UNIVERSITY OF CALIFORNIA AGRICULTURAL EXPERIMENT STATION 
 COLLEGE OF AGRICULTURE E J - wickson. director 
 
 BERKELEY 
 
 CIRCULAR No. 68 
 
 August, 1911 
 
 THE PREVENTION OF HOG CHOLERA 
 
 Introductory Note. — The value of the Dorset-Niles anti-hog cholera serum 
 in preventing hog cholera, has been demonstrated beyond question. Over 
 twenty state governments have taken steps to protect their hog-raising indus- 
 tries by appropriating funds to establish plants for the manufacture of the 
 serum. California has appropriated $16,000 for this purpose, the plant to be 
 established at the California Agricultural Experiment Station, Berkeley. The 
 serum will be sold by the Regents of the University of California at actual 
 cost of production, and, in cases of outbreaks of hog cholera, will be furnished 
 free to hog raisers in amounts not exceeding five hundred cubic centimeters 
 (about one pint, enough to immunize twenty pigs averaging one hundred pounds). 
 Hypodermic syringes and other necessary equipment in using the serum can also 
 be secured from the University. 
 
 In outbreaks of hog cholera, the best way to stop further losses and stamp 
 out the disease is by the use of anti-hog cholera serum. All hogs on the infected 
 premises, exposed to contagion, but not visibly ill, should be immunized with 
 the serum; those not exposed may be treated by the simultaneous method, using 
 both serum and vaccine. 
 
 One of the most successful uses of the serum is to immunize valuable pure- 
 bred hogs before shipment. 
 
 C. M. Haring, Veterinarian. 
 
 GENERAL PREVENTIVE MEASURES. 
 
 All that is necessary to prevent hog cholera is to keep the germ of 
 the disease away from the herd. It has been shown that in the vast 
 majority of cases this germ is transported mechanically, in the bodies 
 of sick hogs and on the feet of men, or animals, including birds. It 
 thus follows that the chances of an outbreak of hog cholera will be 
 greatly lessened, if not completely avoided, if a herd is protected from 
 these carriers of infection. The enforcement of a complete quarantine 
 is, however, not practicable under average farm conditions, and the 
 best that can be hoped for is the lessening of the opportunity for 
 infection by placing the herd on a part of the farm that will be the 
 least accessible to men or animals from other farms. Hog lots should 
 never be located near public roads if this can be avoided. All newly 
 purchased stock should be kept separate from the main herd for at 
 least thirty days. 
 
 In addition to protecting the herd by methods of quarantine, 
 careful attention should be given to the general health of the herd. 
 The hogs should be provided with clean, dry, sleeping places, and the 
 lots and feeding troughs should be kept clean. It is well, occasionally, 
 to scatter slaked lime about the lots and to wash and disinfect the 
 
troughs. Probably the best disinfectant for this purpose is the com- 
 pound solution of cresol (U. S. P.), which can be prepared at any drug 
 store. One part of this should be mixed with thirty parts of water 
 and the troughs scrubbed with it. The disinfectant is then washed out 
 of the troughs with water. 
 
 After an outbreak of hog cholera the yards and pens should be 
 thoroughly cleaned, all dead hogs should be burned or buried deep 
 with quicklime, the litter should be collected and burned, and lime 
 scattered freely over the ground. The sheds and hog houses should 
 be washed thoroughly with the solution of cresol as above described 
 before new stock is brought on the place. Feeding troughs that have 
 been used by sick pigs should be burned if made of wood, but if this is 
 not practicable, they should be scrubbed clean and thoroughly soaked 
 with cresol solution, the latter being washed out before the troiighs 
 are used again. 
 
 It is possible to start an outbreak of hog cholera by bringing 
 into the herd hogs that have had the disease and have apparently 
 recovered. We have no definite information concerning the length 
 of time that such hogs may be able to communicate the disease to 
 others, but for safety's sake two or three months should be allowed 
 to elapse after complete recovery before placing such an animal with 
 susceptible pigs, and then only after washing or dipping in a dis- 
 infectant solution (compound solution of cresol, 1 to 100). 
 
