Canine SLO FAQ

By Andrea J Chee

With many thanks to the members of the SLO mailing list, for use of their questions and answers in this FAQ.

What is SLO?

 

SLO is an autoimmune disease of dogs which can cause severe claw problems in otherwise apparently healthy dogs. It is characterised by the loss of claws from more than one paw - eventually all claws may be lost. Other symptoms may include: receding quicks, secondary infection (often with a strong smell), claw splitting (usually down the back of the claw), pain, distorted/twisted claws and lameness.

 

What is an autoimmune disease?

 

Essentially, AI diseases are related to allergies.

 

The immune system is supposed to attack foreign substances which pose a risk, such as viruses or bacteria.

 

If the immune system reacts to things which are essentially benign, like pollens or nuts, you get an allergy.

 

If it attacks some part of its own body, you get an AI disease.

 

Your dog's claws are damaged because the dog's immune system is damaging them.

 

The immune system needs to be in balance - if it's too weak it can't fight off infection, if it's too active it attacks things it shouldn't.

 

What is the anatomy of the claws?

 

The claw is made up of three general layers. The outside part is hard dead material, analogous with human fingernails. In the centre of the claw is the living part, complete with nerves and blood supply, called the ‘quick’. Between the two is a layer of spongy material.

 

The nail forms at its root, which is located deep inside the toe near the endmost bone of the toe. The newly formed nail grows out towards the external part of the toe for about 3-4 months before it emerges and becomes visible. It takes about 9 months for a nail to grow from root to full length.

 

Where does SLO claw damage occur?

 

The damage occurs while the claw is forming at the root, although the claws usually don’t shed until the damaged part emerges from the toe. As a result, damage you see now actually occurred several months ago, and the results of treatment can’t be assessed for some months after it’s started.

 

What are the typical characteristics of affected dogs?

 

Size

 

Typically, SLO dogs are medium to large dogs, however some dogs of other sizes have been reported with SLO.

 

Age

 

Most dogs first show symptoms of SLO at 4 or 5 years of age, however dogs of all ages have been reported as having developed it, including puppies under one year of age.

 

How is SLO diagnosed?

 

There are three main methods of diagnosis – diagnosis by aetiology (the characteristics of the disease), diagnosis by response to treatment, and diagnosis by biopsy.

 

Diagnosis by aetiology

 

Someone who is familiar with SLO may well be able to make a diagnosis of SLO on sight, particularly if it follows the typical characteristics of the disorder. The possibility of fungal and bacterial infections needs to be eliminated first, as these are more common and can produce similar symptoms. Unsuccessful treatment of bacterial and fungal infections increases the likelihood that SLO is the cause.

 

Diagnosis by response to treatment

 

In many cases, where SLO is suspected, the owner or vet may decide against a biopsy and choose instead to commence treatment immediately. The treatments for SLO are quite specific, and usually if the problem responds to the treatment one can consider the diagnosis confirmed.

 

Diagnosis by biopsy

 

Diagnosis by biopsy is done by taking a sample of the root of an affected claw and examining it under a microscope. This method is easiest if the dog had affected dew claws, since a dew claw can easily be removed for study.

 

Until recently, taking a biopsy from a claw other than the dew claws has been a major step for most owners, as it involves amputating the distal phalanx (last bone) of the toe.

 

More recently there has been a new biopsy technique involving using a biopsy punch to get a sample of the root. This technique is described in the file:

 

https://groups.yahoo.com/group/SLOdogs/files/onychobiopsy.pdf

 

What causes SLO and autoimmune diseases?

 

No-one knows. The most likely explanation is a complex combination of risk factors and triggers, which may even be different in every single dog. There is likely to be a genetic component, most likely caused by a spontaneous mutation. Food additives, vaccination, other infections, pollution and other possible causes have all been speculated on. Certainly, it is possible that they may be part of the combination of causes. However, there is no evidence that any one of these causes autoimmune disease.

