Principles of antibiotic treatment in reproduction cases and xertes

Question 1

Case: Clinically ill dairy cow

T=39.5, P=80, R=25, anorexia, hypovolaemic, wobbly on her feet

Vaginal exam: nasty intrauterine odour,RFM present

1 day post partum, assisted delivery, dead calf
You decide she’s got clinical metritis (in cattle often caused by E.coli and a variety of anaerobic bacteria) and want to start antibiotic therapy.

1.List the factors that influence your choice of antibiotics

Answer 1

Additional questions wendelaw ould want to ask:

• Farm protocol? What the farm normally uses as an Abs?
• Known resistance?
• Level of current management? Like to know how accurate they are and good they are at giving the treatment/compliance, hygiene and cleanliness at farm, risk of secondary infection on the farm
• Any treatment thus far? ALWAYS ASK THIS. E.g If she’s already had pen-strep then would rather continue this for extra 2 days

My considerations:

• You need a systemic antibiotic, intrauterine antibiotic is not sufficient when the cow is clinically/systemically ill
• Check VMD product database: what is available (registered for metritis in cattle)

Question 2

Compare antibiotic choices?

Answer 2

• We want to avoid fluroquinolones and 3 rd and 4 th gen cephalosporins (WHO)
• Withdrawal time is not a major decision maker as a truly ill cow milk would not go in bulk tank anyway.
• OTC: large volumes to give every 48 hours
• Price is considered depending on how profitable a milker she is
• TMPS not effective in a pus filled infected uterus
• Cefalexin: not a great gram –effect

Question 3

Discuss decision making in this case with regards to antibiotic choice?

Answer 3

Decision making

• Skip cefquinome/marbofloxacin until you find a good reason
• avoid fluoroquinolones and 3rd/4th generation cephalosporins if we want to use antibiotics responsibly
• Skip TMPS as it does not work well in areas with lots of tissue debris.
• Skip cefalexin because you need good G+ & G-cover.
• Left with OTC, ceftiofurand amoxicillin

Question 4

Discuss antibiotic decision making in this case further?

Answer 4

As you’re treating a severely ill animal, you don’t want to risk ab-resistance delaying cure, I would therefore probably skip OTC (VR paper Sheldon), in addition to potential resistance issues, the dose rate is massive and gives big lumps when admin IM, but cheap and you may want to find out for next time if resistance exists on farm.

Responsible AB use: prefer amoxicillin over a 3rd generation cephalosporin.

If animal is truly ill a 60h milk withdrawal will not be a major push from economics point of view, particularly when in first 5 days postpartum. However, 0 milk withdrawal is much easier to manage on a dairy farm (no risk of positive tank) and that with the smaller dose will make farmers prefer ceftiofur. Ceftiofuris 3rd gen cephalosporin though!

Question 5

In this case as important as antibiotic choice…or sometimes even more important are the following:

Answer 5

• NSAIDs
• Fluids
• TLC (more specific, soft dry bedding, in/out with friends, access to food without competition, plenty food and water in front of them, warm enough)
• Enough access to feed if she is lame
• Remove RFM? If it can be drawn out without pressure yes if membrane is still attached don’t pull it out.

Question 6

A huge number of factors underly the decisions made by vets in practice when selecting an antibiotic to use. When you are a new graduate it’s easy to be influenced by the pizza-wielding drug reps or what is nearest to grab, but you do need to bear some important factors in mind

First steps?

Answer 6

• Is the ‘problem’ infection?
  
  • If so, bacterial, fungal, viral, mycoplasmal, parasitic or rickettsial?
• Likely organism involved and site?
• Do you need to confirm that or will you use empirical antibiotics?
• Does the infection warrant therapy?
• If so, with what?

Question 7

Things to consider when trying to understand what kind of infection is it?

