Abomasal Impaction of Cattle in SaskatchewanR.A. ASH CROFT

Department of Veterinary Clinical Studies, Western College of VeterinaryMedicine, University of Saskatchewan, Saskatoon, Saskatchewan 57N 0 WO

SUMMARY

Seventy-five necropsy reports of cattlediagnosed as abomasal impaction bythe Pathology Department of theWestern College of Veterinary Medi-cine were reviewed. Twenty percent ofall affected animals had lesions oftraumatic reticuloperitonitis and 60%were believed to be primarily dietary inorigin resulting from the ingestion oftoo much fibre. The remaining 20%did not fit into either category. Abom-asal tears, ulcers, and necrosis of thewalls of the rumen, omasum, orabomasum were recorded in almosthalf of the cases. Pyloric stenosis wasnot encountered. The disease occurredmostly in winter in association withstraw feed. Sixty percent of impactedbeef cattle suffered from the dietaryform, but the majority of dairy cattle,which would have been fed betterdiets, had the traumatic form whichmay have been precipitated by dryfibrous feeds. There was no indicationof a higher incidence in heavily preg-nant animals. Thirty-five of the ani-mals necropsied had been presentedalive, and the clinical features of thetwo main types of abomasal impactionwere examined. Cattle with impac-tions associated with traumatic reticu-loperitonitis were sick for a longerperiod than those animals with dietaryrelated impactions, were single inci-dent cases, and had a statistically sig-nificant rise in serum protein.

R t S U M t

Impaction de la caillette, chez des bo-vins de la SaskatchewanCette etude consistait a effectuer uneanalyse approfondie de 75 rapports denecropsie de bovins chez lesquels onavait diagnostique une impaction de lacaillette, au departement de patholo-

gie du College de Medecine veterinairede l'Ouest. D'apres ces rapports, 20%des cas s'accompagnaient de lesions dereticulo-peritonite traumatique, tan-dis que 60% semblaient resulter d'unealimentation trop riche en fibre; ledernier 20% n'appartenait A ni l'un nil'autre de ces deux varietes. Danspresque 50% des cas, le rapport men-tionnait une dechirure ou des ulceresde la caillette, ainsi que de la necrosede la paroi du rumen, du feuillet ou dela caillette; il ne fit toutefois jamaisallusion a une stenose pylorique. Lacondition sevissait surtout en hiver etelle accompagnait l'alimentiton a lapaille. Les animaux a boeuf souf-fraient de la forme alimentaire de lacondition, dans la proportion de 60%,tandis que la plupart des bovins laiti-ers, auxquels on donne ordinairementdes aliments de meilleure qualite,presentaient la forme associee a lar'ticulo-peritonite traumatique etapparement acceleree par des alimentssecs et fibreux. La condition ne semblapas affecter les vaches en gestationavancee plus que les autres. Trente-cinq des bovins soumis pour necropsiearriverent vivants et on porta uneattention particuliere aux signes cli-niques susceptibles d'aider a reconnai-tre l'une ou l'autre des deux principalesmanifestations de la condition. Ceuxdont l'impaction de la caillette accom-pagnait la reticulo-p&ritonite trauma-tique furent malades plus longtempsque les sujets chez qui elle resultait del'alimentation; ils constituaient aussides cas isoles et affichaient une eleva-tion du taux de leurs proteines seriquesqui se revela significative, du point devue statistique.

I N T R O D U C T IO N

Abomasal impaction is an importantproblem of cattle wherever straw or

similar poor quality fibrous feed con-stitutes a large portion of the winterdiet. The disease has been described indairy cows associated with adhesionsor abscesses of the reticulum (1) orabomasal adhesions (2). One reportdescribes five cases in dairy cows inwhich peritoneal adhesions were notfound at postmortem (3). Vagus indi-gestion has been investigated in Eng-land, related to reticulitis, andincluded abomasal impaction (4).Although the dietary form is well rec-ognized (5) there are few publishedreports of the condition. An outbreakof sand impaction of the abomasuminvolving beef cattle has been reported(6). This description of a series of casesincludes both beef and dairy cattle.

