Why Are My Dog Or Cat’s Blood CK Levels High Or Low?
Creatine Kinase
Ron Hines DVM PhD
Your Pet’s Creatine Kinase Level Also Known As CPK, CK, Creatine Phosphokinase, Phosphocreatine Kinase
Creatine and Creatinine Are Not The Same Thing
Creatine kinase enzyme is found in many of your pet’s tissues; and some is always present free in its blood stream. But veterinarians tend to associate situations when the blood level of CK is abnormally high with muscle damage somewhere in your pet’s body.
Creatinine phosphokinase (CK) is not stable in your pet’s blood stream, so when its level is high, veterinarians know that the muscle damage was recent – or is still in progress. That is why we call it a “leakage enzyme”. Your pet’s CK levels will be part of its standard blood chemistry panel.
Health Issues That Might Cause Your Pet’s CK Levels To Be High:
In cats, the most common cause of a high CK reading, when other lab values are normal or unchanged from the prior reading and there is no history of trauma, is forcible restraint and/or difficulties hitting (entering) a vein to withdraw a blood sample for analysis. As you know, cats can be quite uncooperative patients.
Other Causes:
Muscle Damage
Over-exertion and stressful exercise can cause muscle damage that cause a rise in CK levels. For instance, beagle dogs that completed a 60-minute race (at a leisurely jogging speed of 5.6 mph) sustain a moderate CK increase of 2.5-fold (80 vs 240 u/L – still in the normal range) (read here) ; whereas CK blood levels reached over 4,000 u/l after sled dogs ran 320 km in an Alaskan endurance race.
The muscle bruising that results from car accidents, dog fights, electrical and other burns as well as severe trauma of any kind will also cause high CK levels. Sight hounds are particularly prone to muscle cramps after exertion (e.g. azoturia in sight hounds aka “greyhound cramping” aka exertional rhabdomyolysis). That problem is often the cause of high CK levels in those breeds.
Injections of irritating (painful) medications that are given intramuscularly (such as the melarsomine used to treat heartworms (read here) or tetracycline antibiotic) An antibiotic, chloramphenicol, can also cause muscle damage that raise CK levels (read here) or any medication injected into your pet’s muscles in large volumes can also raises its CK levels.
The seizures of epilepsy or the cramping associated with heat stroke or high fevers can be the cause of high CK levels. So can the seizures that occur subsequent to certain poisons (insecticides, strychnine, tetanus toxins, Easter lilies etc.) can be responsible for high CK levels. So can the ingestion of xylitol sugar substitute.
The muscle damage caused by large abscesses, such as those resulting from cat or dog fights can also be responsible for elevated CK. So can the muscle damage caused by snakebite (read here), the stings of other venomous creatures (read here) or a lack of sufficient vitamin E/ and selenium in the pet’s diet.
Heart Damage
The damaged to heart muscle that occurs in acute cardiomyopathy in dogs or in cats can also cause CK levels to be high since heart muscle is also high in CK. In addition, pets with sudden heart disease often generate blood clots (thromboembolisms, saddle thrombi in cats) that deprive muscles throughout the body of oxygen, probably liberating additional CK from that source as well. (read here)
Overdoses of medications that cause the heart to beat too forcefully can also result in abnormally high CK levels (read here)
In some situations, it is difficult to decide if elevated CK levels are due to heart muscle damage, other muscle damage, or both. The high CK levels that are sometimes seen in gastric bloat – a situation where heart muscle, diaphragmatic muscle and the muscles of the gastrointestinal tract could all be the source – is one of those situations is one of those situations. (read here & here)
Autoimmune Disease
Muscle inflammation due to many autoimmune diseases (Masticatory myositis, Eosinophilic Myositis, Polymyositis, Myositis Ossificans, Fibrotic myopathy, etc.) can be the cause of high CK blood levels – particularly early in the disease or during flareups. These troubling problems are most common in larger breeds – particularly German shepherd dogs; but Cavalier King Charles spaniels also seem predisposed to the problem.
Excess corticosteroid levels in a pet’s circulation can also be a cause of high CK values. That can be due to Cushing’s disease or prolonged medication with corticosteroid medications (prednisone, dexamethasone, etc.). Cushing’s disease is most commonly seen in dogs, but it can occur in cats as well. When CK levels rise in the disease, it is probably related to the muscle wasting (atrophy, shrinkage) that is evident in many of these pets.
Infections
Infection with parasites that encyst or migrate through the muscles of the body, such as trichinosis or toxoplasmosis, caused by eating the uncooked meat of infected prey animals or exposure to cat feces can also cause elevated CK levels (infectious polymyositis).
Other infections that have result in high CK levels are neospora, hepatozoon, babesia, leishmania, trypanosomes, sarcocystis, leptospirosis, rocky mountain spotted fever, ehrlichiosis and even parvovirus infections (also read here) and FIP in cats.