 In Circular No. 3 of the California Agricultural Experiment 
 
 Station is given the following formula for a medicine which was used 
 
 many years ago as a preventive and cure for hog cholera : 
 
 Pounds. 
 
 Wood charcoal 1 
 
 Sulphur i 
 
 Sodium chloride 2 
 
 Sodium bicarbonate 2 
 
 Sodium hyposulphite 2 
 
 Sodium sulphate 1 
 
 Antimony sulphid (black antimony) 1 
 
 Experience has shown, however, that this medicine is not to be 
 regarded as a cure or preventive in the true sense of the words, but 
 it is, nevertheless, a very good condition powder. This powder is 
 mixed with the feed in the proportion of a large tablespoonful to 
 each two hundred pounds' weight of hogs to be treated, and should 
 not be given oftener than once a day. This medicine cannot be relied 
 upon to prevent the occurrence of disease, except in so far as it 
 improves the general health of the hogs. Therefore, even though this 
 remedy be used, strict attention must be given to quarantine and 
 
sanitary measures if the disease is to be warded off when in the 
 neighborhood. 
 
 PKEVENTION BY INOCULATION. 
 
 Careful and persistent attention to preventive measures, such as 
 quarantine, disinfection, proper feeding, etc., on the part of farmers 
 generally, would no doubt result in a material reduction in the yearly 
 losses from hog cholera, and the importance of observing these pre- 
 cautions cannot be overestimated. However, as it is regarded as 
 impracticable to enforce a general and completely effective quarantine, 
 the Bureau of Animal Industry has endeavored for a number of years 
 to find a medicine or serum which could be used for preventing hog 
 cholera or for curing hogs sick of that disease. It is a well-known 
 fact that hogs which have recovered from hog cholera are thereafter 
 immune from the disease. The experiments of the Bureau of Animal 
 Industry resulted in the discovery that when such immunes are 
 injected with the blood from a sick hog the immune is not made sick, 
 but as a result of this injection its blood acquires the power to protect 
 other hogs from hog cholera. The details of the early experiments 
 which served to establish this fact are given in Bureau of Animal 
 Industry Bulletin 102.* Since that bulletin was issued a great deal 
 of additional work has been carried out, and it has been established 
 beyond question that the early observations were correct, and that it 
 is entirely possible to protect hogs if they are treated with serum 
 from a properly treated immune hog. 
 
 The method of producing this serum is briefly as follows : 
 
 A vigorous immune hog — that is, one which has recovered from an 
 attack of hog cholera or one which has been exposed to the disease 
 without contracting it — is treated with a large quantity of blood from a 
 hog sick of hog cholera. After a week or two blood is drawn from the 
 immune by cutting off the end of the tail. After standing, the blood 
 clot is removed and the serum or fluid portion of the blood is mixed 
 with a weak solution of carbolic acid and filled into sterilized bottles. 
 We have in this fluid portion of the immune 's blood the serum which 
 will protect hogs from hog cholera. This serum is used in either one 
 of two ways, namely (1), the serum inoculation, and (2), the simul- 
 taneous inoculation. These two methods of treatment are carried 
 out as follows : 
 
 Serum Inoculation. — The hogs which are to be protected are 
 injected on the inside of the hind leg with a suitable dose of the serum 
 alone. This injection will serve to protect hogs from hog cholera for 
 
 * Can be obtained only from Superintendent of Documents, Government 
 Printing Office, Washington, D. C. Price, 15 cents. 
 
4 
 
 several weeks and, in some cases, for a longer time. But if the hog 
 is not exposed to hog cholera within a few weeks after this treatment, 
 the immunity which is conferred by the serum will gradually lessen 
 in degree and the hog may again become susceptible. If, however, 
 the hog is exposed to hog cholera within a short time after the injec- 
 tion of the serum, the immunity becomes, so far as experiments have 
 shown, of permanent and lifelong duration. 
 
 From what has been said, it will be seen that the injection of the 
 serum alone is especially to be recommended in cases where there is 
 immediate danger of exposure, especially when valuable hogs are 
 carried to fairs, and in herds where the disease has already broken out 
 but has not progressed very far. In herds of this character all of the 
 well animals may be treated, and even in the case of slightly sick 
 animals much good may be accomplished by the serum injection. 
 
