Health issues present in today's U.K Alaskan Malamutes dogs: Cushing's and Hypothyroidism
Hypothyroidism in Alaskan Malamutes (Under active Thyroid gland)
We are one of the very few Alaskan Malamute breeders in the UK that tests and screens ALL our dogs annually for Thyroid function. There is a thyroid epidemic within the canine community that is hugely mis-understood with misinterpreted results given by veterinary surgeons. Any dog carrying the (TgAA) antibody regardless of result, should be on HRT of Thyroxin medication and is classed as genetically affected, (hereditary hypothyroidism). The gland is under attack but the bloods will only show as low T4 hormone when 60-70% of the gland is destroyed. They could be at 56% and you wouldn't know!
These antibodies can change in value and so annual testing is crucial, as after the age of 8 they will all of vanished, due to the gland being fully destroyed. This is when most owners notice their dog has suddenly 'gone old' but no! The gland is no longer functioning at all! You can however monitor the function with annual blood tests and nip the condition in the bud. Why wait for your companion to feel so ill he turns his back to you and no longer appears to enjoy life when a 14p tablet twice a day makes him feel amazing again.
Some breeds are more likely to have thyroid issues and the Alaskan Malamute is one of those breeds. Even without the antibodies present low T4 indicates 'auto-immune thyroiditis' which is genetic. Any change in results means that dog should not be used in a breeding program . Only dogs with a genetic potential can develop auto-immune thyroiditis, hence their compromised immune system is fragile to vaccinations and external influences such as flea-treatments and also easily develop food allergies.
Anti-bodies will be seen by the age of 4. This is the best age to decide whether the dog is suitable for your breeding program or not. The mode of inheritance of hereditary hypothyroidism is inconclusive to date. Malamutes just carry a higher genetic load of hypothyroidism causing genes. It affects the same amount of male to female as a ratio.
Thank you to Jerold S Bell DVM and Professor Jean Dodds DVM for all their help in blood results, our research and personal emails. Feb'21
I have no experience in over active Thyroid issues, (Hyperthyroidism occurs when your thyroid gland produces too much of the hormone thyroxine. Hyperthyroidism can accelerate your body's metabolism, causing unintentional weight loss and a rapid or irregular heartbeat ) however under-active is the form most likely in Malamutes.
What is this 'Gland?'
The thyroid is a butterfly shaped gland in the neck that regulates the metabolism of the body’s cellular functions by producing hormones such as thyroxine (T4). Hypothyroidism occurs when the thyroid doesn’t produce enough T4.
90 percent of cases hypothyroidism is from an autoimmune disorder. This autoimmune thyroiditis happens when the body mistakenly interprets its own thyroid gland and hormones as foreign threats. The body then produces antibodies to destroy the functional thyroid gland cells, resulting in loss of function.
As much as environmental factors also play a role: chemicals in medicines, flea and tick products, heartworm drugs and vaccines are all environmental triggers for autoimmune reactions some breeds for whatever reason as more prone.
There is also secondary hypothyroidism, which involves all three glands – the hypothalamus, pituitary gland and thyroid – that work in conjunction with each other. The pituitary gland secretes TSH (thyroid stimulating hormone) that stimulates the thyroid to function. But the pituitary gland gets its “orders” from hormones released by the hypothalamus so these three glands can’t work properly without proper input from the others; the thyroid might be normal, but is not receiving the messages it needs to function. This could be from injury or disease of an individual gland.
Hypothyroidism Symptoms:
The classic symptoms of hypothyroidism are familiar to many:
Behavioral changes which should never be over looked. As a clinical canine behaviorist (in training) I will be asking for this on every veterinary referral to our clinic.
Food allergies appear from no where.
Phantom pregnancies, menstrual irregularities, stillborns, abortion, low sperm levels, decreased libido or fertility issues.
Seizures appearing as idiopathic epilepsy.
Please insist on blood drawn for FULL thyroid panel test before treating with phenobarbital, as this drug lowers the T4 results, hence vets will not link the two together. ANY seizure appearing from no where needs veterinary treatment to rule out poisoning and then ask for thyroid testing during routine bloods. British veterinarians are unaware of the link between Alaskan Malamute THYROID FUNCTION and Epilepsy type SEIZURES. The TgAA auto-antibody alone can cause seizures and needs Thyroxine BEFORE epilepsy medicines are considered.
Weight gain when food has not been increased (idiopathic obesity)
Loose joints, patellar sub-luxation, torn cruciate ligaments
Gastrointestinal (bowel) problems .
