An Approach to Lameness

Lameness issues are often a problem faced by in-practice vets and it can be sometimes hard to identify the primary cause. In this article we will discuss the possible primary causes of lameness in backyard poultry and the basics behind diagnosing and treatment.

There are roughly seven different causes of lameness. A common primary cause is bumblefoot, an infection of the foot pads and the most common bacteria isolated from these infections is staphylococci. Bumblefoot can present in many ways including a swollen and hot foot pad. The swelling can be soft or hard, depending on its chronicity. In early cases of bumblefoot, a 3-5 day course of Meloxicam at an intitial dose rate of 2mg/kg is recommended, followed by a daily dose of 1mg/kg. A concurrent use of broad spectrum antibiotic can also be used. I often find that a 7 day course of Amoxiclav at a dose rate of 125/150mg/kg PO for 12 hours a day or 125-150mg/kg given IM every 24 hours helps. This is an off-license product and will therefore require a 28 day meat withdrawal and 7 day egg withdrawal period. If this approach does not work for the initial presentation, if it is too severe, then a local incision to open up the infection may be required and a conversation with one of our vets about the details of this procedure should be sought.

As many more people keep chickens and look after them well, the length of a chicken’s lifespan is increasing. Many vets have questioned whether or not chickens, like many other domestic species, are susceptible to osteoarthritis. In my opinion, there is no logical reason why they would not be and I have seen a few cases with no apparent cause of lameness, where a course of NSAIDS has worked to resolve the instance of ongoing lameness. Diagnosis of osteoarthritis can be very difficult, as even with appropriate x-rays, there is very little literature to support what a normal radiograph would look like. For this reason, the age of the birds and the lack of identifying a primary cause generally leads to a clinical diagnosis of osteoarthritis and maintaining the birds on a low level of NSAIDS. In theory, a dose rate of 1mg/kg and tapering this to the lowest effective dose would be the best approach. However, the efficacy and safety of this product in situations like this has not been tested and continual monitoring is recommended. Unfortunately this this is an off-license product and will therefore require a 28 day meat withdrawal and 7 day egg withdrawal period, but as the age of the hens is usually quite old it normally suggests the bird will be laying very few eggs.

Joint infections tend to be more common in younger birds, however can occur at any age. Sometimes, there is an obvious cause for the infection such as a penetrating wound, however, more often than not there is no cause that can be identified. Situations where the joint is swollen and hot is suggestive of a joint infection and a radiograph could possibly highlight the swollen tissue in the joints. However, radiographs are expensive and not usually necessary. A 3-5 day course of Meloxicam at the previously stated dose, and a 5-7 day course of Amoxiclav at a dose rate of 125/150mg/kg PO for 12 hours a day or 125-150mg/kg given IM every 24 hours normally treats these situations.

Occasionally I see cases of what is most likely tendon or muscular damage causing lameness. This can often be caused by treading behavior to either the cockerel or the hen. They normally present as acute mild lameness, no signs of swelling around any joint and no signs of bumblefoot. Diagnosis again can be difficult and can be a matter of ruling everything else out first. Antibiotics have no affect which can often point in the direction of muscular/tendon damage. A 5 -7 day course of NSAIDs such as Meloxicam at the initial dose rate pf 2mg/kg and then following with 1mg/kg dose. I normally suggest isolating this bird, especially if there is a cockerel around during this course and then arrange to see the bird at the end of treatment to assess if further investigation is needed or not.

I do occasionally see chickens with broken bones, these have usually caught their feet somewhere such as between pallets/floor boards or have flown down from a height and landed awkwardly. In this instance euthanasia is the usually the best option both due to financial constraints but also the lack of experience by anyone in the practice to perform surgery to correct the break. Euthanasia should be carried out using a pentobarbitone based product such as Pentobarbital 20% solution at a dose rate of 150mg/kg this should be attempted to be given intravascularly using the wing vein. If this is not possible, then an intrahepatic or intraperitoneal injection should be adequate as a second option.

Mycoplasma synoviae (MS) infections could progress as either acute or a chronic disease with symptoms of arthritis, synovitis and bursitis as well as other systemic symptoms. Unfortunately MS can look like several other infections and to identify the cause the best methods include take vent swabs and send them off for PCR testing or to take blood samples to look for antibody titres, however analysing blood results can often be difficult if the history and especially vaccination history is unknown. Treatment includes the use of Denagard which is licensed for Mycoplasm Synoviae and is also licensed for laying hens. The standard dose rate for Denagard 12.5% oral solution is 25mg/kg for 3-5 days. This drug has a 2 day meat withdrawal period after the end of treatment and a zero egg day withdrawal period.

And finally Marek’s disease, although there are many forms and presentations of which are to detailed to go into this article, Marek’s can present as bilateral lameness. The chronic (classical) form is encountered as neural type, fowl paralysis. Both limbs are generally equally affected and there are very few other causes of bilateral paralysis. If this is presented, then bloods can be taken to ascertain the antibody titres, however histopatholgy is often the best method of diagnosing this disease. If you are highly suspicious of mareks disease it is usually advised, although every situation is different, to euthanase the affected bird as it is not likely to recover and this will hopefully minimise the possibility of spreading the virus to other flock birds. A detailed discussion with the client about disinfection of all equipment and housing as well as the possible use of Marek’s vaccination, depending upon their set-up should be discussed. Marek’s can potentially remain on a site for several months if not years in anything even dust particles, for this reason it is a very difficult disease to remove once established on a particular farm or garden.