 Simultaneous Inoculation. — In this form of vaccination the same 
 serum is used as is employed when the serum alone is used, but in 
 addition to the serum there is injected on the opposite side of the body, 
 in the same manner as the serum, a very small amount of blood taken 
 from a hog sick of hog cholera. This simultaneous injection of serum 
 and virulent blood confers upon the injected pig a permanent and 
 lasting immunity, and is therefore to be recommended in cases of well 
 herds which may not be exposed for some months after the treatment. 
 
 Safety of the Methods. — Properly prepared serum when used 
 alone, without the employment of blood from a sick hog, is entirely 
 harmless and incapable of giving rise to an attack of hog cholera. 
 Nor does this injection interfere in any way with the growth of the 
 treated hogs. 
 
 The simultaneous inoculation, involving as it does the use of a 
 disease-producing virus, requires much more care when employed than 
 does the serum-alone inoculation, for, if through careless prepara- 
 tion or from any other cause the serum should be weaker than is 
 required, injury to the vaccinated hog might result. This danger, 
 which is extremely slight when carefully tested serum is used, is met 
 with in practically all processes which are now employed for produc- 
 ing a permanent and lasting protection against infectious diseases, and 
 although it would be very desirable to eliminate even this slight 
 element of danger, we can hardly expect to do this without at the 
 same time sacrificing to some extent the high degree of immunity and 
 the prolonged protection which follows the simultaneous method in its 
 present form. 
 
 Practically, in deciding which method to use one must be governed 
 
largely by the length of immunity which is required. If this is needed 
 for only a few weeks, or if the treatment can be repeated at short 
 intervals, as in the case of exceptionally valuable pure-bred hogs, 
 where the increased cost would not be objected to, the serum alone 
 may be used. In other cases the simultaneous method is recommended. 
 In either process of vaccination it is considered highly desirable for 
 the treatment to be applied by competent veterinarians who have had 
 special training in this class of work, and only such skilled men should 
 employ the simultaneous process. For the present, virulent blood for 
 the simultaneous method will not be furnished for use unless the work 
 is to be done by a qualified veterinarian. After treatment by the 
 simultaneous method the herd should be kept under observation for 
 ten days or two weeks, and if any of the inoculated hogs show serious 
 symptoms of disease the herd should be immediately re-treated with 
 the serum alone. When properly performed, the simultaneous inocu- 
 lation does not seem to injure the hog or to interfere with its growth 
 in any way, and if the precautions indicated above are taken, it is 
 regarded as safe enough for practical use. 
 
 The serum is carefully tested before it is seat out. — All serum dis- 
 tributed by the California station will be carefully tested for potency 
 before it is sent out. The standard of potency is that adopted by the 
 Bureau of Animal Industry, United States Department of Agriculture. 
 
 Practical Tests. — Field tests made by the United States Bureau of 
 Animal Industry in an extended manner on farms and at stockyards 
 under practical conditions have proven beyond question the value of 
 the Dorset-Niles serum. In these practical experiments a number of 
 hogs were generally left untreated, so that we might be sure that the 
 herd actually had hog cholera and also be able to determine better 
 the action of the serum. In these tests approximately two thousand 
 hogs, located on forty-seven separate farms, were treated. Some of 
 the herds treated were apparently perfectly well at the time, but were 
 in the neighborhood where hog cholera was prevalent. In other cases 
 the disease was just beginning, as indicated by the sickness of one or 
 two animals. In others the disease had progressed to a considerable 
 extent, a number of the animals in the herd being sick at the time of 
 treatment; and in still another class of herds the hogs had been 
 exposed to disease by contact with sick animals, but had not developed 
 symptoms of illness at the time of treatment. The tests were carried 
 out under farm conditions, and aside from the serum injections no 
 attempt was made to save the treated hogs. Upon summarizing the 
 results at the end of the season it was found that more than 85 per cent. 
 
of the treated hogs had been saved in the herds that were sick at the 
 time of treatment, while of the hogs left untreated in the same herds 
 only 25 per cent, survived; more than 95 per cent, of the treated 
 animals were saved in the herds which had been exposed at the time 
 of treatment, while of the untreated hogs in the same herd only 11 
 per cent, survived ; of the treated hogs in the herds that did not become 
 exposed until after the treatment none were lost, whereas only 35 per 
 cent, of the untreated hogs in the same herds survived. 
 
