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Mange treatment in dairy sheep and goats

 

I recently posted the following discussion point by Email.  Unfortunately the Email format did not allow for a good discussion, which is a great shame given the usefulness and pertinence of each of the responses that I received.  Thank you so much to those of you who responded.  At least four important themes have emerged:

 

1.     Different types of mange are present in different regions.  (It would be interesting to know more about the regional distribution of psoroptic and sarcoptic mange, including those regions from which the diseases are completely absent in small ruminants.

2.     Problems of treating sheep scab in dairy sheep and goats.  (It would be useful to know more about the different legislative frameworks in different regions.  It would also be useful to better understand the efficacy of eprinomectin as a pour on.)

3.     Availability of licensed drugs in general for use in small ruminants.  (In some regions, this is clearly a very important topic.  It would be good to hear a broader range of opinions.)

4.     Selection for anthelmintic resistance when using macrocyclic lactone endectocides for the management of ectoparasites.  (This is a huge concern in the UK and South Africa, but is there any empirical evidence in support of the risks?)

 

There is clearly a lot still to discuss: please join in! I think that with more input reflecting a broader range of perspectives across Europe and globally, we have the opportunity to formulate guidelines on the management of mange in small ruminants. 

 

My original discussion topic on mange treatment in dairy sheep and goats:

 

For some time now, I have been part of an advisory group to the Scottish Government on sheep scab control that meets once a year.  Our group was instrumental in bringing about our Sheep Scab (Scotland) Order 2010, which involves:

 

A legal obligation on any person who suspects that sheep may be infected by sheep scab to notify the DVM.

Voluntary movement restrictions apply until the sheep are treated, slaughtered or a negative diagnosis is made.

Failure to take action could lead to compulsory movement restrictions and a requirement to treat or slaughter affected animals unless a negative diagnosis is made.

Failure to take action (persistent offences) could lead to prosecution (and has done so).

Powers to act when sheep scab is discovered at markets and to deal with (treat or remove) stray sheep.

 

As background context, animal health in the UK is devolved, hence Scotland has separate legislation from the rest of the UK.  Scottish Government has always been supportive of animal health.

 

It has recently come to our attention that our legislation creates a conundrum when dairy sheep are affected with sheep scab (psoroptic mange), because we have no products that are licensed for use in milking animals, hence the only legal options are to treat and stop milking, or slaughter.  Fortunately, in this regard there are very few dairy sheep in Scotland, and most if not all are kept in lifestyle or hobby flocks.  This is probably why the issue has taken so long to surface, but it is nevertheless a concern.  We are keen to find out more about how mange is managed in milking sheep and goats in other countries (including the rest of the UK), and how this fits in with different legislative frameworks.  

 

Could you please let me know how you manage mange in dairy small ruminants in your country?  I am also interested in any legislation surrounding this.

 

Responses:

 

Delia: Eprinomectin pour-on is widely used in dairy animals in Spain.

 

Thanasis: In Greece, we use eprinomectin (pour-on) to treat mange in dairy sheep and goats due to the zero withdraw time.  In the past, the use of eprinomectin used to be an extra-label use, but as far as I know the companies currently have got the licence to use it in dairy small ruminants as well.  Attached you can find an abstract from a relative project we recently had, where we investigated the effectiveness of eprinomectin in two flocks with mange.  In general, it seems to be effective, but great attention needs to be given on the appropriate administration (on the skin rather than on the wool).  (My understanding of the WAAVP abstract was that the eprinomectin pour-on achieved 76.4% and 92.3% reductions in sarcoptic mange mite numbers in sheep.  While useful for treatment of individual animals, anything less that 100% reduction would be inappropriate for the control of psoroptic mange/ sheep scab.)

 

Nektarios: Pointed out that psoroptic mange is not seen in Greek sheep, albeit Psoroptes caprae does cause otitis in goats.

 

Helder:  In Portugal we have the possibility of deltamethrin (withdrawal period 36 hours). Eprinex in sheep (unlike cattle) has no manufacturer's indication for the treatment of scab. This is a current and important topic which can be included in the small amount of therapeutic solutions available to small ruminants. In  

Portugal we have about 200 products licensed for sheep and less than 90 authorized for goats. And many of these products have the same indications: vaccines, oxytetracyclines, ivermectins...Whereby the veterinary practitioners of small ruminant have great challenges every day.