Answer 7

• You need to have a working understanding of what kind of pathogens are likely to occur in that site in that species. You should have had this information in your antibiotics lectures - it might be worth you making a list of the common pathogens and their characteristics which you can refer to.
• Whilst culture can be informative in certain circumstances, you often need an empirically chosen (ie best guess) antibiotic to cover the 5-7 days until you get the culture results back. In addition, in vitro sensitivity does not always correlate well with in vivo effectiveness. This may be because the bacteria you’re culturing are actually not the primary pathogen.
• Particularly for farm animal infection scenarios, such as BRD you will have a good idea of the likely pathogens involved in the secondary infection, and culture is not that useful in those situations. In other situations, it may be worth screening a group of cases for bacteriology, for example in mastitis cases.

Question 8

What spectrum of activity do you need in an antibiotic how to choose?

Answer 8

• If you know what you are treating, the narrower the spectrum the better to avoid resistance. If you aren’t sure then a broad-spectrum choice might be better. Also, worth thinking about whether the drug works on a time or concentration dependent mode, which we’ll talk a bit about later.
• Again, worth thinking about making a list of these for the species you will be working with.
• Also remember that the MIC for penicillin is typically lower in susceptible organisms so it is not just about resistance, it is about efficacy; e.g. when treating Streptoccus infections, penicillin is an excellent choice.

Question 9

Discuss Bacteriostatic vs bacteriocidal antibiotics?

Answer 9

Bacteriostatic

• Require animal’s own defence mechanism to aid pathogen removal - not good if immunocompromised.
• Act via interference with bacterial protein synthesis

Bacteriocidal

• Kills bacteria via interference with cell wall, ribosomes, DNA topoisomerases
• Don’t mix the two as they will inhibit each other

Question 10

Discuss drug penetration of antibiotics?

Answer 10

• Where does your drug need to get to? Abscess walls, pus, pH, anaerobic environments all cause problems with getting the antibiotic to the site of infection, and may mean that an antibiotic which would be helpful for an infection in one location is not so good in a different location.
• For example, sulphonamides are inactivated in the presence of low pH tissue and tissue debris (pABA)

Question 11

Discuss licensing with regards to antibiotics?

Answer 11

Is it licenced?

• Most of the older antibiotics are licensed for a wide-range of bacterial infections, and some of the newer antibiotics tend to have specific indications.
• Where can you get this information?
• Either from the datasheet in the box, or from the NOAH website or VMD product database
• You can search by species, drug name or ingredient…

Question 12

Discuss rate and dosage of antibiotics?

Answer 12

• Dose
  
  • Bodyweight
  • Formulation; beware trade names
  • Minimum Inhibitory Concentration (MIC) - this is not the same as the Maximum Residue Limit (MRL)
• Rate of administration
  
  • Is the drug concentration dependant or time dependant?
  • Remember that there are differing withdrawal periods if you go off-label; and that standard withhold periods apply
  • i.e. At least 7 and 28 days milk and meat
• Toxicity and side effects?
  
  • E.g. oxytetracycline may be an irritant to large animals and may discolour teeth in small animals under 6 months of age

Question 13

What route can antibiotics go?

Answer 13

What route?

• Intravenous?
• Intramuscular?
• Subcutaneous?
• Intraperitoneal?
• Intramammary?
• Intra-occular?
• Per os?
• How to decide? Well, the route for which the drug has been licenced and is available is a good start. Then think about how easy it is for you/ the owner/ farmer to administer the drug by the different routes and how frequently it needs to be given. Also how well that drug will be absorbed; subcutaneous drugs are no good in a dehydrated animal, oral antibiotics are no good in an animal which is being sick.

Question 14

Consider what is the withdrawal time of antibiotic?

Answer 14

• For food animals only. Variable between drugs and for the same drug through different routes. Typically, newer drugs tend to have a shorter withdrawal period than older ones.
• Remember that if you get this wrong in a dairy cow, a whole bulk tank might have to be discarded and you won’t be very popular.
• Make sure that the farmer knows the withdrawal period of the drugs given!

Question 15

Discuss antibiotic cost?

Answer 15

• How much does it cost?
• Important for farmers, pet owning clients, and especially charity clinics such as the PDSA. More expensive doesn’t necessarily mean better….
• What mark-up is applied?
• Is it cheaper to dispense in bulk to avoid serial drug administration fees?
• Can you legally use a generic version/ cheaper form? Beware that they might not be licenced by the same routes, palatability may be different etc.

