A hole in the foot (Day -275)

Cow in crush after amputation

When you put your finger into a hole in the foot of a cow and can feel bone you know it is going be interesting for you and very painful for the cow.

Now to understand what happens here you need to understand that cows have two toes (or claws) that contact the floor on each foot. With such a severe problem involving the bones and tendons of a toe the normal treatment would be amputation of that toe. Cows can generally survive on a single toe pretty well just so long as regular foot trimming and management is carried out.

However in the case of this cow the second toe of the same foot was affected though it was only a mild case at this stage. So if we had done amputation here of the really bad toe, the second toe would deteriorate further to the point where it would not be able to support the cows weight, and so the amputation would be pointless.

Economics unfortunately come into play as each cow in the herd has a value, both as meat and as a milking cow. This can justify the cost of the amputation surgery or whether the cow goes to slaughter – however if she is a good milker it is often the farmers wish to avoid this. Now the economics of amputation followed by slaughter in a week or two do not balance and so a clinical gamble based on years of experience was taken by the doctor here.

Amputation is necessary however this amputation would only be done if the other toe recovered. However as with any infection the key is to remove the source and so it was decided that the necrotic bone, tissue and some of the toe would be removed from the toe that would potentially be later amputated.

This level of injury is painful, and so requires good anaesthesia. In cows anaesthesia is usually local – so it only affects the area of the body where the surgery takes place much like if you yourself go to the dentist.

For the legs we apply a tourniquet to separate the foot from the rest of the body, and then make an injection into the veins of a local anaesthetic drug. This time the anaesthetic drug we used was procain – it is another topic however just quickly when using drugs in cows we have to really careful to use drugs that will not get into meat or milk to protect humans.

I was offered the chance to try to make the anaesthesia, and after my dismal first attempt at blood collection on Monday made amends by putting the needle, and then the anaesthetic drug directly into the vein on my first attempt (yay!). Still really believe it was complete beginners luck as me and cows have not really ever got acquainted.

The doctor removed the sesamoid bone and the tendon around this before then debriding the open bone surfaces of the digit. In this process the bottom of the joint capsule was lost and so in an attempt to help preserve the toe for another two weeks for the second toe to heal we also placed antibiotic drugs into the joint space.

Just to show how well an amputation heals (and to avoid gross photos) I’ve chosen today’s photo to be a cow that had an amputation around 6 weeks before.

Tail blood (Day -276)

Cow reproductive management

Blood collection is one of the basic skills of medicine as blood can tell you so much about a patient. Something I’ve very little experience with however is cow medicine – and in cows you normally take blood from the tail. This is because the cow is massive, generally is a safe place from being kicked, and usually is quick when moving through a row of cows.

Theory going into practice though my first calf with this method I failed my first two attempts on the tail so decided to go for the jugular instead which was a lot easier for me to get. Getting a jugular vein in an adult cow however is a big effort as the cow needs to be properly restrained and often into a crush to do it safely.

So disaster for me – even though I had got the blood needed for testing from the jugular – it was still a really harsh personal insult that I had failed from the tail. The theory with collecting blood from the tail is that you insert the needle directly in the center of the underside of the tail until you hit bone. Pull back slightly and then the blood will flow. So simple yet I had failed.

There was still time though with maybe another 50 older calves to go. These were harder to restrain, a lot more work, and a lot bigger. Being bigger also meant that these calves had larger tail veins, and so every cow going forward I had no problem collecting my blood from the tail vein.

The second thing with cows that is important when it comes to cow medicine is managing the herd behaviour. For cows will run away from you, and look for a path to escape, and cows will fall especially if in a herd. And then the others in a panic will walk over the fallen ones to escape. So what was a herd of unvaccinated cows will become a herd of broken, beaten, unvaccinated cows.

We wrestled our way through these 50 calves using brute force and the fence of the pen to restrain them. With the last calf we were happy to be done, and the calves happy to see us go.

Dehorning and holes into the skull…

Dehorning cows - a hole into the skull

Friday again, another morning spent on the farm working with the dairy herd in diseases of ruminants. With Easter so close a lot of people have travelled home and so today’s group is really small. Last time was reproduction work so today is orthopaedics and other surgery unrelated to the reproductive tract including today dehorning.

Cows are generally gentle loving animals, however their heads are one of their primary weapons, and with horns they are actually quite formidable. This endangers workers, plus also the other animals in the herd. Most of time the tissue that grows the horn is removed when they are calves so that the horns do not grow, however if there is a problem with this then the horn can still grow.

These horns are basically made keratin which is the same as your finger nails – however in cows after they reach about 2 months the horn “bud” attaches to the skull underneath and the sinus cavity inside the skull will expand into the horn as it grows. This is where the photo is from – it is the hole that is left after the horn has been removed looking into the frontal sinus.

The horn has a nerve going to it (the cornual nerve) which goes from behind the eye so before we do anything this is blocked by using procaine as a local anaesthesia which means that there is no feeling anywhere around the horn.

After the horn bud attaches to the skull at around 8 weeks only a vet is allowed to remove it – farmers can only remove the tip of the horn so that it is not sharp. Removing the tip however doesn’t remove the danger as it can cause significant bruising and damage to others. So at this stage it is still beneficial to remove the horn, this is done by a surgical wire saw and usually takes under a minute to do (the record here is apparently 17 seconds). Once the horn is removed any bleeding from the blood vessels is controlled by ligation and antibiotic spray applied to the site.

Unfortunately this is the only way to remove the horn, and there is not enough loose skin in this area to close over this so it is left open. It takes around 4 weeks for a scab to form over this opening – and then a further few weeks for it to form a proper scar.

This does not cause as many side effects as may be expected – having a patch over the hole with a bandage is generally not liked by cows and they tend to remove it within hours. And from the studies I have read having a patch does not reduce the healing time. The only recommendation here is to keep the cows that have been dehorned separate to the rest – this is good from a management point of view as it is easier to check that nothing is going on with them.

The rest of the morning went do checking on some patients post digit amputation. One of these had a large abscess higher up the leg which was removed. This lead to some bleeding and I was allowed to ligate the bleeding vessels here. Today was my first suturing ruminants and it was pretty different for me with how thick and tough the skin is so I was pleased to get the practice. However even after ligation of the main bleeding vessels there was still significant capillary bleeding and so we applied a tourniquet to the leg to reduce the blood flow and allow clot formation before we released the cow back to the herd.

We were pretty disgusting when we finished, however went straight into lectures for contagious disease… The joys of vet school.