CASE NOTES


FACIAL ECZEMA IN THE BEGA VALLEY

Helen Schaefer, South East Local Land Services, Bega

Posted Flock & Herd April 2017

INTRODUCTION

The first recorded cases of facial eczema (FE) occurred in 1908 in New Zealand. It was another fifty years before the causative organism was identified as the fungus we now know as Pithomyces chartarum. It was initially identified as Stemphylium, and then recognised as Sporidesmium bakeri Syd. The toxin produced by the fungus was isolated during this period of time, and was thus named sporidesmin. Taxonomic changes in 1960 gave us P. chartarum, the hand grenade shaped spores of which are recognised to produce the toxin we continue to know as sporidesmin.1

A vast amount of knowledge was gained about the pathology of, and the weather and pasture conditions associated with, FE in the first five decades of awareness of the disease. A number of factors contributed to the delay in identification of the fungus as the cause of FE. The main factors were the lag time between ingestion of the toxic pasture and the clinical signs appearing; the relative unpredictability of the occurrence of the disease, and the very low numbers of diseases being recognised as being caused by fungal toxins at that time. 

Much has been determined and defined about facial eczema over the last one hundred years. In summary:

What is Facial Eczema?

What causes FE?

What can be done to predict occurrence of FE?

What can be done to prevent outbreaks of FE?

Diagnosis of FE

Serum GGT levels are particularly sensitive to cholestatic disease. GGT is therefore the best measurement of the severity of liver damage in FE. As a general rule, GGT values greater than 800U/L indicates severe liver damage; 300-800U/L moderate damage; 100-300 mild damage; levels less than 100U/L are not clinically significant. GGT levels in FE outbreaks tend to be >1000U/L 4 PLUS

CASE REPORTS

December 2015 – The question was asked: Does FE occur in the Bega Valley?

An ex-Gippsland dairy farmer, dairying in Bega for eighteen months, asked his Bega Cheese contact if FE was a problem in the Bega Valley as it was in Gippsland.

After discussion amongst Bega Cheese, Dairy NSW, local veterinary practitioners and the District Veterinarian from the Local Land Services in Bega, it was determined that the incidence was unknown. There was no recollection of any outbreaks being definitively diagnosed. It was decided that given the atypical wet, warm summer we were experiencing, it was advisable that information be put out to, and the question be asked of, the farming community.

March 2016 – Question answered: Yes, it does.

CASE A. 7/3/16  Milking herd Dairy farmer south of Bega, who had asked the question, rang the DV – thinks he has an outbreak of FE.

History:

Investigation: Farm visits and testing

8/3/16 (day 7) 

Figure 1. GGT levels for the 9 cattle sampled 8.3.16
Table 1. Pasture spore counts 8.3.16

13.3.16 sampled pasture doing a top cut (F1a), as cattle would access in a light grazing, and a lower cut (F1b) as per standard for pasture sampling for spore counting ie. down to 1cm above dirt. Results: F1a 25,000 spores/gram pasture, F1b 60,000 spores/gram pasture. 

16.3.16 (day 14) 56 x blood samples for GGT, 5 were repeats from 8.3.16 (ref table 2)

Table 2. GGT levels in 5 cows sampled twice over 1 week. The elevation in GGT levels at the second bleed indicates the first bleed was taken early in the course of the disease.

18.3.16  organised 2 affected cattle sent for slaughter to Young to have liver histopathology done; GGT levels previously recorded (ref samples 5 & 7 in Figure 1, and sample 1 in table 2).

8.4.16  (day 38)  17 x blood samples from milkers for GGT + Zn levels; plus 17 x blood samples from dried off cows for GGT 

12.5.16 (day 72)  31 x blood samples  - 11 for GGT + Zn,  20 for GGT only 

Tables 3 and 4 display the results of the blood testing for GGT and zinc levels.

