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Cystitis and Pyelonephritis

(260) This is an important cause of mortality in all ages of dry sows. Where disease is widespread total sow mortalities can often exceed 12% per annum. If a herd has an annual mortality of more than 5% some sows may be dying from unrecognised cystitis/pyelonephritis. In such herds post-mortem examinations of all sows that have died without apparent cause should be carried out. Urine passes from the kidneys down the two tubes (ureters) to the bladder where they enter and continue along the surface for approximately 30 to 40mm as straw like structures called the ureteric valves. As the bladder fills up pressure on them stops the urine being squeezed back towards the kidneys. In diseased sows the ureteric valves are often shortened from their normal length to as little as 10mm and if cystitis is present the bacteria can reflux back to the kidneys producing a very severe reaction. This causes the kidney function to cease (renal shunt) and death results in a matter of a few hours. Cystitis is inflammation of the bladder and pyelonephritis inflammation of the kidney and the two are often concurrent, particularly as sows get older. Occasionally it may be seen in gilts although this is uncommon unless there has been gross and prolonged faecal contamination of the vulva.

The bacteria associated with cystitis include E. coli, streptococci and in particular an organism called Actinobaculum suis (originally called Eubacterium suis and Corynebacterium suis). This latter organism is a common inhabitant of the preputial sac in the scrotum of the boar and occasionally the vagina of the sow. It has the ability to adhere specifically to the lining of the bladder and urinary tract and does not get easily flushed out with the flow of urine. It is thought that E. suis and sometimes E. coli may be deposited into the vagina at mating and when certain conditions prevail (which are not clearly understood) the organism can ascend the urethra and gain access to the bladder. Reproductive failure is not associated with this disease unless the sow is ill and as a consequence either dies or aborts.

Clinical signs

Acute disease
The sow appears very ill and off her food with the mucous membranes of the eye injected and red. The area around the vulva is wet and soiled with evidence of blood and pus in the urine. Sows showing these clinical signs often die or there will be a poor response to treatment with chronic cystitis developing. Disease can be so acute that death is the only sign. Post-mortem examinations will identify disease. It is more common in the first 21 days post mating because the urine of the sow becomes alkaline and both E. suis and E. coli will survive and multiply in alkaline urine.

Chronic disease
When nephritis caused by E. suis is present the disease is usually rapidly fatal but when cystitis occurs alone without progressing to nephritis the disease may be prolonged and not fatal. In these cases the appetite and the general condition of the sow can be normal, the only clinical signs being pus in the urine or a slight discharge clinging to the vulva. This should be distinguished from endometritis and vaginitis. (See chapter 6; Endometritis).

Diagnosis

This is best carried out by post-mortem examination. In the live animal, diagnosis is based upon clinical signs and evidence of blood and pus in the urine. Urine can be tested for the presence of blood, protein and the pH (acidity or alkalinity) by using paper strip tests. Urine can be collected in clean receptacles, especially if sows are made to stand 2-3 hours after feeding when they tend to urinate. Affected animals show evidence of blood and protein in the urine and a pH of 7 or more. (Normal urine is slightly acid, that is, less than the pH7.) Sows showing a pH of 8 or more have up to a 30% chance of dying in their next pregnancy.

Similar diseases

Cystitis can be confused with a vulval discharge which comes from the vagina or the womb and is usually of a salad cream consistency, whereas that from the urine contains pus and blood.

Treatment

  • Antibiotic treatment is indicated to destroy the incriminating bacteria but it must be excreted in the urine.
  • Lincomycin is effective at a dose level of 10mg/kg. This medicine is active against E. suis.
  • A more broad spectrum antibiotic however may be required if coliforms or other bacteria are involved. In such cases either ampicillin or amoxycillin at 10 to 15mg/kg should be given daily for 4 to 5 days.
  • On a herd basis, treatment is best carried out using either CTC or OTC at levels of 600g/tonne for a period of 14 days. It may be necessary to repeat this treatment every 4 to 6 weeks.
  • An alternate method is to inject the sow at weaning or at mating with a long-acting single injection of penicillin or amoxycillin.
  • Sows could also be medicated from weaning to 21 days post mating during the most susceptible period by top dressing with in-feed supplements. The dose used is based on the assumption that the sow will eat 2.5kg of feed per day during this period and the amounts of top dressing should be calculated on the basis of 600g to the tonne of active antibiotic. In most cases using a 10% premix this will be between 15 and 20g of premix powder per day. In a herd with major problems the prepuces of all the boars should be swabbed and forwarded to a laboratory to determine the isolation rate of E. suis bacteria and its antibiotic sensitivity. In a normal herd the isolation rate would be less than 30% but in a diseased herd this can approach 100%. In such cases attention to hygiene and management in the boar pens is required. Wet poorly drained floors accumulate urine and this is an ideal environment for E. suis to multiply in. Avoid shavings or sawdust as bedding.
  • Antibiotic mastitis tubes or liquid antibiotics can be instilled into the prepuce daily for five days to reduce the weights of infection.
Management control and prevention