Question 16

Consider how the owner can give the antibiotic?

Answer 16

Can the owner give the medication?

• Especially for the fractious cat, but also for the fell pony or cow in a massive field - there is no point dispensing a medication which the client cannot administer, so a long acting injection may be better if available.
• Remember that this is not just oral medication; if an ear is too sore for you to look down with an otoscope, there is little chance of the ear drops you prescribe getting to where you need them to go…

Question 17

Compare choice factors for antibiotics choice in different species?

Answer 17

Question 18

What would the consequences of blanket antibiotic resistance be?

Answer 18

The real implications of spreading drug resistance will be felt the world over, with developing countries and large emerging nations bearing the brunt of this problem. Routine surgeries and minor infections will become life- threatening once again and the hard won victories against infectious diseases of the last fifty years will be jeopardised. Hospital stays and expenses, for both public health care providers and for out of pocket payers will increase significantly. Drug resistant infections are already on the rise with numbers suggesting that up to 50,000 lives are lost each year to antibiotic-resistant infections in Europe and the US alone. Globally, at least 700,000 die each year of drug resistance in illnesses such as bacterial infections, malaria, HIV/AIDS or tuberculosis

“We have reached a critical point and must act now on a global scale to slow down antimicrobial resistance”; Professor Dame Sally Davies, UK Chief Medical Officer

Question 19

Discuss primary and secondary pathogens in BRD?

Answer 19

• Primary pathogens
  
  • Often viral (PI3, BRSV, IBR) with Gram negative organisms in early stages (e.g. Mannheimia)
• Secondary pathogens
  
  • Gram positive opportunists in late stages (e.g. Trueperella)

Question 20

Discuss therapeutic antibiotic treatment for BRD?

Answer 20

• Which calves do we treat?
  
  • Early stages should be treated, when rectal temperature >39.0C
• False negatives?
  
  • Calves that are missed for treatment, consequently have a poor response to treatment when started later on due to irreversible lung damage
• False positives?
  
  • Chance of ‘unnecessary’ treatment, due to over-diagnosis when only based on a few clinical signs

Question 21

What kind of antibiotic would we like in the ideal world?

Answer 21

• A broad spectrum antibiotic which is above the MIC for the pathogens involved
• Ideally an older drug to reduce resistance rates
• Bacteriocidal or bacteriostatic?
• Low dose volume, low dose frequency for ease of adminstration, to minimise stress of handling and to minimise labour input
• Subcutaneous route (pain?)
• Low cost
• Low meat and milk withdrawal

Question 22

• A 3-wk old Holstein heifer calf with a 24 hour history of ocular and nasal discharge and coughing. On clinical examination, there are harsh lung sounds especially in the cranioventral lung fields and core temperature is 41C*
• Which of the following antibiotics would be your choice to treat the ill calf? We’ve called two answers correct; as with many of these antibiotic decision making exercises, there is often more than one appropriate answer…..
• TMPS
• Oxytetracycline
• Tilmicosin
• Florfenicol
• Tulathromycin

Answer 22

• TMPS
  
  • Duphatrim (TMPS) would need injecting every day (compliance, muscle damage (IM), handling/stress), and does not penetrate well into areas with pus/tissue debris, so may not be the best choice - try again.
• Oxytetracycline
  
  • Oxytetracycline would be appropriate in many respects (and is cheap!); Although there is evidence that resistance amongst calf pneumonia pathogens is relatively common (relative to other antibiotics), many farms find that they get good treatment outcomes; if this is the case then they should be encouraged to continue using oxytet.
• Tilmicosin
  
  • Micotil has very similar properties to Draxxin (the other macrolide drug in this selection), except that it is cheaper. However, it has some important operator safety issues (check out the data sheet). It can only be administered by a veterinary surgeon (which might be important as further cases may require treating in the future, and this would often be done by dispensing product to the farmer). There is little reason to choose this over the other options. Micotil has now been superseded by other macrolides that persist for longer;e.g. gamithromycin, tildipirosin meaning it is less likely to chose Micotil over these other options
• Florfenicol
  
