Krimpsiekte (Cardiac Glycosides)
By Dr Mackie Hobson BSc(Agric),BVSc

Cardiac Glycoside Poisoning (‘Nenta’, ‘Krimpsiekte’)

Although Nenta poisoning probably has a higher incidence in goats (more common in kids), other animals like sheep, cattle and horses are also susceptible. Angoras reportedly are more prone to “krimpsiekte” than boer goats.

Click here for video of symptoms

Cardiac glycoside-containing plants, collectively, is the single most important plant poisoning in South Africa. Two types of cardiac glycosides are contained by South African plants,

• cardenolides
• bufadienolides

 All the important cardiac glycoside-containing plants in South Africa have bufadienolides as their active principles (Keller man,Coetzer, Naudé & Botha 2005).

• Chronic intoxication with cumulative bufadenolides results in
• Acute poisoning resembles that induced by other bufadenolides.

This results in a gradient of clinical signs depending on dose and length of exposure. Generally cardiac and intestinal signs decrease and paresis increases with chronicity.

“Krimpsiekte” (Cotyledonosis)

The majority of the cardiac glycoside poisonings in small stock is ascribed to “krimpsiekte”, which is one of the limiting factors for small stock production in the Little Karoo and southern fringes of the Great Karoo in South Africa. (ref: Prof Christo Botha)

  “Krimpsiekte” occurs mainly in the Little Karoo and southern fringes of the Great Karoo in South Africa.

 Distribution:

Nenta poisoning ("krimpsiekte") is more common in the districts of Prince Albert, Uniondale, Willowmore and Oudtshoorn.  More than 90 per cent in the case occur in hilly areas, and as a rule occur on the shady side.  On the plains and in valleys and watercourses the incidence is under 5 per cent.

When does it occur?

After a drought (23%) and especially after good rains (61%) is when Nenta poisoning is generally more prevalent. As far as grazing is concerned, 80% of farmers experienced the problem after a camp had been rested while 20 % of farmers had the problem even though there had been stock in the camp for some time and report it being more prevalent when the camp becomes overgrazed.

In some regions “krimpsiekte” occurs mainly during the winter and spring (May to September), while in others the incidence is highest in spring or early summer (July to late November), and during spells of summer drought. This variation is ascribed to seasonal differences, climatic conditions and plant species involved. “Krimpsiekte” can nevertheless, to a greater and lesser extent, occur throughout the year.

Symptoms:

Although symptoms mostly involve the nervous system, affected animals may also show signs of acute abdominal pain. These symptoms may also be features of other diseases. Sudden death, which may occur especially in young goats, is quite a common in a large number of diseases other than plant poisoning. Furthermore, certain infectious diseases, like chronic pulpy kidney may give rise to similar nervous symptoms.

Poisoning by bufadienolides may be either acute or chronic, depending on whether the bufadienolides contained by them have a cumulative effect or not.

• Acute poisoning

Acute often occurs when hungry goats consume larger quantities of the plant material. This affects the respiratory, cardiovascular, gastrointestinal and nervous systems, usually leading either to death (with 1-3 days) or recovery within days.

• Found dead (1-3 days after exposure) without having been ill
• Sometimes, however, affected animals are visibly sick and either lie down in obvious pain or remain standing, in both cases with signs of bloat.
• Salivation, lodging of food at back of throat due to spasm of masticatory muscles. The goats usually stand in the shade with an open mouth and drip saliva.
• Initially the goats may appear bloated but then become thin as can’t chew.

• Chronic poisoning is more common.