The sow mortality rate from nephritis may become unacceptably high, particularly in herds in which the sows are in individual confinement in stalls or tethers throughout their breeding lives. The overriding reason for this is low water intake and infrequent urination. If the stalls or tethers are (as they should be) comfortable dry and free from draughts, if the ambient temperature is constant day and night, if the sows are fed a satisfying balanced diet once a day and if they are otherwise undisturbed, most will tend to lie down for very long periods. They develop a state of what is termed 'passive withdrawal' or 'self narcosis', and become too lazy to stand up to drink and urinate. The bladder is not flushed out regularly and fills with thick turbid urine and salts. The female urethra (i.e. tube leading from the bladder to the vagina) is short and negative pressures may result in faecal matter and other contaminated material being sucked up into the bladder predisposing to cystitis. Contamination of the urethra and hence the bladder may also occur at mating. The nephritic organism, E. suis, is able to adhere to the lining of the urinary tract and to multiply there and it is not flushed out when the sow urinates.

Cystitis/pyelonephritis problems arise in a herd where there is a poor water supply or sows have a restricted water intake. If the disease is present as a herd problem check the points below to identify the problem areas.

  • Ensure a good supply of clean fresh water and always check the quality if there is any doubt.
  • Feed sows in confinement twice daily to encourage animals to rise and giving water particularly at the same time.
  • If sows are fed in a continuous trough always put a small amount of water in first before the feed to encourage intake.
  • Wherever possible use water troughs as drinkers, rather than nipple drinkers, particularly in loose-housed sows.
  • If once-a-day feeding is practised in confinement or in loose housings either convert to a twice daily feeding system or scatter small amounts of feed into the trough at watering time.
  • If there is a herd problem look carefully behind each sow daily to identify any showing clinical signs of cystitis. Treat these and check the urine as described under diagnosis. Sows that are showing blood, protein or high pH in their urine are best culled.
  • Check that drinkers are at the correct height and provide easy access. The ideal height for sows is 800mm. In loose housing provide one nipple drinker per 10 - 15 sows with the water flow rate of 2 litres a minute . Alternatively provide water troughs with a minimum depth of 100mm.
  • Check the water supply daily.
  • In herds in which the sows are kept in individual confinement and in which there is a high mortality from nephritis, the most important preventative factors are to induce the sows to drink and urinate more frequently than they might otherwise do. They may be induced to drink more by increasing the salt in the ration to 0.9%. Walking a boar in front of the sow stalls daily will encourage them to stand and urinate. These actions alone usually result in a gradual decline in nephritis deaths.
  • Reduce or prevent contamination of the vulva with faeces particularly from weaning to 21 days post mating. This occurs in stalls when solid back boards drop down to the ground level. There should be a 100mm gap between the bottom of the board and the floor to prevent faeces building up behind the sow.
  • Sows that are too big for the stalls often adopt a dog sitting position with the vulva becoming heavily contaminated, allowing excessive bacterial multiplication.
  • Badly drained boar and sow pens increase the risk of infection.
  • The disease is more common in herds that have high numbers of old sows and boars.
  • If group housing is used at weaning make sure the pens are well drained. Do not use sawdust for bedding and wash and disinfect pens regularly.
  • Do not handle the prepuce at mating. Squeezing the prepucial sac increases the bacterial load transmitted to the vagina, (which may also result in increased returns to service).
  • Always wear gloves at mating time to prevent the spread of the E. suis infection.
  • Treat the boar's prepuces with antibiotic to reduce levels of E. suis.
Eradication

It is impossible to eradicate the organisms associated with this disease. They are present in every herd.


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