Archive for the ‘Dogs’ Category

IMHA in dogs: What do you need to know?

IMHA stands for Immune Mediated Haemolytic Anaemia. It’s a bit of a mouthful so is often known as its less tongue-twisting abbreviation. It’s not as complicated as it sounds and here we will attempt to demystify it.

What is IMHA?

IMHA belongs to a group of diseases known as autoimmune diseases. These occur because the body’s own cells are incorrectly identified as foreign by the immune system. These cells are then attacked and destroyed. With each autoimmune disease, different cells are targeted. With IMHA, red blood cells are targeted and destroyed leading to reduced numbers (anaemia). Two thirds of dogs with IMHA also experience a similar destruction of platelet cells. Platelets are involved in clot formation, and a lack of them (known as thrombocytopenia) leads to abnormal bleeding and is known as Immune Mediated Thrombocytopenia (ITP). When the two conditions occur together we call it Evans syndrome.

What causes this?

Body cells have a protein on the surface called an antigen. The immune system uses this protein to identify its own cells. In IMHA, red blood cell antigens are falsely recognised as foreign which stimulates the production of an antibody by the immune system. The antibody attaches to the antigen and causes the cell to swell and burst. Cells also become more likely to clump (agglutinate) giving higher risks of abnormal clotting.

When the cause of a disease is unknown we call it idiopathic. This is the case in around 70% of IMHA, so we call it idiopathic IMHA, or primary IMHA.

In the other 30% there is an underlying cause called secondary IMHA. Certain infections, mainly spread by parasites like ticks, can lead to secondary IMHA. Most are uncommon in the UK, but should be considered, especially if your pet has travelled abroad. Certain medications have been known to trigger IMHA, such as some antibiotics and painkillers. Some forms of cancer can also trigger IMHA. Recent vaccination has been suggested to trigger the disease but lacks evidence at present. Vaccination prevents serious life-threatening diseases and in the majority of dogs the benefits vastly outweigh the risks.

There seems to be a genetic predisposition in cocker spaniels and Old English sheepdogs, but any breed can be affected.

What are the symptoms?

Symptoms are largely due to the resulting anaemia. Signs may be vague such as weakness, lethargy and a poor appetite. Red blood cells are needed to carry oxygen around the body, so there is often a fast heart rate and breathing rate as the dog tries to compensate for the lack of oxygen. Usually we see pale gums, but there may be a yellow tinge to the gums as when red blood cells rupture they are broken down into a yellow tinged product called bilirubin.

Damage through lack of oxygen within any organ can cause varied signs and, as there is a tendency for red blood cells to clump, clots may form anywhere.

How is IMHA diagnosed?

After an examination and taking a history we may be suspicious.

Firstly we confirm the presence of anaemia. Anaemia has many causes so we need to further define the type of anaemia present. Most dogs with IMHA have a regenerative anaemia, where the body is stimulated to produce more red blood cells to make up for lost ones. In rare cases where the bone marrow is affected then a non-regenerative anaemia is possible.

Next we rule out other causes of regenerative anemia, and other rarer causes of haemolysis like onion poisoning or heavy metal toxicity, and identify whether your pet has had any recent medications or vaccinations. We may carry out further tests to identify infectious causes or cancers.

We often examine the blood under the microscope, looking for certain types of cells known as spherocytes, which are small, round red blood cells often associated with IMHA. We may see more immature red blood cells (reticulocytes) telling us the anaemia is regenerative. We often send samples to a lab for confirmation alongside other specific tests such as the Coombs test, which looks for antibodies on the red blood cells. A saline agglutination test looks for clumping of red blood cells when mixed with saline. It is quick and relatively inexpensive, but can be hard to interpret.

Can this condition be treated?

The first-line treatment for many autoimmune conditions is a corticosteroid called prednisolone, which suppresses the immune system. High doses may be needed initially, aiming to lower and possibly stop medication in the long run. A second immune suppressing drug can be tried in severe cases, or if prednisolone causes severe side effects or doesn’t work. Azathioprine is most commonly used as it is inexpensive, but takes time to work and requires handling precautions. Cyclosporine is licenced for use in dogs but expensive, has an unpredictable dose range and side effects.

A last resort is to help stop red cell destruction in the spleen by removing it (splenectomy). Pets by this stage are very sick and the procedure risky. Many owners would sadly have to consider euthanasia as an alternative.

If we think there’s a risk of excessive clotting we may prescribe medications such as aspirin to mitigate this.

A blood transfusion may seem obvious, but new cells may be destroyed quickly, worsening the signs. However, damage caused by the lack of oxygen in severe anaemia may be a bigger risk, so a transfusion may be recommended.

