In my early days of Greyhound medicine, a high proportion of the consults I received were about “normal Greyhounds with abnormalities on physical exam or lab reports”. As it happens, most of these issues were sighthound idiosyncrasies. This section answers commonly asked questions.
Greyhounds and several other sighthound breeds have hematology (blood cells) and blood chemistry values different from those in most dog breeds. For example, their red blood cell counts are higher, and their platelet and white blood cell counts lower. Some of their kidney values (mainly creatinine and SDMA) are also high. IDEXX laboratories in the US now uses “Greyhound specific” reference intervals (RIs) when reporting values. As an example, below is a graphic of the hematocrit (HCT) or red cell mass in Greyhounds (box) compared with the normal values for dogs (dotted blue box).
Greyhounds have creatinine and SDMA concentrations that are typically higher than those in other dogs (higher than the RIs listed for other breeds of dogs); in addition, some Greyhounds have high BUN (blood urea nitrogen). If the urine concentration is normal, the high creatinine/SDMA/BUN concentrations are not indicative of kidney failure. Chronic kidney disease (CKD), a common disorder in senior dogs of most breeds, is quite uncommon in Greyhounds. The graph below shows creatinine values for Greyhounds and the RIs for dogs.
Greyhounds and several other sighthound breeds are known to have “normal” or physiologic flow murmurs. The main pump in the heart (left ventricle), is very large, and it pumps blood at higher velocity, so it swirls creating a murmur (abnormal heart sound). These murmurs are mild in nature (grade 1-2 out of 6) and are heard best over the left base of the heart (high in the left armpit) with the bell of the stethoscope. Thoracic radiographs (X-rays) and/or echocardiography (ultrasound) will help determine the actual status of the heart. Most Greyhounds have bigger hearts on radiographs, and thicker heart muscle on echocardiograms. Heart disease is also uncommon in Greyhounds, but prevalent in other sighthound breeds (e.g.; Deerhound). Below is a left lateral radiograph (X-ray) from a Greyhound (left) and a Boxer (right). The Greyhound heart is much larger.
Most modern-day anesthetics are perfectly safe in sighthounds. The bad reputation about anesthesia in Greyhounds started in the 80s, when using short- and ultra-short acting barbiturates, that are cleared very slowly from their system; these drugs are no longer used in clinical practice. However, most Greyhounds metabolize sedatives and anesthetics a bit different from other dogs, and dosages may need to be adjusted accordingly. Please consult with your veterinarian about dosages. In addition, prolonged anesthesia (>90 minutes) can result in release of potassium from the muscles into the blood, where, if high enough concentrations are achieved, can cause severe cardiac bradyarrhythmias (slowing of the heart rate) and even death.
Although malignant hyperthermia can occur, it is extremely rare. In most cases of anesthesia- or surgery-related hyperthermia, nervous Greyhounds start shivering and shaking prior to being anesthetized, and thus generate heat from muscle contraction. Your vet will advise you on how to sedate your hound either at home or as soon as they arrive at their office, if he/she is the nervous type.
These days, TBDs are extremely rare in Greyhounds. In Ohio, the prevalence of TBDs is <1%; in the 80s, as many as 70% of Greyhounds were positive for Ehrlichia canis (EC) and/or Babesia canis (BC) due to poor tick control. In an unpublished study conducted in a West Virginia racetrack, we found no dogs positive for the common TBDs. PLEASE REMEMBER: a positive test for TBDs does not mean that your dog is sick because of that particular organism, since antibodies against the bug can persist for months to years. Your vet can test your dog with in-office kits (e.g.; SNAP 4DX PLUS®).
Most every normal Greyhound has low thyroid values. Most vets measure blood total T4 (TT4), which in non-Greyhound dogs should be in the 1-4 µg/dL (or 15-50 nmol/L); in Greyhounds, Salukis, and most other sighthound breeds, most normal dogs have values <1.5 µg/dL (or <15 nmol/L). In other words, a low thyroid “level” is ABSOLUTELY NORMAL in a Greyhound! Confirming a diagnosis of hypothyroidism usually requires measuring thyroid stimulating hormone (TSH) levels in a reference lab. Please do not give them “thyroid pills” unless your vet has documented hypothyroidism by other means.
There are numerous treatment options for dogs (and Greyhounds) with OSA. The standard of care is limb amputation followed by chemotherapy (we use 6 doses of carboplatin). Dogs treated by amputation alone live 3-4 months, whereas dogs treated by amputation and chemotherapy live 14-18 months. Most Greyhounds undergoing chemotherapy DO NOT HAVE ADVERSE EFFECTS.
Up to 35% of Greyhounds can bleed excessively after routine surgery. Bleeding usually starts at the site of the surgery, but it may become generalized. Most dogs have normal results of clotting tests during the bleeding episodes. Currently, there are no tests that can predict the probability of bleeding.
The bleeding is likely due to hyperfibrinolysis, where the “clot busting” system works overtime. In most dogs, administration of aminocaproic or tranexamic acid prevents, minimizes, or causes improvement in the bleeding. Please consult with your vet about using one of these drugs if your hound will have surgery.
Recently, Washington State University discovered the genes associated with this issue in Deerhounds, and developed a genetic test (DEPOHGEN). As of now, this test has not been validated in other sighthound breeds.
