A snapshot of hog production health concerns from 895 production sites in USDA's Swine 2000 survey reveals breeding herd diseases and vaccination and antibiotic treatments.

The two most common swine health problems reported plaguing breeding herds were roundworms (at 40% of sites) and PRRS (porcine reproductive and respiratory syndrome) at about 21% of sites (Figure 1).

For large operations (500-plus breeding females), PRRS was by far the most common disease at 58% of sites, followed by roundworms (38%) and Mycoplasmal pneumonia (34%).

For medium-sized operations (250-499 breeding females), roundworms topped the list of concerns (54.7%), followed by PRRS (40%) and swine influenza virus, H1N1 (38%).

Nursing Pigs

The top three preweaning pig diseases reported in the survey were Escherichia coli, Streptococcus suis (meningitis, polyserositis, arthritis) and greasy pig disease (Staphylococcus hycius), as indicated by at least half the sites with 250 or more sows. PRRS was found in preweaned pigs at nearly 11% of sites overall.

Mycoplasma Vaccination

Large sites with sows (46%) were more likely to vaccinate for Mycoplasmal pneumonia than small sites (15.3%). Nearly 40% of breeding females were vaccinated for myco-plasma, meaning about 60% were not vaccinated (see Figure 2).

The vast majority of sites that vaccinated breeding females for myco-plasma vaccinated them as young gilts prior to entering the breeding herd (nearly 75%). In more than half the herds, breeding females received only one vaccination for mycoplasma. In the majority of cases, it was given prior to entry into the breeding herd.

PRRS Vaccination, Control

Just over half of breeding females (53.5%) were on operations that vaccinated for PRRS. Figure 3 pinpoints the type of PRRS vaccine used in the percent of breeding females during the previous six months. It shows modified live vaccine was most commonly used at 37.7%. Just 37% of all operations reported vaccinating breeding females for PRRS. But nearly 70% of operations on large sites did so.

Modified live vaccines were the most common given for PRRS, used in about 30% of operations. Some 19% of all sites reported using more than one type of PRRS vaccine in breeding females. In medium-sized operations (250-499 sows), 38.2% reported using multiple PRRS vaccines.

Timing of PRRS vaccination was also surveyed. About 81% of sites with breeding females inoculated gilts at the time of entry into the breeding herd.

The most common management strategy used to control PRRS was to receive only PRRS-negative semen or PRRS-negative boars (Table 1).

Table 1. Management Strategies to Control PRRS
Percent Sites
Size of Site (Sow and Gilt Inventory)
Control measure Small (less than 250) Percent Medium (250-499) Percent Large (500 or more) Percent All Sites Percent
Obtain replacement gilts from PRRS-negative source 18.4 48.2 46.7 23.9
Test replacement gilts for PRRS 4.5 24.6 32.2 9.0
Acclimate incoming gilts to PRRS 8.8 45.6 57.1 16.7
Herd closed to new gilt introduction(no purchased gilts) 26.2 16.6 28.1 25.4
Receive only PRRS-negative semen/boars 28.2 53.2 56.9 33.3
Other measures, exluding vaccination 0.8 1.0 5.1 1.2
Any of the above 50.4 86.2 89.9 57.4


Table 2. Swine Influenza Virus Vaccination Practices
Percent Sites
Size of Site (Sow and Gilt Inventory)
Vaccine Type Small (less than 250) Percent Medium (250-499) Percent Large (500 or more) Percent All Sites Percent
Killed SIV H1N1 vaccine 3.0 33.8 32.2 8.7
Autogenous SIV H1N1 vaccine 0.2 6.3 7.9 1.5
Any SIV H1N1 vaccine 4.4 39.4 42.4 11.2
Killed SIV H3N2 vaccine 3.9 21.9 27.4 7.7
Autogenous SIV H3N2 vaccine 0.4 5.3 9.9 1.7
Any SIV H3N2 vaccine 5.0 29.4 41.5 10.6
Both SIV H1N1 and H3N2 vaccines 2.9 28.5 28.1 7.6
Any SIV vaccine 6.5 40.2 55.8 14.2


Table 3. Timing of Swine Influenza Virus Vaccination
Percent Sites
Size of Site (Sow and Gilt Inventory)
Time Period Small (less than 250) Percent Medium (250-499) Percent Large (500 or more) Percent All Sites Percent
Prior to entering the breeding herd, i.e., as young pigs 2.1 10.2 23.3 4.8
As gilts at time of entering the breeding herd 2.7 27.0 35.4 8.4
During gestation up to 4 weeks before farrowing 0.6 7.6 13.2 2.4
During the last 4 weeks of gestation 1.8 14.9 11.9 4.0
Between farrowing through weaning 0.2 11.1 4.2 1.7
After weaning through breeding 1.0 2.6 3.1 1.3
Once or twice a year, regardless of reproductive stage 0.5 6.0 5.9 1.5
Vaccinate during at least one of the above time periods 4.4 39.4 42.4 11.2


Acclimation of gilts prior to herd entry is a fairly common practice for PRRS control, except at small sites.

Swine Flu Vaccination

Use of any type of swine influenza virus (SIV) vaccine for control of flu symptoms was reported by 44% of sites with breeding females. Use of both types of SIV vaccine (H1N1 and H3N2) was noted for 31% of sites with breeding females.

Breeding females were vaccinated against the traditional H1N1 strain of SIV on 11.2% of sites. The newer H3N2 SIV vaccine was used on 10.6% of sites, while both vaccines were used on 7.6% of sites overall.

As depicted in Table 2, medium and large sites used one or both vaccine strains to a much larger degree in protecting breeding females.

Just 8% of all sites vaccinated gilts for H1N1 SIV at time of entry into the breeding herd, compared to 35% of large sites (see Table 3). Similar figures were recorded for sites vaccinating breeding females for H3N2 SIV.

Sow Antibiotics

Over 60% of all sites gave sows antibiotics to treat various disease conditions. For medium to large sites, more than 80% treated sows with antibiotics.

Records of antibiotics given to sows were kept by nearly 59% of sites surveyed. The most common records maintained were drug used, date of use and animal identification.

The owner was the key decision-maker on which antibiotics to use for breeding females on 46% of sites.

Gilt Introductions

Almost 70% of sites introduced at least one group of gilts into the breeding herd during the six months prior to the survey. A third of the operations introduced three or more groups of gilts during that time period. One- fifth of sites added 50% or more of their total breeding female inventory within the previous six months.

About 53% of sites selected replacement gilts during finishing. Over 40% of sites selected gilts at 26 weeks of age or older.

At over 60% of sites, gilts weren't made part of the female breeding herd until they were 30 weeks of age or older.

Over half (54%) the gilts were introduced during the previous six months from a parent herd/multiplier herd. About a quarter of the introduced gilts were raised as commercial stock.