What is up with lab values and Greyhounds?

Like I have said previously, I am a nurse and a researcher.  I like to figure out why things do what they do.  When I got Jethro I was amazed by the difference in laboratory (lab) valves in greyhounds and non-greyhound dogs. 

I searched the Internet looking for studies to show why the difference existed.  I recently found a literature review that does a good job with this but it is very science driven and not accessible to most greyhound owners.

Due to the numerous differences in the greyhound and non-greyhound labs, I am going to do a lab series on the blog looking into the different abnormalities. 

Today I am going to dive into the red blood cell values of the greyhound.

First, let’s talk about the red blood cell (RBC) or erythrocyte.  The RCB is the most common cell in the body.  It is disc-like cell that looks like a jelly doughnut with the jelly squeezed out.  RBCs are important because they house hemoglobin (Hgb), which carries oxygen to the body.  Hemoglobin is a protein within the RBC.  The hemoglobin molecule accepts oxygen from the lungs and carries it throughout the body, bringing nutrient rich blood to our organs.  The hematocrit (Hct) is a measurement of the volume of RBCs in the body—this value is needed to get an accurate hemoglobin measurement.  There are two additional RBC values that are different in non-greyhounds and greyhounds.  They are the Mean corpuscular volume (MCV) and the Mean corpuscular hemoglobin (MCH).  The MCV measures the size of the RBC and the MCH measures the color of the cell. 

Adult blood smear by scooterdmu

That is very basic RBC science.  Let’s now talk about the abnormalities in the greyhound’s valves and what they could mean.  Greyhounds have higher RBC counts.  The higher RBC cases an increase in Hgb concentrations and Hct.  These higher values allow for oxygen to reached stressed muscle cells quicker.  Initially selective breeding, training, and racing were deemed the cause of these changes; however, there are additional studies looking at other possible causes.

An argument against training and racing as a cause for these changes was completed looking at Hemoglobin and Hematocrit values in 5-6 month greyhounds and 9-10 month greyhounds.  This study showed that at 5-6 month the greyhound Hbg and Hct were not much different from non-greyhound dogs and much lower than the greyhounds in the 9-10 months group.  They then looked at the 9-10 month group vs. 12-13 month greyhounds. The differences in Hgb and Hct at 9-10 months vs. 12-13 months were statically insignificant, suggesting that at 9-10 months greyhounds have adult lab valves.

Sashi at 6 months by Cindy Frezon

On the other hand, there are studies to suggest that selective breeding is the cause for these changes.  The hemoglobin molecule in the greyhound has a higher affinity for binding to oxygen.  These studies also found unique amino acids mutations on the Hgb to allow for enhanced oxygen-binding capacity. 

You may be asking, how would breeders know this and know which greyhounds to breed?  Most likely the early dogmen breed greyhounds to be hearty, fast, and recovery quickly to hunt again whenever new quarry was seen.  This need for fast recovery influenced breeding practices, meaning that these hounds that were able to recover quickly again had higher RBC counts and more efficient hemoglobin.  These factors are still considered in breeding programs today – talk to any dogman or woman and they will tell you that test-mating or selecting a breeding pair is a time-consuming task with lots of consideration.  

Darla at the Christmas Cup 2015 by Cindy Frezon

Another interesting fact about greyhound RBC valves is the lives of their RBCs.  In non-greyhound dogs, the life of the RBC is around 100 days.  In Greyhounds the life of the RBC is about 50 days.  There are multiple theories about why this is.  Some believe that greyhounds trap their RBCs in their spleen; however, there is no proof to this theory.  Another theory is that the greyhound’s immune system selectively rids its self of older cells, but again this needs to be studied further for more clarity. 

Greyhound’s blood counts also show elevated MCV or large RBCs.  This was thought to be related to elevated reticulocytes (immature RBCs) in the blood but that is not the case. The increased size is breed specific and most likely due to the higher hemoglobin content within the RBC.  This would allow for more oxygen to reach the muscles and allow for continued activity. 

I hope that after this review you have a better understand of the RBC and why it is different in the greyhound.  As I had said before greyhounds are special dogs that do special things.  I think it is fitting that their labs are special too!  Check in later this week for differences in WBCs and Platelets in greyhounds.