 While in practice the serum may not always give as good results 
 as these, there can be no doubt that if used properly and in the early 
 period of an outbreak of hog cholera it will effect a very large saving. 
 
 Results of the use of the Dorset-Nile serum in other states. — During 
 the past two years the success of the Dorset-Niles serum in saving hogs 
 from cholera has, in several important hog-raising states, confirmed 
 the experiments of the United States Bureau of Animal Industry just 
 mentioned. In Kansas the mortality from hog cholera has been 
 reduced from 80 per cent, to 10 per cent, in infected herds, when 
 serum has been administered at the beginning of the outbreak. Equal 
 results have been obtained in many of the other states. The value of 
 this treatment is evident when the cost of vaccination and the loss 
 without treatment, are considered. The 10 per cent, loss can be 
 accounted for in part by the fact that some hogs are infected, without 
 yet showing visible symptoms at the time of vaccination. The serum 
 is only a preventive, not a cure. 
 
 HOG CHOLERA IN CALIFORNIA. 
 The losses from cholera in hogs in this state have been extensive. 
 This is evidenced by the report of the State Veterinarian for the two 
 years ending June 30, 1910. He says : 
 
 Numerous reports of deaths in hogs from cholera were received and investi- 
 gated by this office. In the following counties the losses from this disease were 
 quite extensive: San Luis Obispo, Fresno, Los Angeles, Mendocino, Kings, 
 Tehama, Santa Cruz, San Joaquin, Tulare, Santa Clara, Monterey, Merced, 
 Colusa, and Shasta. Hog cholera is, however, pretty well distributed throughout 
 the hog-raising sections of this state, and acts not only as a menace to hog 
 raising, but also prevents the natural development of this important industry. 
 California is particularly adapted for the raising of hogs. The large areas in 
 this state which have in the past few years been turned into dairies through the 
 development of irrigation, offer an excellent field for the production of pork. 
 The by-products from these dairies, as well as the class of feed that can be 
 grown under the system of irrigation, insures the production of pork at a 
 relatively low cost. To what extent hog raising can be reached in California 
 is only limited by the protection that can be afforded hog raisers against the 
 ravages from hog cholera. 
 
 At the present time we raise a very small part of the pork which is consumed 
 in this state. Nearly all of our pork is brought into California in refrigerator 
 cars in sweet pickle from the packing centers of the Middle West. For fresh 
 
pork many carloads of hogs are purchased by California packers in other states 
 and hauled out here for slaughter. Why this condition should exist in an 
 agricultural state like California, where every facility exists for hog raising. 
 sufficient to supply at least our own consumption of pork, is undoubtedly due, 
 in the opinion of the writer, to the fact that a hog breeder is afraid to take 
 chances with cholera decimating his herd. This opinion is shared by many 
 others in this state. The deaths from this disease are so rapid that under 
 present conditions in California it spreads rapidly from one animal to another 
 until in a very short time practically the entire herd is dead. 
 
 It appears from the above data, and from investigations made by 
 veterinarians of the California Agricultural Experiment Station that 
 losses have occurred in nearly every hog-raising district of the state. 
 
 Anti-hog Cholera Serum provided for California. — In response to 
 a demand by many interested in swine raising, the following bill was 
 prepared, and passed the State Legislature in 1911. Six thousand 
 dollars of the appropriation became available June 21, 1911, but to 
 expedite the work of establishing the serum plant, the Regents of the 
 University of California advanced three thousand dollars soon after 
 the Governor signed the bill, and the work of preparation was 
 prosecuted with all possible diligence. 
 
 An Act to provide for the preparation and distribution of serums or vaccines 
 for the prevention of the disease known as Cholera in Hogs in the State of 
 California, making an appropriation therefor and prescribing the duties of 
 the controller and treasurer in relation thereto. 
 
 The People of the State of California, represented in Senate and Assembly, do 
 
 enact as follows: 
 
 Section 1. The Regents of the University of California are hereby directed 
 to cause to be prosecuted with all possible diligence, through the Agricultural 
 Experiment Station, the preparation of serums or vaccines that will produce 
 immunity in hogs against the disease known as cholera. 
 