  • Nuflor has an appropriate (broad!) spectrum of activity for this indication. Although it has no label claim for activity against mycoplasmae in the UK, this has been added to the label in the USA, and there is evidence that florfenicol will cover these pathogens. A single treatment using the subcutaneous regime should give about four days of cover. If the patient was very near to slaughter weight, the long withdrawal period might be a problem (but this is not usually the case). Resistance is rare, and it’s not a compound which is used much in human medicine; good choice! Don’t forget adjunctive therapies too; NSAIDs are invaluable in cases like this.
• Tulathromycin
  
  • Although we might expect a macrolide like Draxxin to have a Gram-positive-biased spectrum of activity, Draxxin has label claims for Mannheimia haemolytica and pasteurellae. It also has an extremely long duration of activity (probably 10 days for most pathogens), which can be very important. If the patient was very near to slaughter weight, the long withdrawal period might be a problem (but this is not usually the case). Resistance is rare. However, although tulathromycin is not used in human medicine, macrolides are often considered as one of the next most important families after the currently promoted CIAs (3-4 Cephs and FQs) and we therefore aim to use them as a last resort
• Best combination – oxytetracycline and florfenicol

Question 23

• A 4th parturition cow has gone down with mastitis at one of your top dairy farms and the farmer wants it sorted sharpish. You get there as soon as you can and find that it’s quite a severe case; she is sick with grade 3 mastitis and you suspect she has endotoxic shock.
• It’s almost impossible for you to know what bugs might be in her udder at the moment but you remember James Breen telling you that gram negatives were pretty high up on the list.

What are the important components of therapy when treating a severe mastitis?

Answer 23

• Antibiotics
  
  • Antibiotics - definitely but for perhaps different reasons than you may expect ; there is limited evidence that cows with severe coliform mastitis are actually bacteraemic, so we have to question the role of antibiotic to treat the mastitis when clinical signs are driven by endotoxamia and pathogens in the udder are probably not viable. Instead we suggest systemic antibiotic is important because the cow is clinically unwell and we need to provide broad-spectrum cover against secondary infections. So not the be all and end all….but a difficult decision to leave them out entirely.
• NSAIDs
  
  • NSAIDs are really important here to reduce inflammation and pyrexia +/- endotoxins, well done.
• Regular stripping of the quarter
  
  • Stripping the quarter is very useful to reduce the LPS levels; remember to advise your farmers to do this
• Nursing care
  
  • Ensuring that the cow has good access to food and water to include fluid therapy if needed, making her comfortable if she is down etc are almost as important as anything else here.

Best is a combination of all of the above!!

Question 24

• A 4th parturition cow has gone down with mastitis at one of your top dairy farms and the farmer wants it sorted sharpish. You get there as soon as you can and find that it’s quite a severe case; she is sick with grade 3 mastitis and you suspect she has endotoxic shock.
• It’s almost impossible for you to know what bugs might be in her udder at the moment but you remember James Breen telling you that gram negatives were pretty high up on the list.

Will you give this cow a systemic antibiotic or an intra-mammary one?

Answer 24

• Intra-mammary
  
  • No definite right answer here (you’ll be getting used to this by now…), and many people will use intra-mammary preparations, though our cattle vets typically wouldn’t. Just make sure that they are sufficiently broad spectrum
• Systemic
  
  • Systemic antibiotics would be the choice of our farm vets.

Question 25

By which route would it NOT be appropriate to give systemic antibiotics if the cow is dehydrated?

Answer 25

• IV
  
  • I/V would be a good route as long as the drug is licenced for that route and the farmer can give it if repeated treatment is needed; i/v meds will penetrate quickly and will not be affected by dehydration for example. Remember you have to abide by the licenced route for your drug of choice though or withdrawal periods as claimed go out of the window….
  • Have a look at the others too
• Sub Cut (correct this would be wrong)
  
  • You’re right, probably not great for a potentially dehydrated animal where the drug might not be absorbed for a long while…. Remember you have to abide by the licenced route for your drug of choice though or withdrawal periods as claimed go out of the window….
  • Your answer is correct
• IM
  
  • Again depending on licenced routes but again this would overcome any hydration issues so would probably not be a bad choice.
  • Remember you have to abide by the licenced route for your drug of choice though or withdrawal periods as claimed go out of the window.