 

Food

 

If it was just food, it would have been spotted long ago. There have been study after study on diet in autoimmune diseases, especially in humans, and if the cause were that simple it would already have been found. Dogs suffering from SLO have come from all sorts of different backgrounds and have been fed all manner of diets, from proprietary foods to raw diets.

 

Inheritance

 

It’s possible that a faulty mutation can be inherited, but such mutations seem to serve only to make a dog susceptible to such diseases. It’s likely that they still need the other combinations of factors to trigger the disease, as there doesn’t seem to be a prevalence of SLO in specific bloodlines.

 

Vaccines

 

Vaccines challenge the immune system, and as such could be a trigger factor in combination with other things (just as infection also challenges the immune system – so the same trigger effect could occur if the dog becomes ill). There is no evidence that they specifically cause SLO though, or the disease would be much more common.

 

Heartworm Treatments

 

There is unlikely to be a connection between heartworm preventatives and SLO, although like everything a dog comes into contact with it could combine with other things to be a trigger. While many US dogs have used heartworm preventatives prior to SLO, most (probably all) of the UK dogs have never taken such a preventative in their lives, as they don’t have heartworm there. Yet there are plenty of SLO dogs in the UK.

 

Neglect

 

Many people, especially greyhound owners, ask if SLO could be caused by abuse or neglect. If SLO were solely down to poor diet and absence of care, I'd expect a whole lot of labradors here considering how many there are that are badly bred and end up neglected. In general, racers are well cared for, since no athlete can run at his best unless he is fully fit. Your average racer at least gets regular food, daily stimulation and contact, exercise, grooming and a dry warm place to sleep - there are a lot of pet dogs who don't get anywhere near that much.

 

My dog has infected claws – could that have caused the SLO?

 

Infected claws are common in SLO, since the shedding and damage allow infection in. However, it seems to be neither a cause nor a true symptom. Instead it is a common secondary affliction of affected dogs.

 

Once the nails have dropped off, can they grow back normally?

 

In most cases, if the treatment is working well, the claws can grow back normally or nearly normally. Most people have commented that the re-grown claws still look a little flaky or are a bit twisty, but they do keep growing without dropping off.

 

How long, on average, does it take the nail to regrow?

 

A full claw takes about 9 months to grow, from the point where the nail forms deep inside the toe to full length. It takes about 3 months for the nail to grow to the point where it emerges from the toe, and about 6 months from when the new growth is first visible until there's a full- length claw. All dogs are different though - this is just an average, so some dogs will have slower or faster growing claws.

 

How often can the condition recur in the same dog: Yearly? Every  few years?

 

It doesn’t recur so much as it is ongoing - it's just that the claws need to grow to a certain length before they're visible and then keep growing until there's enough claw for the pressure on them to make them fall off again. That produces an apparent pattern where the claws drop off until they're all gone, then they regrow over months until they're long enough to start falling off again, and that repeats over and over.

 

So to the owner it appears as if there are times when the claws appear to be doing a good job of growing, interspersed with times when the claws seem to be falling off at a rate of knots, followed by times when the dog seems to have no claws growing - with a little bit of unpredictability because not all claws grow at the same rate or fall off as quickly as others. That makes it look like there are bad periods and good periods, but I'm not convinced that there's actually any difference.

 

On treatment, it varies depending on how well the dog responds. There are dogs which have no relapses at all if the treatment is working well.

 

Can the condition go dormant and never recur?

 

Not that anyone knows of. There are other claw conditions that do go away with time or treatment, but SLO is an autoimmune disease and they tend to be a lifetime thing.

 

Does having an autoimmune disease mean he is at risk of catching infections? Is his immune system weak? Should I keep him away from other dogs?

 

There's a difference between an autoimmune disease and an immunodeficiency one. His immune system is still working - if anything, it's doing too much rather than too little. I'd avoid actively exposing him to known sick dogs, simply because you don't want to constantly challenge the immune system of an autoimmune dog which will encourage it into even more activity, but if he does come across a sick dog on his normal travels his immune system is still able to attack disease. It's immunodeficiency rather than autoimmune diseases that prevents them being able to fight off diseases.

 

In other words, if you work at a vet's I wouldn't take him to work with you, but normal contact with other dogs is fine.