Sluggishness, fatigue, anxiety & depression (sit in corner of rooms/avoid interaction) dislike/no desire of exercise
Scurfy skin, dark pigmentation/patches of skin, hair loss such as undercoat leaving bald patches or just guard hair
Oily greasy coat & dislike of the cold as they are genuinely struggling to keep warm and a very 'sad' look .
S ome say the first signs they noticed was the dog became ' grumpy ' with other dogs and presumed had temperament issues when in fact it is a sign of very early thyroid damage.
Obsessive compulsive behaviours, sudden fearfulness or bizarre snapping.
Smelly ears and ear infections .
Testing:
The in-house T4 blood test alone is useless because it can be affected by many other factors such as diet and medications. Diagnosis should never be based on T4 alone. This is normally the quick blood test available in all veterinary surgeries. What you need is the complete thyroid antibody profile, measuring at least T3, T4, Free T3, Free T4, and TgAA. If your vet doesn’t offer this please insist on having the blood drawn and sent to another lab that offers this testing. This test with consultation, blood drawn and posted with full analysis cost around £180 (Nov 2018). After medication is prescribed a in-house blood test with reveal how efficient the dose is and whether to change amounts. 3-6 monthly check ups are normally sufficient after that. Remember the dogs weight should decrease well over this period due to the bodies metabolic rate increasing so re-testing is vital to make sure you don't accidentally over-dose.
Treatment Options:
If your dog is diagnosed with hypothyroidism conventional synthetic thyroid replacement is available as a tablet or liquid. The liquid is to be stored in the fridge and given once per day. Most likely to be Leventa: Levothyroxine sodium (as multihydrate) 1mg (equivalent to 0.97 mg levothyroxine). The tablets are to be given twice a day on a strict 12 hour interval and has to be on an empty stomach. If you travel alot and like to sled on evenings out the tablets are the best option. These are most likely to be Thyforon flavoured 400 microgram tablet contains 400 microgram levothyroxine sodium per tablet equivalent to 389 microgram levothyroxine. A Large Malamute of 59 kgs (only fed a tiny 400g of raw food per day!) would be on 1.5 tablets twice a day now down to 43 kgs our dose is 1 and 1/4 tablets.
Denali had been diagnosed in November 2018 after a few months of showing these signs that gradually have increased since May 2018. Treatment was quickly diagnosed and medication prescribed straight away. He was not used in our breeding program.
Cushing's Disease
Cushing’s disease is a serious condition found normally in middle aged and elderly dogs and not uncommon in Alaskan Malamutes. The most obvious sign is usually hair loss where patches of skin are eventually exposed. However, Cushing’s can be misleading.. Typically, a combination of symptoms will be seen, some of which also occur naturally with aging. Its is often seen as 'old dog' syndrome as we presume the dog is simply naturally aging. Cushing’s disease is due to an excess production of hormone from the outer part of the adrenal gland. It is usually caused by a tumor in the adrenal gland (located on the top of the kidney) or, more commonly, by a benign tumor located on the pituitary gland (which stimulates the adrenals).
The pituitary gland is the “boss”, so to speak, of the endocrine system. Its main responsibility is for producing hormones which control the various other endocrine glands in the body. The growth of a tumor in either gland causes an over-production of corticosteroid hormones which, when released into the system, produce symptoms such as hair loss. (The over-use of steroid drugs can have the same effect.) excessive stimulation of the adrenal glands by the pituitary gland, usually as a consequence of a pituitary tumor (pituitary origin)
the unregulated production of cortisol by the adrenal glands (adrenal origin) occasionally, administration of steroid-containing medications may result in the development of Cushing's disease (iatrogenic origin)
Cushing's symptoms:
The sign's often seen first are, excessive thirst without extra exercise, pot belly appearance/dipping back, excessive urinating (from the high intake of fluid) so they may struggle to hold their bladder over night. It is easy to tell the dog off here thinking they are becoming lazy. Under coat doesn't grow back after moulting and bald patches increase including a rat tail look. Other symptoms (in both dogs and horses) can include sweating, weight loss (in spite of increased appetite), listlessness, increased intake of water, and anemia (look for pail gums). However, the most recognisable symptom is hair loss and poor skin quality. Whatever you do never withhold water from them no matter how much they drink. The kidneys are over working and needing the fluid to keep functioning even though it is faster than normal they still need the fluid passing through.
Testing:
Here's the complicated part. Its involves lots of tests and evaluation to conclude if they have the disease. From experience ,I have had all these tests come back and many results appeared normal yet she still had the disease (concluded by two surgeons in two surgeries) Thyroid glands should be tested on full blood analysis (see below on Hypothyroidism) to rule this out.
Screening & Analysis:
There are characteristic laboratory changes related to Cushing's disease, which may be noted on evaluation of your pet's blood and urine samples. Not only will the documentation of such changes help in the diagnosis of Cushing's disease, these laboratory tests may also uncover other conditions related or unrelated to excessive cortisol production.