Question 26

Discuss the pros and cons of

Framomycin 15% (Framycetin Sulfate)?

Answer 26

• Aminoglycoside such as framycetin (such as Framomycin);1ml per 30kg IM 3 days; LICENSED. Check the datasheet for why this is a good bet - it’s a relatively broad spectrum aminoglycoside

Question 27

Discuss the pros and cons of

Engemycin 10% DD (Oxtracycling Hydrochloride)?

Answer 27

• Oxytetracycline (Engemycin 10% DD) 60-70ml deep IM injection once (but in a cow with shock better to give 20-25ml IV daily for few days). CHEAP. Label claims that it is formulated to not give pain on injection too.
• Chris adds “oddly the BVA formulary says tetracyclines don’t work against enterobacteriaceae; never been able to find any other texts saying this! Certainly normally seems to work (but maybe this is evidence that ABs aren’t that important!). If I use this I often go iv at the time and get the farmer to do a LA dose the next day”

Question 28

Discuss the pros and cons of

Duphatrim (Sulfadiazine & Trimethoprim)?

Answer 28

• TMS injections such as sulphadiazine/trimethoprim; can go IV, broad spectrum, bacteriocidal via dual protein synthesis inhibition – CHEAP

Question 29

Discuss pros and cons of

Cobactan (cefquinome) or Synulox (amoxycillin plus clavulanic acid)?

Answer 29

• Cobactan: Not appropriate; cefquinome is a 4th generation cephalosporin and is a CIA (critically important antibiotic, together with fluoroquinolones and sometimes macrolides) and should only be used if there is evidence that other antibiotics such as amoxycillin (similar spectrum) are not efficacious.
• Synulox: Potentiated amoxycillin (amoxycillin plus clavulanic acid) has a similar spectrum and many other properties to cefquinome, and like cefquinome is licensed in combination with intramammary tubes (if you are considering this route). Cost is similar, although potentiated amoxycillin has a longer withdrawal period and higher dose volume).

Question 30

Discuss the pros and cons of

Marbocyl (Marbofloxacin)?

Answer 30

Quinolones in mastitis

James and Chris would like you to note the following:

• Ethical and moral issues surround extensive use of these critically important antibiotics (CIAs) in production animal practice, although peracute/acute mastitis is a licensed indication for fluoroquinolones.
• There is little peer-reviewed literature comparing products and often data sheet / advertisement blurb is based on small studies looking at treatment of induced E. coli mastitis in heifers compared to a negative control (saline); therefore relevance to field situation? A study published in Scandanavia has compared the use of fluoroquinolones (FQ) and NSAID versus NSAID alone in a large-scale field based randomised control trial and concluded that the addition of the FQ to acute cases of clinical mastitis caused by E. coli did not significantly improve the outcome. This paper has been used as a subject for a BestBET, the link is at http://bestbetsforvets.org/bet/168
• We therefore recommend to NOT use these CIA, unless you are in a situation where other non-CIA don’t work…which is currently unlikely in most on farm situations concering dairy and beef.
• and to add a bit more controversy/complication to the topic…
• Quinolones such as marbofloxacin (Marbocyl), enrofloxacin (Baytril) and danofloxacin (Advocin 180) are all LICENSED and can be administered IV. Fluoroquinolones are typically concentration-dependant which means a large single dose only is required. They are bacteriocidal without lysis of cell wall (acting on DNA gyrase). Expensive? In terms of cost per treatment they’re often not all that expensive as you only need one dose…. Now then, there’s some really confusing licensing/marketing going on here which is worth being aware of. All the manufacturers produce a daily dosing type product (ie NOT using a regime that makes the most of the conc-dependent pharm of the product, e.g. Marbocyl 10%, Baytril 10%, Advocin 2.5%) AS WELL AS a one-off treatment/high dose type product (e.g. Marbocyl Solo, Advocin A180, Baytril Max).
• Ok so far? The one off drugs would seem more appropriate to maximise the benefits of the concentration dependence in gram negative infections, BUT these one hit wonders aren’t all licenced for mastitis. In summary, for mastitis, licensed FQs are: Marbocyl 10% (daily dose) NOT Marbocyl Solo (one off) Baytril 10% AND Baytril Max (NOT Bayril 5%!) Advocin A180 (one off) NOT Advocin 2.5%