 

Will he develop other disorders because he has SLO?

 

You can't really tell what the effect will be in terms of developing other disorders. Some dogs don't seem any more likely to catch things. Others seem to be more susceptible, whether because of the treatments (pred, for example, has significant immunosuppressant effects - it reduces the activity of the immune system) or because the SLO is running them down.

The action of the immune system is quite tiring - ask any hayfever sufferer and they'll tell you the effects make them feel far worse than some sneezing and a stuffy nose should do. So some dogs do get tired and may catch things.

 

On the other hand, if you suppress the immune system, it can't attack infections so the dog may catch things because of that.

When it comes to AI diseases, most dogs only seem to get one but a small number of dogs may develop more than one, in the same way that most hayfever sufferers never get any other allergies but a small number of people may get more than one.

 

When was the first recorded incident of SLO?

 

It’s likely that SLO has always been around, but it has only recently been recognised as a separate disorder in its own right.

 

SLO as a separate disorder was only really first described and named in a paper which was published around 1995, based on research going back to the late 80s. This information then took time to spread beyond the limited research community (it's still doing so), and as a result awareness that it is a separate disorder from the more general pemphigus diseases is very recent and still patchy. Before that, it was simply referred to as pemphigus, since it was recognised to be one of the pemphigus group of disorders.

It frequently gets mentioned in greyhound books in particular as pemphigus. For example, Care of the Racing Greyhound was first published in 1994, before the authors could have known about SLO as a separate entity, so it's described as pemphigus. They're correct in terms of the knowledge they had available to them when the book was written.

 

Treatments

 

The treatment protocol most used by members of the SLO group is the combination of EFAs (essential fatty acids or omega 3 and 6 oils) with niacinamide and tetracycline.

 

EFAs (for example, EFAcaps, DermCaps, EfaVet, Efapet - most vets have a favourite they already use) are given at double the dose normally used for skin problems.

Tetracycline and niacinamide (must be niacinamide, not niacin or nicotinic acid) are given at a dose of 250mg of each 3 times a day for dogs weighing less than 10 kg, and 500mg of each 3 times a day for dogs weighing more than 10 kg.
 
The tetracycline is usually stopped after a couple of months, then once the claws are growing well the other treatments can be reduced. This needs to be done painfully slowly. Because nails grow extremely slowly the nail you can see was actually created months ago, so treatment changes you make now show up months later. The nail you can see appearing out of the toe started forming about 2-3 months ago, and a full-length claw takes about 9 months to grow.

The main purpose of the tetracycline is as an anti-inflammatory, and it's known to work in combination with the niacinamide (which improves blood flow). However, it is also an antibiotic so tends to have the side-effect of treating infection if it's present.
 

In severe cases, or those which don’t respond well to the above treatments, steroids such as prednisolone/prednisone may be prescribed.

 

EFAs

 

EFAs are Essential Fatty Acids, the most important of which in terms of SLO are Omega 3 and 6 oils. They are usually found in combinations of fish oils and oils of plant origin such as evening primrose or flaxseed oil. In some cases, improvement of SLO has been noticed using EFAs alone.

 

Tetracyclines

 

It's been my understanding that tetracyclines have several positive effects besides their antimicrobial properties. One thing they can do is reduce inflammation, thus their usefulness in certain varieties of autoimmune disease. Combined with the niacinamide, which increases blood flow, the theory is that these two actions should be able to keep the inflammatory process in check and allow new nails to grow. The antiinflammatory effect is much milder than it would be with steroids, but may be enough in some cases to provide good control of the condition.