We would monitor the response to treatment with blood tests regularly. Hopefully once a response is seen, we can taper any medication gradually, whilst continuing to sample for any worsening in parameters. We may also want to monitor for any side effects of the medications.

What is the outlook?

The prognosis with IMHA is variable, carrying a mortality rate of 30% to 70% within 1-2 months of diagnosis. If patients suffer IPT at the same time, or if the bone marrow is affected, the outlook may be worse. The condition can come back, and some animals need lifelong medication.

What is haemangiosarcoma?

Haemangiosarcoma is an aggressive type of cancer which arises from cells that line blood vessels. In this blog we will focus on haemangiosarcoma in dogs as, although it can occur in other species such as cats, this is very rare.

Where do dogs get these tumours?

These tumours have a point of origin (primary tumour), but very often metastasise (spread) to other organs causing tumours elsewhere (secondary tumours).

As blood vessels are almost everywhere in the body, they can occur in many places. Primary tumours most commonly appear on the spleen, but they are also frequently seen in the heart, liver, skin and subcutaneous tissue.

Haemangiosarcoma is the most common type of tumour affecting the heart, accounting for around 69% of heart tumours. It is also the most common malignant tumour to affect the spleen. Much of this blog will relate to haemangiosarcoma of the spleen (splenic), as this form often creates the most discussion, concern, and questions.

Why did my dog get this?

We do not know why certain individual dogs are affected, although we know that, in skin, haemangiosarcoma is linked to sun exposure.

Certain breeds are predisposed. While German shepherds and golden retrievers are prone to the visceral (organ related) forms, whippets, dalmatians and bull terrier breeds are prone to the skin forms.

What signs might my dog have?

The signs depend on where the tumour is.

Haemangiosarcomas of the skin usually appear as a small red or bluish-black lump. They can also occur in deeper subcutaneous tissues, often sitting under normal looking skin.

Haemangiosarcomas located in the liver or spleen often grow rapidly, forming cavities containing blood, often only revealing signs when they rupture causing bleeding. This sudden blood loss can lead to weakness or collapse, and is the most common way dogs with this condition present to vets for the first time. Collapse can also be caused by disturbances in the rhythm of the heart, which can happen in primary heart tumours, but also those in the spleen. Occasionally these tumours are picked up early due to swelling of the abdomen or vague signs of illness. Because the tumour and blood loss can cause clotting issues, bleeding from the nose, or another area, may occur.

How will my pet be diagnosed?

The appearance of skin or subcutaneous masses may lead to our vets advising a biopsy, or removal of the mass. Samples sent to a lab can confirm a diagnosis.

With the visceral (organ) forms, diagnosis can be challenging. Dogs we suspect of having a heart, splenic or liver haemangiosarcoma often arrive as an emergency, with severe internal bleeding. Suspicion may be increased by finding a mass via ultrasound scan of the heart or abdominal organs. However benign tumours, malignant tumours (such as haemangiosarcoma), or non-tumours can look similar on an ultrasound scan, but would all carry very different outlooks. If there is evidence of more than one organ being affected, metastasis is suspected, increasing the likelihood of haemangiosarcoma. There is currently no concrete way of confirming the mass type until tissue samples are examined after surgery. A recent study showed that 63-70% of dogs that present to the vets with abdominal bleeding (not caused by trauma) have haemangiosarcomas.

Occasionally a mass is picked up during an ultrasound scan for a different problem. This gives more time for decision making and surgical planning.

How are these tumours treated?

The skin and subcutaneous tumours can be surgically removed with margins of normal skin. As 30-60% of these tumours will metastasise, it is important to remove them. However they may have already spread at the time of diagnosis. Tumours extending into deeper tissues may benefit from chemotherapy (anti-cancer drugs), or radiotherapy, in addition to surgery.

Treatment of splenic haemangiosarcoma involves surgery to remove the spleen, with an additional option of chemotherapy. These drugs are usually well tolerated but can sometimes have side effects like lethargy, anorexia, vomiting, diarrhoea, and fever. Mild to moderately low white blood counts occur in up to half of dog cases but usually do not require treatment.

Because splenic masses often present as an emergency, decisions regarding surgery often have to be made before a clear diagnosis, and thus prognosis, can be given. Removing the spleen is a major operation and can be risky, with some dogs not surviving the procedure. If the dog is subsequently diagnosed with haemangiosarcoma then the outlook is very gloomy.

Factors such as age, other illnesses and signs of spread must be taken into consideration with decision making. All situations are individual, but for some dogs euthanasia may have to be considered as a treatment option, especially if the outlook is poor.

