Hypoglycaemia
This is seen in neonatal pigs which have not received adequate energy, e.g. in very cold conditions when a sow has farrowed outside in winter. Convulsions will be seen in piglets. Hypoglycaemia can also be brought on by low levels of various infections in piglets. The farrowing fever complex syndrome, which will decrease milk output, will put piglets at risk. Treatment is proprietary energy fluids by mouth or in extreme cases injections of 15 ml of 5% w/w glucose intraperitoneally (ip) every 4 h.
Osteomalacia
This condition will mainly be seen in very badly fed adult, aged backyard pigs. Calcium has to be virtually absent from the diet. The bones are very brittle. The pig may have multiple long-bone fractures and be unable to rise (Fig. 2.2). Prompt euthanasia is the only course of action.
Vitamin A deficiency
This will cause blindness and so the pigs will appear to show nervous signs. The condition is certainly a possibility in badly fed backyard pigs. Once there is blindness recovery is impossible, even with vitamin A injections. Single or pairs of affected pigs might be thought to have a reasonable quality of life but euthanasia should be seriously considered.
Vitamin B deficiency
This may occur in backyard pigs fed either a very fatty diet or solely on bread. Normally pigs go off their hind legs; this is followed by a progressive paralysis. They may recover with good nursing and a proper diet.
Vitamin K deficiency
This occurs as a result of eating rat bait containing warfarin.
Skin Diseases Caused by Changes in Nutrition
Biotin deficiency
The main signs are hair loss and hoof lesions. Normally hoof lesions precede hair loss. Treatment with biotin in the food readily controls the condition and can be used as a diagnostic tool.
Fig. 2.2. This pig is not receiving an adequate diet and is suffering from osteomalacia.
Iodine deficiency
This is an extremely rare condition of piglets born to iodine-deficient sows. The piglets will be hairless but will not show goitre.
Parakeratosis
This is caused by a deficiency of zinc in the diet or by a conditioned deficiency from high levels of phytic acid in soy. It is found in young growing pigs and is manifest as scaly papules. Diagnosis should be made with a skin biopsy as testing the blood for zinc levels is unreliable. Treatment is restoring the zinc level in the diet to 100 ppm taking into account the level of soy in the food. The response to treatment can be used as a diagnostic tool.
Vitamin A deficiency
This is extremely rare and is manifest as a generalized seborrhoea. It is seen in weak piglets born to deficient sows. Other signs of vitamin A deficiency, e.g. neurological signs, particularly blindness, are going to be much more obvious than the skin disease. The neurological signs are irreversible.
Vitamin B deficiency
Other than biotin deficiency, which is relatively common, deficiencies of niacin, pantothenic acid and riboflavin have been reported as well but they are extremely rare. Skin disease signs are very variable but are usually seen as dry scaly areas. Total recovery will occur if the diet is corrected.
3 Making a Diagnosis and Post-mortem Technique
Clinical Examination
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’).
Diagnostic Laboratory Tests
Blood sampling
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
Saliva is an interesting tool because of its potential to reflect both oral and systemic health conditions and, with the advent