MATERIALS AND METHODS

The cattle in this study originated fromfarms in the Saskatoon area. An exam-ination was made of necropsy reportsfiled in the Pathology Department ofthe Western College of VeterinaryMedicine (WCVM) for cattle exam-ined from April 1975 to March 1982,in which abomasal impaction waslisted as a pathological diagnosis. Thisreport does not include cases whichwere listed simply as dilatation of theabomasum without impaction, orcases of omasal or ruminal impactionwithout abomasal involvement.

Seventy-five necropsy reports wereexamined. It was possible to divide theimpactions into three groups - thosewhich were associated with traumaticreticuloperitonitis (TRP), those whichwere related primarily to the diet, and"other" impactions.Animals which had significant

fibrous adhesions and suppurating fis-tulous tracks or abscessation betweenthe reticulum and the omasum werelisted as having TRP as a major asso-

Can Vet J 1983; 24: 375-380.

Present address of Dr. Ashcroft: Box 55, Trochu, Alberta TOM 2CO.This work was done while the author was Practitioner-on-Sabbatical at the Western College of Veterinary Medicine, and in receipt of a grant from theAlberta Department of Agriculture.

375

ciated finding. Animals in which theonly abnormalities found were thoseresulting from an abomasum impactedwith dry fibrous feed were recorded asdietary impactions. Some cattle hadabomasal impaction with various dif-ferent associated features. These werelisted as "other" impactions.

Details of postmortem findings,time of year, environmental tempera-ture, breed, age, sex, pregnancy statusand diet were examined, if these wererecorded.

Thirty-five of the cattle necropsiedhad originally been presented alive atthe clinic, either by the owner orreferred from veterinarians. The his-tory was taken and they were exam-ined by staff.

Twenty-nine of these cattle wereeventually classified as dietary or TRPrelated on the basis of the necropsyreport, and the clinical features andlaboratory findings were examinedfrom the medical records file.An attempt was made to determine

the features which may aid in futurediagnosis.

RESU LTS

Necropsy FindingsIn the majority of the 75 cattle,

impaction of the abomasum was listedas the most important feature. Theabomasum was described as beingdilated to several times its normalvolume, and impacted, distended, orpacked with coarse or fine, dry,fibrous roughage or straw. This des-cription applied equally whether theetiology was thought to be dietary,TRP, or other. Five cattle were foundto have very small quantities of grainpresent in the abomasum, with onehaving abundant grain.

In 20 animals, there was a tear in theabomasum, which had occurredbefore death. The tear was often lin-ear, 8-30 cm long and in various posi-tions. Usually it was near the omaso-abomasal orifice, but occasionally itwas central or near the pylorus. Thetears sometimes had irregular edgeswhich were hemorrhagic or edemat-ous, and resulted in the release ofingesta and an acute diffuse peritoni-tis. Three of those tears were fromTRP related impactions and 15 weredietary.

In ten animals, ulcers were presentin the abomasum. Eight of the ulcershad perforated resulting in local peri-tonitis (one) or diffuse peritonitis(seven). Two nonperforating ulcerswere described as chronic.

Five animals had perforations asso-ciated with areas of necrosis of theabomasum. Animal #26 had an area 10cm in diameter in the greater curvatureof the abomasum which was necroticand perforated, and a similar largearea of necrosis was present in the leftventral wall of the omasum. The dietwas thought to be responsible in eachinstance. The extreme pressure andsolid consistency of the abomasal con-tents resulted in ischemia, followed bynecrosis, perforation and peritonitis.The omasum was usually filled and

impacted with dry fibrous feed similarto that found in the abomasum, butless severely so. The size of the oma-sum was estimated at two to eighttimes normal. One animal had a 10 cmantemortem rupture or tear in the dor-sal omasal wall.

