Infectious reproductive disease in cattle Flashcards
List questions you might ask a farmer when investigating infectious reproductive disease?
- How many cows do you have?
- How many are affected?
- When did it start?
- What are they vaccinated against?
- How long they have been affected?
- Closed/open herd? Any movement or change?
- Do they use a sweeper bull?
- Clarify that they are definitely a closed herd.
- Stress?
- How are they managed? Indoor/outdoor?
- Calving management? Block? Year-round? Where is this process are you?
- What clinical signs have they noticed?
- Are the cows systemically ill?
- What groups are affected? Dams? Dry cows? Calves?
- What other animals are on the farm?
- Any effects on other species on the farm including farmer etc.?
- How they are serving? Natural service or AI?
Infertility/failure to conceive
- How they are serving? Natural service or AI
- Do they use heat detection methods? How?
- Have they actually seen oestrus behaviour?
- Has there been a new bull brought onto the farm (venereal diseases e.g. campylobacter)?
- Any history of endometritis (campylobacter, Trueperella pyogenes)?
Abortions
- When are they aborting?
- Any clinical signs associated?
- Any dogs on the farm or other animals (e.g. neospora)?
- Any public footpaths going through the farm?
- What do the foetuses look like? Any deformities?
- Where are they aborting? In a specific group?
- What is he doing with the carcasses? How quickly does he remove any aborted material?
- Any neurological signs (listeria)?
- Storage of feed (listeria and salmonella)?
- General feeding
- Milk yield in the ones that have aborted?
- Historical abortion cases
- Any other farms are affected?
- Time of year?
- Any scouring (salmonella)?
Milk drop
- Is it acute or chronic onset of milk drop?
- Any signs at milking, e.g. changes in teat conformation, udder, discharge?
What is Trueperella pyogenes?
T. pyogenes is a well-recognized Gram-positive, non-motile, non-spore-forming, short, rod-shaped ‘coryneform’ bacterium.
Discuss trueperella pyogenes as a cause of abortion?
- Infectious agents are thought to be the most frequent cause of bovine abortion
- Common bacteria found in the environment which can be the cause of sporadic abortions in a dairy herd
- Get to placenta and foetus via the cow’s circulatory system
- May not cause disease symptoms in the cow but the foetus appears more susceptible due to its immature immune system
- The growth of the bacteria can cause death of the foetus and results in it being aborted and expelled from the uterus
- This, alongside bacillus and streptococcus species are the most commonly identified cause of bacterial abortions in dairy cattle
Discuss Trueperella pyogenes as a cause of endometritis*?
*Cattle endometritis is a common condition that causes 3 weeks or more after calving
The main consequence of endometritis is poor fertility, and it therefore has a major economic impact by increasing calving interval, services per conception and cull rates and by decreasing milk yield.
The uterus is contaminated by environmental microorganisms during parturition or immediately postpartum.
The main bacteria involved is Trueperella pyogenes however a number of gram-negative anaerobes may also be involved
The presence of this opportunistic bacteria can delay return to service and cyclical activity, prevent fertilisation and cause early embryonic death by producing a hostile uterine environment
This bacteria also increases the incidence of ovarian cysts
How is endometritis caused by Trueperella pyogenes diagosed?
Diagnosis is based on calving history and clinical signs following vaginal and rectal exam. Definitive diagnosis can only be achieved by endometrial biopsy however this is rarely indicated.
What is the treatment for endometritis caused by Trueperella pyogenes?
- Treatment includes antibiotics, hormones and intrauterine antiseptics (?)
- Antibiotic: broad-spectrum, active against Trueperella pyogenes and gram-negative anaerobes – ideal antibiotics are cephalosporins and oxytetracycline
- Intra-uterine cephalosporin should be considered the most effective antibiotic treatment
- (sulphonamides, aminoglycosides, nitrofurazones and penicillin’s have decreased activity as a result of the uterine environment and bacteria present)
- Hormones: prostaglandins are mainly used in chronic cases, and are administered parenterally
- Treatment of choice if CL is present
- Removes inhibitory effect of progesterone on the uterus and induces oestrus, which both improve the uterine defense mechanisms
- They may have the added benefit of clearing the luminal contents
- No milk withdrawal so ideal for dairy cattle
- Antiseptics: intrauterine chlorhexidine and metakresol sulphonic acid have reported to be effective alternative to antibiotic treatment, however few studies to confirm and some detrimental effects on fertility reported.
Discuss Trueperella pyogenes as a cause of mastitis (‘summer mastitis’)?