Your Dog Or Cat’s Genetics
Certain rare, inherited, genetically based, diseases that cause muscle destruction can also be the cause of high CK levels (primary metabolic myopathies, myotonia congenita, etc.). These have been seen in Clumber and Sussex spaniels, Old English sheepdogs, Jack Russell terriers and Wire-haired pointing griffons.
Inherited Myopathy of Great Danes. (read here) Distal Myopathy of Rottweiler puppies and Centronuclear Hereditary or episodic Myopathy of Labrador Retrievers are three other causes that occasionally elevate CK. Similar problems occasionally occur in cats (Nemaline Myopathy). Muscular Dystrophies of Golden retrievers, German Shorthair pointers and Rottweilers, Devon Rex and Sphinx cats are more of these genetically based disease that can be the cause of high CK levels.
A particular form of muscle pathology occasionally affects the muscles of the esophagus of dogs. This leads to difficulty swallowing and regurgitation (megaesophagus). Among their other symptoms, It is common for those pets to have high blood CK values.
Cats that have had a bad liver reaction to diazepam therapy occasionally report elevated CK levels – probably as a result of their elevated blood bilirubin levels.
Muscle Atrophy
Pets that have been unable to rise for considerable periods of time (prolonged recumbency) can have increased CK levels. Veterinarians believe that that could be due to muscle wasting (disuse atrophy) or poor muscle circulation when animals are confined to a single position.
For unknown reasons, CK has also been found to be high in some cases of prostate disease in dogs and in cats that refuse to eat for a variety of reasons and have gone on to develop hepatic lipidosis. Those cats are generally quite depressed and immobile – but we do not know if muscle atrophy is the underlying cause of their CK rise.
Hypothyroidism
Hypothyroidism (an under active thyroid gland) in dogs can also cause muscle atrophy. Hypothyroidism is very rare in cats. But when it does occur in either species, CK levels can be increased as a result of the muscle damage.
Cats with thyroid problems can also have high CK values. However, in the case of cats, it is usually due to an overactive not an under-active thyroid gland (hyperthyroidism).
Low Blood Potassium
CK levels can increase when blood potassium levels are too low (=hypokalemia) which cause CK to be released from damaged muscle cells. This occurs occasionally in Burmese cat kittens. (episodic hypokalemia in Burmese kittens) or in cats fed bizarre diets (read here)
CK has also been known to rise in situations where blood potassium levels were too high (periodic paralysis of American Pit Bull Terriers).
Your Pet’s Age And Breed Are Also Factors
CK levels are slightly higher in puppies than adult dogs (read here & here) and often slightly higher in smaller breeds.
Recent Surgery
Recent surgery can also result in high CK levels. We do not know if that is because of muscles affected during surgery, the positional restraint required during surgery, the effect of anesthetics on the heart or a combination of all these thing.
Sampling Problems
As I mentioned earlier, a hemolyzed blood sample or a misdirected or poorly placed blood collection needle will falsely raise CK levels; so can high blood bilirubin levels. I do not know if the elevation is real or if the Hemolyzed blood causes the lab’s analysis equipment to falsely record a high CK reading.
Complementary Tests:
CBC and blood chemistry values values that include AST, ALT and Free T4, a muscle biopsy, TSH test, 2M Antibody Blood Test for myositis, radiography and ultrasound, pre- and post-exercise blood lactate levels, PCR tests for infectious agents such as toxoplasmosis, ProBNP (or other natriuretic peptide test, e.g. Antech Cardio-BNP) for acute heart disease (cardiomyopathy), free myoglobin, blood potassium level.
Frequently, these and other test that your veterinarian ordered, the pet’s history and the veterinarian’s physical examination will point to the source and cause of your pet’s abnormally high CK level. But when your veterinarian is still uncertain, there is another option: The total amount of CK in your pet’s blood is composed of a number slightly different molecules (isoenzymes, macroenzymes) depending on where in the body they originated. Physicians have long used tests that assay the amount of each type of CK isoenzyme to help determine where in the body the problem is originating (skeletal muscle, heart muscle or some other source). The normal levels for each of CK’s isoenzymes have been determined for dogs and cats. (read here) This test can be ordered for dogs and cats. The test is available through Antech Labs/VCA or at Cornell (# S7592 CPK isoenzymes).
Are There Situations When My Pet’s CK Level Might Be Too Low?
Some time ago, a study was performed to see if a deficiency in the heart isoenzyme of CK (CK MB) might be responsible or involved in the sudden heart failure seen in Doberman pinschers (acute cardiomyopathy). The scientists reported that that isoenzyme was indeed low in dogs experiencing that form of heart failure. (read here)
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