 

There has been some interesting research lately in the field of human arthritis and the tetracyclines. Besides the antiinflammatory effect, tetracyclines also seem to be able to prevent the breakdown of cartilage, which makes them useful for both rheumatoid and osteo-arthitis. There is a study floating around somewhere that showed clinical effectiveness in dogs with osteoarthritis, so if nothing else, our SLO dogs that are taking tetracyclines should at least get some joint benefit from it (though doxycycline has been shown to be superior to tetracycline in its ability to infiltrate joint fluid)

 

Steroids

 

In Care of the Racing Greyhound which talks about this  condition in Greyhounds, although they refer to it as Pemphigus, it  recommends using prednisone/prednisolone according to this schedule:

 

5mg 3xday for 5 days, then
5mg 2xday for 10 days, then
2.5mg 3xday for 10 days, then
2.5mg 2xday indefinitely

Dr Suzanne Stack, a greyhound vet who has a lot of experience treating SLO with pred, prefers to get them onto an every-other-day maintenance dose rather than
the above, since that seems to be better tolerated with fewer side-effects.

 

Trental

 

Pentoxifylline (Trental) is a new drug which some consultants are now prescribing for SLO. It is not yet licensed for dogs, but is licensed for use in humans, and this does allow them to try it. Pentoxifylline works to improve the circulation, which is what the niacinamide also does, so it is not recommended to use them together. It probably also has the side-effect of causing doziness. Dogs in the SLO group who are taking it have suffered from this problem, and humans taking it are warned not to drive or do things requiring alertness.

 

Alternative treatments

 

Do be wary of using treatments which are not recommended by vets or others experienced with dogs, or which are not already in common use in dogs. In some cases, treatments which would normally be safe in people are not so in animals. In other cases, small doses might be safe but larger ones may not. One dog from the SLO group suffered from severe poisoning after the topical use of tea tree oil as recommended by a pharmacist. Never give any alternative therapy without researching whether it is safe for use in dogs.

 

Reducing treatment

 

Watch out for reducing too soon. Some dogs do have a period where they seem to improve, whether they're on treatment or not - it can go through cycles. But weeks or months into the treatment they are still growing out the damaged part of their claws, so don't be surprised if they suddenly go through a phase of losing claws again. They can do that even if you haven't reduced the treatment, as the last of the damaged claws are being shed. It’s very common for the SLO to apparently get worse after starting the treatment, as the old damaged claws are lost.

Usually you need to stay on the full treatment for about 4 months before you see the effects. Then when you reduce treatments, you need to wait the same amount of time before you can be certain if the reduction is going to cause problems. The claw you see emerging from the toe is still untreated - it forms deep inside the toe and takes time to grow to the point where you see it.

 

There is no set maintenance dose. Some people have good maintenance on very low doses of niacinamide alone, or EFAs alone. Others find that various combinations work well for them. A certain amount of trial and error is required before you find what works for your dog.

 

Vets, Specialists and Consultants

 

While some skin specialists are familiar with skin-related autoimmune diseases in general and/or SLO in particular, don’t be surprised if you are referred to someone who seems to know little more than you do. SLO is something of an overlooked condition, and many veterinary specialists may not have come across it before. If you are fortunate, you may find someone who has treated it before. The most important thing is to find an open-minded vet who is prepared to look at any information you provide to him and work with you on finding a treatment that works.

 

Vaccines

 

There are certainly arguments for using different vaccination protocols, such as the three-year cycle, in all dogs. There are also arguments for and against the use of titres. But there aren't any specific vaccination recommendations or protocols for SLO (or AI diseases in general) as yet. Some people recommend vaccinating dogs which already have AI diseases as little as possible, because their immune system is compromised. Others don't.

It's really a decision for the individual, in consultation with their vet, taking into account the local risk associated with infectious diseases, because there's little information at the moment to guide your decision.

 

In general, reducing the number of vaccinations given doesn’t normally increase the risk of contracting the various diseases, and many top vet schools are now advocating vaccinating less often. There is more information on vaccination protocols here:

 

https://www.critterfixer.com/k9%20vaccination%20chart.htm

 

Rabies

 

In some parts of the world, notably the USA, rabies vaccine is required by law. In the USA, this requirement varies from state to state. In many states, it is possible to be exempted from the legal requirement (or go to a three-year protocol in a state which requires annual vaccination) with the co-operation of your vet. Contact the local government authority which deals with the rabies requirements in your area for information on whether this is possible and to find out what letters etc you may need to provide from your vet in order to gain exemption.