In 28 of 44 reports in which therumen was described, there was enlar-gement, with moderate to severe dis-tension. Two were said to be of normalsize. One animal had a large necroticarea in the rumen thought to be due topressure and venous occlusion. Therumen contents were often very fluid,although a few were more normal inconsistency, and occasionally dry con-tents were described. Some grain wasmentioned as being present in therumen of four cattle.The small intestine was either com-

pletely empty or contained a smallamount of fluid.Many of the cattle with abomasal

impaction had important associatednecropsy findings which sometimesmay have been etiologically signifi-cant. These included pleuritis, perito-nitis, periodontitis, actinomycosis andsand in the abomasum.

EpidemiologyDuring the five month period from

June through October in the sevenyears under study, only seven impac-tions were seen Table 1. One of thesewas associated with diet and three withTRP.

Figure I shows all impactions plot-

TABLE IMONITHLY DISTRIBUTION OF A BOMASAL

IMPACTIONS iN BOVINES N ECROI'SIED Al THEPAT HOLOGY DEPARTMENT, WCVM, 1975-82

Dietary TRP Others TOTAL

Jan 7 1 1 9Feb 8 2 4 14Mar 5 3 - 8Apr 9 3 1 13May 3 1 2 6June 1 1 3July - - IAug - - - -

Sept - - - -

Oct - 1 2 3Nov 5 - 3 8Dec 7 3 - 10Total 45 16 14 75

ted against the mean monthly temper-ature for the Saskatoon area over theseven years of study..' impactions werenot recorded during the coldest Feb-ruary in the series (1979) whilst threewere recorded during the warmestFebruary (1977). On the other hand,impactions were not recorded duringthe warmest November (1981) but byChristmas, the temperature wasrapidly falling and the following Janu-ary was over 4°C colder than any ofthe others. One impaction occurred inthat month, but five followed inFebruary.The main finding from the breed

incidence (Table 11) was that the dairybreeds were less affected with dietaryimpaction than the beef breeds, buthad a higher percentage of TRPrelated impactions. In the beef ani-mals, there was a high proportion ofcattle from the recently introducedbreeds.The disease was diagnosed in 61

females and 14 males. Where age wasindicated, the range was from one toten years in the females, and from sixweeks up to four years in the males(Figure 2). The males included two 18month old steers.The details of the state of pregnancy

of the animals are given in Table 111.Of the 44 animals in which the state ofpregnancy was recorded, 32 werepregnant.

In this retrospective study, a physi-cal condition score was not used, butin the 56 impactions where physicalcondition was recorded, there wasalmost as many dietary associated

'From Atmospheric Environment Service, Environment Canada, Saskatoon, Saskatchewan.

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p~~~~~~~~~~~~~~~~~~~~~~0

FIGURE 1. Monthly occurrence of 75 cattle with abomasal impactions necropsied at WCVM andmean monthly temperature, Saskatoon, April 1975-March 1982.

cases in good condition, whereas allcases ofTR P impactions were listed aspoor to average condition only (TableIV).

Of the 40 animals with dietaryimpaction in which the diet was de-scribed, cereal straw was the main feedcomponent in 32. In 14 of the 32, the