The disease is generally regarded as having a complex aetiology, involving a variety of bacteria. The main agent is Trueperella (formerly Arcanobacterium) pyogenes, which has a widespread presence in the respiratory and genital tract of cattle. However, severe glandular damage is not generally expressed without the presence of such organisms as Streptococcus dysgalactiae, Peptococcus indolicus and Fusobacterium necrophorum.
Discuss summer mastitis?
Predisposing factors/transmission:
Trauma and irritation of the udder, which may cause leaking and disruption of the keratin seal normally present in the teats of non-lactating cattle.
Presence of the sheep head fly, Hydrotaea irritans, which is a commonly observed nuisance parasite around livestock in the summer months
Clinical presentation:
During the acute phase of the disease, a cow will typically show an enlarged gland, with altered gait due to pain and swelling.
It is characterised by the production of abscesses within the gland – often with the production of large volumes of odoriferous purulent material and varying degrees of toxaemia.
A foul-smelling secretion may be expressible from the teat, containing purulent material.
The affected animal may be depressed and, in severe cases, death may ensue due to the effects of bacterial endotoxin.
Recovered animals invariably lose the functional use of the quarter.
Severely affected animals may show a post-recovery slough of the gangrenous gland.
In less severe cases, the first indication of a problem may be the gland is found to be non-functional post-calving. A typical observation of such cases shows the teat to have a hard central core of fibrous scar tissue as a result of the necrotising effect of endotoxins.
In a herd with a reported high incidence of “blind quarters” in heifers, it is worth investigating pre-lactating heifer management for indicators of poor protection from summer mastitis.
Discuss treatment for mastitis caused by Trueperella Pyogenes?
Treatment:
As stated, the affected gland usually does not recover functionality. Treatment is generally a salvage exercise to mitigate the toxic effects of the infection.
A successful outcome would generally be the animal survives and is fit to be presented for slaughter in due course.
Antibiotics are usually administered; injectable penicillins are indicated (Zastempowska and Lassa, 2012; Hirvonen et al, 1994). Intramammary preparations are generally regarded as ineffective.
NSAIDs, such as meloxicam, should be administered, together with supportive oral fluid therapy, to minimise the systemic effects of bacterial endotoxins.
Amputation of the affected teat is sometimes advocated by veterinarians, with the aim of effecting drainage of the purulent secretion.
There are arguments against this however – firstly, as the secretion is generally very thick and does not usually drain easily and, secondly, the uncontrolled leakage of material could potentially act as a source of new infections for other animals in the group.
Euthanasia of severely affected animals may be indicated where disease has become life-threatening and welfare is compromised.
Prevention
Good pasture management, ensuring vegetation will not damage the udder, and trying to avoid areas with lots of flies if possible
Pour-on fly preparations, generally those containing permethrin, are recommended for vulnerable groups. During times of heavy fly challenge – usually July to August – reapplication of insecticide may be indicated, typically on a four-weekly basis.
Internal teat sealants have been proven to be beneficial in the reduction of infections in the nonlactating udder, which is also true of the summer mastitis complex.
Discuss general prevention strategies for mastitis?
- Effective fly-control programme as well as maintaining clean, dry environments, especially for calving areas
- Cleaning of waterers and feed bunk areas
- Isolation of affected dam/removing her from herd
- Minimising stress
- Killing or drying off infected quarter or removing the cow from the herd
- Prognosis following infection is poor
- Care during milking not to cause damage to the teats (associated with teat injury), also care with general trauma due to wound contamination environment
Discuss Bacillus licheniformis?
The bacteria is widespread in the environment and is associated with food spoilage.
B.licheniformis is thermophilic, its optimal growth temperature is about 50°C.
It causes abortion in cattle and sheep, possibly from spoiled silage or hay.
What is the challenge of bacillus licheniformis?
It is a much bigger problem in beef than dairy herds suggesting that changes could be made to reduce the risk in beef cattle.
When studied, bacillus licheniformis has caused abortion in cattle from month 4-9.
How is bacillus licheniformis spread?
Non sexually transmitted
Spread via ingestion and then haematogenous spread
What is the typical case presentation of bacillus licheniformis infection?
Abortion in housed, pit silage fed, spring calving beef cows in the last two months of pregnancy
How is bacillus licheniformis diagnosed?
Gross appearance of placenta
Isolation of bacillus from placenta, foetal stomach and vaginal discharge
What are some preventative measure for preventing bacillus licheniforms infection?
- The following suggestions are practical steps farmers could take to help reduce cow exposure to B. licheniformis.
- Feed the best available silage to late pregnant cows.
- Never feed silage that is obviously mouldy or spoiled.
- Consider feeding silage from the top and edges of the pit to youngstock
- Use a shear grab and feed out the silage face in the shortest possible time.