Common initial screening tests may be performed in your veterinary surgery using blood or urine samples. They include:
Complete blood count (CBC)
The red blood cell, white blood cell, and platelet components in a blood sample are evaluated. Often an increase in the number of white blood cells (neutrophils and monocytes) is noted with Cushing's disease. This increase is usually related directly to the effects of excessive cortisol, but occasionally an increase in these cells may indicate underlying inflammation or infection.
Serum biochemistry profile is more thorougher analysing of their blood
Serum (the liquid portion of blood) contains enzymes, proteins, lipids (fats), glucose (sugar) and metabolites. These serum components are derived from different organs such as the liver, kidney and pancreas, and can give you an indication of the function of these organs. Specific changes in the serum biochemistry profile may support the diagnosis of Cushing's disease and may give us an indication of overall their organ function. (I had this done before and after surgery, both results negative for Cushing's)
Typical findings with Cushing's disease may include increases in blood glucose and in liver related enzymes. A certain liver enzyme (S-ALP, steroid alkaline phosphatase), increases directly in response to increased blood cortisol levels. Increases in blood lipid and cholesterol are also often noted.
Because dogs with Cushing's disease typically drink large amounts of water, the urine produced is very dilute. A special instrument called a refractometer assesses urine concentration. Infection of the bladder (cystitis) is a common finding in Cushing's disease. By looking at the cells voided into the urine, and by sending a urine sample for bacterial culture (checking for the growth of bacteria), the presence of infection can be assessed. Some dogs with Cushing's disease also have concurrent diabetes. The presence of diabetes may be detected by glucose in the urine as well as by an increased concentration of glucose in the serum biochemistry profile.
Urine cortisol/creatinine ratio:
The amount of cortisol being lost in the urine is increased with Cushing's disease. This cortisol can be measured and compared to the amount of creatinine, a normally occurring urinary component that is produced at a constant rate. The urine cortisol/creatinine ratio is usually elevated with Cushing's disease. However, stress and other illnesses may also increase this ratio. While an increased urine cortisol/creatinine ratio is suggestive of Cushing's disease, it cannot absolutely confirm the diagnosis, more extensive diagnostic tests will be required to confirm the diagnosis of Cushing's disease.
If a large number of changes characteristic of Cushing's disease are found with these initial screening tests, then more extensive diagnostic tests will be required to confirm the diagnosis of Cushing's disease and to establish the type of Cushing's disease that your pet has. To reiterate, it is very important to know the type of disease so that an effective treatment plan can be formulated and the possible outcomes can be predicted. So youv'e had the blood screening and urine screening and still more tests will be needed.....
Extensive/diagnostic tests:
The more extensive tests may include an ACTH stimulation test, dexamethasone suppression tests, and/or endogenous ACTH concentrations.
How does the ACTH (Adrenocorticotropic Hormone) stimulation test work?
ACTH is a hormone naturally produced by the pituitary gland (located in the brain). The purpose of ACTH is to tell the adrenal glands when and how much cortisol to produce. As the blood level of cortisol increases, it causes the pituitary gland to decrease its production of ACTH, which results in a lowering of the cortisol level. The ACTH simulation test mimics this natural stimulatory pathway and demonstrates the capacity of the pet's adrenal glands to produce cortisol in response to an injection of synthetic ACTH.
This test requires two blood samples. The first blood sample is taken, then an injection of synthetic ACTH is given, and the second blood sample is taken 2 hours following the injection. When the levels of cortisol in the two samples are compared, they may show a normal response, an exaggerated response or very little response.
What do we expect to see if the patient has Cushing's disease?
With pituitary origin Cushing's disease, we normally see a markedly increased cortisol level following the synthetic ACTH injection. This exaggerated response occurs because the adrenal glands have been over-stimulated with naturally occurring ACTH secreted by the diseased pituitary (pituitary origin Cushing's disease). These adrenal glands are therefore highly responsive to stimulation by the synthetic ACTH. With adrenal origin Cushing's disease, an exaggerated cortisol level after the synthetic ACTH injection may also be seen.
"Since the ACTH stimulation test may be positive in both types of Cushing's disease..."
Since the ACTH stimulation test may be positive in both types of Cushing's disease, the test confirms that your pet has Cushing's disease, but not the type or cause of Cushing's disease. Some dogs with Cushing's disease of either pituitary or adrenal origin do not respond to the ACTH stimulation test and so additional diagnostic testing is required to confirm a diagnosis.