 

I’ve been reading the SLO list, and it seems that the SLO dogs suffer from lots of other problems – is this really the case?

 

I think it just gives that impression. I've not seen any evidence that it genuinely leads to other conditions, although there are a small group of dogs that may be susceptible to autoimmune conditions in general – in their case though, the SLO is a symptom of a generalised autoimmune problem; it didn't cause the other diseases.

We did a poll on this subject a while back, which showed that 75% of the people who responded had dogs with SLO only, less than 10% had another autoimmune disease as well and 15% had non-AI conditions plus SLO (which can include everything from cancer to bitch spay incontinence). The poll only asked about long-term illnesses, and ignored the more brief things that people often ask about on the group. It's just that the group has become a good place for people to ask all sorts of doggy health questions, because we're all friends and can share info.

Assume for a moment that each of our 115 members has just one dog (and we know that there are plenty who have more than one), and each of those dogs gets a non-SLO problem just once every three years (numbers off the top of my head, since some dogs seem to get one thing after another and other dogs never seem to have problems). If each of those people mentioned their problem on the group, we'd be hearing of a new problem every 10 days or so! Because the problem may be a topic of conversation for a while rather than just getting one mention, it means that we'll always be discussing some non-SLO thing or another.

So it sounds like there are lots of problems, but it's not really the case. It's just the normal range of things that will crop up in any large group of dogs.

 

BARF and other raw diets

 

There is usually nothing wrong with a well-balanced raw diet being fed to healthy dogs.

In terms of SLO dogs, I wouldn't recommend it. Even with the best possible handling, raw meat will always contain some bacteria. In healthy dogs, this does no harm - indeed there is an argument that it helps encourage the development of good immunity by offering a challenge to the immune system (in the same way that it's not recommended to get too carried away with protecting kids from germs since it does their immune systems good in the long run to learn to cope with potential infectious agents).

For the same reason, raw food does represent a higher risk in dogs with immune system disorders. Dogs with immunodeficiency problems may not be able to fight off bacterial infections that healthy dogs deal with easily, while those with autoimmune disorders such as SLO have the opposite problem and their immune systems may over-react to the challenge, leading to more immune system activity than you want.

Challenging the immune system with the bacteria in a raw diet is really no different to challenging the immune system with vaccinations. Neither is recommended in dogs with autoimmune diseases - their immune systems are already too active.

 

Clipping Claws

 

Of course, when a claw is lost, it can’t be clipped. However, once it starts growing back in, you may have to decide when and how to clip it. Common sense is the rule here. SLO dogs frequently lose the hard outer shell of the claw and retain the quick in the centre of the claw. Claws should not be routinely clipped before the claw growing in extends past the quick. Once it has grown beyond the quick you can clip them as normal. Occasionally a claw will have a ragged end which catches on things, and you can clip off any of the hard shell of the claw that is ragged in order to prevent this. You may have to do this while the quick is still exposed, so take care only to clip the hard nail itself. Clipping the quick can be very painful and cause bleeding.

 

Dremels

 

Many people now use Dremels or other hand-drill type gadgets to file the claws down. SLO dogs can be Dremelled, again using common sense. There is a good guide to Dremelling dogs’ claws to be found by following the link at the bottom left-hand corner of this website:

 

https://www.doberdawn.com/

 

Resources

 

The SLO Page:

https://www.bloodaxe.demon.co.uk/SLO/

 

The SLO Yahoo Group:

https://groups.yahoo.com/group/SLOdogs/

 

Understanding Autoimmune Diseases:

 

https://www.niaid.nih.gov/publications/autoimmune/textonly.htm

 

MesaVet article:

https://www.mesavet.com/library/symetrical_lupoid_onychodystroph.htm

 

An early SLO study:

https://www.beaconforhealth.org/Onchodystrophy.htm

 

‘Canine Symmetrical Lupoid Onychodystrophy’, Journal of Small Animal Practice (BSAVA, UK), February 2001 issue.

 

Care of the Racing Greyhound, Linda L. Blythe, James R. Gannon and A. Morrie Craig, 1994