What is the prognosis?

Skin and subcutaneous tumours, once removed, can be examined to give better information on the severity or ‘stage’ of the tumour. Stage I tumours just affect the skin and are associated with an average survival rate of 2 years, whereas stage II and III tumours that either involve the subcutaneous tissues or muscle have a worse prognosis if treated with surgery alone. Chemotherapy or radiation therapy may improve this.

Sadly haemangiosarcoma of the spleen tends to carry a poor outlook. They are often malignant, and most individuals survive less than 3 ½ months with surgery alone, with very few living beyond a year. If there is no evidence of spread, or tumour rupture, and chemotherapy is used, there is an average life expectancy of around 8 months. If the tumour has ruptured, it can be expected to reduce to an average of 6 months.

Although haemangiosarcomas can be found in many places, the splenic form often creates most difficulties in decision making. Our team will be there to support you, talk you through all of the options, and help you through any difficult decisions. If you have any questions on what you have read, or need more information, please talk to one of our vets.

Why shouldn’t my collie have ivermectin wormers?

Ivermectin is a very commonly used wormer, suitable for horses, cattle, sheep, birds, and a wide range of small mammals. It is occasionally used in dogs – but never in collies and other herding breeds.

What is Ivermectin?

Ivermectin is part of a family of drugs called the avermectins (which, in turn, are one variety of macrocyclic lactones). They work by binding to receptors in worm, mite and insect cells which control how much chloride enters the cell. The drug causes chloride to flood into the cell, causing paralysis and death.

That sounds horrible! Why do we use it in our pets if it’s that nasty?

Because the cells in most of a mammal’s body have a different type of receptor, and ivermectin doesn’t bind very well to it. So, at normal doses in normal dogs, it’s a very safe drug. The one caveat is that you mustn’t inject it into the brain (not that most people would…), as there are receptors in the brain that the drug does activate – but giving it by mouth, or by injection under the skin (or even into the bloodstream directly) is fine.

So what stops it getting into the brain, if it’s in the dog’s bloodstream?

All mammals, including dogs, have a special membrane surrounding the brain, called the Blood Brain Barrier. It works to prevent nasty chemicals getting into our brains and causing problems with the sensitive nerve cells there.

So there’s something unusual about the Blood Brain Barrier in collies then?

Yes, exactly. There is a particular genetic mutation, called MDR1? (also known as ABCB1, just to confuse people…) that means the barrier doesn’t work properly, and allows certain types of chemical through. One of these types is (you’ve guessed it!) the macrocyclic lactones – including ivermectin.

So all collies have this mutation do they?

No – but lots (perhaps as many as 75%) of them do. And a wide range of other dogs also have high incidence of this mutant gene – in fact, we’d generally advise against the use of ivermectin in any herding-type dog.

So, what problems does it cause? Do they become paralysed too?

Not normally – a dog’s brain is a lot more complicated than that of a worm or a flea! The typical symptoms seen include:

  • Altered behaviour – typically sleepiness, lack of normal responses, or coma.
  • Wobbliness and difficulty standing up.
  • Drooling and vomiting.
  • Slow heart rate and breathing (in some cases, the heart may even stop).
  • Tremors or twitches.
  • Seizures.

Can it be treated?

In most cases, toxicity will be managed symptomatically – with drugs to control the seizures and other symptoms until the body can deal with the poison. However, this particular drug is excreted by the liver into the bile; the bile then moves into the intestine, and the drug is then reabsorbed into the body. This is known as enterohepatic recirculation, and means it takes the body a long time to remove it.

As a result, the preferred treatment involves symptomatic therapy (intensive care nursing, intravenous fluids, drugs to prevent seizures and vomiting, and in severe cases medically inducing a coma), plus a specific antidote. This is a treatment called “Intravenous Lipid Infusion”, where a fatty chemical is injected into the bloodstream to “mop-up” the ivermectin.

Are there any other drugs I should avoid? What about selamectin and moxidectin – they sound very similar…

They sound similar because they’re part of the same family. So is milbemycin oxime (another common wormer). However, these drugs are safer in collies (and other affected dogs), because they have an even lower affinity for mammal receptors. However, it is very important that if you are using them, you give exactly the right dose – because it’s much easier to overdose an MDR1? dog than a normal one. For example, if you give your dog an anti-flea spot-on containing moxidectin, you mustn’t give a wormer containing milbemycin at the same time, because together, they could result in an overdose.

If in doubt as to what drugs you can mix, have a chat with one of our vets about it!

If you think your dog may be a high-risk breed and has been exposed to ivermectin, get them to us as soon as possible.