TABLE 11BREED DISIRIBUTIiON OF CATTLE Wil1-H ABOMASAL IMI"ACTIONS NECROPSIED AT- WCVM, 1975-82

Dairy Beef M ixed

Holstein 4 Hereford X 25 Jersey ISimmental 8 S. Horn I

Dietary Charolais 4Angus 2

4 39 2Holstein 3 Hereford X 4 Holstein X IAyrshire I Angus I

TRP B. Swiss I Charolais IJersey I Chianina I

Maine Anjou ISimmental I

6 9 1Holstein 4 Hereford X 6

Others Charolais 2Simmental 2

4 10 0Total 14 58 3

TABLE IllSTAT-E OF PREGNANCY OF CATTLE WITH ABOMASAL IMPACTION NECROPSIED AT WCVM, 1975-82

Females Dietary TRP Others Total

Pregnant(5 months - term) 18 9 5 32

Not Pregnant(calved at least2 weeks) 7 3 2 12

Not Stated 18Females Total 62

TABLE IVBODY CONDITION OF CATTLE WITH ABOMASAL IMPAC1ION NECROPSIED AT' WCVM 1975-82

Dietary TRP Others Total

Poor 12 6 4 22Average 12 3 6 21Good 10 - 3 13

Total 56

straw was chopped or cut from 1-3 cmlong for handling and mixing pur-poses. In two cases, from an outbreakon one farm, a diet of oat/ barley strawwas fed chopped for two weeks priorto impaction. In 14 reports, hay wassaid to be included with straw, but norecord of the amount was available.Sometimes the hay was fed on alter-nate days, and in only two cases was itthe main roughage component, anddescribed as poor quality native grasshay (slough hay and "prairie wool").Green oat hay was fed in eight cases, infive of these along with straw. Grainwas reported as being fed to 24 ani-mals, but in seven of these cases, thenecropsy report noted that no grain atall, or only a few kernels were found inthe stomachs. The amount of grain fedwas mentioned in four cases as 2 kg perhead of barley or oats. Cases 51 and 52were from a farm in which green oathay and wheat straw were fed, and thecattle had been without water for 12-24 hours a few days previously.A diet which included straw in the

roughage portion was fed to six of 12cattle with TRP related impactions.Average to good quality hay andgrain, but no straw, were reported tohave been fed to six cattle. Varyingamounts of grain were fed in ten of 12TRP related cases, one kg was men-tioned in two cases.

CLINICAL DATA FROM29 CASES SEEN ALIVE

HistoryThe animals subsequently assessed

as having TRP associated impactionhad been sick from four to 20 daysprior to death, commonly around aweek to ten days, whereas the dietaryimpactions were recorded as being sickfrom two to five days.

All animals were anorexic and mostwould not drink. Icicles were some-times reported around the mouth.Vomiting was seen in one. Ownersusually said the animal looked bloatedor full, and was not passing feces,although two cases were said to havediarrhea.Ten of the 19 dietary associated

impactions were from farms on whichone or two other similar deaths hadrecently occurred, whereas all of thoselisted as TRP were single incidentcases.

377

111 F fllTfl4 S 6

YEARS OF AGEE0 TRPM3 OTHER

DIETAR'

4 YEARS OF AGEFIGURE 2. Age and sex incidence of 70 cases of abomasal impaction of cattle necropsie1975-1982.

Clinical FeaturesImportant findings are summarized

in Table V. The body temperature waseither normal or low, none was higherthan 39.4°C and eight were less than380 C. The pulse was usually rapid andvaried from 60 to 120 per minute. Therespiration rate was unremarkable,and varied from 12 to 60, with a meanof 28 respirations per minute.

Clinical ChemistryValues were available from 27 cases

of abomasal impactions (Table VI).Abnormalities included an elevatedtotal protein and uremia. There washypochloraemia which was sometimes

severe, but serum sodium wThe hemogram showed

ring in 21 of43 cases of"vagus indiges-tion" which were examined postmor-tem. Impaction was not mentioned assuch in their postmortem examina-tion, although it was stated in the clini-cal aspects and discussion that itoccurred. The consistency of theabomasal contents was described as"thick porridge". In the series reportedhere, the abomasal contents weremuch more solid. There may be differ-