 Sec. 2. The Regents of the University of California are hereby further 
 authorized and directed to furnish such serums or vaccines in quantities not 
 exceeding five hundred cubic centimeters as soon as possible after this act 
 takes effect free of charge to any bona fide resident of the State of California 
 who is engaged in the raising of hogs, upon application by such bona fide 
 resident hog raiser. 
 
 Sec. 3. The Regents of the University of California are also hereby further 
 authorized and directed to furnish any bona fide resident of this state, who 
 is engaged in the raising of hogs, such serums or vaccines in quantities in 
 excess of five hundred cubic centimeters, upon the applicant paying therefor 
 the actual cost of production of such serums or vaccines. 
 
 Sec. 4. It is herewith provided that no serums or vaccines shall be furnished 
 free of charge to anyone unless the applicant shall have first furnished sufficient 
 evidence that the disease known as cholera exists among his hogs or among 
 the hogs in his immediate neighborhood, and in such case evidence shall be 
 furnished by said applicant that there is danger of the disease being com- 
 municated to the applicant's hogs. 
 
 Sec. 5. Any person who shall sell, give away, or misuse any of the serums 
 so furnished shall, upon conviction thereof be deemed guilty of a misdemeanor, 
 and be punished as in such cases provided by law. 
 
 Sec. 6. The Director of the Agricultural Experiment Station shall obtain 
 and establish such assistance, equipment, materials, appliances, apparatus, and 
 other necessary incidentals as may be necessary to the successful prosecution 
 of this work within the appropriation herein specified. 
 
Sec. 7. The sum of sixteen thousand ($16,000.00) dollars is hereby appro- 
 priated out of any money in the state treasury not otherwise appropriated, six 
 thousand ($6,000.00) dollars of which shall be available for the balance of the 
 sixty-second fiscal year and ten thousand ($10,000.00) dollars of which shall be 
 available during the sixty-third and sixty-fourth fiscal years for the use of 
 said Experiment Station to be expended by the Regents of the University of 
 California in carrying out the purposes of this act, and the State Controller is 
 hereby authorized and directed to draw his warrant for the same, and the State 
 Treasurer is hereby directed to pay such warrant. 
 
 Sec. 8. All money appropriated under this act, and all money received for 
 the sale of said serums or vaccines as provided for in section three of this act, 
 shall be paid to the Regents of the University of California, and shall be 
 expended under the direction of the Director of the Agricultural Experiment 
 Station of said University for the specific purposes herein named. 
 
 Cost of the Serum. — Owing to the short time that this experiment 
 station has been making serum, it is not possible at the present time to 
 estimate the average cost of production for the year. Every economy, 
 not detrimental to the production of a potent serum will be practiced, 
 and the price fixed at actual cost of production. For the time being, 
 the price has been fixed at 2y 2 cents per cubic centimeter, which 
 would make the cost of the dose for a hundred pound hog, 50 cents. 
 
 How to secure Anti-hog Cholera Serum from the University. — All 
 applications for serum should be made out on blanks furnished for 
 that purpose. These application blanks may be obtained by writing 
 to the Director of the Agricultural Experiment Station, Berkeley, 
 California, or to the State Veterinarian, Sacramento, California. 
 Copies have been sent to the County Live Stock Inspectors in the 
 various counties having such officials, and an effort has been made to 
 place application blanks in the hands of as many hog raisers and 
 veterinarians as possible. 
 
 In cases of emergency where no application blanks are available, 
 the following form may be filled out and sent by telegraph as a night 
 letter, or by mail as a special delivery letter : 
 
 Director of the Agricultural Experiment Station, 
 Berkeley, California. 
 
 Send hog serum C. O. D. to 
 
 (Insert name of express office here) 
 
 ^>r hogs, total weight 
 
 ( Number of hogs ) ( Total weight in pounds ) 
 
 Before using serum, I agree to fill out, sign, and mail to you 1 
 • plication blanks furnished with serum. I am a resident of Calif orn 
 
 (Signed) 
 
 (Signature of owner of hogs)