- Clean away uneaten silage before adding more.
- Clean out water troughs regularly
Discuss controlling bacillus licheniformis?
Difficult – the organism is ubiquitous
Improve ventilation
Avoid poor quality and bedding
Discuss Brucellosis (notifiable)?
The most common clinical manifestation of brucellosis in natural hosts is reproductive loss resulting from abortion, birth of weak offspring, or infertility.
Discuss the Aetiology and Epidemiology of brucellosis (notifiable)?
- Infection spreads rapidly and causes many abortions in unvaccinated cattle. In a herd in which disease is endemic, an infected cow typically aborts only once after exposure; subsequent gestations and lactations appear normal. After exposure, cattle become bacteraemic for a short period and develop agglutinins and other antibodies; some cattle resist infection, and a small percentage of infected cows spontaneously recover.
- A positive serum agglutination test usually precedes an abortion or a normal parturition but may be delayed in ~15% of cows. The incubation period may be variable and is inversely related to stage of gestation at time of exposure.
- Organisms are shed in milk and uterine discharges, and the cow may become temporarily infertile.
- Bacteria may be found in the uterus during pregnancy, uterine involution, and infrequently, for a prolonged time in the nongravid uterus. Shedding from the vagina largely disappears with the cessation of fluids after parturition. Some infected cows that previously aborted shed brucellae from the uterus at subsequent normal parturitions. Organisms are shed in milk for a variable length of time—in most cattle for life. B abortus can frequently be isolated from secretions of nonlactating udders.
- Natural transmission occurs by ingestion of organisms, which are present in large numbers in aborted foetuses, fetal membranes, and uterine discharges. Cattle may ingest contaminated feed and water or may lick contaminated genitals of other animals. Venereal transmission by infected bulls to susceptible cows appears to be rare. Transmission may occur by artificial insemination when Brucella-contaminated semen is deposited in the uterus but, reportedly, not when deposited in the mid-cervix. Brucellae may enter the body through mucous membranes, conjunctivae, wounds, or intact skin in both people and animals.
Discuss Clinical findings of Brucellosis (notifiable)?
- Abortion is the most obvious manifestation. Infections may also cause stillborn or weak calves, retained placentas, and reduced milk yield. Usually, general health is not impaired in uncomplicated abortions.
- Seminal vesicles, ampullae, testicles, and epididymides may be infected in bulls; therefore, organisms are present in the semen. Agglutinins may be demonstrated in seminal plasma from infected bulls. Testicular abscesses may occur. Longstanding infections may result in arthritic joints in some cattle.
Discuss BVD
- BVD is one of the biggest disease issues facing the UK cattle industry. Bovine viral diarrhoea (BVD) is a widespread disease of cattle causing various symptoms including infertility, abortion, stillbirths, diarrhoea, pneumonia, poor condition and a lowering of resistance against other infection
- BVD can cause devastating losses if introduced into a susceptible group of breeding cows or heifers during the mating period.
- Adult cattle: Although severe disease can occur in adult cattle, most infected animals will show no signs of ill health at all. Signs such as an elevated temperature, milk drop, reduced feed intake and diarrhoea may be apparent but these animals usually recover quickly and with good immunity against the virus. The impact that BVD has on fertility is primarily dependent on the cow’s pregnancy status at time of infection.
- Infected Bulls: The impact on bulls can be devastating particularly when a herd is relying on the performance of a bull or bulls for the year’s production. Infected bulls may develop a high temperature which can cause a reduction in semen quality for as long as two months after infection, by which time the breeding period may be over. Bulls can also be an important reservoir of infection as they may go on to shed BVD virus in their semen for a long and sometimes indefinite period of time.
- Pregnant cow infected during first 3 months of pregnancy –> outcome of infection = embryonic death and early abortion
- Pregnant cow infected in mid-late pregnancy –>outcome of infection = late abortion and/or weak or deformed calf born
- If BVD virus is active on your farm then the costs are likely to be significant, possibly ranging from £50-£100 per breeding animal. The fertility costs - reduced conception rates, embryonic death, abortion and bull infertility - make up a large proportion of the total costs associated with BVD
Discuss outcomes of BVD infection in relation to gestation?
Pregnant cow infected during first 3 months of pregnancy –> outcome of infection = embryonic death and early abortion
Pregnant cow infected in mid-late pregnancy –>outcome of infection = late abortion and/or weak or deformed calf born
When is BVD most likely to infect a herd?
- The majority of infections with BVD virus occur after birth. In this case animals become acutely or transiently infected before recovering and becoming virus-negative, typically within 3 weeks or less. Transient infections may occur without obvious clinical signs but depending on age, sex and immunity they can lead to a range of reproductive problems, including abortion and poor calf health with scours and pneumonias that respond poorly to treatment.