Question 31

In summary, for mastitis, licensed FQs are:

Answer 31

Marbocyl 10% (daily dose) NOT Marbocyl Solo (one off) Baytril 10% AND Baytril Max (NOT Bayril 5%!) Advocin A180 (one off) NOT Advocin 2.5%

Question 32

Summarise cow mastitis?

Answer 32

Not that easy is it? Looks like from the last example that the most important thing is whether the drug will actually kill the sort of bugs you think you have, then everything else comes second to that.

In conclusion, James said he would mainly use oxytetracycline (Engemycin) or a trimethoprim-sulphonamide (Duphatrim), mainly on the grounds of cost and antibacterial resistance issues with CIA’s (critically important antibiotics such as (fluoroquinolones and cephalosporines).

Question 33

A 4 year old Collie called Bess whelped 2 weeks ago giving birth to 5 healthy pups. Her owners bring Bess in to your surgery for a check over. For the last couple of days Bess has been less willing for the pups to suckle her caudal teats and today she has been off her food and did not want to go for a walk thie morning. The pups are fine still though one looks a bit more empty than normal.

What other questions would you like to ask her owner?

Answer 33

• Has Bess had any access to odd foods, toxins etc? No she hasn’t
• Have you given Bess any medications at home? Not other than the Panacur wormer she’s been on
• Has Bess been sick or had diarrhoea? No
• Is she still drinking normally? Yes

Question 34

• You give Bess a check over. She is quiet in the consulting room but apparently this is normal for her. Most of a general clinical examination is unremarkable but you note that her right caudal mammary gland is very red, hot and firm and the secretions look more like pus than milk. The skin over the glands looks normal with no evidence of ulceration. She has a rectal temperature of 40.1C which is higher than you would expect even in a stressed dog
• So Bess has the problems of:

Answer 34

• Anorexia
• Reduced willingness to exercise
• Mastitis
• Pyrexia
• The first two are probably linked to the pain from the mastitis, the pyrexia is significant because it suggests that the inflammation or infection is causing a systemic problem for poor Bess.

Question 35

What is the best course of action for Bess? There is more than one right answer!

Answer 35

• Take blood from Bess for haematology and biochemistry
  
  • Bloods probably won’t change what you do, though checking her blood glucose and calcium might not be a bad idea as she’s lactating.
• Antibiotics
  
  • Abcs are definitiely a good plan, more on these in a minute.
• NSAIDs
  
  • Check the data sheet contra-indications for meloxicam and carprofen. The concern is that the puppy’s kidneys are not fully developed so may be damaged. You may well need to wean the pups anyway to let Bess’s mammary glands recover in which case this would be ok…. If not you could think about tramadol, though its not licenced
• Warm compresses and massage of the mammary area
  
  • Compresses may help for several reasons, probably most importantly of all that if her owners are doing this twice a day then they will be carefully visually inspecting the area and may be able to intervene if there is a subtle change for the worse
• Wean the pups
  
  • Whether or not to wean depends on how badly affected Bess is and whether you go down the NSAIDs route, but this may well be needed. Her owners need something like Welpi or Lactol and lots of time! If she’s not too bad, limited supervised feeding might be alright.
• Hospitalise Bess for fluids and IV antibiotics
  
  • Hospitalisation: If Bess’s mammary glands were starting to ulcerate then certainly this would be a very good idea but at present, as long as you tell her owners what to look out for, you will probably be better to send her home to a more comfortable environment.
• Take a sample of milk for culture
  
  • Ideally yes you would culture though remember that you will have to chose antibiotics emprically anyway as the results won’t be back for about a week. You could do some in house cytology to look for what type of bugs there are but if you don’t you have a good idea about what to expect anyway. Most vets probably wouldn’t do this in a case which is not too severe

Question 36

You remember from your lectures at vet school that mastitis is most likely to be caused by Staphylococcus spp, Streptococcus spp and Escherischia coli. You think a broad-spectrum antibiotic might be the best bet. There are a large number on the shelf for you to choose from. So where will you start?