17 m ences in diet for dairy animals betweenCheshire and western Canada whichmay account for this. The aboveauthors did not mention tears or ulcersof the abomasum which were seen inthis series.Abomasal tears have not been pre-

viously described. They were probablycaused by excessively fibrous and dryabomasal contents in concert with theextreme distension. Perforated ulcers

d at WCVM, have been mentioned as a cause of"fvagus indigestion" leading to a localperitonitis, and hence abomasal

as normal. impaction (7,8). The cases here exam-I a mild ined featured a more diffuse peritoni-

neutrophilia.The only statistically significant

(P 0.02) difference between cattle withdietary related impaction and cattlewith TRP related impaction was intotal serum protein. This was higher inimpactions associated with TRP-9.77 ± 1.6 g/ L (mean ± standard devi-ation), whereas the mean for dietaryimpactions was 8.45 ± 1.12 g/ L.

D I S C U S S IO N

NecropsyNeal and Edwards (4) described

gross abomasal distension as occur-

TABLE VCLINICAL FEATURES OF ABOMASAL I MPACITION (DIETARY AND TRP) OF CATTLE SEEN ALIVE AND

LATER N ECROPSIED AT WCVM, 1975-82

Recorded Frequency Out of 29 Cases Signs- Rumen movements weak or absent- Dehydrated- Abdominal distension- Scant or mucous-coated feces- Dry crusted muzzle or seropurulent nasal discharge- Depressed- External palpation of hard mass

behind lower right rib cage- Fluid filled rumen- Recumbent- Expiratory grunt or groan- Weak or staggery- Evidence of some diarrhea- Bloody stools- Bright and alert- Positive grunt test

tis, and in no instance was the impac-tion described as secondary to anulcer, rather the reverse. Extremepressure and solid contents were theprobable cause of the necrosis andassociated perforations of the aboma-sum and other stomachs.One feature worthy of mention is

the failure to find any suggestion ofpyloric stenosis. Other writers haveexpressed doubt that this is a cause ofabomasal impaction and this studywould tend to support them.The distinct seasonal incidence of all

the abomasal impactions is illustratedin Table 11. Even TRP impaction wasfor the most part a winter disease,which would indicate that the finalsyndrome is actually a result of twocombined factors - too much fibrousfeed and TRP. The temperature fallsrapidly at the end of October in theprairie provinces of Canada, and bythe beginning of November supple-mentary feeding commences andimpactions soon occur. When temper-atures fall, reticular contractions risecausing an increase in the rate of foodpassage with consequent reduced fibredigestibility. The increased feed intakein cold weather while occurring at theexpense of lowered fibre digestion,may increase the total supply of ami-noacids and other essential nutrients,

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TABLE VILABORATORY VALUES IN CATTLE WITH ABOMASAL IMPACTION EXAMINED AND LATER NECROPSIED ATWCVM, 1975-82

Cows with Abomasal ImpactionsStandard No. of Normal Cows

Item Units Mean Deviation Impactions Range Interpretation

Hemogram- Neutrophils x109/ L 4.80 3.14 26 0.6_4a Increased- Band neutro x109/L 0.300 0.357 26 0-0.12a Increased- Lymphocytes x 109/ L 2.33 1.199 26 2.5-7.5 a Decreased- Packed cell volume L/L 0.381 0.090 27 0.24-0.46a

Plasma Proteins- Total Proteins g/ L 86.6 14.2 27 57-81 b Increased- Fibrinogen g/ L 6.81 3.66 27 3-7 a

Serum Chemistry- Calcium mMol/L 2.04 0.35 20 2-2.62b- Chloride mMol/L 81.04 18.91 25 95_11ob- Creatinine mMol/L 506 470 12 90-240b Increased- Phosphorus mMol/L 2.49 1.40 18 1.30-2.25 b- Potassium mMol/L 3.84 1.30 25 3.9-5.8b- Sodium mMol/L 137.9 9.9 25 132-152b- Urea Nitrogen mMol/L 26.2 19.1 12 2-9.5b Increased

aNormal values from Veterinary Hematology by O.W. Schalm, N.C. Jain and E.J. Carroll, third edition, Lea & Febiger, Philadelphia, 1975.bNormal values of Western College of Veterinary Medicine.

and therefore in general be beneficialfor survival (9).