 
Feature Photo Credit: Cindy Frezon
Zaldívar-López, S., Marín, L. M., Iazbik, M. C., Westendorf-Stingle, N., Hensley, S., & Couto, C. G. (2011). Clinical pathology of Greyhounds and other sighthounds. Veterinary Clinical Pathology / American Society for Veterinary Clinical Pathology40(4), 10.1111/j.1939–165X.2011.00360.x. http://doi.org/10.1111/j.1939-165X.2011.00360.x

Dog digestion and feeding

Dog GI system

After writing my myths BUSTED post, I began thinking about how often I am asked about what I feed my greys. I felt that this topic is worth spending more time discussing.

 First let’s discuss the gut of a dog. All mammal digestion begins in the mouth. This is where we begin to break down the particles in our food to extract the important elements needed for sustained life. Most mammals produce amylase, an enzyme that breaks down carbohydrates, in their saliva. Amylase is not produced in a dog’s saliva.

We must remember that our sweet cuddly greyhounds are natural born predators that are more than able to crush through bone and muscle meat with ease. Carbs were not often on the menu.  Open up her mouth and check out those huge teeth!

After reading this about amylase I was confused as to how dogs break down kibble. Let’s dive into the dog’s GI tract to learn how this happens.

After your hound ravenously devours her food, she swallows it. The esophagus allows the passage of food from the mouth to the stomach. The esophagus is just a connection, nothing exciting happens here.

Then the food enters the stomach. Dogs have single chamber stomachs like humans. The stomach pH of a dog is about 2, which is the same acidity as lemon juice.  The strong gastric acid combined with the muscle strength of the stomach begins to break down food into absorbable molecules- but minimal absorption actually occurs in the stomach.

© Hill’s Pet Nutrition, Inc.
© Hill’s Pet Nutrition, Inc.

 

Once the food has been broken down by the gastric acid, the food enters the small intestine. Mammals have three parts that make up their small intestine: the duodenum, jejunum, and the ileum. The small intestine is a large organ and can be about two and half times the dogs total body length!

© Hill’s Pet Nutrition, Inc.

The duodenum is the smallest part of the small intestine but the most important. The duodenum connects the small intestine to the stomach. While food is in this section it is combined with enzymes from the gallbladder, pancreas, and liver. The duodenum is where amylase, lipase, and proteinase begin to break down carbohydrates, fats, and protein, creating the building block for life.  In the duodenum, kibble is broken down.

After the food is further broken down, it enters the jejunum. The jejunum is the longest section of the small intestine. The jejunum has a large surface area to allow for absorption of nutrients.

After the jejunum successfully absorbs all important nutrients from the food, the remaining intestinal contents are released into the ileum. The ileum connects the small intestine to the large intestine.

Once the intestinal contents reach the large intestine most nutrients have been absorbed and broken down. The job of the large intestine is to absorb water and create feces. The large intestine is critically important in the hydration status of the dog. Once most water is absorbed, the feces enters the anus and then rectum. Once in the rectum the dog will be able to expel its waste.

© Hill’s Pet Nutrition, Inc.

Dogs have quick digestive systems and depending on your fed, digestion can take them 6-12 hours per meal.

Feeding

 Now we have a basic understanding of how a dog’s gut works. Let’s talk about what to feed your greyhound.

 

When I first read that dogs do not have amylase in their mouth I felt that raw food was the only way to feed a dog.  Since learning more about dog digestion and monitoring my dogs on raw my opinion has somewhat changed.

I have three greyhounds. They were fed raw for about three years. I have followed both the BARF (bones and raw food) method and whole prey.  I feel that whole prey worked better for my dogs and aligned with my concerns regarding no amylase in dog saliva. I used multiple protein sources and felt very good about the diet they were receiving.





However, Jethro never thrived on raw. His coat was dull, thinning, and he was very skinny (even for a greyhound). I tried to increase his rations but he began to refuse to eat. After about 10-14 days of him barely touching his food I knew something had to change.