Table 3. GGT levels in samples taken 14 days, 38 days and 72 days after initial clinical signs were observed

Table 3 demonstrates the variation in GGT levels amongst the cows and the variations in the GGT trends in individual cows over subsequent measurements. Table 4 however shows that the overall trend over time is a reduction in GGT levels.

Table 4. Comparison of mean GGT levels over three sampling times
Table 5. Serum zinc (Zn) levels in cows three and a half weeks after commencing  Zn in their feed, and  one week after they had stopped having Zn in their feed. They were on Zn  for a total of 7 weeks 

While only 8/17 had levels in the desired range of 20-35umol/L, the herd appeared to be improving well in their appetite and milk production, plus it has been observed that while “supplementation with zinc in the feed does not always reach the required levels, experience would indicate that it is reasonably effective in most cases” 4

Table 6. Spore counts from a number of pasture samples, taken on six different occasions, highlighting the two million plus spores/gram of pasture identified on 8.3.16.
Table 7. Spore counts as in table 6 with the two million plus counts removed to allow for the observation of more detail of the other counts. 

Cost to producer A:

 “With significant loss of cow numbers and the stage of production that our cows were in (majority freshly calved prepared to start a full lactation) combined with significant loss in milk production in our herd over the first three weeks and months following, as well as the extra fodder used to feed the herd in the crisis period, we estimate this has cost our business in conservative figures, $150,000 plus. Added to this, the emotional stress and extra work involved in managing this crisis was phenomenal.”  Producer A.

CASE B. 11/3/16 Young heifers Dairy farmer in Bega read the FE information in the local newspaper online and thinks that’s what has been affecting some of her heifers

History:

Investigation: Farm visits and testing

14/3/16 

Figure 2. GGT levels and clinical observations of the 13 heifers examined and sampled
Table 8.  GGT levels of 13 heifers. Samples 1-2 from older  heifers; samples 3-13 from younger heifers
Figure 3. Case B. Spore counts for Paddock 1 and Paddock 2

Cost to producer B:

All 17 heifers died over a number of months. The cost of the loss of these replacement heifers is estimated to be a minimum of $30,000.

CASE C. 22/4/16 Yearling heifers  Dairy farmer north of Bega rang with a mob of 160 x 12 month old Friesian heifers, number showing signs of photosensitization.

History:

Investigation: farm visits and testing

27.4.16 Farm Visit

Figure 4.  Case C. Spore counting results  from 2 paddocks, 2 samples/paddock 

29.4.16 Farm visit

Table 9. Clinical sign severity vs serum GGT levels in 51 heifers 

24.5.16 Three pasture samples collected – two from the same areas of the same paddocks, and a new paddock the producer was concerned about. 

Table 10. Pasture spore counts from samples taken 27.4.16 and 24.5.16

30.5.16  Farm Visit

Table 11. GGT levels from two sampling times showing the extent of differences in GGT levels amongst individuals, and the variation in change in GGT  in individuals  one month later

The remaining heifers were weighed on 29.5.16 and again on 14.9.16. Their average daily weight gain was compared with their GGT levels measured on 29.4.16. Ref table 11.

Table 12. Average daily weight gains vs GGT levels

There does not appear to be a direct relationship between the GGT levels observed at the first testing and the average daily weight gains observed over a subsequent three and a half month period.

Cost to producer C:

18 heifers died, lost contract for export of heifers to China – booked to export May 16. Producer estimates losses in deaths, lost export opportunity, increased feed utilized, delay in first mating has cost a minimum of $150,000.

MANAGEMENT OF THE RISK OF FE IN THE BEGA VALLEY 2017

There has been a significant amount of producer education about FE over the first three months of 2017. This has occurred via local radio, newspaper, producer networks and an information evening held late February.    

Due to the collection of the above data from pastures and affected cattle confirming outbreaks of FE in the Bega Valley in autumn 2016, Dairy Australia (DA) incorporated the Bega Valley into their 2017 GippsDairy Facial Eczema Spore Monitoring Program. The program has been running in Gippsland for a number of years to great effect. 