Cumulative or krimpsiekte causing bufadienolides involves mainly the nervous system sometimes resulting in:

• Sudden death
• Paresis or paralysis (more common)
• Affected animals typically assume a characteristic pose (with the feet together and back arched), lie down frequently and develop protracted paresis /paralysis. A few display persistent torticollis (Kellerman et al.2005).
• Goats often do not exhibit symptoms until driven or disturbed. These symptoms include shivering, staggering, muscular twitching and even convulsions, trembling of lips. This can be 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.
• Tire easily when chased and get left behind.
• Can lead to abortions

Post Mortem

• There are usually NO typical post mortem lesions but in acute cases can occur.
• Signs of pneumonia may be found due to aspiration from inability to chew and swallow (intestinal content found in trachea)
• Epicardial petechial haemorrhages; haemorrhages in the atria and ventricles.
• Congestion and oedema of lungs, with froth in trachea
• Congestion of the liver and slight oedema of kidneys;
• 
• On microscopical examination myocardial degeneration or even necrosis and pulmonary oedema are present. In more chronic cases foci of myocardial fibrosis are seen.

Treatment

• 2g per kg body weight activated charcoal mixed with water and stomach tubed is a must.
• Farmers should be warned that the excessive stress of restraining and dosing the clinically affected animal might induce fatal cardiac disturbances. After dosing minimize stress to prevent catecholamine release and keep the animals calm and rested in a kraal or small paddock.
• Rest and shade

Other treatments may be less effective but often used by farmers:

• Supportive rumen treatment of dosing Rumix or homemade recipe of vinegar, sugar (brown) and yeast may only have limited value
• Hypo in drinking water

Prevention:

• Transferring stock to camps free of Nenta
• The majority of farmers follow a system of grazing. Management.
• During droughts supplementary feeding will ensure that the animals consume less “plakkies”.
• The issue of developing a vaccine against poisoning by cardiac glycoside-plants is being re-examined.
• The eradication of the plants is sometimes attempted

Plants

Members of three genera of the Crassulaceae (Cotyledon, Tylecodon and Kalanchoe), generally referred to as “plakkies”, contain cumulative, neurotoxic bufadienolides and may cause either acute or chronic poisoning.  The chronic form of the poisoning is colloquially referred to as “krimpsiekte” and is primarily a disease of small stock.

“Tulp” poisoning (induced by various Moraea species) and “slangkop” poisoning (caused by various Drimia species) induce only acute intoxication as these species contain non-cumulative bufadienolides

BUFADIENOLIDE-CONTAINING PLANTS:

• Tylecodon spp. (nenta/“kandelaarsbos”)

• Cotyledon spp.( pigs ears/“hondeoor-plakkie”)

• Kalanchoe spp (“plakkie”) –Occurring Northern Cape

• Moraea spp. (Tulp)

• Drimia spp. (Slangkop) Northern parts of SA

• Melianthus spp (Kruidjie-roer-my-nie )

• Thesium lineatum (“vaalstorm”, “witsorm”)

• Thesium namaquense (poison bush, “gifbossie”)

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)

CARDENOLIDE-CONTAINING PLANTS

• Nerium oleander (oleander/“selonsroos”)

• Gomphocarpus fruticosus (milkweed/“melkbos”)

Poison- how much is needed?

In trials it has been demonstrated:

• 7 g of freshly cut and shredded Tylecodon ventricosus leaves, administered on three consecutive days, caused typical signs of the disease within four days and death within six days of commencement of dosing. All of the eight goats included in the trial developed typical signs of krimpsiekte and six died.
• 240 g Coteledon orbiculata plant material was fed to an Angora goat, which subsequently developed clinical signs reminiscent of krimpsiekte and died 10 days later.
• Coteledon orbiculata dosed orally to sheep to confirm toxicity. A single dose of only 1.0 g/kg of this particular batch of plant material (semi-dried stems and leaves) was lethal for sheep.
• An adult goat (38 kg) was poisoned by 17 g fresh, minced leaves administered over 25 days.
• A three-month-old goat kid also died within seven days of receiving 24 g minced flowers.
• As little as 50 mg/kg plant material daily (nine dosages over 13 days) producing intoxication (Terblanche & Adelaar 1965)

Reference:

Kellerman, T.S., Coetzer, J.A.W., Naudé, T.W., Botha, C.J., 2005, Plant poisonings and mycotoxicoses of livestock in southern Africa (2nd edn), pp. 116-146, Oxford University Press, Cape Town.

Dr Marius van Tonder (Grootfontein)

P.Botha (Grootfontein)

C.J Botha (Pretoria University)