 


I started him back on a very high quality kibble. Seriously, his eyes about popped out of his head when he saw a bowl full of kibble. I realized that raw was not for him. He did not do well on it.

 

I do still give him raw bones to help with tarter build up.


 

After my experience with Jethro I wanted to learn why greyhound trainers would feed kibble and raw together. After all, this goes completely against everything I had learned about the horrors of feeding raw and kibble at the same time.

 

I researched this more, reading accounts on what Henry VIII fed his hunting greyhounds, what open field coursing greyhounds are fed, and what top US racing greyhounds eat.  A theory for feeding carbohydrates continued to surface throughout my research; it stated that greyhounds need a lot of ready-to-use energy for sprinting. The carbohydrates in kibble, pasta, and rice that trainers often feed help with this. The balance between the raw protein source and the kibble create a balanced diet for quick acceleration from an energy standpoint.

I encourage greyhound owners to try different diets and see what their hound thrives on. There are easy options for raw and kibble. The most important thing to remember when choosing a food it how you dog looks, feels, and preforms on that diet.  After all a dog’s diet is not a bragging point between humans but an elemental point of existence for your hound.

The illustrations in this post are reprinted with permission by the copyright owner, Hill’s Pet Nutrition, from the Atlas of Veterinary Clinical Anatomy. These illustrations should not be downloaded, printed or copied except for personal, non-commercial use.

My Greyhound’s leg is broken, now what?

About 10 months ago Jethro broke his leg lure coursing.  It was a beautiful December day and we were in Moreland, Ga.  Jethro ran his first course and looked very strong and was having a blast.  I decided to run him in his second course because he looked so good and was having such a nice day.  During the end of the second course, he came up lame.  His left wrist was extremely swollen and he was not bearing weight.  I was very concerned by to looks of the injury but tried to tell myself it was OK.  I examed his wrist and felt crepitus (boney cracking) and my fears were certain he had broken a bone in his wrist. 

 Photo credit: Cindy Frezon

 

I called my vet and told him that I thought the leg was broken.  He advised me to stabilize the leg and come in the next morning. 

Overnight the swelling had increased and was causing Jethro a lot of pain.  We went to the vet and had x-ray.  His stopper bone was broken.  We discussed an experimental surgical technique to stabilize the bone with a small screw or splinting and stabilizing the joint for 8-12 weeks. 

I decided to splint and stabilize the joint.

Jethro is a very headstrong dog.  He had other plans than lying around the house for 8 weeks.  He wanted to be running and playing with his pack.  Keeping Jethro calm was incredibly hard and we ended up have to give him trazodone to keep him calm as he busted out of two crates and wrecked multiple x-pens.

While he was in the splint he developed a pressure ulcer on his elbow.  I was at my tipping point!

The pressure ulcer was extremely painful for Jethro.  I called the vet thinking we were going to have to begin antibiotics ( I am a nurse after all) but dogs are amazing creatures and their infection threshold is much stronger than humans.

I read all I could about pressure ulcers in dogs and found this article about a “doughnut dressing”.  This was a dressing shaped like a doughnut causing the pressure of the splint to be distrusted evenly around the wound allowing no pressure to be on the ulcer.  After a week of using the doughnut dressing the ulcer was healing and you could no longer see bone.

Jethro was such a good patient and supper lucky to have two nurses taking care of him.

After nine weeks in a splint, Jethro was free!  Clint and I were pushing getting the splint of ASAP due to the pressure ulcer.  I was so glad to hear the bone had nice regrowth and looked stable.  

After the splint was off Jethro still walked like he was splinted.  It took him about a week to resume a somewhat normal gait. 

After the splint was off the hard part began.  We had to rehab a dog.  He had lost a lot of muscle and was was stiff from the splint.  We began doing stretching and strength training.  I knew that the rehab was key in correcting Jethro’s gait. 

This video shows some of the rehab techniques I used to help Jethro to regain strength and balance in his leg. 

Jethro had a great outcome due to a great vet, serious human support, and his will to be able to run again.  If you are ever in the situation, I hope this post helps you and your hound. 

 

Photo credit: Cindy Frezon