 

Rhoda: Currently we also do not have many milking sheep in South Africa, but we do have milk goats and also use Eprinomectin as an off-label option. Part of the control measures in South Africa are yearly injections with Ivermectin in sheep (mainly Dorpers) for the prevention of sheep scab. We are of the opinion that this has contributed greatly to the development of Ivermectin resistance in Haemonchus contortus. The injection of Ivermectin is recommended practice in the Dorper Breeders' Association and occurs in winter which leaves few worms in refugia. We do, however, have fewer cases of scab than we used to and it is often seen now when there are imported live animals (speculators).

 

Paula: At this point we only have psoroptic mange in bighorn sheep in British Columbia (fingers crossed it stays there) but we do have chorioptic mange and lice.  In Canada it is illegal to use pesticides extra label and of course, nothing for dairy sheep (or goats) is licensed.  We have pushed our Pesticide Management Regulatory Agency to support licensing of pesticides for small ruminants - nothing for dairy yet however and nothing on the horizon that I am aware of.    So treatment is done when dry - far from ideal but not as much of a welfare issue as psoroptic mange.  My guess is that also producers purchase Eprinex and use that - with no vet involved.

 

Gareth: South Africa has a small Milch goat industry and an even tinier sheep milk industry, really just boutique in both cases. We've tried to control sheep scab for hundreds of years but the problem remains. We have enough effective remedies to eradicate scab and its relatives on individual farms. The provocative question is, why do we continue to keep it a state-controlled disease? Old thinking dies hard. A definite diagnosis of the mite is essential in every case.

 

Pierre: I work as a practitioner in the middle west of France were the psoroptic mange is quite endemic in some sheep flocks, it is not the main area for dairy milk. The legislation about psoroptic mange is not so drastic as in Scotland (Psoroptic mange is ranged in Danger Sanitaire niveau 2), it is one of the reasons because this parasite is endemic.  The protocol that I try to apply in the flocks is following: the farmer must be involved in the treatment by an accurate diagnosis (showing the Posroptes under the microscope), the serologic test is not yet available in France.  The treatment must be performed as soon as possible after diagnosis.  All the flock (lambs, rams, ewes...) must be treated within 48-72 h with either dips or injections (shower and pulverisation are not efficient). The dips should be preferential, but if contra indicated (ewes in late or early pregnancy, too young lambs...) injections should be performed.  The buildings were the animals are housed should be disinfected with the rest of the dipping emulsion.  Two treatments should be performed in an interval of 2 weeks for dipping, 1 or 2 weeks for injections depending of the drug (ivermectin or doramectine or moxidectin). In dairy flocks: dips with deltamethrine (Butox 50pm - withdrawal period for lactating ewes is 24 h), dimpylat (Dimpygal  2 days).  Phoxim (Sebacil) is forbidden except more than 2 months before the first lambing.  Pour ons as Eprinex multi is not registered for psoroptic mange and neither external parasites, and I have doubts about its efficacy.  Injections are available with drastic contra indications regarding milking period, except Eprecis injectable which is registered on dairy cattle for Sarcoptes and should be used on Psoroptic mange of sheep but without registration, but it is compulsory in France, in case of using a not registered drug on sheep, to apply the cascade principle with 7 days for milk. 

 

Margit: With regards to treatment of mites in Holland, our farmers can still use diazinon themselves. As we don’t have an injectable moxidectin it is normally the way people solve the issue. With regards to diary goats/sheep, people have started using eprinex during the dry period. I have not come across the issue yet but I know it happens. 

Thank you for this interesting discussion. There are published articles on Anthelmintic resistance in South Africa specifically to the Macrocyclic Lactones. I do believe as previously mentioned that their use against ectoparasites has played a role as our Dorper industry is large and timing leaves few worms in refugia. How this relates to resistance in the milk goat industry I guess needs to be determined. I can only offer that some farms do have mixed flock/herds and this could play a role. We have even seen resistance to Startect develop quite quickly after the launch in some areas in SA and that is in my opinion owing to the resistance we already have to MLs. There are of course other contributing factors such as indiscriminate dosing and incorrect dosing etc. How exactly would one go about establishing the risk that treating for ectoparasites poses? I suppose one could do a small trial and get sheep or goats from a herd that still have worms susceptible to MLs (as close to 100% as possible), dose them in winter and see how long it takes to develop resistance...

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