During the winter of 1971-72, John-son in Saskatoon fed cows a diet ofrapeseed and straw, and two abomasalimpactions occurred in a pen of tenanimals. He believed that the impac-tions were related to the onset of aperiod of extremely cold weather (10).On the other hand, Mathison, whoalso produced impactions, found noapparent relationship between theappearance of the impactions andenvironmental conditions (11,12). Inthe series reported here, a clear rela-tionship between the mean monthlytemperature and the number of impac-tions was not demonstrated. Theapparent seasonality of abomasalimpactions may be better related to thefeeding of poor quality dry fibrousfeed during an average winter ratherthan monthly temperature fluctua-tions.The breed incidence shows that if a

beef cow is presented with impaction,there is a three to one chance that theproblem is primarily related to thediet, whereas if the subject is a dairycow, it is more probable that the etiol-ogy involves TRP. The age and sexdistribution of the impacted animalsparallels the age and sex of cattle in theaverage breeding herd.

It has been suggested that heavilypregnant cows are more susceptible toabomasal impaction (5). As can beseen from Table 1, the highest inci-

dence of dietary related impaction is inwinter, when most beefcows should bepregnant, but over one-third were notpregnant. Four had calved from two toten weeks previously and one eachwere seen not to be pregnant inDecember and May. Moreover, themonthly figures did not show a steadyincrease as winter advanced and ute-rine enlargement continued in preg-nant cows. Furthermore, fourteen ofthe cases reported here occurred inmales. In the females, the proportionof impactions due to all causes seen innonpregnant as compared to pregnantanimals was about equivalent to theproportion of nonpregnant animals inthe cattle population at large. There-fore, it would appear that pregnancyplays little part in the pathogenesis ofthis condition.

In only one case was there recordeda possibility of a problem with waterintake.

In the cases described in this series itwas often not possible to obtain detailsof feeding regimes but it was evidentthat the amount of grain fed was lowand that in about half of the straw-fedcases, the roughage was chopped.A diet of 86% chopped barley straw

and 13% barley was fed to cows and noimpactions were reported ( 13). Abom-asal impactions occurred in cows fedon rapeseed and 90% long straw (10).Four impactions were produced incows fed on a diet containing 95-100%of both long and chopped barley straw

(11). In the latter experiment it wasdifficult to assess whether choppingresulted in a true greater intake of thestraw, since wastage occurred. Aninteresting observation was that thecows fed a 15% grain diet did notdevelop impactions but actually atemore straw than cows on diets contain-ing a greater proportion of straw inwhich some animals died.From the above, it can be concluded

that impaction occurred when straw,either long or chopped, was fed to cat-tle, and that for the prevention at least15% of the diet should be in concen-trate form.As a preventative measure, molasses

may be a useful but expensive foodadditive. Some promise is being shownby treating straw and chaff with anhy-drous ammonia, a process that canresult in a sizeable increase in thenutritive value of poor roughages (15).

Clinical FindingsClinical features of abomasal

impaction are shown in Table V. Clin-ical chemistry is of limited help in con-tinuing the diagnosis of abomasalimpaction. Many cows were dehy-drated on physical examination andthis accounts for elevated packed cellvolume and total serum protein. Theuremia was also probably secondaryto dehydration since there were nosigns of renal lesions at necropsy.Hypochloraemia with normal serumsodium concentrations suggests a fail-

379

ure of ingesta transport from aboma-sum to small intestine similar find-ings occur in torsion of the abomasum(15). Differences in total proteinbetween dietary and TRP associatedimpactions probably reflect the stimu-lus of chronic inflammation in cowswith TRP which tend to elevate totalprotein.