By what route(s) do you want to be able to treat Bess? There are two right answers

Answer 36

• Oral tablets
  
  • Tablets will be the easiest for her owners to administer once Bess goes home.
• Oral liquid
  
  • You could give a liquid but for an adult dog you would need a large volume so probably not the best choice.
• IV injection
  
  • The drugs would start working more quickly by the intravenous route but probably not vital if she’s going home, plus it starts to limit your choice.
• Sub Cut Injection
  
  • An injection to start Bess off since she’s not eating might be welcomed by her owners, and most dog and cat antibiotics are given s/c so good plan.
• IM injection
  
  • There aren’t many antibiotics which go via the intramsucular route in dogs and cats and it probably isn’t necessary for Bess to have an i/m injection.
• Oral tablets + Sub Cut injection: correct answer

Question 37

So you want an antibiotic which can be given by injection and in the form or oral tablets. Which of the following which fit the bill would be the best bet for Bess (there are two possible right answers)?

Answer 37

• Oxytetracycline (could use)
  
  • You could use oxytet but on the down side it needs three times daily dosing an hour before food, is bacteriostatic not cidal (arguably better in some cases of E.coli but we’ve not confirmed the infection type here) and has high resistance levels in some bacterial groups. Probably better with something else.
• Enrofloxacin
  
  • Inappropriate as it is a fluoroquinolone and therefore listed as a CIA which should only be used if no other more suitable antibiotic is efficacious; good alternative is potentiated amoxycillin (i.e. with clavulanic acid).
• Marbofloxacin
  
  • You could use Marbocyl and it has the advantage of once daily dosing, but it’s a CIA as is enrofloxacin, so whilst both are licenced and indicated it is best to preserve them for situations where ‘first line’ antibiotics (potentiated amoxycillin) are known to be unsuccessful.
• Potentiated amoxycillin (correct)
  
  • Good one, yes the potentiation of the amoxycillin should allow it to cover the gram negatives better, it’s easy to dose and not too expensive plus widely used so not so much of a worry about it being a ‘second line’ drug. You will cover anaerobes to an extent with this drug too. There are lots of generics now as well as such as Noroclav, Synulox and Clavaseptin, some more palatable than others!
• Amoxycillin
  
  • Amoxycillin is good in that it’s cheap and has been around for ages but without the potentiation of clavulanic acid many of the bacterial species will be resistant to this, so best avoided.

Question 38

How long would you treat Bess for?

Answer 38

7 days

• Seven days is probably too short, though you could dispense this as an initial course to check she’s responding before you give more

14 days

• 14 days as a minimum, you may need longer, depending on her response to therapy. I would re-check her every 7 days and continue for at least 5 days after all visible problems have gone

21 days

• It depends on how bad she is; I would re-check her every 7 days an continue for at least 5 days after all visible problems have gone.

28 days

• Some severe cases will need 28 days, It depends on how bad she is; I would re-check her every 7 days an continue for at least 5 days after all visible problems have gone.

Question 39

What treatment did bess get?

Answer 39

Bess went home with potentiated amoxycillin tablets at the upper end of the dose range for an initial week’s period and her owners elected to hot compress the gland but let the pups suckle from the other glands. Luckily her mastitis was caught in time and did not progress so she was on antibiotics for 14 days only. Bess was fortunate; dogs with necrotic tissue must be anaesthetised and the tissue debrided. They may slough large areas of their mammary tissue so need to be hospitalised on fluids, intravenous antibiotics and analgesics. This is when a culture is vital, and if you didn;t do one at the outset, getting a positive result now is hard because the bugs don’t grow very well on a plate once antibiotics are in the system even if infection is still present. You must tell owners how serious this condition can be, a percentage of bitches will die of sepsis if aggressive treatment is not instigated.