How are Erythrocyte different in animals

Firstly let's know what's erythrocyte: 
Any of the oval or disc-shaped cells that circulate in the blood of vertebrate animals, contain hemoglobin,and give blood its red color. The hemoglobin in red blood cells binds to oxygen for transport and delivery to body tissues, and it transports carbon dioxide, excreted as a metabolic waste product, out of the tissues. The red blood cells of mammals have no nucleus, while those of other vertebrates do contain nuclei. Red blood cells are formed in the bone marrow called  erythrocyte.
                            Erythrocyte 

How is a red blood cell adapted for its function

The shape of it is biconcave (and like a flattened disc). This increases surface area over volume.It has no nucleus, so that there is more space for more haemoglobin to be packed.It contains haemoglobin, which is a molecule which binds reversibly to oxygen.It is flexible and elastic - so that it can squeeze through the capillaries.Thin wall: for easy diffusion of Oxygen and Carbon dioxide in and out of the cells.Thin cell: providing a short distance for diffusion and increasing efficiency.


Erythrocyte in different  animals
Dog: Cells are large (7microns),uniform in size and have central pallor (biconcave disc).

dog  Erythrocyte
Cat: Cells average 6 microns in diameter , only very slight central pallor , slight anisocyte (variation in size of RBC) . Up to 1 % of the cells may contain Howell-jolly bodies(nuclear remnants ) .
                                      Howell-jolly bodies 
Cow: Average diameter is 6 microns . Red cells may appear flat disc with little or no central depression (no central pallor) anisocytosis is common.
Sheep: Average diameter 4.5 microns ,flat disc ,with little central depression
Goat: Erythrocyte are the smallest 4 microns and most variables in shape .Spindle,rod, or sphere-shape red cells may be observed (normal pokilocytosis)
Camel: Erythrocytes normal elliptical in shape and lake of cental depression .
                                         camel erythrocyte
Horse: Erythrocyte have rouleaux formation ,Average diameter 5.7 microns ,uniform in size no central pallor .

                                         rouleaux formation 
Poultry: Mature erythrocyte is oval cell with an oval central nucleus .
                                          Avian erythrocyte 

Life Span

The life span of the erythrocyte varies from 70-160 days in domestic species although the life span is often shorter in juvenile animals (e.g. calves and lambs) compared to adult animals. Erythrocytes in small animals have a shorter life span than in the larger domestic species
Life span (days)
Cat
Pig
Dog
Goat
Horse
Sheep
Cattle
70
85
120
125
145
150
160






   Transfused dog erythrocytes last around 21 days