Spring Lamb Paralysis
By Dr Mackie Hobson BSc(Agric),BVSc

1. Diseases

Tick paralysis is an acute, progressive, symmetrical, ascending motor paralysis caused by a salivary neurotoxin produced by certain species of ticks. See article on The Karoo Paralysis Tick (Ixodes rubicundus) .

Brown Ticks (Rhipicephalus) include the Red-Legged tick (Rhipicephalus  evertsi evertsi)

The saliva of engorging female ticks contains a toxin that causes paralysis, particularly in lambs, but it may also affect adult sheep and goats. This toxicosis is known as spring lamb paralysis because of its seasonal occurrence. Several females are necessary to produce this effect and they must have fed for about 5 days.

Red-legged tick – Rhipicephalus  evertsi evertsi

                                                                                 Photo Dr.W. Fowlds

Has banded legs and at first glance can be mistaken for hyalomma (bont legged tick)

Sites of attachment

Adult ticks attach under the tail around the anus and sometimes can be found in the axilla, groin and on sternum.

The Nymphs can be found deep down in ear canal.

Distribution in Angora producing areas where rainfall is above 250-289mm. It is a two host tick.

Other diseases:

Apart from spring lamb paralysis the red-legged tick may potentially also cause Borrelia theileri in goats (spirochaetosis).

Large infestations of immature ticks may damage the ear canal of its host.

Removal  of the ticks can lead to recovery after 48 hrs.For tick treatment options see https://www.angoras.co.za/page/ectoparasite-2016#40

Other animals effected:: Adults prefer horses, zebras, elands, cattle and sheep. Larvae and nymphs utilise the same hosts as the adults and also scrub hares and various antelopes. The adults are found on the hairless area around the anus as well as the inguinal region of equids and sheep. The immature stages attach deep in the ear canals.

REFERENCES

Prof Maxime Madder, Prof Ivan Horak, Dr Hein Stoltsz (University of Pretoria)

C.J.Howell, J.B.Walker, E. Nevill (University Onderstepoort)