DA funding has allowed the engagement of three sentinel farms in the region (Quaama, Bemboka, and Candelo) who are submitting pasture samples to the Bega Veterinary Hospital every one-two weeks. Spore counting to monitor the situation will last from January through to April, as this is the typical period during which outbreaks of FE occur. The results of the spore counting are made available on the Dairy Australia website.

The risk of FE occurring increases when pasture spore counts are trending upwards of 20,000 spores per gram of pasture, minimum night time temperatures are over 12-15 degrees Celsius and the humidity is greater than 90%, for a few days. 

If the risk of FE does increase in the area according to the above indicators, alerts will be sent to Bega dairy farmers and other producers in the Valley via the media and producer networks. Producers will be recommended to submit their own pasture samples to the Bega Veterinary Hospital to gauge their individual situation. There is some funding available to facilitate these extra spore counts as we endeavour to gain a picture of the FE risk in our area. Producers will be reminded that spore counts can vary dramatically amongst districts, farms, and even amongst paddocks on the same farm.

Producers with at-risk dairy cattle will be advised to consider administering zinc oxide in the feed as a preventative for FE. Special attention will need to be given to the method and dose rate, as over dosage can result in significant toxicity issues. Management of dry dairy cattle, bulls, and other livestock, to minimise their exposure to toxic levels of the spores will need to be conducted as administration of zinc oxide via feed to those stock is rarely practicable.

The FE risk in 2017 vs 2016 

The hot and wet summer of 2015/16 was atypical for the Bega Valley. This led to an abundance of on-ground feed encouraging the buildup of dead leaf material on paddocks plus the practice of topping pastures. 

The summer of 2016/17 was much drier. While autumn has brought warm nights and significant rain, there is not the buildup of dead pasture material to encourage the abundant growth and sporulation of P. chartarum observed last season as shown in Figure 5.

The tables below illustrate the differences in monthly rainfall and monthly mean minimum temperatures over the months of August through to March 2015/16 and the 2016/17. 

Table 13. Monthly rainfall totals in Bega 2015/16 and 2016/17
Table 14. Mean Monthly Minimum temperatures in Bega 2015/16 and 2016/17

The results of spore counts done in the three sentinel herds in the Bega Valley this year are shown below. This is as they appear on the Dairy Australia GippsDairy Facial Eczema Spore Monitoring Program Report 29th March which covers the sentinel farms across Gippsland and in the Bega Valley:

Figure 5. Excerpt from the Dairy Australia GippsDairy Facial Eczema Spore Monitoring Program Report 29th March

DISCUSSION

The experience with FE in autumn 2016 in the Bega Valley has confirmed and highlighted a number of points worthy of consideration:

The collection of more data, the longer term follow up of affected animals, and further research into the toxicity of the sporidesmin containing spores of P. chartarum, are areas worth pursuing in order to give us greater understanding of this unpredictable, significant disease of ruminants.

ACKNOWLEDGEMENTS

With many thanks to and great appreciation of:    

References

  1. M. E. Di Menna , B. L. Smith & C. O. Miles (2009) A history of facial eczema (pithomycotoxicosis) research,  New   Zealand Journal of Agricultural Research
  2. Radostits OM, Gay CC, Hinchcliff KW, Constable PD. Veterinary Medicine. A textbook of the diseases of cattle, horses, sheep, pigs and goats. 10th Edition. Elsevier Ltd 2007
  3. Dairy Australia Facial Eczema Working Group, A Review of Facial Eczema (pithomycotoxicosis), Dairy Australia November 2011/Updated 2013
  4. Dr. Jakob Malmo pers com
  5. Parkinson TJ, Vermunt JJ, Malmo J. Diseases of Cattle in Australasia. A comprehensive textbook. Vetlearn 2010 p268
  6. Patrick Staples, Veterinary Pathologist, EMAI

 


Site contents and design Copyright 2006-17©