 

Reducing Roaming

One of the most common causes of death for dogs is, sadly, traffic accidents. However, entire male dogs are at a significantly higher risk than others. The reason is biological – but the risk can be dramatically reduced by neutering!

Why do we recommend neutering?

There are a number of advantages to having a dog neutered – eliminating the risk of testicular cancer, reducing the risks of prostate disease, some types of anal cancer, and unwanted behaviour such as humping and, crucially, “roaming”.

What is roaming?

When a female dog is in season, she releases pheromones that can be smelt by dogs for miles around. Male dogs are driven by instinct to seek out the bitch to mate. As a result, even well trained dogs will sometimes run away when lured by the attractive scent. This behaviour is sometimes called “roaming”, but in our modern built-up environments, this usually means crossing busy roads and potentially coming to grief.

What is the procedure?

Neutering of a male dog is a very straightforward procedure, involving the removal of both testicles under a general anaesthetic. Your dog will come in to us in the morning, have the procedure, wake up, and then almost always go home the same day. In fact, in most cases the procedure only takes 15 minutes or so! Without testicles, the dog no longer produces significant amounts of testosterone, and this instinctive behaviour is dramatically reduced.

If you want to know more, please get in touch and talk to one of our vets!

Strange Things Dogs Do…

People are from Mars, are dogs from Venus?

Dogs seemingly do some weird things sometimes. From following you to the bathroom, to chasing their tails, and everything in between, we have explanations for you. But in order to comprehend their actions, we have to get into their psyche. So as you read on further, remember, think dog!

First let’s tackle the above mentioned oddity, why do dogs follow us to the bathroom? Firstly, dogs have different social boundaries. They are perfectly at ease in this situation, they would think it odd that we don’t feel so comfortable. What’s more, you can rest assured that the chances are, this is actually a sign of love, they’re interested in what you’re up to and want to be where you are. So you can feel flattered, honestly!

Love can make anyone do strange things so let’s consider some of the other ways your dog shows you affection, here are our top five:

  1. Your dog boils over with excitement when you arrive home. They love you, they want to be with you, so this surely can’t come as a surprise…

  2. They lick your face. Okay so this is pretty unhygienic, especially if they have a tendency for coprophagia (read on to learn about that term, but you might be able to guess!), but it truly is a sign that you are their human.

  3. It’s all about the eye contact. Eye contact can be a complex thing, staring can mean that a dog is anxious or on the verge of aggression. Anyone who has a dog who gives them that kind of soft, relaxed eye contact knows exactly what the ‘look of love’ looks like, you know who you are, you lucky things.

  4. Simultaneous yawning. One study found that some dogs mimic their loved ones in this way, they yawn when we do. Who’d have thought it?

  5. Remaining calm when you leave them. Sounds counterintuitive doesn’t it? If they love you, why are they okay with you leaving them? Some scientists think that this displays a level of trust. If your dog is relaxed when you leave them, you are great parents, they know you’ll return, the bond is strong.

As lovely as all this talk of love is, what about the other weird things dogs do? Let’s delve deeper into those.

We mentioned the term ‘coprophagia’ earlier. Well, this means to eat poo. As unpleasant as this is, if your dogs does it, you’d probably like to know why. For some, it is a learned behaviour. Whelping bitches will ‘clean up’ after their offspring to keep a clean environment. Some simply learn this from their mother and never lose the habit. Others however might be lacking important nutrients in their diet or their food might simply not be satiating them. Either way, it’s worth discussing this with one of our vets just to be sure.

Ever seen your dog spinning in circles in their bed before settling down? This is apparently to do with the inherent desire to create a safe and comfy ‘nest’. It looks to us like they’re just fussy when it comes to comfort!

Dogs chasing their tail is a classic comedy sight, many dogs do it at some point in their lives. Interestingly, there are numerous reasons a dog might do this, ranging from sheer intrigue to boredom, and from a flea infestation to compulsive disorder.

With so many potential causes of this bizarre behaviour, if your dog does it repeatedly, and especially with a kind of distracted frenzy about them, best get it checked out by the professionals.

What about head tilting? Are there certain words that get your dog’s head tilting from side to side? This unbelievably cute action actually serves a purpose, they are trying to hear you better. They are adjusting their ear pinna (the bits that flap in the wind) so that they may hear you as best as possible. ‘Did you really say walkies?’

These are just some of the more common oddities we see in our beloved canines, each dog has their own personality and we have no doubt they surprise you daily with the funny things that they do. So provided they are well both physically and mentally, enjoy delving into your dog’s mind – you could learn a lot about them.