nenta poisoning, since this is such a common consequence of a vast number of non-related diseases.

True nenta poisoning may either assume an acute or a chronic form, depending on the intensity of exposure to the plant. In the acute form, he says, affected animals may be found dead one to three days after exposure without having been noticed to be ill beforehand. Sometimes, however, affected animals are visibly sick and either lie down in obvious pain or remain standing, in both cases with signs of bloat. These animals also tend to show salivation and lodging of food in the back of the mouth, caused by clonic spasm of the masticatory muscles. Some animals may die soon after the appearance of the symptoms or may survive for a few days, while in milder cases the condition may pass over to the chronic form and recover eventually.

In the chronic form of nenta poisoning, which is more commonly encountered, the animal may appear visibly affected when found, but more often does not exhibit symptoms until driven or disturbed. These symptoms include shivering, staggering, muscular twitching and even convulsions, followed by sideways pulling of the head and recumbency.

Accompanying symptoms are dribbling of saliva, rapid breathing and the collection of food in the mouth. Some of the animals may die within a few days, but more often animals recover spontaneously within a variable period if left undisturbed.

There are usually no typical post mortem lesions.

Although nenta poisoning probably has a higher incidence in goats, other animals like sheep, cattle and horses are also susceptible, says Dr van Tonder. The higher incidence in goats seems to be due to a greater opportunity to exposure. Strange as it may seem, he says, dogs and even man may contract this disease on eating meat of affected carcasses.

The complicated nature of this disease demands that as accurate a diagnosis as possible should be obtained when investigations are conducted. If this is not done, Dr van Tonder concludes, research into true nenta poisoning may be severely hampered.



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