ACKNOWLEDGMENTSThe author wishes to thank the follow-ing for their help in the preparation ofthis paper: Drs. C. Doige, F.M. Bris-tol, S. McGillivray, J. M. Naylor andO.M. Radostits of the Western Col-lege of Veterinary Medicine and Dr.J.M. Howell of the School of Veteri-nary Studies, M urdoch University,Western Australia.

REFERENCESI. POPE DC. Abomasal impaction of adult cat-

tle. Vet Rec 1961; 73: 1174-1177.

2. JONES RS, PIRIE HM. Abomasal impaction.Vet Rec 1962; 74: 582-583.

3. MERRI-I1I' AB, BOUCHER WB. Surgical treat-ment of abomasal impaction in the cow. JAm Vet Med Assoc 1967; 150: 1115-1120.

4. NEAL PA, EDWARDS GB. "Vagus indigestion"in cattle. Vet Rec 168; 82: 396402.

5. BLOOD DC, HENDERSON JA, RADOSITIS OM.

Veterinary medicine. 5th edition. London:Bailliere Tindall, 1979: 194-196.

6. HUNI-ER R. Sand impaction in a herd of beefcattle. J Am Vet Med Assoc 1975; 166:1179.

7. REBHUN wc. Vagus indigestion in cattle. JAm Vet Med Assoc 1980; 176: 506-5 10.

8. WHITLOCK RH. Bovine stomach diseases. In:Anderson NV, ed. Veterinary gastroente-rology. Philadelphia: Lea and Febiger,1980: 410418.

9. WESTRA R, CHRISIOPHERSON RJ. Effects ofcold on digestibility, retention time ofdigesta, reticulum motility and thyroidhormones in sheep. Can J Anim Sci 1976;56: 699-708.

10. JOHNSON MC. Gestation and lactation per-formance of thin beef cows fed oat strawbased on rations under low temperature

conditions. MSc Thesis. Saskatoon, Sas-katchewan: U niversity of Saskatchewan,1972.

11. MAI HISON Gw. Further studies with strawdiets for wintering beef cows. 55th Annualfeeders day report. Department of AnimalScience Ageiculture Bulletin, Faculty ofExtension, Edmonton, University ofAlberta, 1976: 9-1 1.

12. MAIHISON GW. HARDIN RT. BECK BE. Sup-plemental protein, magnesium and sele-nium plus vitamin E for beef cows fed strawdiets in winter. Can J Anim Sci 1981; 61:375-392.

13. WEISENBBURGER RD, MA[I'HISON GW. Proteinrequirements of beef cows fed pelleted,ground or chopped barley straw in the win-ter. Can J Anim Sci 1977; 57: 719-725.

14. SMIT H DF'. Right-sided torsion of the abom-asum in dairy cows: Classification of sev-enty and evaluation of outcome. J Am VetMed Assoc 1978; 173: 108- 111.

15. KERNAN J, KNIPFELJ.Ammoniation of strawand chaff. Publication No. 453. Division ofExtension and Community Relations, Uni-versity of Saskatchewan, Saskatoon. June1981.

ABSTRACT

CARRILLO BJ, POPISCHIL A,DAHME E. Pathology of a bovineviral necrotizing encephalitis inArgentina. Zentralblatt fur Veteri-narmedizin, B 1983; 30: 161-168.(Centro Invest. Ciencias Vet.,INTA, 1712 Castelar, Argentina).

Pathological findings in specimensfrom 8 to 18 months old cattle in fiveoutbreaks of bovine encephalitis occur-ring during 1980 and 1981 in variousareas of Buenos Aires Province are de-scribed. Microscopical examinationshowed a necrotizing encephalitisaccompanied by a non-purulent lepto-meningitis. Intranuclear inclusionbodies were observed in neurons andglial cells. Electron microscopy showedviral particles with herpes morphology.The association of morphologicalchanges in the CNS and IBR infectionis discussed.

Reprinted from the "VeterinaryBulletin': Volume 53, No. 8, August1983.

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