3 Making a Diagnosis and Post-mortem Technique Examination of large pigs is not easy as they resent handling. Pigs need to be kept out of arks to examine them (Fig. 3.1). Quietness is vital for auscultation of the heart, lungs and abdomen. This is difficult to attain in most situations. Patience will allow palpation of the abdomen, mammary glands, limbs and feet. Rectal temperature is extremely useful in the pig. Reference levels for the clinical examination are given in Table 3.1. The lack of hair allows a good examination of the skin, particularly in white pigs. This is obviously helpful for actual skin disease. It is also helpful with the diagnosis of many systemic diseases either because these diseases have specific signs on the skin, e.g. erysipelas, or because there are changes of colour of the skin, e.g. cyanosis in PRRS (‘blue ear disease’). Obtaining blood samples is not easy from any age of pig. Piglets weighing <10 kg are best held in dorsal recumbency on the lap of a sitting person, who holds the front legs firmly with the head towards the veterinary surgeon. The surgeon then holds the piglet’s head in one hand and directs the 25 mm needle from the jugular groove in a caudo-medial direction into the anterior vena cava. Older pigs are also best bled from the anterior vena cava with the nose held up in a pig snare. The blood vessel cannot be seen or palpated but the needle has to be directed medially from the indentation at the base of the neck. Only in adults can blood be drawn from the jugular vein. The animal is best restrained in a crate with the head held as high as possible by the snare. The needle must be at least 38 mm long and should be directed at 45° in a dorsomedial direction from the caudal end of the jugular furrow. Blood can be drawn in adults with large ears from an ear vein. A tourniquet of a thick rubber band and a pair of artery forceps is placed at the base of the ear. The small veins can be seen on the outside of the ear between the skin and the cartilage. Blood can be drawn using a 23 mm needle on the end of a syringe to apply a small amount of suction. Normal haematological and biochemical parameters are given in Tables 3.2 and 3.3. Saliva is an interesting tool because of its potential to reflect both oral and systemic health conditions and, with the advent of proteomics, biomarkers can be identified for specific pathological disease processes to help in the early detection of disease in farm animals. A study in Spain (Guiterrez et al., 2012) discovered potential salivary markers for systemic disease in pigs. Saliva samples can be obtained by allowing the pig to chew on a sponge for 2 min. Serological results can show positive results for PRRS, swine influenza virus (SIV) and porcine circovirus type 2 (PCV-2). Fig. 3.1. The pigs need to be kept out of their house to examine them. Table 3.1. Reference levels for the clinical examination of pigs.
Clinical Examination
Diagnostic Laboratory Tests
Blood sampling
Saliva
Parameter | Values |
Body temperature | Lower critical point, 38.4°C; normal, 39°C; upper critical point, 40°C |
Pulse | 70–80 beats/min, rising to 250 beats/min in the newborn piglet |
Respiration rate | Adults, 10–20 breaths/min; growers, 20–30 breaths/min; newborns, 40–50 breaths/min |
Table 3.2. Normal haematological parameters in pigs.
Parameter | Normal range |
Packed cell volume (PCV) | 37–46% |
Red blood cells (RBCs) | 6.5–8.0 ×1012/l |
White blood cells (WBCs) | 10.0–23.0 × 109/l |
Platelets | 250–700 × 109/l |
Haemoglobin (Hb) | 11.0–14.2 g/dl |
Urine samples
Obtaining urine samples requires considerable patience by the pig keeper. If required by the practitioner, catheterization of sows restrained in a crate is not difficult with a canine oesophageal tube. It is impossible to catheterize male pigs and so practitioners have to rely on a free-flowing sample. Normal urine parameters are as follows:
• Specific gravity (SG), 1.020.
• pH, 5.5–7.5.
• Protein and sugar, none.
Bacteriological examination of the urine can also be useful. Care needs to be exercised as certain bacteria will be grown as contaminates. The clinician will have to evaluate the bacteriological findings in the light of the clinical signs to decide from where in the urinary tract the bacteria originate.
Diagnostic Imaging
Radiography
Ten years ago radiography would not have featured in a book on pig surgery. That is not the case today, when we regularly radiograph pigs’ legs. Good restraint and normally a general anaesthetic (GA) are required (Fig. 3.2). Radiographs are useful for: fractures, arthritic joints, sand cracks and septic joints. Obviously this is not in a commercial situation, but radiographs are very useful to aid not only in making a diagnosis but also in making a prognosis. The author finds the procedure extremely useful when dealing with rescued pigs in sanctuaries so that unnecessary suffering is avoided.
Head radiographs are useful for diagnosis of cheek teeth disorders. The author expects radiographs in pigs to be used more frequently in the future, particularly for pet pigs.
Ultrasonography
As yet ultrasonography has had limited use in pigs. With the advent of much loved pet pigs this may change. At the present time its use is restricted to pregnancy diagnosis and for visualization of stones lodged in the small intestine.
Table 3.3. Normal biochemical parameters in pigs.
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