- Infection of the unborn calf between approximately 30 and 120 days of pregnancy will result in it becoming persistently infected (PI) for the rest of its life with BVD virus if the calf is not aborted. If a calf is not PI at birth it will never be PI.
What can be done to prevent/protect against BVD?
Aims:
- Prevent poor conception rates, embryonic loss and abortion
- Prevent further PI calves from being born
- Remove PI animals and persistently infected bulls
To achieve 1+ 2 you must prevent pregnant cows from being infected with BVD virus. This can be achieved by keeping the virus out of your farm or by using the very cost- effective BVD vaccine. Removing PI animals and infected bulls will reduce the amount of virus circulating on your farm.
How can a farm find out it’s BVD status?
- Speak to your vet about bulk and heifer milk samples (dairy) or heifer and calf blood sampling (beef and dairy). If you are completely free of BVD then this is great news. However, your cattle may have no immunity to the virus which means that if infection did enter the herd then the results could be catastrophic.
- If you are ‘BVD free’ review your measures for keeping it out and consider vaccinating.
- If you are one of 90% of herds which has been exposed to BVD this does not necessarily mean that you have an active problem. Heifer milk samples and youngstock blood samples will determine whether BVD is a current or historical problem.
After finding out BVD status what are the next steps?
Once you know your status you can assess the risk to your herd with your vet. Given that determining your BVD status can be achieved at little or no cost this is a must for all cattle farmers. When you know the risk you can make an informed decision on what action to take. Steps taken will vary and may include:
- Review biosecurity
- Review purchased stock policy
- Vaccinate
- Remove all PI animals
Discuss Leptospira?
- Common infection in dairy and beef herds causing infertility, abortion and poor milk yield.
- Also zoonotic and causes flu like symptoms with severe headaches and can be treated effectively. Farmers are particularly at risk from infection when urine splashes onto their face whilst in the milking parlour.
- Pasteurisation destroys the organism that is secreted in the milk.
What causes infection with leptospira?
- Two important types of Leptospira hardjo:
- Leptospira borgpetersenii serovar Hardjo
- Leptospira interrogans serovar Hardjo
- Infection from contact with infected urine or abortion products
- Disease is spread most often in spring and summer months whilst cows are at pasture
- Leptospires are susceptible to drying, exposure to sunlight, pH <5.8 or extremes of temperature
- Not carried by wildlife or vermin but can be carried and excreted by sheep – mixed grazing is a risk factor
What are the risk factors for leptospira?
- Open herds
- Using shared bulls
- Mixed grazing with sheep
- Shared grazing with common watercourses
What is the clinical presentation of leptospira?
- Sudden drop in milk yield 2-7 days after infection of susceptible cows
- Udder becomes soft and flabby with colostrum like secretions or blood-tinged milk in all quarters
- Signs may be mild/ sub-clinical
- Some cows become lethargic and stiff, with a fever and reduced appetite (anorexia)
- Abortion may occur 3-12 weeks following infection – most occurring during the last 3 months of pregnancy
- Infection may also produce premature and weak calves
- Circumstantial evidence of infertility
- May also cause embryonic death
- Venereal transmission is possible but may not adversely effect preg rate as is killed by uterine defences during oestrus
- Split herd vaccination trials have shown improved fertility parameters in vaccinated cows in herds with endemic lepto infections
What are the other differentials apart from leptospira for Marked drop in milk?
- Sudden feed changes
- BVD
- Lungworm
- IBR
- BRSV (bovine respiratory syncytial virus)
- Influenza A
- Salmonellosis
What is the lifecycle of neospora caninum?
What is this?
Anterior uveitis ‘silage eye’ caused by listeriosis
- Causes anterior uveitis (ovine iritis) following conjunctival infection with Listeria monocytogenes
- Occasionally seen in sheep of all ages being fed on big bale silage
- Initial presenting signs are excessive lachrymation, forced closure of eyelids and photophobia affecting one or both eyes.
- Within 2-3 days, the surface of the eye develops a bluish-white opacity
Discuss Schmallenberg virus?
- Late abortion or birth defects in newborn sheep, cattle and goats
- Up to 50% malformed lambs reported
- Deer, bison and llamas all have antibodies
- Milk disease in adults (milk drop, pyrexia, diarrhoea)
- Transmitted by insect vectors (miedges)
- No evidence that it is zoonotic
- Foetal deformities vary depending on when infection occurred during pregnancy
- Virus does not affect the muscles, effects the neuronal system so muscles are not appropriately primed to form
When is the fetus most sensitive to shcmallenberg?