Dogs that are showing signs of Cushing's disease due to the effects of corticosteroid containing medications (called iatrogenic Cushing's) will show either a very mild or no response to synthetic ACTH injection. This type of muted response, in conjunction with a history of medication use, is confirmatory for iatrogenic Cushing's syndrome.
Another use for the ACTH stimulation test is to monitor your dog's response to therapy for Cushing's disease. Periodic ACTH stimulation tests during the initiation and maintenance phases of treatment will be required. As your dog responds to treatment, the increases in cortisol will become less exaggerated in response to injection of synthetic ACTH.
How does the Low-dose Dexamethasone Suppression Test work?
ACTH is secreted by the pituitary gland and stimulates the adrenal glands to produce or secrete cortisol. As the blood cortisol level increases, it causes the pituitary gland to lower its production of ACTH, which results in a lowering of the blood cortisol level - a controlling mechanism called a negative feedback loop. This feedback loop is capable of causing rapid changes in blood cortisol levels in response to the body's needs. Mimicking what happens naturally, when healthy dogs are given an injection of synthetic cortisol (dexamethasone), the production of ACTH is suppressed, as is the production of cortisol. The Low Dose Dexamethasone Suppression Test requires three blood samples. The first sample is taken prior to dexamethasone injection, and the second and third samples are taken 4 and 8 hours after injection.
What do we expect to see if the patient has Cushing's Disease?
With Cushing's disease, this negative feedback loop is diminished or lost because cortisol is high all the time. If the patient has pituitary origin Cushing's disease, the negative feedback mechanism is only diminished, so we expect to see a small decrease in the 4 or 8-hour cortisol levels from the pre-injection sample. With adrenal origin Cushing's disease, the negative feedback loop is lost, so we do not see any reduction in blood cortisol concentrations at either the 4 or 8-hour cortisol levels.
"In most instances, the low dose dexamethasone suppression test will allow the diagnosis of Cushing's disease to be made..."
In most instances, the low dose dexamethasone suppression test will allow the diagnosis of Cushing's disease to be made, and will indicate of the type of Cushing's disease (pituitary versus adrenal origin) that is present.
How does the High-dose Dexamethasone Suppression Test work?
This test is performed works on the same principle as the low dose test, and is used when no reductions in cortisol levels are seen on the low dose test. The purpose is to determine definitively which type of Cushing's disease we are dealing with. In rare instances with pituitary origin Cushing's disease, the negative feedback loop is more resistant to the effects of dexamethasone. A higher dosage of this synthetic cortisol may be required to overcome this resistance and demonstrate the negative feedback mechanism. If we get a reduction in cortisol levels at either 4 and/or 8 hours after the higher dose of dexamethasone, then we have diagnosed pituitary origin Cushing's disease. If the levels don't budge from the high values of the pre-injection sample, then the diagnosis is adrenal origin Cushing's disease.
Endogenous ACTH Concentrations:
Endogenous (originating from within the body) ACTH concentration can be measured in blood samples, as a screening test for the diagnosis of Cushing's disease. With pituitary origin Cushing's disease an increased concentration of endogenous ACTH will be found in the blood. With adrenal origin Cushing's disease, or with iatrogenic Cushing's disease (caused by cortisol containing medications), the amount of endogenous ACTH in the blood will be decreased. Unfortunately, the concentrations of ACTH found in blood with these different types of Cushing's disease may overlap and not allow a clear differentiation of the cause of the disease.
In most instances, a combination of these tests either will allow your vet to make a diagnosis of Cushing's disease, or will allow them to rule out the disease in your dog. Occasionally, ancillary testing such as abdominal radiographs (x-rays) or ultrasound may be required to determine whether an adrenal tumor is present.
In very rare instances, referral to a veterinary facility with MRI (magnetic resonance imaging) or CT (computed tomography) imaging may be needed to rule out or demonstrate the presence of pituitary or adrenal tumors.
After all the tests above and clear X-rays and ultra sound, I had full exploratory surgery to find out what was causing Kinley's symptoms after all tests above proved 'inconclusive' we discovered a large tumour on her adrenalin gland of which it was removed. All seemed well from 2 days later, however all the symptoms returned after 2 weeks. We were referred to Swanbridge surgery (the best in the area) and after full blood chemistry she was still showing all healthy functioning organs and we presumed the tumour had regrown or she also had the pituitary gland tumour too. I choose the gamble of daily steroid tablets instead of MRI and more surgery and she lived another 18 months to 13 years and 8 months old. Kinley was not used in our breeding program and stayed very happy on a daily tablet with short walks and good healthy balanced diet. It was only when a retest on bloods after struggling to get up we discovered her liver and kidneys were showing signs of failure with an internal bleed and it was kinder to let her go whilst she wasn't in pain.
